HomeMy WebLinkAboutCoastal Zone Atlas of Washington Vol 6RECEIVED
AUG 80 197~
CITY OF RENTON
MAYOR'S OFF ICE
State of
Wlshington
Del2artment
of Emlogy
oasa __ one
VOLUME SIX
King County
July, 1979
Dixy Lee Ray, Gov.ernor
State of Washington
Wilbur Hallauer, Director
Department of Ecology
The preparation of this document was aided by the Washington State Department of Ecology through a federal grant from the Office of Coastal Zone Management under the National Oceanic
and Atmospheric Administration of the United States Department of Commerce, as authorized by the United States Coastal Zone Management Act of 1972 .
Publication No. DOE 77-21-6
Introduction
During the late J 960 's, a series o f conflicts over environ-
mental 'issues erupted in the State of Washington. Many of
the most ser ious related to the use an d abuse of the State's
invaluable water resources and adjacent shorelincs. The
threat of thermal and industrial waste pollution, the depletion
of fishcries, offshore oil drilling and o il spi lls , and the loss of
beaches to residential and commercial development all be-
came the focus of intense and often protracted controversies
involving a broad range of citizens, private interest groups,
and private and public o rgan izations. At first , controversies
centered o n particular projects and specific sites. Dut as the
number and variety of incidents increased, the need for a
more comprehensive approach to the protection and en -
hancement o f the environment became obvious.
In partial respon se to this need, the Legislature created the
Dcpartmcnt of Eco logy in 1970. This Department was cre-
ated for the express purpose of consolidating the State's new -
ly ap prec ia ted re sponsib il it ies for env ironmental regulation
int o a manageable entity.
Also in 1970, a citizen initiativ e was presented to the Leg-
islature requesting the estahlishment of a State-controlled
system of shorel ine protection with the limit of jurisdiction
be ing essen tially 500 feet from the subject water body. As is
their prerogative, the Legislature opted not to impl ement the
initiative and voted instead to authorize an alternative which
was known as the Shoreline Management Act of 1971. This
piece of legislation p rovided for loca l co ntrol (under State
guidelines) and a reduced jurisdictional area comprising 200
feet from subj ec t water bodies as well as wetlands associated
with such watcr bodies. The Leg islature f urthcr direc ted that
the vote rs of the State be given an opportunity to choose be -
tween the citizen initiative, thcir alternative measure , or no
form of s horeline management at t h e next general e lection.
In the November, 1972 general e lection , th e voters of the
State opted for the alternative measure voted by the Legisla-
ture. Thus, the Shoreline Management Act of 19 71 was rati-
ficd and emerged as pcrhaps thc most comprchcnsivc to ol for
shorcline managcment to be found in thc nation.
The Unit ed States Congress passed the Coastal Zone Man -
agement Act in 1972 as an expressio n of their int erest in
promot ing wise management of the nation's coastal resourc-
es . This Act provided in centiv es to the states to develop coas -
tal zone management programs of their ow n . The State of
Washington began the development of it s CZM program in
1974. The essence of th e program development eitort was a
belief that within existing State programs lay all the elements
n ecessary to w in program approva l. Proceeding on this as-
sumption, a two-year effort was begun to articulate a Stat e
CZM program which incorporated the Shoreline Manage -
ment Act, the State Environmental Policy Act , the Environ -
mcntal Coord inati on Proccdures Act, an d numerous other
pieces of legislation and programs from thc Department of
Ecology as well as many other State agencies.
The program developmen t effort culminated in June o f
1976 with formal approval of the Washington State Coastal
Zone Management Program by the Offi ce of Coastal Zone
Management of the National Oceanic and Atmospheric Ad -
ministration, Li .S. Department of Comme rce. Simultaneous
with program approval was thc award of a grant for program
administration under Section 306 of the Coastal Zone 'vlan-
agement Act. It is this and subsequent funding which sup-
ports production of th e Coastal Zone Atlas.
OVERVIEW OF COASTAL RESOURCES
The fifteen counties which con tain Washington's 2,337
miles of marine shorelin e constitute one of the richest re-
so urc e pools in the nation. The coastal counties contain on ly
29 percent of the State's land , but fully two thirds of its
3,570,000 residents. Nutrient-rich estuaries a nd streams not
only support local spo rt and commercial fisheri es but also
scrve as propaga ti on waters fo r salmon of central importance
to national and international fishcries. Dccp , sheltcred har-
bo rs contribute significantly to int ernatio nal trade as ports
for the ex port of grain a nd fores t products to Asian countries
and th e import of processed goods . With its position in t he
northw este rn corner of the contiguous states, the zone is a
key terminus for transportation and commerce with Alaska.
It s strategic location for national defense has made it the site
of several large military in sta llat ion s.
Basic Resources
The coastal zone consists o f two types of land formation:
glaciated regions in thc north, and coasta l plains to the south
and west. Thc northcrn arca, including Puget Sound, the
north shore of the Olympic Penin su la , and the Pacific Coast
south to the Quinault River, was scu lptured by glacial activi-
ty an d is characterized hy rugged mountains and glaciaJ val-
leys. The heaches are narrow an d rocky and are backed by
high forested bluffs. Rocky outcrops and islands are common
offs hore. Limited tloodplains and deltas assoc iated with the
largest rivers provide the only low tlatlands and are excellent
agricultural lands. Although a few fishing villages are located
along the northern coast of the Olympic Penin sula on the
Strait o f Juan de Fuca, t he State's northern Pacific Coast
proper is sparsely populated and remains largely unaltered.
There are no large estuaries, good harbors, or industrial s ites.
The so uthern part is a broad coastal plain with wide sandy
beaches, dunes, and extensive low lands . Sand for this region
originates locally and is also provided hy the northward litto-
ral drift of sediments al o ng the Pacific Coast. The extensive
elongated dunes have formed major estuaries at th e mouth s of
the Cheh alis and Willapa Rivers, which drain this area. The
dunes are the most attractive recreation a l beaches in the
State.
In terms of basic resources , the Washington coast may be
conveniently divided into two broad coastal areas: the Puget
Sound/San Juan Island/Strait of Juan de Fuca complex; and
the Pacific coastlinc including thc Columbia River , Grays
Harbor, and WiUapa Bay.
Puget Sound is a complex system of interconnected inlets,
bays, and channels with tidal sea water entering from thc
west and freshwater streams entering at many po ints through-
out the system. Most of the Sound was formed by glacial ac-
tion that terminated near Tenino in Thurston County.
Pugct Sound is a deep body of water with depths o f 100 to
600 feet found less than one mile offshore. Shoal areas are
virtually nonexistent and large tidetlats and marshland areas
are restricted to mouths of the major rivers: th e Skagit Day,
Padilla Bay, and Samish Bay flats in the north and the
N isqually River delta in the south are the mo st notable. Small
tideilats and marshes are found frequently in the numcrous
inlets in South Puget Sound and Hood Canal.
The shoreline resources of Puget Sound include few beach
a reas which are not covered at high tide . Bluffs ranging from
10 to 500 feet in height rim nearly the entire extent of the
Sound, making access to beach and intertidal areas difficult.
For this reason, the relatively few accreted beaches which ar e
not inundated at high tide are extremely valuable for public
recreation purposes. The ubiquitous bluffs a re also a ser ious
topographic constraint La develo pment , which has necessitat-
ed the filling of tidal estuarine and flatland areas for po rt and
industrial uses. The estuaries that remain largel y unaltcred
a re highly valued, in part becaus e of their increasing rarity.
Because o f their glacial till composition , the Puget Sound
bluffs and adjacent hillsides are susce ptible to fluvial and ma -
rine eros ion and can be serious slide hazards. Although the
Sound is protected from the direct influencc of Pacific Ocean
weather, storm conditions can create very turbulent and occa-
sionall y de st ructive wave action. Without an awaren ess of the
tremendous energy containcd in storm wavcs, the develop-
men t of sho reline resources can be hazardous and deleterious
to the characteristics which make Puget Sound heaches at -
tractive. Mil es o f phy sically unsuitabl e shorelines were
committed to residential and re creatio na l subdivisions before
the r ecen t up surge of environmental analys is. Some areas
have already experienced slide lo s s. and others are now
known to be haza rdous for future deve lopment.
Ten major rive rs , 14 minor r ive r s, and a great many smal l
streams t10w into Puget Sound. While most of the Sound 's
waters are usually well mixed, the a re as near the mouths of
major rivers will approach freshwater conditions during peri -
ods o f continuous heavy rainfall. Mixin g by stron g winds oc-
curs in some areas of the south Sound during winter months
due to Pacific storm patterns, but stratificat ion often occ ur s
in the late summer in sheltered south Sound bays. Flooding
with in the coastal zo ne includes coasta l type wh ich resu lt s
from the high spring tides combined with strong winds from
winter storms, riverine overbank flooding, a nd a combination
of the two . Storms that producc thc surges also bring hcavy
rains and, thercforc, thc high r ivcr flows are hcld back by
tides producing tloodin g at ri ver mouths. Major damage oc-
curs within the fl oo d plains which have exper ienced the
g reatest growth and development; these are the streams
dra inin g westerly into Puget Sound.
Thc Paci fi c coastlinc offcrs a differcnt kind o f panorama.
From Capc Flattery on t hc north to Ca pc Di sa ppo intment on
the south, there are approximately 160 miles of beaches,
rocky headlands , inlets , and es tuaries. The shoreline from
Cape Flattery sout h to th e Quinault R iver is generally char-
acteriz ed as rugged and rocky with high blu ffs. South of the
Quinault R iver, it is made up pred o minantly of flat sandy
beaches with low banks and dune s. During the winter , Pacifi c
currents set toward the north; during summer months they set
t o the so uth. Associated with the s ummer currents is general
offsho re movemcnt of the surface water, resulting i n upwell-
ing of watcr from lower depths. The upwelled water is cold ,
hi gh in salini ty , low in oxygen content, an d rich in nutrients.
It is this last named characteristic which causcs upwcll cd wa-
ter to he extremely signi ficant in biological te rms , since it of-
ten t riggers h looms of marine plant life. Directions of wave
action and littoral drift of sediments shift seasonally with Pa-
cific Ocean storm s. Although very littl e data a re available on
t he net direction of littoral transport, st udies indicate a nor -
therly o ffshore tl ow .
Fisheries and Wildlife Resources
COlllmercial and s port fisheries are a significan t coastal re -
so urce . Estimates indicate that one half of the State's resi-
dents fish for spo11 or commercia l us e, in a dditi on to thou-
san ds of visitors who fish for salmo n. Commerci al fish ermen
annually harvest over 6 milli o n sa lmon , 20 million pounds of
hottom fish , and 6 million pounds of shellfi sh . The total
processed value of t he commercial fishing industry, including
shellfi sh, bottom f ish, sa lm on , and miscellaneous food fish
amounted to $153 million do llars in 19 76.
Pug et Sound wa ter s are rich in nutri e nts and support a
wide variety of marin e fis h and shellfish species. An estimat-
ed 2,820 miles of streams are utilized by anadromous f ish for
spawning and rearing throughout the area, including Chi -
nook , coho, sockcye , pink and churn salmon, ste el head,
searun cutthroat and D olly Varden trout. All the se fish spend
part of their live s in the saltwaters of Puget Sound an d the
Pacific Ocean before returning to the streams of their origin
to sp aw n. Their offspring spend varying amounts of time in
the shore waters o f th e area before moving to sea to grow to
maturity.
Shellfish a houn d throughout Puget Sound and on the Pacif-
ic Coast. Several varieties of clams, some of which are indi-
genous to the Pacific Coast li ke the well known razor clam,
and a variety of crabs including th e famed Dungeness , are
fo un d in the State's coastal waters. Other noteworthy shellfi sh
include butter and littl e neck clams; small Olympia , Japa-
nese , and rock oysters; shrimp ; and king clam o r geoduck. In
the Pacific Ocean, larg e numbers of hake, halibut, ocean
pcrch, and Columbia River smelt are taken each year. In
some ycars, depcnding o n the ocean currents, albacore tuna
catches are significant.
Pug et Sound has traditionally supported s ubstantial fish
populations. However , with the development o f surrounding
areas some of these fisheries, particularly in the so uthern
So und, havc declined. The principal causes of the decline
have been habitat degradation brought about by industrial
and domest ic wastes and unfavorable land practices , con-
struction of upstream water devclopment projects, and poor
timher harvesting practices. The effect of dikes and fills on
fi sh populations is not clearly understood, but a substanti al
lo ss of nursery and rearing hahitat has occurred.
The decline in fisheries is pa11ially balanced by the fact
that aquaculture or sea farming is beginning to corne into it s
own in the Puget Sound complex. Mass production of
seaweed, clams, gcoducks, scallo ps, shrimp, oysters, small
salmon, lobsters, and othcr marinc life looms as a n important
new industry . Effective shoreline management is p articularl y
crucial to the success of sea farming. Aquaculture on any
scale can coexist with maritime shipping and shorelands i n -
dustrial activities only by careful planning and regulation.
Puget Sound is an important resting place, feeding area,
and wintering ground for thousands of birds in the Pacific
Flyway.
The maj or wintering areas for waterfowl in Puget Sound
are the Skagit, Snohomish, and Nisqually flats, and Padil-
Ia/Samish Bays . Each small bay and inlet provides a distinct
shelter for native and migratory water fowl. For example, 20
to 30 thousand snow geese winter in Skagit Bay , the only
concen tr a ti o n of these geese found in the State of Washi ng-
ton . Waterfowl hunting is a major recreational activity on the
Sound in fa ll and early winter. Nearly on e third of Washing -
ton's duck and goose hunting occurs in Puget Sound.
Harbor seals, kill er whales, and porpoise are commonly
found in Puget Sound, and mammals inhabiting adjacent
freshwater areas includc beavcr , muskrat, mink, weasel, ot-
ter, and raccoon.
Congregati ons of various animals during feeding, re st ing ,
hreed ing , o r in a nursery state are often vulnerable to a vari-
ety of human impacts. These critical hiological areas are nec-
essary to maintain a nd provide fo r perpetuation of the spe-
cies found in Washington State.
The development of the Puget Sound area has brought with
it a noticeable d eterioration of wildlife resource s due to
habitat disruption, though t he lo ss of wildlife habitat has not
totall y heen quantified.
An inventory and analysis of the di str ibution a nd ab un-
dance o f various habitat types will provi d e a better perspec-
tive on habitat loss an d the vul nerability of various habitats
to human impact.
Population
In gcne r a l , Washington has experienced a growth rate in
excess of the national average sincc World War II. Ccnsus
figures for 1974 indicate that about 2.5 million pcople live in
the Puget Sound area, compared with o nly 80,000 on the
State's Pacific Coast.
The majority of the population is concentrated in the cen-
tral an d sou thern regio ns of Pu get So und. The four Pu ge t
Sound counties of King, Kitsap, Pierce , and Snohomi sh con -
tain over 50 percent of th e total State population , as we ll as
two of the State's largest metropolitan areas, Seattle and Ta-
coma. From 1960 t o 1970, these coun ties experienced an
overall increase of 28.1 percent, with Snohomish County
achieving the fastest rate of growth at 54 percent. Large gains
were reali zed by the smalle r suburban communities su r-
ro und ing the Seattle arca, while mctropolitan Seattle experi-
enced a 4.7 perce nt decl in e.
Resource Ownership and Use
About 75 perce nt of Washington 's shore line landward of
the extreme high water li ne is in private ow ner sh ip , as is
about 60 percent of the State's tidelands. Of the publicly-
owned coastline, the fe deral government owns abo ut 155
mile s, including the Olympic [\'ational Park and various wild -
lifc rcfugc arcas. Nonfederal public owners hip totals 107
miles, consisting primarily of state, county, and c ity parks.
When tidelands (betwecn cxtremc low tide and o rdinary high
tide) which are ow ned by t hc State and managed by various
publ ic agenc ie s are included , th e publ ic access sho relin e
mileage in creases to 735 miles. Some of thc nonfedcral pub-
lic la nd is o wned hy port districts and utilized fo r waterborne
comme rc e. In addition , ahout 40 mil es of privately owned
shor el ine is us ed for re creation al purposes, such as resort and
Inarinas.
Most of the 3,000 miles of marinc beds o ut to the three
mile l imit a re owned by th e Statc and managed by the Wash-
ingt o n State Department of t"atural Rcsourccs , which also
ow ns and adm inisters leases for nearly 40 pcrccnt of the in-
tertidal areas. State owned intertidal areas often abut uplands
owned by another l andowner. Thus, with in the sho re-
lin e/t id eland int erface, there are many miles of marine re-
sources wi th a pri vate or local port district upland owner and
a State bedland o r ti da l owner. This s ituati o n leads to
inherent conflicts between the as pirations and d es ires of th e
upland owner, as often ex pressed in local land lise pl a nnin g,
a nd the State's interest as the manager of the bedlands or
tidel a nd s .
Each of the 15 coastal counties and 38 coastal cities is r e-
spon s ible for applying a variety o f building, land use, an d
health codes to shoreline segmen ts . Many localities, support-
ed by separate local taxing port distr ic ts, compete for com -
merce and industry in the coastal zone. J n these sa me areas ,
county and regi o nal effo rts are often t hwart ed by city annex-
ations which promote proposals inconsistent with local
regi onal objectives. On th e other hand, well founded town
and c ity plans and p rog ram s are all too often disregarded or
bypas se d in favor of locating development s in physically un -
s uitabl e county areas where codes may be less st ringent.
Washington State 's coastal zone has more than 100 sepa -
rate institutional organi7.ations which are faced with the awe-
some task of maximizing the us e potential of what amounts to
an incredibly ri c h coastal resour ce. The primary competing
use s to be balanced include timber harvest , indu st ry , com -
mercial fis hing , recreation, tourism, seco nd home develop -
ment , and agriculture. About 77 mile s of shoreline hav e non-
r ec reational commercial and industrial development.
PURPOSE AND USE OF THE ATLAS
The basis for Washington's coastal zo ne management pro-
gram is the Shoreline Management Act. Linder the Act, local
governments have the primary responsibility for making lan d
and water use decisions for the shoreline areas and marine
aquatic areas under their jurisdiction. In addition, large areas
of water surface and bcdlands are under State management,
and resource allocation dccisions are made for them on a
continuing hasis by various Statc agencies, most notably the
Department of Natural Resources. Many fe deral agencies
have management responsibilities in coastal arcas which jux-
tapose in various ways with those of Statc and local agcncies.
Special use districts, such as port districts , make important
decisions regarding the allocation of shoreline areas for the
conduct of their activities. Lastly, but perh aps most impor-
tantly , private enterprise initiates hundreds, if not thousands ,
of projec ts annually which determine the us ag e o f l arge areas
of shoreline . Taken collectively, the interaction of these pro-
cesses result in coastal zone management in the State of
Washington . A common need perccived by these diverse
groups was, and is , the availability of detailed, accurate, and
uniform se ts of data for certain types of environmental infor-
mati on.
The effe ctiveness of the management effort is dependent
upon three things: the inherent quality of thc applicable legis-
lation, the reliability of the data base upon which decisions
are founded, and the skill of the user in meshing the data and
legislation into a management decisi on. It is the second of
these considerations which the Coastal Zone Atlas is intend-
ed to upgrade by filling present data gaps. This should result
in improved effectiveness of Washington coastal zone man-
agement.
Individual Components
The informMion cont~inecl in this Atl~s clisplays seven cli f-
feren t data categories considered essential for effective
coastal zone management and land use decisions.
1. Coastal Geology Survey The term "coastal geology"
refers to the stratigraphy and lithology of rock materials and
their structural relationships, resource potentials, and main
engineering properties. The purpose is to provide basic infor-
mation utilized in land use planning from which usefu l data
can be extracted for evaluation of geologic hazards and prob-
lems and wh ich will furnish a com p rch cnsivc basis for intcr-
pretivc environmcntal gcology.
This will assist in avoiding geologic land use contlicts and
increase the safety and life expectancy of numerous types of
ground hreaking devel opments.
2. Coastal Slope Stability Survey "Slope Stability" is a
relative tcrm and rcfers to the resistance of an inc l ined or
uneve n gro und surface (i.e., of slope-form ing materi als)
against failure and mass movement in the form of slides ,
sl umps, and falls. The purpose of this survey is to identify
unstahle or potentially unstahle areas, determine the nature
of the instability, and explain th e cause-effect relat ionship
that would le ad to and trigger a ha7.ard , due to either natural
causes or manmade impacts.
This will permit avoidance of th e most hazardous areas ,
development of nonconflicting use s compatible with the natu -
ral geologic constraints in o th er locations, and e mployment
of a controlled approach of engineering design and construc-
tion in areas where instability is moderate a nd is amenable to
rcmcdial cnginccring.
3. Coastal Flooding Survey The coastal tlooding surv ey
is a preliminary study with the sole purpose o f delineating
those areas of the marine shoreline which hav e been subj ect-
ed to f100ding in th e past or show a potential for inundation.
4. Sand and Gravel Resources Active, abandoned, and
exhausted excavation o perations are shown in add ition to
formations where useful aggregate exists. The formations are
sho wn with a simp le ass ignment for suggest ing rec ov erability
of the material.
5. Critical Faunal and Floral Areas Critical areas refer to
those geographic lo cations where certa in criti cal eco log ic a l
processes occur. Two major processes have bee n d efined.
The fi rs t and most d ifficult to document are sp ecific popula-
tions which, because of unique oceanographic or environ-
mcntal conditions , provide the major sources of recruitment
for a djac ent popul atio ns. The second criteria for def inition of
critical areas arc breeding, nesting , nursery, feed ing, and
resting a r eas. Rarc , endangered, or threatened species have
also becn identified.
Some 200 animals , birds , and fish were reviewed for this
study, wh ich included commercial and recreationally impor -
tant species found in Washingt on.
All thos e concerned with coastal ac tivities from develope r
th rough public official usually do not intcntionally w ish to
caus e an adverse impact to a spec ies whose existence may be
of direct concern t o them. These data should, thcrefore,
prove extremely serviceahle to the us er.
6. Coastal Drift Sector Inventory A "Drift Sector" is a
segment of the shoreline along which littoral alongshore
movements of sediment occur at noticeable r ates. It allows
for uninterrupted transport or drift of beach materials and it
contains within its boundari es all sources of such sediments,
hoth crosional and depos itiona l. The intent is to explain the
dyn am ics of littoral drift sys t ems on an i ndivi dual, local ba-
sis; to descrihe their imp o rtance as a constantly active pro-
cess modifying the shape and form of the marine l and-water
in terfac e; and to contrast these processes with coastal land
use activities , from both a h ist o ric an d predictable impact
analysis perspective. This will allow loc ati ng and im plement -
ing developments in areas where they would be most compat-
ible with existing land charact eristics, so that devel o pment
will cause minimal disruption of natural systems and will re-
ducc individual and accumulative adverse effect s .
7. Land Cover/Land Usc Upland land cover classifica -
t ion s are associations of plants which occur together due to
soil types and moisture con tcn t, slope, and other factors. As-
sociated with these cover types a re various bird, m ammal,
reptile, a nd amphihian habitats. Some species occ ur in on ly
one or two vegetative uni ts, others range over a number of
land cover class ifications Int ertidal hahitats can be defincd
on t he basis of either the sediment characteristics or the sur-
face macroscopic plants , o r both. D etails o f the ani-
mal/habitat relationship s are being developed a nd will appear
as a supplement to this volume in th e future.
MAP LIMITATIONS
Utilization of the information contained in the maps is lim-
ited by two constraints: scale and accuracy of data collcction.
At a scale of 1:24,000, 1 inch o n the maps represents 2,000
feet on the ground; a boundary line on the maps would cover
approximately 50 feet at scale, so data can only be mapped in
largcr areas. The user should be prepared to verify
designatio ns in the field whenever a specific site is near a
boundary. In addition, while certain data such as beach sedi-
ment composition were gathercd at a larger scale, hetero -
geneous areas wcrc lumped together in order to display the
info rmation at the chosen map scale.
Secondly , much Atlas data were derived from a review of
the literature and interviews, and was then placed directly on
t he maps. In many cases , an inventory was made us ing int er -
pretation of aeriaJ photographs verified by field checks.
However , not every foot of ground was field checked. As a
result , given availahle time and funds, there was a tendency
to (1) group data in heterogeneous situations and (2) locate to
within only 100 feet or so the actual boundary wherc various
classes grade into one another.
These constraints do not diminish the utility of thc data fo r
regional decisions and "first look" assessments of specific
project sites. Final decisions on these will usually involve site
inspections.
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differentiated. The usc of lithologic units rather than forma-
tions allows for mapping of specific textures of earth
materials, whereas many formations include a variety of tex-
tures.
Qdb Double Bluff Drift was mapped at its type locality,
D ou ble Bluff, and at an important reference section, Posses-
sion Point, both on southern Whidbey Is land. It consists
largely of till and glaciomarine drift. Because of uncertainties
wi th correlation between northern and so uthern Puget L ow-
land stratigraphy, pre-Fraser lithologies similar to Double
Bluff Drift were included in undifferen tiated pre-Fraser drift
(Qdr).
Qpd Possession Drift was only mapped at its type lo -
cality, P ossess ion Point on Whidbey Island. It consists of till
which overlies the Whidbey Formation and underlies Vashon
Dri ft. Because of uncertainties with correlati o ns between
northern a nd southern Puget Lowl and s tratigraphy, pre-
Fraser till s s imilar to Possessio n Dri ft were included in undif-
ferentiated pre-Fraser drift (Qdr).
Qdr Undifferentiated pre-Fraser drift are glacial depos-
its consisting largely of till, poorly sorted and unstratified
gravel , and pebbly silt. In some places, pockets and lenses of
stratified sediments afe mapped. Many of the pebbly silts
contain marine microfossils and are considered to be gla-
ciomarine drift. Where microfoss ils were not identified , the
pebbl y silts may be glaciomarine o r glaciolacustrine in ori-
g in , a ltho ugh they generally lack rh y thmic bedding typical of
glaciolacustrine deposits. The unit includes many deposits
mapped by others as Possession , Doubl e Bluff, and Salmon
Springs Drifts.
Qw Whidbey Formation was mapped at is type locality ,
the cliff se p arating Double Bluff and Useless Bay on Whid-
bev Island ; a nd at Possession Point , Whidbey Island, an im-
po~tant reference section. At Pos session Point, the Whidbey
Formation is underlain by Double Bluff Drift, and overlain
by Po ssession Drift, implying that there were at least two pre-
Fraser glaciations separated by an interglac iation. No other
exposure in this regio n 'S shoreline area has evidence to s ug-
gest more than one pre-Fraser glaciation. Furthermore, litho-
logies similar to those of the Whidbey Formation have been
mapped in the southern Puget Lowland as Kitsap and Puyal-
lup Formations; Olympia-age sediments; Lawton Clay; and
basal clays of the Colvos Sand. Until definitive correlation
criteria have been established through research, it was felt
that lith o logies similar to the Whidbey Formation should be
includ ed in undiffere ntiated pre-Fraser nonglacial sediments
(Ons).
Qns Undifferentiated pre-Fraser nonglacial sediments con-
sist largely of stratified silt, sandy s ilt , and clay. Organic beds
of peat and wood are common. Inter beds of sand, silty sand
and pebble gravel occur and are commonly stained by iron
oxides. The rhythmically bedded clays and silts of the Law-
ton Clay member of Vashon Drift are included in this unit,
although they have been interpreted to be glaciolacustrine in
origin by previo us investigators. The unit includes sediments
mapped by o thers as Whidbey, Kitsa p , and Puyallup Forma-
tions ; Lawton Clay; Olympia-age sed im ents ; a nd the basa l
clays o f the Colvos Sand.
Qps Pleistocene sand deposits older than Vashon till
consist of sands, silty sands, and pebbly sands which are com-
monly bedded and may contain local gravellcnses and in-
terbeds. They were deposited by streams of nonglacial and
pro-glacial o rigin. With the exception of being older than
Vashon till , th ey are age-undifferentiated. This unit does not
include sands that have the lith o log ic characteristics and s tra-
tigraphic re lati o n ships of the Esperance Sand (Qve). H ow -
ever, where those criteria are lacking, Esperance Sand is
probably included in this unit.
Qpg Pleistocene gravel deposts older than Vashon till
are gravels and sandy gravel of glacial and nonglacial origin.
With the exception of being o lder than Vashon till , they are
age -undifferent iated. Gravels o lder than Vashon till are o ften
cohesive and/or slightly cemented by iron oxides. In the ab-
sence of stratigraphic evidence, those properites have not
been demonstrated to reli a bly differentiate Vashon advance
gravels, Skokomish gravels , and gravels of Salmon Springs
Drift as mapped by previ o us inves tigators. Therefore, this
unit includes all thrce of those units except where gravels can
be independently determined to be Vashon advance in o rigin.
Qve Esperance Sand is the oldest member of the Vash on
Drift . It represents the first deposits of Fraser glaciation and
o ften rests on a former erosional surface. It generally consists
of moderately well sorted, stratified sand with scattered peb-
bly laye rs. It may grade upward into a thin layer of advance
o utwash and then till, but commonly it is directly overlain by
till , with an abrupt erosional contact. The Esperance Sand is
well exposed in the beach bluffs of both Camano and Whid-
bey Is lands and is characterized by angle of repose s lopes.
Where lithologic characteristic s and stratigraphic rel ati on-
ships are lacking, Esperance Sand is prohahly included in
Pleistocene sand deposits o lder than Vashon till (Qps).
The Espcrance Sand can probably be correlated with the
upper p ar t of the Colvos Sand , which has been mapped previ-
ously o n Vashon, Maury , and Anderson Islands , and on the
Gig Harbor and Longbranch Pen insulas . Because the Colvos
Sand includes a lower unit of s ilt and clay, it was not mapped.
In stead , the angle of repose sands were mapped as E s perance
Sand. The Colvos Sand silt s a nd clays were placed in the pre-
Fraser nonglacial silt and clay unit (Qns) in order to maintain
lith o logic consistency, and because the distinction between
glacial and nonglacial silts and clays is often impossible to
make.
Qva Vashon advance outwash is a member of the
Vashon Drift which ranges from well stratified and well
sorted gravel and gravelly sand to practically unso rted a nd
uns tra ti f ied sand, gravel, a nd s ilt. As this unit grades upward
or laterally into the Vashon till , it may co ntain abundant s ill
fragments. These blocks of compact silt and sandy silt are
commonly angular and may be ten feet or more long. Th is
unit may be deposited directly on oldcr nonglacial sediments,
with the Esperance Sand absent. Where stratigraphic rel a -
tionships are lacking, this uni t may be included in Pleisto-
cene gravel deposits older than Vashon till (Opg).
Qvt Vashon till is the till member of the Vashon Drift
consisting of a very compact un stratified or vc r y crudely
stratified mixture of silt , sand, and gravel with e rrat icall y
scattercd and generally angular boulders. It may occur as a
thick deposit that cuts across older materials and forms gray
vertical cliffs or as a hori zonta l laye r a few feet thick near the
top of a bluff of older sediments.
Qvr Vashon recessional outwash is the youngest member
of the Vashon Drift and consists of sandy and gravelly melt-
water or ab lation deposits that have not been compacted by
the continental ice sheet. However, it does not inclu de thick
deltaic gravels (Qvg and Qeg). Recessional outwash or abl a -
tio n d e pos its are absent or very thin (less than three f eet)
ove r much of the uplands, where it i s co mmonly m apped as
Qb. In places, it is difficult to distinguish from weathered till ,
ice -margin deposits, o r the later Everson gravel.
Qvg Vashon deltaic gravel consists primarily of thick
gravel and gravelly sand deposits with well developed fossi l
beds and a horizontal upper surface. The unit includes
smaller deltaic deposits mapped elsewhere as Vashon reces -
sional outwash. Vashon deltaic gravels were depos it ed in gla-
ciallake deltas by me lt water s treams during rece ss io n of the
continental ice sheet.
Slope Stability
Why a re slope s tability maps inc lud ed in the Coastal Zon e
Atlas? Shorelines are dynamic env ironments where processes
caused by wind , tides , and gravity are active . Slope stability
maps portray a relative mcasurement of the rapid downslo pe
movement of earth materials. This process affects erosion
and depOSition in the shore e nvironm ent not on ly at the par-
ticular s it e but "down drift " along the beach. There is also a
feedback, wherein wave proces ses in turn af fect slope stabil-
ity o n the adjoining land. Finally, as with other dynamic
shoreline factors, slope stahility is an important considera-
tion in planning for the urban , recreati o nal, and industrial
pressures that occur in the coastal zone .
The accompanying maps give a generalized picture of the
stability of the coastal strip in Is land, Snohomish, and King
Counties . These maps pr~~ent th e best estimate of the stabil-
it y of the a rea as seen by th e geologists who mapped that par-
ticula r area. While not definitive o n a si te -by-site basis, these
maps can provide broad guidance fo r many land usc dcci-
sions. They identify areas where the developer or home
builder would be wise to seek individual geologic and engi-
neering adv ice before making plans. They also identify areas
where stability problems are not apt to occur.
Slope stability is interpreted as the resistance to, or lack of,
a tend ency for landslides. The term landslide is used here in
its broad sen se to mean the rapid (greater than one foo t per
year) move ment , in any manner, o f masses of earth materials.
Thus , it is meant to include rock or so il movement in the
form of falling, sliding, and/or 11 0w ing. Most "landslides "
move in a t least two of these modes from their initial point of
failure to fi nal resting place. Not included are slow mass
wasting proces ses such as soil creep o r surficial erosion in the
form of s h eet eros ion or gUllying.
Map Limitations
Indi v idual data areas on slope stab ility maps contain local
exceptions due to limitations of map scale , gencralization of
mapping units, or lack of information. Not all of the deli-
neated areas were directly observed. The maps are a result of
aerial photographic interpretatio n supported by as many
field obse rvations as time permitted. Stable areas adjacent to
unstable slopes may locally be subject to the same degree of
"hazard" as the adjoining less stable slope. For example, a
deep seated landslide in a coastal bluff may undercut the flat
and otherwise stable upland. Similarly, the stable beach area
m ay be threatened by slides from above . For such reasons
these maps are not a substitute for professional site-by -site
analys is in the field. Obviously , the degree of detail necessary
in field in ves tigation s varies not o nly with the clas s of slope
but with the particular land use being considered.
The slope ca tegor ies (except for "modified land ") relat e to
natural conditions. Even the most stable slopes can be made
unstable by poorly engineered excavations, abnorm al concen-
trations of water, or o the r human-induced conditions. Con-
versely, an unstable area can often be made relatively stable,
at least locally , through drainage, buttressing, or other engi-
neering techniques .
As implied in th e title , thi s mapping relates to s lop e
stability only, without any reference to foundation c ha ra cter-
is ti cs. For example, a peat bog may be considered stable from
a "lac k o f mov e ment" point of view because it is practically
le ve l, and yet may be extremely weak (unstable) in regard to
it s load bearing capacity.
SLOPE STABILITY FACTORS
Slope The slope angle of the land surface is probably the
most o bvious factor inv o lved in a naly zi ng the stabili ty o f a
given area. Other factors such as materials and water being
constant, a change in slope alters thc effcc t of gravity on the
tendency of material s to fa ll , slide, or flow downslope. How-
ever, in nature the var iability of other factors may more than
offset the inlluence of s lope. Thus, a stability assessment
based on slope alone can be grossly misleading. Alth o ugh the
angle at which various uniform materials of different mois-
ture contents will be stable can be predicted rather accu-
rately, catastrophic earth flow s have occurred in a reas of im-
perceptible slupe where underlying marine clays have
liquified. Similar matcrials, if well drained, may stand in ver -
tical banks for years under different conditions and not slide .
Some near-vertical "high ba nk " coastal areas of till are rela-
tively stable, whereas an a djacen t gently sloping "low bank "
tract of different material may be the site of an ancient
landslide and hence subject to renewed movement.
Materials The geologic materials making up a sl ope are
a major factor in the behavior of that slope. (See th e tab le un-
der Coastal Geology for a discu ss ion of the engineering prop -
erties of geologic units). Uneo hesive materials such as gravel
o r sand with little silt o r clay "binder" will tlow , even when
Qv Vashon Drift was deposited by the V ashon Stade of
the Praser Glaciation. The Vashon Drift is generally considered
to have four me m bers: Esperance Sand COve); Vashon ad-
vance outwash (Ova); Vashon till (Qvt); and Vash on reces -
sional outwash (Qvr). Vashon Drift is usually mapped where
(I) thin or discontinuously distributed till overlies advance
outwash or (2) thin recessional outwash and/or gravelly abla-
tion deposits overlie till. In southern King County near Du -
mas Bay, sand was mapped as Vashon Drift because it could
not be determined whether it was Esperance Sand, Vash on
advance outwash, o r Vashon recessional outwash.
Qe Everson Glaciomarine Drift was formed during the
Everson Interstade when marine waters inundated the north-
e rn Puget Lowland. Sediment deposited during this time in-
terval is typically glac iomarine drift, which consists of mas-
sive pebbly silt wi th w id e ly sca ttcrcd boulders. It is generally
oxidized to a pale ye llowish tan, hut retains its origin a l gray
color at sea level occurrences. Where oxidized, it is
characterized by inten sive d ess ication cracking, generally
with a strong vertical pattern. Shells are locally abundant but
are generally sparse. Even whcrc shells are absent, microfos-
sils confirm the marin e origin. The drift appears to have ac-
cumulated as a rain of sediment on the sea floor from the
melting of shelf and/or berg ice.
Qeg Everson Gravel is restricted to Island County where
it consists of ice-con ta ct and deltaic gravels a nd gravelly
san d s depos ited during the Everson Interstade high sea
levels. It includ es the kettled tcrrace depos its previously
mapped as the P artridge Gravel, and deltaic o r beach depos-
its lying on erosional terraces at the mouths of former melt-
water channels .
Qu Undifferentiated Pleistocene deposits consist of un-
differentiated glacial and nonglacial deposits. They are
mapped where (I) scale and/or steepness of seacliffs do not
permit more detailed delineations and (2) insuffici ent data
prohibit a more spec ific identification and correlation of the
unit. Where possible, stratigraphic columns show mo re de-
tailed subdivisions , correlations , approximate thicknesses ,
and lithologics at spec i fic seacl iff exposures.
Holocene Deposits
The following Ho loce n e units represent the Quaternary
history of Island, Snohomish, and King Counties since the
Pleistocene. Some of the units span the entire time since re-
treat of glaciers from the area to the present t im e. Others may
repr~~ent only the past few thousand years of hi story .
Qls Landslide deposits are mapped where there is a to -
pographic expression of old or continuous slid e activity. To-
pographic maps and aerial photos were u sed to delineate
most of these areas. However, in almost every case , disrupted
sediments were observed at the site. Superficial activi ty such
as dry bank ravelling were not included.
Qd Dune sand is mapped where there are accumulations
of three to five feet o r more o f wind deposited sand . The most
s ignificant a rea mapp ed is the well developed primary an d
sccon dary dun e system at beach level near Cranberr y Lake
o n Whidbey Is land. Dunes havc also formed along the tops of
bluffs where nonvegetated sandy slopes are exposed to strong
onshore winds.
Qos Saturated, organic-bearing sand, silt, and clay is
mapped where fresh and sa ltwater swamps, marshes, a nd
bogs contain fine-grained, saturated depusit s th a t are high in
organic matter.
Qp Peat is mapped where the accumulation of partially
decompo sed and disintegrated organic matter is interpreted
to bc relativcl y thick a nd free of sand, silt, and clay . Identifi-
dry, to their particular angle of repose (roughly 30-35 dc-
grees). Materials with a high si lt content s uch as g lac ial till or
even some silty sa nd s w ill s tand near-vertical for years. Till
especially can be practicall y immune to collapse unl ess un -
d c rcut. Instcad of co ll aps ing, it surficially erodes s lowly from
frost action o r a lt ernate wetting and dry ing.
Slopes und erl ain by bedrock can have highly variable
s lope stability. Bedrock units lIlay experience little or 110
landsliding on slopes much stccper than typical unstable
slopes in unconsolidated units. However, poorly co nsoli-
dated, clay-rich bedrock units may be subject to s lump s and
flows similar to unconsolidated units. Bedrock slo pes gener-
ally expericncc different landslidc types . Depending on the
orientation of bedding a nd fractures within the rocks , rock
s lides and rock falls may occur.
Probably m o re important to slope stability than indi vidual
geologic units th emselves are the relation ships between these
units. These relationships generally affect slope stab ility most
when there is a pronounced change in physical p roperties be-
tween two geologic units . In areas where till overlies sand or
gravel the lower unit erodes faster, undercu tting the till,
which eventually collapses as large hlocks. Where sand over-
lies till , silt, or some oth er relatively imp er meable material ,
the infiltratio n of groundwater is slowed and a perched water
table forms locall y within the sand unit. This saturate d zo ne
represents a la yer of weak nes s that commonly results in
slumping and mud flows.
Water The presence o r absence of water available to per-
colate into the ground and through earth materi a ls play s lin
important role in the relative stability of slopes. Generally,
the availability of water is a function of local climate ; there-
fore the types of landslides, their relative activity and fre-
quency varies fro m wet to dry climates. In much of wes tern
Washington , prec ipitati o n is high. During the rainy season
there is little o r no evaporation; thus much of the water infil-
trates the ground a nd forms various zo nes of saturation
within the sediments and rocks. The movement of the water
and the number and locati on o f saturation zones (a quifers)
a re controlled by the types of earth materi als. The strength of
earth materials c hang es drastically once they are saturated
with water. When types of material, slope, and water com-
bine in such a way that the vertical force of the weight (due to
gravity) is greater than the strength of the saturated mate ri -
als, a lands lide occurs.
cation and delineation of this unit is based la rgely on inter-
pretation of aerial photographs.
Qb Beach deposits consist mainly of gravel, sandy
gravel, and sand accumulations above high tide. They repre-
sent areas of accretion, in contrast to o ther shorelines which
are eroding at various rates.
Qal Alluvium, sand, and gravel consists largely of sand,
pebbly sand , and pebble-to cobble-sized gravel depOSited by
streams. It includes some silt, clay, and organic-bearing sedi-
ments.
Qa2 Alluvium, sand, silt, and, clay consists primarily of
sand, silt, and clay deposited by streams. It includes some
gravel and organic-bearing sediments.
af Artificial fill is mapped where humans have modified
thc to pograp hy by the addition of soil , sediments , rock, vege-
tative debris, garbage, or other assorted and varied types of
material ; generally five or more feet thick , but us ually it is an
unknown thickness.
BIBLIOGRAPHY
Arm st rong , J. E., Crandell, D. R., Easterbrook , D. J., and Noble , J.
B. 1965. "Late Pleistocene Stratigraphy and Chr onology In Southwest -er~ Briti sh Co lumbi a and" orthwestern Wa shi ngt on," Geological Soci-
ety America Bull., v. 76, p. 321-330.
Artim , E. R., 19 73 , "Geology in Land Use Planning ," Was hington
Divi sion of G eo log y a nd Earth Resource s, Information Ci rcul ar 47 , 18
p ., 2 pl ates.
Bret z, J. H ., 19 13, "Glaciation of th e Puget Sound Regio n," Wash-
ingron Geolog ical Survey Bull . 8, 244 p.
Crande ll , D. R., 196 5, 'The Glacial Hi story of Western Was hington
and Oregon ," Th e Quaternary of th e U"ired Stat es: Prin ce ron . Prince-
ton Univer s ity Press, p. 341·353 .
Crandell , D. R., Mulline aux . D. R., and Waldr on, H. H., 19 58,
"Pleistocen e Sequence in Southeastern Part of the Pugcl Lowland,
Washington," Am. J o urnal Sci., v. 256 , p. 384·397.
Easterbrook , D . .I ., 1969. "Pleistocene Chr onology of the Puget
Lowl and and San Juan Islands, Washingt on," Ge o logica l Society
America Bull., v. 80, p. 2273·2286.
Flint, R. F., 19 7 1, Glacial and Quaternary Ge o lo gy , John Wiley and
Sons. New York , 892 p.
Garling , M. E., Molenaar , Dee , Bailey , E. G., Van Denburgh , A. S.,
and Fiedler , G. H .. 1965, "Water Re source s and Geology of the Klt sa p
Peninsula and certai n adjacen t island s," Washin gton Division of Wafer
Resources Water Supply Bulletin 18 ,309 p.
Liesche , B. A., Price, C. E., and Walter s, K. L., 1963 , "Geology and
G ro undw ater Resource s of Northwestern King County, Washington ,"
Wa shin gron Division of Waler Resources Waler Supply Bulletill 20 ,
241 p.
Lu zier, J. E., 1969, "Geology and Groundwater Resources of
Southwestern King Co unty , Washington ," Washin gt on Departmenr of
Water Resources Water Supply Bullerin 28,260 p.
Rei chert , W. H .. 19 78 , Annotated gu id e to so urces of information
on the geo logy , min era ls, and groundwater resources of the Puget
Sound region , Was hin gton , King County section , Division of Geology
and Earth R eso uces, Information eirel/lm' 61 , 63 p.
Ri gg , G. B., 1958 , "Peat Resource s of Washington ," Washington Di-
vis ion of G eo logy and Ean" R esources Bull. 44 ,272 p.
Smith , Mackey , 19 75, Preliminary surfi cial ge olog ic map of the
Mukil teo and Everett quadrangles , Snohomish and King Co unties ,
Washin gton, Was hington Geology and Ea rt h Re so urc es Division Geo-
logic MapGM -14.
Smith, Mac key. 19 76, Preliminary surfi cial geologic map of the
Mukil teo and Everett quadrangles, Snohomi sh Co un ty, Was hington,
Wa shingt o n Divi sio n of Geology and Earth Re so urces Geologic Map
GM -2 0, 1:24,000. map and text on one sheeL
Snyder , D . E., Gale, P. S., and Pringle . R. F., 1973 , Soil Survey of
King County Area, Washington: U.S. Department of Agriculture Soil
Co nse rv at ion Serv ic e, 100 p., issued in portfolio with 22 maps .
Waldron , H. H., 1961 , Geology of the Pov erty Bay quadrangle ,
Wa shingt on : U.S. Geological Survey Quadrangle Map of the United
States , Map GQ·158 , map and text on one sheet.
Waldron , H. H., 1962 , Geology of the De s Moine s quadrangle,
Wa shin gto n: U.S. Geological Survey Geologic Quadrangle Map of the
United State s, Ma p GQ-159, map and text on one shee t.
Waldron , H. H., 196 7. Geology of th e Duwamish Head quadrangle ,
Wa sh in gton: U.S. Geological Survey Geologic Quadrangle Map bf the
United States, Map G()-706, one sheet.
Waldron , H. H., Liesch , B. A ., Mullineaux, D. R., a nd Crandell , D .
R .. 1962 , Pr elimin ary geo logic Ill a p of Seattl e and vicinit y, Washing-
ton: U.S. Geologic Survey Miscellaneous Geologic Inv es tig at ions , Ma p
1·354, one sheet.
Willi s, B., 1898b , "Drift Phenom ena of Puget Sou nd ." Geol. Society
of America Bulletin, v. 9, p. 111 -16 2.
As mentioned above, the geologic materials and their rela-
ti onsh ips commonly dictate if and how grou ndwater will
accumulate and move. In the Puget Lowland, a groundwater
incrcase is probably the most common s lid e triggering factor.
Consequently , most o f the slides occur in w inter and spring.
rail r a in s seld om cau se the sl o pe stab ility problems that a
storm of equal intensity would cause in th e spring. That is be-
cause groundwater levels have not yet been restored from
their lows during the dry summer season.
Natural groundwater levels can be significantly altered by
human ac tivity, espec ially on a loc a l setti ng. The diversion of
storm runoff is a common cause of ab norma lly high infiltra-
tion rates in a relatively small area. Septic tank e ffluent can
also have a p ro fo und efred on local groundwater conditions
and thus s lope s tability . In a new residential development
s uch effects may not fully develop for man y years.
Wave Erosion In a broad sense, the coastline can be
grouped into act iv e ly eroding and actively acc reting shore-
forms. The effects of these shore alignment processes on
slope stability are variable (because of o th er factors) but pro -
found. The most impo rtant effect of wave erosion on coast-
line s is that wave action steepens and undercuts slopes and
prevents stab ili z ing d e bri s accumulation at the toe of slopes
thu s ens uring continuing erosion. High strengt h material s
like till are unstabl e where such active erosion occurs.
On the o ther hand , areas of beac h accretion provide pro-
tection for coastal slo pes. New, stable sl ope angles and mass
balances can be achieved where erosion has essentially
stopped. Although the effect of groundwater 011 earth materi -
als can still render a protected coastline face unstable, gcner-
ally slopes behind accreting beaches will be more stable than
slopes behind erod ing shorelines.
The interplay between materials, groundwater, and shore
processes forms a sys tem in which the configuration of the
coastline a nd slope stahility are the res ult of the combination
of several factors , and the feedback from o ne process to an-
other. For example, landsliding coupled with active wave
erosion can provide sediment for transport along the shore
and accretion elsewhere. The accreting shore in turn will pro-
tect adjacent upland slopes from erosion and will probably
reduce land sliding.
Other Factors The environm ent during the time when
the sed iments were deposited and the influ e nce of post-dcpo-
2
sitional events (geo logic history) can have a pro fo und effect
on the strength o f slop e-fo rming materia ls. T he sil t that un-
derlies IlIany Puget Lowland blu ffs has diffe rent properties
than silt be ing dep os ited on modern river fl oo dpl a ins and del-
t as because the o lder sil ts have bcen compacted by continen-
tal ice she ets thou sa nds o f feet thick.
Kn ow le dge of a ny fo rmer slide movem e nt can be cr itical in
assessing the lo ng -term sta b ility o f a n area. An anci e nt
lands lid e is an area o f di sturbed material s a nd groundwater
conditions eve n t ho ugh it may no t h ave moved fo r ce nturies
o r even th ousands of yea rs. Such an area can be fai rly stable
in its natural state . Yet it may respond diffe rent ly th a n adja-
cent sl o pes o f th e sa m e mate r ia ls to excavati ons o r changes in
groundwater. Thu s o ld landslides have bee n m a pped where
recognized.
Human activ it ies can modify any o f th e above factors. Ar-
tificial cuts stee p e n slo p es. Artificia l fill c h anges the lo ad a nd
character o f m ate rials on slopes. Septic tank drain fields in-
crease infiltratio n . A lth o ugh the effects of these modifica -
tions may be unpredictahle, comm o nly they reduce slope
stability. On th e other ha nd , engineerin g tec hniques such as
artificia l draining of wat e r-bearing strata o r th e decrease of
rainwate r infiltrati o n by paving and appropriate storm drains
can incre ase s lope st abili ty . On -s ite inves tig a ti o ns o f in terme-
d iate a nd uns table areas, coup led wi th suitabl e l and u sc plan-
ning , are a prerequisit e fo r a sound balan ~e between hazard
to l ife a nd property, cos t o f l and impro ve m ents, a nd real
es tate values.
DESCRIPTION OF RELA TIVE SLOPE STABILITY
UNITS
S Stable Slopes usua l ly ris e ge ntly , ofte n 10 percent (6
d eg r ees) o r less, a nd are predom in an tl y underl ain by compe-
te nt mat e rial such as till and outw as h , or tl at -Iying deposits
Coastal Drift Sectors
A "drift sector " is a segment of the shoreline alo ng wh ich
littoral , alongsho r e movem e nts of sediments occur a t no tice-
ab le rates. It all ows fo r uninterrupted m ove ment o r d r ift of
beach m a terials. Eac h dri ft sector includes:
A feed so urce that supplies the sediment.
A driftway a lon g whi c h th e sed im e nt moves.
A n accretion termin a l where the drift m aterial is depos -
it ed.
Bo unda r ies wh ich se parate indi v idual sectors from each
other.
This Atlas pre se nt s in fo rmation relati ve to beac h sediment
t ypes , wave climate an d exposure, so urc es o f beach materials,
a nd relati llC litto r a l transport r ates. Based o n thi s in for m a-
ti o n, indi vi du al drift secto rs along the state's sho rel in es a re
ide ntifi ed .
The basic mec hani sm s o f drift sectors are relatively sim -
ple . Wav es continua ll y att acking th e sho re lin e with hy drau li c
a nd pneum a ti c actio n cause turbulence whi ch leads to ero-
sion. E rosion r ates depend largely on kin d a nd composition
of material in the f eed so urce . Along rocky coasts r ates are
slow, whil e in un co nsolidated glacial materials in bluffs,
wh ich comprise over 70 percent o f Washin gton's coastal
zo ne , they may exceed one foot per year. Streams a lso suppl y
beach materi a ls, but to a lesser ex tent. Once drift material is
r e moved from it s deposition locale , it ca n t he n be swe pt , ei-
th er con tinu ously o r in seaso nal cycles, by wind waves and
wi nd -and tid e -ge ne rated currents , along th e shor es in a mo re
or less parall el motion. Eventually it may be red epos ited , i.e.
a cc re te d on the beach a t so me dis ta nce dow ndri ft, or acc umu-
l ate d offshore in d eeper water.
Virtuall y a ll shorelin es, in particular h igh gl acia l bluffs ,
a re suhj ect t o co nt inuing erosi on (Photos I , 2 and 8). Usually
this process is not co ns ider ed significan t until human en-
c ro ac hm en t onto th e sho r eli nes or occupati on o f t he adjacent
u p lands has occurred. To retain lan d, people o ften build pro-
tective structures . Such structure s, however , may re move the
major so urce o f littoral materials. A lso, dam s built across
strea ms rem ove li tt o ra l materials fr o m th e natural sys tem,
but to a lesser ex te nt. This natural system will adju st to th e
reduction in avai lable litt o ra l materials by steepening and/or
lower ing the beach profil e and by in creasing eros io n pres -
sures o n unprotec ted land until a state of equilibrium is
reach ed. M a nm ade structures, such as groins (Pho t o 10) and
breakwaters, also interrupt th e movement of beach materials ,
res ulting in th eir acc umu la ti o n on the updri ft s ide of th e
structures . I f these mate r ia ls are not allow e d to pass, erosio n
will increase jus t do wndrift o f the structures. Mining o f beach
materials just a bove the low water lin e rem oves l itto ra l mate-
r ials from th e sho r e corr id o r , resulting in s ign ific ant eros io n
of adjacent uplands and downdrift sho relin es.
The coasta l zo ne as a who le is a dy n am ic e nv ironment , in
that the land-water bo und a ry and contiguous land fo rms are
continu ously modi fied a nd realigned by th e forces of th e sea.
Therefo re , it is impo rt ant to identify, rec ogn ize, and under -
s tand the shor e corr id o r mechan ic s of dri ft sectors whi ch p lay
a n important role in beach d ynamics a long th e St a te's 2 ,3 00
miles of sa ltwate r s horelin es.
T he info r mation included in thi s Atlas provides th e plan-
ner, conservati o ni st, and d eveloper with basic dat a to use in
determi n i ng im pacts of pr o posed land us e o r develo pment
a long the shoreline. The Atl as, how eve r , is not intended to
provide exhaus tiv e a nd final answers to th e multifaceted
geohydr aulic processes th a t cau se or affect drift sec to rs and
li tto ral tran s port a lo ng o ur diverse coastal e nvironm e nts. For
in stance, the co mputation s o f wave heigh t roses and drift ar -
rows are based so l ely o n un a djusted wind data from e ight
wind stati ons located around Puget So und (Figure 2).
Offshore bathymetry , sho a li ng effects, wave refr ac tion and
r e tl ecti on, tida l c urre nts a nd impacts fro m boat wa kes, a ll of
which affect, individu a lly o r through interaction , the mo tion
of beach sediments were not co n sid ered in th e littora l trans -
port calculati ons. Such va ri ables are beyo nd t he initial sco pe
of the Atlas. Also , it is important to recogni ze that the coa stal
drift sectors and thei r dy nam ics presented he rein are primar-
il y the res ult of o ne time fie ld observati on s , interpretati o n o r
1974/76 aerial photography and statistic al a nalys is of the few
ava ilabl e publi shed da ta. No lo ng-term mo nitoring or quanti-
Coasta l Ar ea
tative m easure me nt s have been made. Ca uti o n must be use d
in projec ting lo ng -term trends and proc es ses. The d isplay ed
in f ormation shou ld be ver ifi ed thro ugh fiel d evidence and the
gat herin g o f data o n the above variables before co mpreh e n-
s ive li ttor a l d rift analysis can be m ade with resp ec t to lo cal
conditi o ns.
Additional info rmation includ in g written descriptions of
each drift se ctor is avai lab le for rev i ew at the Wa shingto n
St ate Department of E cology and a t the pl anni ng offices in
counties wh ere res pective drift sec to rs are located.
DRIFT SECTOR
The beach is di vided int o reach es, or "drift sec to rs ," with
boundaries p er pe ndicular to t h e shore and exten ding ac ross
t he int e rtid al zo n e. Within each drift se cto r , uninte rrupted
drift of beach mate rials (sediments) can occ u r. Eac h drift sec-
tor contain s its ow n so urces o f se dim en ts. Waves and currents
move litto r a l materi a ls eith er ons hore a nd offshore , o r along-
shore (Figure I) between the fe ed so u rce (area of erosion)
a nd th e accreti o n te rminal (area o f d e pos iti o n). The amount
of littoral mater ials rem a in s rather constant in a g iven sector
except for materials wh ich are swep t offs ho r e beyo nd the low
water lin e. The se materials may be tr anspo rted back o nsh o re
during summ er sto rm s, r emain "stored " offshore, or mo ve
a lo ng th e sh o re l ine and pass into t he influ enc e of an adjacent
drift secto r.
The move ment o f littoral mat eri als r emaining within a
d r ift sector is thu s merely an exchang e o f ma t er ia l sto red
within the sec tor an d sup pli ed from a feed so urce .
Photo 1 Typ ica l eroding bluff with slid e area . The back-
shore is of mixed coars e gravel (MC) and th e foreshore is
sand (S).
Photo 2 A source of littoral materials is provided by this
sandy headl a nd of Puget Sound which forms a promontory
whose slo pes havc been carried away, leav in g a beach that
gra d es fro m sa nd and mixed fine (MF) on the backshore to
cobbles and boulders (Cob) over a mixed coarse grade of
gravel (MC) on th e foreland s .
--Coast -~-+-t-------Be ach --------l .. ~f-o --Nea rsho re Zon e --~~
------+I ...... t-Offsh o re
1
I:"':"~ . Backshore ----Insho re
Crest of Be rm .~~~~~-=--
High o:a ·t~;· __ .~:~ ~ ~'_ <., .. _ __ _______ h __ !~r eakers ~ I _,, __
~'. '---0 "'"" ~ ~ --
Low Wa te r -- ---------~ ~-: -.. ~ ~~~c.'-._. _ ~ ____ -
PI u n g e Po i nt ~~ ': ~-:--:-:-:-.,.. ::. -:-:-::~::-:-. .,. . ...,.-:-:-,,-_JB~o~t~t o~m~
BEACH PROFILES -Related Terms
' ••• " "',' : .. ' : 0
Figure 1
3
su ch as peat. So me s teep, fore sted slo pes underlain by com-
petent materials are con sid ered stable, but usually d o not ex-
ceed 20 percent (11 deg r ees).
Intermediate Slopes co nsist o f areas c o nsidercd to have
le ss t han critical geologic, groundwater, or wavc erosion fac-
to rs , but whi ch may become c r it ical , and therefore s ubj ec t to
l a nds li d ing if d istur be d . A co m mo n example is a stabili zed
and vegetated sand and gravel ta lus slo pe, the surface of
whi ch is slop ing at the angle of re p ose o r less (l ess th an a p -
pr oximately 7 0 percent (35 d egrees)). Inte rmed iate slo pe sta-
bili ty includes heavily vegetated, very steep sl opes und erlain
by sa nd , gravel, till and/o r bedrock. Slopes often range fr om
20 percent (11 degrees) to 100 percent (45 degrces), but are
mos t commonly about 25 p ercent (14 degrees). Erosio n at
the toe o f slo pes will be absent, a nd accreti ng beaches may be
present.
U Unstable Slopes a re gen e ra ll y stee p and con sid ered
FEED SOURCES
Al o ng Was h i ngton 's P ac i fic coas t and a long most o f its
mari ne inland s hor es sufficient k inetic e nerg y ex ists throu gh
wind-generated waves, tidal action and currents to move
sed iments along th e beach. F or the res ul ti ng dr ift sectors to
o pe r ate, a suita ble fced so urce mu st be avai lab le to transfer
materials from o ne loca ti o n to a no ther.
The sho res and litto ra l d r ift sectors in Washington 'S
coast a l zo ne rece ive sed im e nt from three sources: beach es
(Photos I and 2) and o ffshor e a reas (Ph o to 9); the strip of
land co ntigu ous to the shor e; and upl a nd a reas . Obviou sly,
th e greater the erod ibil it y o f th e fee d er source, the mor e sedi-
ment it will contribute to drift. The thick laye rs of we akl y
consolidated, glacial d ep os its aro und Pu ge t Sound are an ex -
cell e nt so urce of detritu s. Many o f them act as feeder bluffs
prov id in g a co nstant supply o f ma terial to drift sec tors.
Once a feed so urce is es ta b l ished , a p rocess must exi st to
break down the material into a tr anspo r table form. Th e most
importa nt processes respo ns ible fo r this transformation a re:
scouring , grinding, and rework in g of deposi ts that form beach
a nd nearsh o re s ubstrates; and physical and chemical weather-
in g of the deposits and rock fo rm at ions forming s lopes and
b lu ffs be hind the beaches (Ph o to I).
If feed so urces are no t loca te d a lo ng the beach zone , there
m us t also be a tra nsp o rt mechani sm whi c h mo ves the bro ke n
d ow n materia l into the sho re co rrid o r. The m ajor tran s po r t
processes that carry upl and det ri tu s to points al o ngshore ar e:
grav ity; surface runo ff ; and streams that move se dim ent in
suspen sio n and as bed loa d in to th e marine r ealm where the
mate ria l may bc stored temp o ra rily or permanen tly as estu a -
rin e and deltaic deposits (Ph o to 3).
T h e more intensive the weathe rin g processes a nd th e more
vigorous the transport mechan is ms , th e m ore detrit u s is pr o-
duced a nd the faster it arri ves in th e shore zo ne and becomes
avail able for transpo rt . In western Washington , high annual
precipi tati o n , d e nse vege tati o n , a nd m ou nt a ino us upland s
reach in g into the coastal zone prevail. These provide weath -
e ring age nts and transport energy throu gh temperature
changes, frequent surface in fi ltrat ion a nd run off, steep ter -
r ain gradients, and peak stream fl ows during fresh ets to al l ow
for co ntinuous transfer of mater ial , often at higl1 rates. De-
pe ndent upon which coastal region, different processes then
interact to suppl y drift secto rs wi th feed material.
Throughou t most o f Puget So und, beach scouring and up-
land weather ing and erosion predomi nat e in gene rating th e
sedime nt s. Along the coast fronting the Pacific O cean , di ffer-
e nt feed source combinations exist. The wide and fl at so uth
b eaches, where sand dun es pr eva il , ow e t heir formati o n al-
m ost entirely to the large vo lum es of clastic detritus from the
Cas c ade Mountains and from a reas further east, carri ed to
the coastal zone by the Colum bia R iv e r. Along the steep an d
rugge d co ast between Point Grenville and Cape Flattery , up-
l and weathering and erosio n and wave cutting along the high
water line generate mo st of th e detritus , augmented by lesse r
amounts of material being flu shed out wi th coastal ri ve rs
draining the Ol ym pic P eninsul a.
DRIFTWAY
Once at the shore and wi thin the re ach of waves, the de -
tritus from the feed sources descr ibed a bove mov es in th e lit-
to r a l zo ne o r d riftw ay which ex te nd s sea ward from the shore -
lin e (high water line) to ju st beyond the breaker zo ne. The
width of the littora l zone varies acco rding to tidal level a nd
wave he igh t. The o uter limit of the zo ne occurs where th e wa -
ter depth is equi valent to ap prox imate ly 1.3 times th e wave
h e ight.
D r ift va lu es shown on th e ma ps a re rel ative co mpari so ns
of the e ne rg y (power) in waves which is availah le to m ove lit-
toral m aterial s. This energy has been r elated to the capac ity
to move medium -sized sand of unlimited supply. L arger litto -
ral mater ials such as gravel and cobbles require more ene rgy
to be transported than does sand. Armored, bulkheaded , and
WIND
STATIONS
Figure 2
unstable becaus e the geo logy, gro undwater , o r wave e rosion
factors are c ritical a nd /or th e slopes show evi dence of p rese nt
or past land sl iding. Un stable areas include landslides and
talu s too sm a ll or obscure to be individuall y mapped. M a p
symbol Urs identifies recent or historically ac tive land slides.
Map symbol Uos defin es old, post-g lac ia l but prehi s toric
l ands lides .
M Modified Slopes are a rea s that have undergo ne artifi-
cial cutt ing and fi llin g . Slo pe sta bilit y is no t interpreted in
modified areas becau se the combinati o n of n atural processes
and a rtificial cuttin g a nd fillin g may have a n unp red icta ble
effe ct o n land sl id i ng .
On-site geol og ic a l a nd e ng in eer ing investig ati o ns a re reco m-
mended fo r sign ifi can t la nd use changes in areas mapped as
Int e rmed iate (1), and sho uld be standard prac ti ce in areas
mapped as Unstab le (U) a nd Modifie d (M) s lopes.
Photo 3 Thc nearsho re consists of a mixed coarse (MC)
grade o f gravels with a mixed medium (MM) grade o f grave l
lying a t the river mouth in a protru sion which forms a barrier
to littoral drift. Rivers are an important so urce o f d r ift mate-
rials from the upland bey ond the coastal zone .
Photo 4 Barrier bea c h with mixed coarse (MC) beac h
materials on th e fore shore and mixed fi ne (MF ) on top o f the
berm. This overwash be rm provides a Class I beach.
Photo 5 A rock island connected to the mainland by a tom-
bolo which has formed over the years.
Photo 6 A spit inside Dungencss Spit formed by the deposi-
tion (accre tion) of drift materials over a lo ng passage of time.
The in side of such s pits is generally sandy s ilt or mud and
forms a perfect environment for the growth of sa lt marshes.
Photo 7 A spit or point of low lying uplands forming a ter-
minal but not impas sable barrier to drift. A marked net dnft
in one season sho uld form a hook in the directi on of stronger
movement.
Photo 8 Sandy beaches being fo rmed (accretion) from the
eroding bluffs downshore.
Photo 9 A Class I beach which is walk able at all tidal
stages , consisting of sand overlain by gravels.
Photo 10 The rock groin h as had som e effect in trapping
and protecting t he croding sa nd to the r.igh t. Note the mixed
medium (M M) grade gravel to le ft movmg around the grom.
Photo 11 A rock jetty at th e mouth of a channel which
serves as a termin a l barrier to littoral drift as well as training
the direction of channel currents.
Photo 12 Timber pile docks and wharves, and rock riprap
protect sand fill s a nd block the transport of littoral materials
alongshore.
Photo 13 A pocket beach o f graded gravel and sand (MM)
formed hetw ee n two masses of rock which form terminal bar-
riers to littoral dri ft.
otherwise protected bluffs and beaches reduce the amount o f
littora l materials available for transp o rt.
Littoral materials are put in suspension by wave action and
moved a long the sh o re by wave-induced currents, a nd to a
les ser extent, by tide-induced currents. During thi s process ,
littora l materials move a short di sta nce along the shore and
settle out. Subsequent waves will resuspend these m a terials
and continue the litto ral process . The direction of littoral
drift movement is always in thc direction of prevailing wind
and may reve rse according to changes in wind direction.
The most significant influence on movement o f littoral
materials is wave action. Waves are generated by wind mov-
ing across the water. The distance that wind blows over open
water is called "fe tc h " and is c xpressed in mile s. The length
of time th a t wind blows across water is called "dur ation ," ex-
pressed in hours. Generally , the greater the wind veloc ity (in
miles per hour), fetch, and/or durati o n, the large r the res ult-
ing wave height . W ave height is thus dependent o n a
combin ati o n of velocity, fetch, and duration and may be lim-
ited by anyone of th ese factors.
Wind Wans Wave height computations are based on
wind veloc ity, wind frequency, fet ch length , and duration for
rep resentat ive locat ion s a long the sho reline. H e igh ts for
waves or igi nating from a given direction are represented by
"wave roses " o n the maps where frequency o f occ u r re nce is
shown for va rious wave heights. For the co mputati o n of each
wave rose, wind rec o rd s collected by the National Weather
Bureau at representative Washingto n State recording stations
served as a data base . Wind magnitude , directi o n , and fre-
quency of occurre nce from the weather s tation s shown in Fig-
ure 2 were combined with fetch length to <.:ampute wave
heights on thc maps. H ow cver, no adjustments were made for
distance o f wind stations fro m locati on of wave height roses
or for loca l effect of topography on win ds.
Wave magnitudes were group cd in to three classes based on
rel ative degrees of expos ure. B eaches ex posed to waves of
0.5 to 2.0 feet were considered to have a she ltered exposure;
2 -to 4 -foot waves occur on a beach with moderat e exposure;
and waves more than 4 fcct occur on a severely exp osed
beach. Generally, 0 .5 -foo t waves will move silts and sands, 2 -
foo t waves will move gravels, and 4-foot waves will mo ve
cobble-sized materials . The wavc hindcasts used for compu -
tati o n o f the wave height roses represent statistical means of
long -term wind d ata collated on an annual basis. Short-term
(less than 24 hour duration), high intensity storm systems and
the max imum wave heights they can ge nerate, canno t be
shown graphically at tru e scale on the wave height r oses be-
cause o f their short durati ons. Such d i sturbances, however,
due to their significant net effect loca lly on the movement of
beac h ma ter ials , were considered in th e vo lumetric calc ula-
tions of the alongshore littoral transport rates.
Littoral Drift Littoral drift is the movement o f loose
sedimentary materials along the beac h between the approxi-
mate line of breaking waves and a lin e above the high water
mark. The materials move under the influcnce of waves and
currents. The m aj o r portion o f mater ia l movement takes
pl ace between the low and high water lines , in the intertidal
zone.
Littoral Transport Direction The directi o n of littoral
transp o rt is depend en t on wind-gen era ted waves and cur-
rents, and to a lesser ex tent, up o n tidal currents. Rel at ive di-
rection s and magnitudes of littor a l tra nsport are indicated on
the ma p s fo r summer (May to October) and winter (Novem-
bcr to Apri l). Material is moved a l ongshore, o nsh o re , and
offshore to points of deposition beyond the reac h o f influenc-
ing wave a nd current action. Thus , it may accumulate (ac-
crete) la ndward above the high tide level , or seaward, in the
form of a bar and/o r a t a water depth where bottom motion of
waves is no long er effective as a tra nsport medium. Influenc -
ing f actors, including win d durati o n, magnitud e and directio n
(w h ich gene rate waves), and tidal period plus e le vatio n , vary
with tim e and season. Beach growth or loss, th er efo re, is best
measured through observ ation over a period of time long
enough to dctcrmine n et effects (Figure 3).
Alongshore Littoral Transport Rate Alongshore littoral
transport rates of unconsolidated sediments in terms of vo-
lumes o f material passing hy a given s ite are largely a func -
ti on of the kinetic wave energy of water in the intertidal zone
and of the type of sediment a vaila b le a t a particular shore
corrido r. T o obtain ac tual figures , these rates should be di -
rectly measured in the field over a period of time. [n order to
determine long -term trends, they s hould be compared with
information which reflects historical changes, such as time
sequen ce ae rial ph o tographs , beach s urveys , previous dredg-
ing , and hi storical records. The high cost and extensive field
effort required by these methods along 2,300 miles of coastal
zone, howev er, are beyond the scope of this Atlas . Therefore,
an indir ec t method of es timating littoral transport volumes
was used. Readily access ible data o n wind direction, speed,
durati o n and fet ch length has been a nal yzed , to gether with
field o bservations on types of inte r tidal and beach sediments ,
degre e of exposure, and beach topography. From this infor-
mation , wave energy available to move littoral m ater ials was
computed and then the relative directi o n and magnitude of
potential alongshore transport of medium sand (in cubic
yardS per seasonal six month peri od) is displayed o n thc
maps. Beaches or bluffs that are protected by manmade or
natural armor may not have sediment av ailable for transport.
Lik ew ise, a bcach consisting o f bedrock usually does not
have s ignificant move ment of litt o r a l material s in s pite of se-
vere wav e ex posure , and a beach a rmored with cobbles may
undergo movement of littoral mat erials between 1/10 and
1/20 th a t indicate d for sand.
The compu tation s displayed in this Atlas are based o n the
assumption that beach material is sand and avai l able in suffi-
cient quantities to allow for unimpeded drift. A long se gment s
of predominantly fine sands and silts, drift volumes would in -
crease; they decrea se where coarse sands or larger materials
prevail.
Beaches Many of the beaches in northern Puget Sound
consi st o f a shallow veneer of sand or gravel over rock. The
sand veneer has resulted from both undermining o f cliffs and
breaking down o f rocks due to wave action. Between rocky
headlands , pocket beaches often occur bound landward by
sheer cliffs of roc k (Photo 14). During winter months, storms
rem ove most of the sand, cxposing cobbles and the un derly-
ing bedrock.
Depositional beach forms consist of berms (Photo 4), bars
(Ph o tos 7 and 8) and spits (Photo 6). These are created by
wave action and currents which tend to straighten the irregu-
lar shoreline, and which deposit loose sediment at accretion
termin als . Also , the backshore is frequently wide and rela-
tiv ely fla t. Erosional beach forms consist o f a narrow back-
shore characterized by the lack of berm s and o ften abruptly
bounded by steep , high banks or bluffs (Photos l , 2 and R).
The face of the fo re shore may also be steepened.
BEACH MATERIALS
Classification Diameter: mm (inches) Classification Diameter: mm (inches)
R oc k/B o ulde r more th a n 2Sl) ( 10) Sand 0.15 to 2
Cobble 64 to 256 (2 .5 to 10 ) Silt/Mud le ss than 0.15
Coarsc Gravel g to ()4 (0.3 to 2 .5) Mud less than 0.062
Fin e Gra ve l 2 to 8 (0.08 to 0.3)
Land Cover Classification Code Classification Description
623 Mar Mars h D e posits Sa lt or bracki sh water
63 1
632
633
634
635
636
637
638
R
Cob
MC
MM
MF
S
S-Mud
Mu d
Summer
Wave FrOn,\
Rock
Cobbles
Mix ed Coarse
Mix e d M edium
Mixed Fine
Sand
Sand/Sil t/Clay
Silt/Clay
Ph oto s 13 , 14
Photo 2
Cobbles, gravel a nd sand with occasiona l boulders
(Photos L 2, 3, 4 )
Grave l and sa nd a nd occasiona l mu d (Photos 3 ,
F in e gravel , sa nd and mud (Photos 2,4)
Photos 1,2 ,8, 10
Wi nter
/wave Fronl
10 , 13)
Relat ive Summe r D ri ft
SEASONAL SHORE ALIGNMENT
Figure 3
Beach materials vary from silt and clay in low energy a reas
(less than 2-foot waves), to cobbles along beaches subject to
high wave energy (g re ater than 4-foot waves). A typic a l
beach co nsists of a low flat sandy portion exposed only at low
tide, with gravel o r cobbles covering the upper beach as far as
Photo 14 Rocky environment of the Strait o f Juan de Fuca,
a typical example of a Class III submerged beach trapping
mixed gravel s to form a Class II (partial) pocket beach.
BARS
Figure 4
Tambalo
TaMBala
-----
BAYMOUTH
BAR
HOOK
Bay
Figure 6
Figure 7
.' . . " .....
the mean high er ti de line (Photo 9). The slope of the beach
face and the size of beach material are interrelated, and both
d ep end o n the exposure of of the beach. Beaches exposed to
high wave act ion are characterized by steep slopes covered by
coarse materials.
Along rocky shores such as those o f the San Juan Islands
a nd the Strait of Ju a n de Fuca, pocket beaches prevail where
sands and gravelS are trapped and removed from the adjacent
passi ng stream of littoral material s (Photos l3 and 14).
Where a beach berm is develop ed , it is usually low and
wide during the summer and becomes higher and narrower in
the winter as mo st of the sand moves offshore . This is caused
by seaso nal changes in wave action. Large winter waves de-
stroy a berm ; s maller summer waves gradually rebuild it.
Beaches can be classi fied according to suitability for re-
creational uses , based on extent of walkable dry beach during
high tide. A submerged bea<:h, including rocky shores with
vertical or steep backshore, is one that is never or is infre-
quently dry (Photos 5 and 14). A marginal beach is sub-
merged each tidal cycle, but narrow portio ns are dry much of
the time (Photos I, 2 and 8). The dry beach has an upland
berm which is infrequently submerged (Photos 4,9 and 10).
For recre ational purposes, a dry berm beach is the most de-
sirable b ut least frequent beach type occurri ng in Puget
Sound .
Intruded Beaches Humans have in truded o nt o beaches to
build such structures as docks, launch ramps, bulkheads,
roadways , causeways , bridges , jetties, and groins (Photos 10,
11 and 12). Many of these structures have served to: provide
various transportation and utility rights-o f -way; stabilize
heaches ; stabi li ze river mouth s or navigation channels ; form
building sites; and to provide protection for the uplands from
e ros io n. Overall, only a small percent of the shoreline is in-
trud ed, with most intrudcd beaches occurring in high popula-
ti on areas .
Intruded bea ches usually cause significant impacts on lit-
toral processes. Protection of uplands removes the major
so urc e of littoral mate rials, and structures extending into the
water interrupt the movement of littoral materials and often
reduce the amount of littoral materials available downdrift of
the structure.
ACCRETION TERMINALS
Littoral materia ls are depo sited when wave action and
wave -and tide-induced currents become too weak to move
the materials. Generally, the m aterials will form beaches with
alignments that are dependent on prevailing seasonal winds.
Material is stored at accretion terminals at the down drift end
of the sccto r (Figure 3).
Significant onshore-offshore transport also takes place
within the littoral zone due to seasonal wave action caused by
variations in wind direction and magnitude. Generally, mate -
rial is brought onshore during the summer and is carried
offshore during the win ter.
Littoral materials are stored naturally in accretion termi -
nals such as hook s (Photo 6 and Figure 7), barrier beaches
(Pho to 4), tombolos (Figure S and Photo 5), bay mouth bars
(Figure 6), spits (Photos 6 and 7), a nd the beac h itself (Photo
8).
Littoral materials can be temporarily removed from the lit-
toral zone by being deposited in dune areas o r as backs hor e
deposits (Photo 9). By wind and wave action they can be
reintroduced into the littoral zone and they can be perma-
nently removed from the littoral zone by being deposited into
submarine can yo ns.
Man has crcated artific ial accretion tcrminals by building
structures in the intertidal zone, such as groins (Photo 10),
jetties (Photo 11 ), and bulkh eaded fills (Photo 12).
BIBLIOGRAPHY
Ba sco m , Willard , 1964, Waves and Be aches, Double day and Co.,
Inc .
I ppen , A. T ., 1966, Estuary and Coasfline H ydrody namics , McGraw
Hill Book Co., New York.
Natio nal Weather Bureau, 196 9, "Wind Data," Climatological
Handbook , Columbia Basin States Me teorology C ommittee, Pacific
NW R iv er Basin Co mmission, Vancouver, Washington.
U . S. Army Coasta l Engineering Research Center. 1973, Shore Pr o -
feeli o n Manual , v. 1-3 , U.S. Government Printing OlTice , Washington ,
D .C.
Wiege l. R. L., 195 3, Waves. Tides. Currents. a nd B eaches, Council
on W a ve Researc h , The Engineering Foundation , University of Cali-
forni a .
4
Sand and Gravel Resources
The economics of the sand and gravel indus tr y are highly
complex, for a wi de variety of social as well as tec hnical rea-
so ns. Basic to many o f these reasons is that gravel is a heavy,
bulky, but relatively lo w value material. Thus , h andling a nd
transportation costs can easily match or exceed the base price
of the raw material. F o r this reason, the value of a sand or
gravel excavation de pends on its proximity to ma rkets , or on
the availability of ine xpe nsive transportation.
Urban and s uburban s prawl adds another e lem e nt of com-
plexity to the indu stry by covering some of the bette r located
and more valuable de pos it s, pressuring oth ers o ut of busi-
ness , and makin g some ncw oncs extrcmcl y d ifficul t to de-
velop. The characteristics of good drainage , ab se nce of
s hrink and swell problems, and the excellent foundation sta-
bility of gravel deposits often make these areas prime loc a -
tions for urban a nd industrial growth. The economic value of
a deposit as a use a bl e aggregate is, in these ins tances , over-
shadowed by the des ir e to locate development in s uc h areas.
Compounding the co mpl ex economic situati o n a re cos ts
and delays accompanying an increasing li st of reg ulati on s, lo -
cal ordinanccs, co urt decisions, and othcr r es tri c ti on s. Thc
net result of the se o ft e n interrelated fac tors is t hat industry
and local governments are faced with the p rob lem of provid-
ing for a growing population and subscqu ent urb an growth
with a diminishing supply of one of its prim e building materi-
als.
In furni s hin g in fo rmation on aggregate r eso urces, it was
beyond the scope of the Atlas to inven tory and evaluate every
available or potential deposit. In mo st cases, res o urce arcas
delineated are bas ed on the geologic ma p units contained in
the Atlas to inventory and are subject to the same limitations
as the geo log ic m a ps. For example, a unit designated as G2
(gravel o f inte rmediate quality) could ex hibit a fai rly wide
range of ph ys ica l properties or contain inclu sions o f entirely
different m at erial s not useable as aggreg a te . These materials
are usuall y too small to be mapped .
It wa s impractical to incorpo ra te loca l zon ing or o ther so-
cia-economic fac tor s into thi s rec o nnais sance of aggregate re-
sources. Therefore , certain depos its may well be cov ered by
urban , su burb an , or industrial development. Aggregate de-
posits covered by such devclopments no longe r represent
exploitabl e reso urc es . The user is referr ed to the Land
Cov e r/L a nd Use maps in making deci sions as to resource
availability. Similarly, beach depos its (often the highest qual-
it y a nd qu a nti ty type of aggregate) cann o t realistically be
co nsidered a potential so urce o f gra ve l or sa nd under existing
environmental laws.
Puget Lowland Sand and Gravel
Sand a nd gr ave l are abundant thr o ugho ut the Puget I ,o w-
land. H owever, for these to be us ed as resources , it is essen-
tial to kn ow their distribution and quality.
Coastal Flooding
The processes res ponsi ble for tlooding of marine shore-
lines individually o r in combination are extreme high tides ,
waves genera ted by winds , tsunamis of distant o rigin , and lo-
cally generated seismic wa ves or boils. They may a ppear
si ngly or in co mbin ati o n. I:ly far the most likel y a nd recurrent
form of coastal fl ood ing in Washington is by wind waves su-
pe rimposed o n e xtr e me high tides. Tsunamis of distant origin
are fairly in etfecti ve in da ma ging shore lin es o f th e protected
inland waters of Puget Sound, because thei r fo rc e is dimin-
ished by th e nar row a nd lo ng entrance th ro u gh the Strait o f
Juan d e Fuca. T sun am is ar e, however, an extre me haza rd to
the beach areas a long the open coast. A repo rt titled , Tsu-
nami Predictions for M Olllerey and San Fran cisco Bays and
Puget Sound , November, 1975, was prepared for the Federal
In surance Administra tion (F IA) by the U.S. Army Engineers
Waterways Ex per im ent Station in Vicksburg, Mississippi.
Another repo rt titl ed Ty pe 16 FLuud Insuran ce Study: Tsu-
nami Prediction for the We st Coast of th e Con tin ental United
Stales , will soon be released by the FlA .
PURPOSE
Access to the waterfront is a prime advantage in d eve lop-
ing low-lying shores. As a n e xample, hom es located on top of
bluffs afford spectacular views, yet without a dry beach at all
tidc levels, waterfront ac tivi t ies such as hoating o r beac h-
co mbing are limited. H ence, in tho se areas where wide, dry
backshores ex ist there will be increased press ure for develop-
ment. These sa me lo w-lying beac hes are most susceptibl e to
the processes whi c h ca use fl ooding. The de linea tion of these
a reas is thu s important in prcventing damage to any future
building a nd deve lopment.
In recognition of thi s a nd to encourage State a nd loca l gov -
ernments to adopt so und fl ood plain man age men t programs,
the F ederal In sura nc e Administration (PIA) of th e U .S. De-
partment of Housing and Urban Devel o pm e nt (HUD) is
presently conducting flo od in surance studies in tidal a nd
coasta l tlo od haza rd a reas . The Flood Ins ura nce studi es will
produce maps whi c h delineate areas subj ect to 100 -year
coastal fl ood ing. In areas presentl y su bject to development or
where dev elo pm e nt is anticipated in th e near future (detai led
study a reas) b ase flood el e vations to th e neares t foot will be
displ aye d. In other areas subject to fl ood ing (a pproximate
study a reas) base flood elevati ons will not be shown . I ,ocal
gov ernm e nt s will reg ulate development and building con-
struction based on this information. Snohomish County stud y
inform atio n w ill b e available in mid-19 79 , th e King County
stud y is completed , the City of Eve r ett st udy is completed,
a nd the I s land County inform ation w ill be available in 19 79.
Contact th e r espect iv e city and co unt y planning office s for
addition a l information. Further information a bo ut flood in-
surance studies can also be obtained from the HUD Federal
Insurance Administration Office in Seattle.
BACKGROUND
Along th e sho r elin es of Puget Sound, la nd forms frequently
pr o ne to coastal fl ooding are po ints, s pits, barrier beaches,
pocket beaches, a nd tombolos, a nd b erms in co njunction with
a low baeks hore . In these areas, acc r e ti o n is commonly in
progr ess or the s horeline, following a period of accretion, has
st a bili ze d produ c ing a backshore . Th e most significant fea-
ture of a wid e backshore is a naturally oc curring storm be!rm.
Under extreme conditions, storm waves supe rimposed on
high tid es can a lso ove rtop a high sto rm berm a nd even de -
stroy it. T he area lyi ng beh ind may t hen become inundated
by ri s ing sea leve ls ei the r in th e form of flowing or still wa-
ters. Hi gh still wa te r leve ls , although damaging contents of
hou ses o r flooding basements, are, in most cases not consid-
ered a ha zard by re sident s in th ese areas because, due to th e
po ro us nature of most shore se!dim en ts, standing water
quickly d isa ppears a s the tide drops . W ave d a mage or dam-
age as a res ult of flowing waters , however do es present a dis -
tinct haza rd to structure!s and real es tate in the coastal zone .
Generally , homes se t beh ind a be rm a re re lative ly pro-
tected unl ess ex tr e me high wave ac ti o n o r sto rm waves from
an abnormal direction breach and erod e the protective
sho re form. Once thi s barrier h as been lowered a nd is over-
topped, furthe r e ncroachm e nt may continu e even at less th an
Sand may be considered a "nui sa nc e deposit," be!cau se
many gravel extraction operations find it an undesirable by-
pro du ct. High yield gravel reso urces, o n the other hand , are
limit ed in many counties beca us e of varying quality and
erratic distribution. Highest quality gravels, which occur in
glacial deltaic deposits , are located only in a few place s. In
many a r eas of the Pllget Lowland, gravel operations must
r e ly o n limited supplies of thin glacial o utwash gravels , river
b ars , o r ex tremel y sandy depos it s with a gravel content of le ss
t han 15 to 20 percent .
In ot her areas, t he onl y available grave l resource ma y be
coated with iron oxides o r ma y co ntain a high proportion of
clay an d silt , forcing gravel pit o per ators to use extensive
washing o perations . Another common difficulty encountered
in gravel ex traction is the nec ess ity to strip and remove over-
b urde n to uncover coarse aggregate.
UNIT DESCRIPTIONS
Sand
SI Low Quality Sand has a high conte!nt of silt and cla y
or th e presence of oxidation effec ts (iron oxide staining a nd
p artially weathered clast s).
S2 High Quality Sand ha s a low content of si It and clay
a nd a relative absence of oxidation effects.
ext rem e water levels . Often , return to normal weather p a t-
te rn s will eve ntually a llow re building of th e berm, provided
ma n has not adversely altered the natural r estoration capac ity
of the shoreline (sec the chapte r o n drift Se!ctors for furth er
inform a ti on).
A g reater h azard exists to st ru c tures built on the berm .
They are subj ected to th e imm e di ate a nd direct force s of
sto rm waves . Wave damage to ho mes is mos t critical and
th erefore this form of Hooding rece iv es the greatest publi c at -
tention. Often associated with sto rm wave damage is the ad -
di t ion a l hazard posed to stru ctures by wave-tossed logs a nd
de bri s . Displacement of beac h material onto lawn s and drive-
way s can be a nuisanCe! although, except in extre!me! cases, it
d oes not present a seriou s pro bl e m.
METHODOLOGY
The coastal flooding survey for l sla nd , Snohomish , a nd
Kin g Cou nti es is primaril y of reconnaissance sco p e. The
a reas s ubj ect to coastal fl oodin g in these counties havc been
id entifie d a nd delineated on th e acco mpanying maps based
on ge ne ra l standards and criteria used in the survey.
Originally, a distinction was to be made between tlood ha-
zard a r eas with a one percent c ha nc e (I OO -ye ar frequency) of
fl ood ing during any year and areas f1oo de!d by an hi storic rec -
or d hi gh tide. These two catego ri es , co mbined with th ose
a reas subj ect to less than o ne pe rc e nt c hance , would ha ve dis -
tinguished three Ievds o f coastal flooding. Howeve!r , the ex -
tre me hi gh ti de occurring in Puget So und on Decembe r 15,
1977 , ca me within several te nth s of th e one percent (100-
year frequency) tide. For exa mpl e, th e tide registered 8.55
feet NGVD at Seattle, equaling the highest tide on reco rd.
Additi ona lly, it was 0 .1 feet high e r than the one percent
eve nt. The tides on tbis day we re very near or e xceeding the
record hi gh values for nearly a ll a reas. The result was the
combining or the one perce nt fl ood haza rd a n:a with the rec-
ord high tid e area on th e acco mp a n yin g maps.
The coasta l flooding information for Seattle and Sno hom -
ish a nd I s la nd Counties was gathered through personal com -
Critical Biological Areas
As a result of th e E ndangere!d Species Act of 1972 , the
Smithsonian In sti tution in Washington , D .C. has pro po sed a
list of rare, endangered, a nd threatened plant s pec ies within
the United States. The Washington Sta te Departme nt of
Game has id entifi ed those areas in the Was hington coastal
zone where exa mple s of these rare, endangered, or threatened
plants are kn ow n to ex ist.
In addition , an analysis of available biological information
was conducted to determine critical and important areas for
critical faunal s pec ie s . The! results of both studies cannot be
considered defini ti ve for a ll species and in a ll areas. The y
should, though , se rv e to a lert Atlas users that certain known
cr itical areas do ex ist a nd that these known areas are mapped
on the preceding Atlas pages . Work in th e a rea o f identifying
additional faunal and floral critical areas will continue and at
an appropriate time , be incorporated into revisions and sup-
plements to this Atl as.
Information contained in the following is not in te nded to
provide a comprehensive assessment of th e life history, dis-
tributional and habitat requirements of each s pecies. The De-
partment of Ecology has published more comprehensive as-
sessments of important biological species which are available
to the public. Further, th e Department's Baseline Program
has a considerable volume of quantitative inform ation by
5
habit a t ty pe for subtidal and int ertidal invertebrates and
nearshore fish. Some census data are ava il a ble for birds and
other coastal zo ne fauna.
CRITICAL FLORAL AREAS
The fol/o wing ar eas h ave been identifie d as known coll ec-
tion sites of rare, endangered, or t hreatened plant species
within W as hington's coastal zone. These loc a lities are based
on collection records contained in the University of Washing-
ton Herbarium. The specific siles n o te d should not be inter-
preted as being sy nonymous with Critical Faunal Areas
within W as hington 's coastal zone, primarily because botani-
cal information on that subject is much less complete. Efforts
are underw ay, both at state and federal leve ls , to gain more
knowl edge about the rare, endangered, and thre atened plants
throughout the state. Plant no mencla ture follows that of
Hitchcock & C ronquist, FLora of the Pacifi c N o rthwest ,
1973. Speci es a re derived from a modified proposed list
compiled at the Smithsonian Institution and published by thc
U.S. Depa rtment of the Interior.
Whidbey Island Tall peppergrass (Lepidium virginicum
L. var. menziesii (DC) Hitchcock) occurs at several locations
on Whidbey l sland. Previous collecti o n sites include the sand
dunes we st of Cranberry Lake, and beaches in the Langley
a nd Crockett Lake areas. Wh ile tall peppergrass is most fre -
quen tly e ncountered in th e beac h gra ss land community, it
ma y a lso occur in other supra littoral communities on sandy
substrate, e.g. sand dune , sa nd is land , vege tated spit. Prior to
a lter at ion , s uch areas throughout the county should be care-
fully inventoried fo r the prese nce of this species. The kn own
geographical range of this variety of tall pe ppergrass is Pug et
Sound to British Colum b ia.
CRITICAL FAUNAL AREAS
An a naly sis of information was conducted to determin e
criti cal an d important areas for 8 marine mammal, 80 ma rin e
bird, 8 1 fish , and 37 inverte bra te sp ecies . Each s pecies is
considered s ignificant either because it is commercially or re-
creation a lly important, or beca us e it is a known important
predator, competitor, o r food item to co mmercial or recrea -
tional s pecies . Time and tinancial constraints limited the
number of species that could b e exa mined.
The two critcria used for determining whether a particular
h a bita t was critical follow:
I. The area supports a population of a spt:Cies that not
o nly co n sistently reproduces itself but, because of favorable
environmental conditions (currents , water temperature, salin -
ity , etc .), provides the major source of recruitment for adja-
Gravel
Gl Low Quality Gravel has a high content of si lt a nd
elay, or the presence of o xid ation effects.
G2 Intermediate Quality Gravel is the most widely dis-
tributed gravel resourc e in the Puge!t Lowland. It ha s a lower
quality than high qua lity gravel (G3) because it s sa nd content
may exceed 50 percent. Silt and clay contents ar e rat he r lo w
a nd oxidation effects are infrequent .
G3 lIigh Quality Gravel has a low sand, silt, and clay
co ntent and oxidation effects are normally a bsent.
BSG t.:ndiffcrentiated Beach Sand and Gravel co nsi sts of
sand, pebbly sand, sandy gravel, or gravel found in s ho reline
beaches, spits, and to mbo lo s (c orresponds to Beach Deposits
(Qb) on Coastal Geology maps).
l J No Known Sand or Gravel Resources is m a pp ed
where there are no kn ow n sand o r gravel d eposit s or where
sand and gravel depos its a re less than five feet t hic k. This
corresponds to the cutoff fo r a mappable dep os it on the
Coastal Geology maps.
munieation with res idents, businesses, industries, a nd
a gencies who observed the high tide on December 15, 1977.
People remembered th e fl ooding from the se tides r e marka bly
well. The Federal Insura nc e Administration Flood In surance
R a te Map provided informa ti on for the! remainde r of t he
King County coastline.
The one perce nt tid e eleva ti o ns were determined fro m var -
iou s tidal bench ma rk s, based on thc a ss umpti o n that storm
e ffect s are nearl y id entica l between Seattle and the Puget
Sound region . Th ese sto rm e ffects are caused primarily by
pressure! systems and d o not include a greate r e levation due
to wave action. Th e ass umption was verifi ed during the D e -
cember 15, 1977, high tid es. On that day, the storm surge
(the difference betwee n th e predicted and o bse rv ed tides) ap-
p eared to be nearly co ns tant throughollt th e stud y a r ea. The
storm surge above th e high waler line at Seattl e for the 100-
year frequency was added to the high wa ter lin e at variou s ti-
dal bench marks throughout Puget Sound and was co nv e rt ed
to the National G eodeti c V e rti c al Datum (NGV D).
F Flood Hazard Areas include those lands with a n ap-
proximate one percent chance (IOO-year frequ enc y) of
flooding during a ny year and th e approximate area flooded
by the near histo ric reco rd high tide elevations observed on
December IS , 1977.
UF Areas subject to less than one percent chance of
flooding during any year ha ve not bee n st udi ed a nd may in-
clude undetermin ed but po ss ibl e flood hazards fro m e ith er
coastal or riverine flood ing. These area s ma y a lso be subject
to Hooding due to dra in age problems.
The maps also includ e th e approximate figures of th e wa -
ter surfa ce elevation for the 100-y ear frequenc y tide a nd the
record tide as observed o n D ecembe r 15 , 1977 . On the ac-
companying maps, th ese figures are indicat ed in boxes lo-
cated offsh o re from th e coastlin e they descri be.
cent areas or regions wh ose populations do no t co n sistently
reproduce themselves.
2. The area consists of a h a bitat type or types th at p rov ide
shelter, food , or oth e r e nviro nmental necessities during a
critical part o f th e s pecies' life history. For example, n esting
sites or shelter from pred a tors during early life hi s tory stages .
In addition, "important a reas" for certain bird sp ecies
have been identified. The approximate limits for both critical
and important areas a r e delineated on the accompan ying
maps.
Birds
Arctic Loon (Cavia arc tica) Common winter vis itor and
migrant, very common spring migrant (May) offsh ore a long
coast; feeds on fish in open water, major entrance channels,
and protected inside waters; important winter conce ntration
areas have been mapped.
Western Grebe (Aechmophorus occidentalis) Common
winter visitor and migrant ; large migrating an d wintering
flocks found in saltwater bays and inlets; feeds on fish a nd
rests in open water in major entrance channels, in si de waters ,
and protected harbo rs ; a r eas of extremely larg e winter con-
centrations have been mapped .
Whistling Swan (Olor columbianus) Fairly common mi-
grant, uncommon winter visitor; fOWId throughout saltwater
area during migration period; intertida l fresh and marine
plant eater; during winter utilizes saltwater shoreline of the
coast and in side waters, prefcrs protected area; large winter
concentrations and migration stagin g areas have been
mapped.
Western Canada Goose (Branta ca nadensis occiden-
lalis ) Uncommon migrant and winter resident; salt marsh ,
tide flat pl an t eater feeding on open waters of large estuaries,
coastal bays, tideflats , and salt marshes of inside waters; large
winter concentrations and staging areas h ave been mappcd.
Black Brant (Branta nigrican) Common migrant and
winter visitor, more common during spring migration; has an
almost exclusive diet of eelgrass; rests on open waters of
large estuaries and protccted harbors, sand and gravel is-
lands, s pits, undeveloped sand beaches and mudt1ats ; feeds
on eelgrass beds; co ncentration areas and stopover sites for
migra ting birds have been mapped.
Snow Goose (Chen caerulescens) Common spring and
fall migrant ; rests in open watcr over tideflats, salt marshes,
and estuaries; feeds on plants and animals in upland mead-
ows, lakes, and rivcrs; critical majo r wintering areas for mi -
grating birds have been mappcd.
Mallard (Anas platyrhynchos) Common migrant and
permanent resident to marine waters; feeds o n plants and ani-
mals and rests in sheltered waters over estuaries, protected
harbors, bays, fjords, mud t1at s, salt marshes, and along
sandy islands; critical major wintering areas for migrating
birds have been mapped.
Pintail (Anas acuta) Common fall an d spring migrant;
considered a winter resident in the San Juan Islands; rests on
open waters o f large estuaries and protected harbors ; forages
in tid e fl ats, sa lt mars hes , and nearb y meadows eating both
plants a nd animals; critical major winter concentration arcas
for migratin g birds havc been mapped.
American Wigeon (Anas americana) Common migrant
and winter resident; rests on open waters of large estuaries
and protected harbors; forag es in tideflats, salt marshes, and
nearby meadows eating plant material; cri tical major winter
concentration arcas for migrating birds h ave been mapped.
Canvasback (Aythya valisineria) Unco mmon migrant
and winter visitor; rests and feeds on both plants and animals
on tideflats, inlets , bays , estuaries, and protected harbors ; im-
portant and critical major winter concentration areas hav e
been ma pped.
Greater Scaup ( Aythya marila) Common migrant and
winter visito r in Puget Sound and a long th e Pacific coast ;
rests and fee ds on tideflats, bays, inlets, estuaries, and pro-
tected ha rbo rs , diving for plant a nd animal food; important
major winter concentration areas for migrating birds have
been mapped.
Common Goldeneye (Bucephala clangu/a) Common mi-
grant a nd winter visitor in sheltered waters of Pugct Sound
and a long coast; rests and feeds on tideflats, protected ba ys,
inl ets, estuaries, and harbors , diving for plant and animal
food ; important major winter concentration areas havc bccn
mapped.
Barrow's Goldeneye (Bucephala is/andica) Uncommon
to common migrant and winter visitor in sheltered waters of
Puget Sound and along coast ; feeds by diving ove r tideflats
and in protec ted bays , small estuaries, and particularly in
protected harbors, eating plants an d animals; important ma-
jor winter concentration areas have been mapped.
Bumehead (Bucephala albeola) Common migrant and
winter visitor in coastal areas and in Puget Sound; feeds hy
diving o n mudflats and in small estuaries, coves, and bays ,
cating plants and animals; rests in suitable sheltcrcd and shal-
low waters of small estuaries, cov es, bays, a nd harbors; im-
portant major winter concentration areas have been mapped.
Old Squaw (Clangula hyemalis) Uncommon migrant and
winter visitor to Puget Sound and coast; feeds by diving and
rests in deep open waters of large estuaries, protectcd har-
bors, and, in particular, major entrance channels, eating
marine animals; important major wint er concentration areas
have been mapped.
White-Winged Scoter (Melanitta deglandi) Common mi-
grant a nd winter visitor to open coastal and s heltered waters
of Puget Sound; feeds by diving and r es ts on mudflats, large
and small es tuarics , protccted harbors and particularly major
entrance channels and open coast, eating ma rine animals; im-
portant major fall and winter concentration a reas for migrat-
ing birds have been mapped.
Surf Scoter (Malanitta perspicillata) Common migrant
and winter res id ent in Puget Sound an d along the Pacific
coast; feeds by diving in open water of large and small es tu ar-
ies, protected and particularly the open waters of majo r en -
trance channels, cating marine a nimals; major fall migration
and winter resident a reas have been mapped.
Rhinoceros Anklet (Cerorhinca monocerata) C ommon
migrant a nd uncomm on winter resident to Puget Sound and
along the coast; common summe r resident; feeds on fish in
open watcrs of major entrance channels, over rcefs and cha n-
nels of inside waters, and in open waters of large estuaries;
nests in deep burrow s along steep banks of rocky islands;
breeding colony areas and important feeding areas during th e
breeding period have been mapped.
Great Blue Heron (Ardea herodias) Common perman ent
resident in coastal areas and inl and lakes and rivcrs of west-
ern Washington; feeds on fish and crabs in shallow waters
and tideflats of rocky and sandy islands , estuaries, sa lt
marshes, waters along sa nd y s pit s and jctties ; ne sts in colo-
nies onshore in tall trees near the water; a reas reprcscnting
known nesting colonics have been mapped .
Dunlin (Calidris alpina) Common spring and fall mi-
grant and locally abundant winter visitor to coastal areas;
most pronounced migration along coast, wintering popul a-
tions more common in Puget Sound; fceds on small beach an-
imal s and rests on sand and mud , tideflats , and in salt marsh
areas in es tuaries , bays and harbors of Puget Sound; sandy
tideflats are preferred feeding sites; important spring and
fall conccntration areas have been mapped.
Long-Billed Dowitcher (Limnodromus scolopa-
ceus) Common spring and fall migrant, uncommon winter
visitor to the coastal and inland marine waters; rests and
feeds on both plants and animals a long mudflats, undevel-
oped sandy heaches of Puget Sound, fine sediment beaches of
estuaries and on the Columbia River estuary islands; impo r-
tant spring conccntration a re as have been mapped .
Western Sandpiper (Calidris mauri) Common spring and
fall migrant, uncomm on winter visitor to coastal arcas and
Puget Sound; feeds on beac h an im als along mudflats, unde-
veloped sandy beaches of Puget Sound, fine sediment beach es
of estuaries and on the Columbia River estuary islands; im-
portant major concentration areas have been mapped.
Surf Bird (Aphriza virgata) Common spring and fall mi-
grant and winter visitor to coasta l waters of Puget Sound;
feeds on small animals along rocky s hores , reefs and gravel
beaches along thc coast a nd in Puget Sound; important mi-
gration a nd wintering a r eas have been mapped .
Black Turnstone (Arenaria melanocephala) Common
spring and fall migrant and winte r visitor along the ocean
coast; less common in Puget Sound waters ; feeds on small
marine animals (limpets, barnacles, and crustacean s) along
rocky a nd mixed coarse beaches, tidal flats, and sandy s pits;
prefers ocean jetties and rocky beaches; important major mi-
gration and winter arcas are mapped.
Northern Bald Eagle (Haliaeetus leucocephalus) Fairly
common per manent resident a long sa ltwater and inland lak es
an d rivers in western Washington; nests in large living trees
normally near the coast lin e; nesting begins in February con -
tinuing through July ; fee ds along most coastal shorelines of
Puget Sound and open coast on fish, birds, and upl and mam-
ma ls; a pproximate, yet critical, lo cations of bald eagle nest-
ing sites a nd importan t areas of particularl y large winter
populations have been mapped.
Fish
Lingcod (Ophiodon e longatus) Can grow to five feet in
length; are high trophic leve l predators ; prized SCUBA and
sport species in Washingto n; behavior pattern involves little
or no movement outside of spawing activities; adults feed on
herring, sand lance, flounder, hake , walleye pollock , cod,
rockfish, crustaceans, octopi, and other lingcod ; spawning
occurs in late winter and early spring, with mature females
mov ing from offshore areas to sh allow intertidal and subt idal
rock y/ke lp reef areas; males guard large egg ma sses which a re
adhesive and attached to crevices in rocky in tertidal and sub-
tidal areas or under boulders; known concentrations of
spawning adults are mapped as critical.
Pacific Halibut (Hippoglossus stenolepi,) Common deep
water sport and commercial fish; feeds on other fish , crabs ,
clams, squ id, and invertebrates; young mature in shallow wa-
ter and move deeper with age; commonl y found on sand or
fine sedimcnt bottom s ; major concentration areas have been
mapped.
English Sole (Parophrys vetulus) Most common com-
mercial tlatfish in Puget Sound; a n important sport fish; eggs
and larvae are pelagic (o pen wa te r) for a short period after
Land Cover/Land Use
A h ab itat inventory to use for evaluating the impact of
propo sed developments on the State's wildlife has not been
available for Washington's coastal zone. A habitat is an area
o r type of environment in which an or ganism or biological
population normall y lives or occurs. One way of compiling
habitat information is to map land cover and land use . That
information combined with knowledge of the relationship be-
tween vegetative cover and fa un a l h ab itats allows biologists
to inter pret locations and ranges of animal species. When the
land use/land cover inventory of Washington 's coastal zone is
complete, such an interpretation will be made and presented
as a supplement to this Atlas.
In addition, it will bc possible to quantify ccrtain land
cover classes at the county, regi o nal , or state levels. Becau se
the data set is in digital form , it is poss ible to calculate the
coverage of any given class, thus establishing degree o f rarity.
If a proposed development would damage vegetation which
sustains one or more animal species, planners could evaluate
the faunal impact of the dev elopmen t. If the land cover were
shown to be unique or rare , upon automated analysis of thc
data, planners could act accordingly to preserve it.
The classification system employed in generating this in-
ventory was derived from a combination of schcmes and was
modified on the basis of field experience . By categorizing
from the general (two-digit delinea ti on) to the specific (four-
digit delineation), the detail of a particular land cover type
sh ould bc casily discernable by its numeric identifier. As an
exam pl e, number 6 refers only to wetlands; 62 indicates
vegetated , nonforested wetlands; 628 is [or kelp; and 6282
refers specifically to dcnsely growing kelp.
It is hoped that the maps will be used in conjunction with
the wildlife descriptions, as they become availablc. Using the
maps alone will redu ce the utility of the land cover/l and use
inventory.
Caution is adviscd that the word 'habitat' is not synony-
mollS with the term 'land cover type.' A particular land cover
type may be only a portion of the habitat for a given species
or, conversely, it may contain habitats for several spec ies
within its boundaries.
1
Urban-This is the general classification for dcvcloped areas
and includcs residenti al, industrial, tra nsportation, and re-
creational areas, either existing or under construction. It has
been used for all urban areas except thosc with value as wild-
life habitats; in such cases a two, three or four digit identifier
will be used , but in all of these the first digit will bc 1.
11 Residential-Includes tho se areas containing dwellings for
human habitation and adjacent lands obviously associ-
spawning occurs; upon metamorphosis to the typical flatfish
shape, the young se ttl e and/or migrate to shallow soft bottom
areas of estuari es and bays; eelgrass beds are a lso important
habitat arcas, found in the intertidal zone or deeper; feeds at
dawn a nd dusk o n clams, clam necks, marine worms, small
crustaceans and othe r small inver tebrates ; shall ow soft-bot -
tom estuarine areas serve as nurser y grounds for juvenile sole
during thcir fir st year of life; significant nurser y areas are
mapped as critical.
Starry Flounder (Platichthys stellatus) An impo rtant
commercial and sport fish in Washington ; usuall y a sh a llow
water (less than 25 fat homs) t1atfish noted for a wide toler-
ance of bottom types and sa linities; prefers soft-bottomed
b ays and estuaries; feeding is apparently water temperature
dependent, mos t intense during the warm season and decreas-
ing or ceasing during the coldest months; feeds on crabs,
shrimp , marine worms, clams, and other small fish; spawning
occurs at s hall ow depths during late winter a nd early spring ;
known areas o f congregating s pawning adults and subsequent
large concentrations of eggs and larvae are mapped as criti-
cal.
Pacific Cod (Gadus macrocephalus) This schooling spe-
cics is an important com me rcial and sport fish in Washing-
ton; congregatcs for spawning in shallow waters and
baymouths or narrow passages during winter a nd disperses
for fee ding during spring ; spawning activity a long ex posed
ocean bcaches may vary; feeds near the bottom on worms ,
crabs, mollu scs, s hrimp , herring, sand la nce, walleye pollock,
and flat f ish : known s ha llow wa ter s pawning ad ult concentra-
tiom; and s~bsequent large concentrations of eggs and larvae
are mapped as critical.
Pacitic Hake (Merluccius productus) An open water,
schooling s peci es; has pote ntial commcrcial importance a nd
is a negligible sport fish in Washington; found offs ho re usu-
ally in deeper water (25 fathoms or more); feeds primarily
bctwcen twilight and darkness on euphausids and sand lance
and to a lesser extent on herring, s melt, anchovy , and s hrimp ;
apparently exhibits local seasonal migration in and around
Puget Sound; concentrates at specific sites during spawning
periods, usually winter and spring ; offshore spawning areas
arc mapped as critic al.
Longnosed Skate (Raja rhina) Of minor commercial im-
portance; wide distribution in shallow to moderate depths;
pr efers mud/sand areas; eggs may be deposited any time of
ycar in shallow waters; nursery generally located in shall ow
fi ne sediment or muddy ee lgrass areas; fceds on bottom
dwelling in ve rtebr ates and sma ll fish; ar eas of notably large
conccntrations have been mapped.
American Shad (A losa sapidissima) Introduced from the
Atlantic Ocean as an anadromous species; they spawn in
lower rcaches of larger rivers at night in late spring but are
not established in a ll river systems; food in open water feed-
ing grounds consists mainly of crustacean plankton; young
shad use estuaries a nd bays as nurscry a rcas before e ntering
o pen water. Habitats are unique since they establish runs in
very few selec ted rivers. Marine and est uarine habitats asso-
ciated with these larger river systems usually have low gradi-
ents in lower reaches; wlique a nadromous es tu arine/river sys-
tem habitats used by shad have bcen mapped.
Pacific Herring (Clupea hare ngus pallasi) Significant
foo d item in the diet of ot her fish species and sea birds; win-
ter a nd early spring activ it y for mass spawning; spawn ing ac -
tivity occurs in lower int ertidal and shallow subt id al; annu al
migrations from in shore spawning arcas to open ocean fecd-
ing grounds; Pacific Herring eggs are adhesive and larvae
become pelagic th e reafter; foo d consists of copepods, eu-
phausids, and larger zooplan kton ; spawni ng sub strates are
primarily eelgrass and algae beds; larvae and j uv eniles are
found in shallower waters of bays and inlets; ad ult s feed in
offshore open waters; spawn ing grounds which are generally
u se d consistently from year to year have been mapped as crit-
ical.
Surf Smelt ( H ypomesus pretiosus) Numerous local races
exist in Puget Sound, the Straits of Juan de Fuca, and the
outer coast of Washington; important local commercial and
recreational species; individual spawn ing periods for specific
races vary from May through March and occurs at specific
beaches; do not die after spawning; normally spawn at high
tide in evening or early morning; beyond egg stage, surf smelt
become pel ag ic , with schoo ling adults segregated by sex; food
consists of a wide variety of copepods, amphipods, molluscs,
larvae, apendicularians , and marine worm larvae ; apparently
not habitat specific except during spawning when beach rc-
quirements are specific; fine gravel beaches where surf action
is not excessive yet ample enough to aerate eggs are selected
by Puget Sound spaw nin g stocks; outcr coast stocks use sub-
strate of similar size but which experience heavier wave ac-
ated with dwellings such as yards, gardens, small
pastures, and outbuildings.
111 Nonwooded Residential-Areas with low density
hou sing (fewer than two dwellings per acre), usually
outside incorporated comm unities. Natural cover is
replaced primarily with horticultura l plantings .
112 IIigh Den sity Residential-Areas with high density
housing including single and multi-family u nits as
well as neighborhood services.
113 Wooded Residelltial -Well wooded areas with low
dcnsity housing (fewer than two dwellings per acre).
The natural cover is minimally a ltered.
12 Commercial/Ser'l'ices-Includes areas developed for com -
mercial or public service purposes.
121 Business/Go'l'ernment-Includes government offices
and facilities, retail outlets, and private office build-
ings. Lsually occurs in business areas of population
centers.
122 Commercial/Light Industrial -Mixed comp lex , in-
cluding small manufacturing buildings with com -
mercial sales , storage buildings , and open storage
space.
123 Institntional-Developed for public service.
tion ; areas include sheltcrcd bays and coves or mouths of
tidal streams; spawning beaches of surf smelt ha ve been
mapped as cri tical.
The occurrence of Sockeye Salmon (Red) on map page IS
7 B is inc orrect. All othe r species listed for Penn Cove apply
as mapped.
Invertebrates
Spot Shrimp (Pandalus platyceros) This is the largest
shrimp species in Washington; significant recreational and
commercial species; normal spawning occurs in the fall and
eggs hatch in early spring; occupy a wide range of depths, 12
to 800 feet; shallowest depth occupied in first 8 -10 months of
life and d eeper depths used before and after that time ; shows
daily vertical mi gration , moving d eeper during the day and
s hallower a t night; this species is apparently unique in using
rocky and mud sub strates as its primary habitat, usually
found in assoc iation with a significant break of slope; feeds
on worms, detritus, and other small c rustacean s; s ignificant
known concentration areas are mapped .
Dungeness Crab (Cancer magister) Mo st important com-
merci al and recreational crab s pecies in W as hington; is a
shallow, o pen water species (0-330 feet), and lives in near-
shore areas most or a ll of its life ; prefers san d bottom/eelgrass
areas; adults mover to shallow water in spr ing to hatch larvae
and move to deeper waters in winter; tidal flat areas of bays
favorcd as significant molting, mating, and nursery grounds;
feeding is mostly nocturnal and reduced in w inter ; food is de-
pendent on crab's location but includes shrim p, small crabs,
barnacles, amphipods, pieces of clam, worm, or fish; only
known s ignifi cant concentration areas are mapped.
Eastern Soft Shell Clam (Mya arenaria ) Possibly intro-
duced from the Atlantic Ocean in the 1800's, conflicting evi-
dence suggests they are native; cons idered e uryhaline, capa-
ble of living in brackish waters at freezing tempcratures;
typi call y found in substrate mi xtur es of sand a nd mud , or
mud and gravel, where sal inity is r educed by the influx of
fresh water from streams or seepage; primarily intertidal but
is also located subtidally ; one of th e high est intertidal clams;
usually 8-10 inch es below the substrate surface; some com-
mercial concentrations found in marine waters through Puget
Sound and in the Pacific Coast estuaries; spawning usually
occurs in su mm er; s ignificant concentration areas are
mapped as critical.
Octopus (Octopus dofleini) A recreational and commer-
cial species that can reach a weight of 100 pounds; reproduc-
tion apparently occurs in spring; during incubation period,
eggs are tended by the female who apparently dies before
they a re hatched; some seasonal migration re ported, move-
ment to shallow waters (less than 50 feet) in winter and to
deeper waters (l00 feet or mor e) in the spring; s pecies mostly
active at night a nd feed nocturnall y on crab, f ish, clams, and
other invertebrate species ; occurs in the inte rtidal zone hut
primaril y frequents subtidal arcas; a rough rocky substrate
with caves, crevices, and other hiding areas for s helter during
the daylight hours is a common habitat requirement large
population concentr atio n s are mapped as critical.
Pacitic Pink Scallop (Chlamys hastata hericia) This scal-
lop species is capable of limited movement in short bursts,
primarily an escape mechanism; usually fou nd from the low
intertidal a reas to depths up to 800 feet; prefers deeper wa-
ters wi th a mixed gravel/shell substrate; a recreational species
and potential comme rcia l species; confi ned a reas of limited
population mapped as crit ical.
Rock Scallop (Hinnites multirugosus) T his scallop is
uniqu e from other scallops in that it firmly a ttache s itself to a
solid rock substrate by its right valve; found from the very
low intertid a l zone to depths up to 200 feet; juveniles of this
species are free swimmi ng ; adults a tt ach themse lv es to roeks
after reaching a shell size of one inch in length; significant re-
crcational species ; confined areas of limited population
mapped as critical.
Pacific Oyster (Crassostrea gigas) Originally importcd
from Japan aronnd 1905; a significant commercial and re-
creational s pecies; is the mo st prolific cultured oyster in
Washington; commercial beds are periodically restocked
with "seed" during spri ng ; tolerates areas of low salinity,
usu ally in estuarine areas; reproduces naturally to a limited
extent in certain Washingto n marine waters; s pawning is
tcmpcrature dependcnt ; su bject to heavy predation by the oy-
ster drill (a snai l) and is quarantined in some areas; signifi-
cant culture areas are mapped ; some of these areas are also
significant to the free swimmi ng larval stages of t hc oystcr
under natural propagation, which are essentia l to co ntinu ed
supply of oyster seed for the entire Pacific Coast.
1231 School-All educational inst itutions and facil -
ities.
1232 Hospital-Incl ud es both public and private in-
stitutions which provide medical services.
1233 Cemetery-An open site usually including ex-
pansive areas of short grass interspersed with
trees and shrubs .
124 Resort/Hotel-Facilities providing lodging for
tourists, and their associated grounds.
125 Other-Other commercial services .
13 Industrial-Such a re as are usually, but not always , heavily
impacted by human structure and activities.
131 Light Industry -Small sca le production complexes
without commercial o utlets.
132 Heavy Industry-Large scale production of manu-
factured goods.
133 Petroleum/Chemical Processing-Facilities involved
in processing crude oil or chemicals.
134 Food Processing-Installation s whose function is to
process food , such as vegetable cann e ries .
14 Transportation/Utilities-Arcas used for transportation
purposes, or utilities (p ower and water) which have an
6
--------------------------------------------------------------------------------~----~------------------~----=-----~------~--~~~~.
important impact on wildlife or wildlife habitat and are
of sufficient size to be mapped.
141 Airport-Areas used for aircraft take-off and land-
ings; usually includes substantial cxpanscs of open
grassland
142 Ferry Service-Ferry landing facilities; usually in -
cludes substantial numbers of pilings and parking
facilities.
143 Highway-Major thoroughfares with associated
median strips or cleared roadside areas.
144 Railroad-Railroad rights-of-way and associated
disturbed areas.
146 Bridge-'v1ajor bridges.
147 Power Line and Right-of-Way-Areas cleared for
power lines, substations, and associated rights-of-
way.
148 Water Treatment and Storage-Sewage treatment
plants and associated treatment ponds, as well as
water supply facilities.
149 Other-Other utility or transportation facilities, such
as radio towers.
15 Port-Facilities located along the shordine and/or extend-
ing beyond the shorcline which are used for servicing
commercial and recreational watercraft and for relatcd
commercial activities; includes those construction fca-
tures necessary for protected moorage.
151 Commercial Cargo and Shipping-Designates piers
used for large scale commercial shipping operations
and shore facilities.
152 Marina-Moorage areas for public or private use
generally consisting of multiple piers or docks and
related service facili ti es.
153 Log Storage -Commercial log raft storage facilities.
155 Dike-Structures used to control water flow for the
purpose of tlood or erosion prevention or for main-
tenance of a navigable waterway.
156 8reakwatt:r-Protective devices, usually built
offshore, and used to prevent beach, bluff or shore
erosion as well as for protection of navigational
areas from adverse wave conditions.
158 Pier -Structures used for providing access to wet
berthing areas, usually in connection with o ff load-
ing of commercial vessels. Most piers are supported
by wood or metal pilings.
16 Construction -Areas undergoing a change in land use due
to the development of some type of structure.
161 Residential Construction-Areas being developed
for single family residential usc.
163 Industrial Construction -Areas under construction
for siting o f industrial complexes , such as factories
and large warehouses.
17 Extractive-Areas used for mining activity.
173 Sand, Gravel, or Clay Extraction-Mining opera-
ti ons which produce sand, gravel, or clay for com -
mercial purposes.
175 Abandoned Mining Operation-Mining operations
no longer in use but in which the natmal vegetation
has not reestablished itself.
18 Open Land-Areas in which vegetative cover has been
stripped away or buried as a result of human activity.
181 Scraped Area-Areas with the vegetative cover re-
moved by bulldozing o r other means.
182 Dredge and FiII-Those intertidal or upland areas
used as disposal sites for sediments dredged from
marine waters. Often used as development sites, and
original habitats at t he disposal sites are perma-
nentlyaltered.
183 Refuse Station -Designates sanitary landfills or gar-
bage disposal sites.
19 Recreation-Includes parks, camps, golf courses or small
woodlots within well-developed residential areas.
191 Park-Areas developed for urban recreational usage,
usually containing pl ayfie lds , grassy areas, and in-
ternal road systems as well as trees and shrub
plantings and areas of relatively undisturbed vegeta -
tive cover.
192 Golf Course -Areas developed for playing golf, usu-
ally consisting of expansive areas of short grass in-
terspersed with trees and shrubs.
193 Urban Wooded -Small areas of undeveloped land
within well-developed residential areas.
2
Agriculture-Inc ludes th os e areas being used, or having been
recently used, for the production of food crops and maricul -
tme. It does not include forest crops.
21 Crop/Pasture-Cultivated, mowed, or grazed land usually
occurring on flat to gently rolling slopes with good mois -
ture regimes. Agricultural usage may change on an an -
nual basis due to crop rotation.
211 Row Crops -Cultivated annual or perennial crops
raised in rows, e.g. corn, strawberries.
212 Field Crops/Pasturc-Cultivated or noncult iv ated
l and supporting crops of grain, alfalfa, grass hay,
etc ., or grazed by livestock.
213 Other-Other agriculture.
22 Orchard/Vineyard/Nursery-Those lands supporting
trees, shrubs, or vines used for agricultural purposes.
221 Orchard-Trees cultured for the harvest of fruits,
nuts, and ornamental foliage.
222 Vineyard-Areas devoted to the culture of
grapevines.
223 Nursery-Sites where plants arc grown for commer-
cial sale, transplanting, or experimentation.
23 Mariculture-Includes those areas used for intensive cul-
ture of marine plants or animals. In Washington the most
common types of mariculture are salmon, clam and
oyster culture. Future maricultural effort will likely be
focused on algal and mussel production,
231 Oyster and CianI Culture-Intertidal areas used for
culture of Pacific and Olympia oysters, or clams
(particularly littleneck and butler clams).
24 Inactive Agriculture-Includes agricultural fields left for
a period of time and undergoing a process of invasion by
7
3
a variety of plant species such as shrubs and broadleaf
trees. Such fields can be diff erentiated from grassland by
their straight boundaries.
Nonforested, Vegetated Uplands-Areas covered by grass or
shrubs which may include bluffs and riparian vegetation not
contiguous with forested areas.
31 Grassland-All open, ungrazed upland areas with grasses
as their dominant vegetativc covcr. Woody species are
not present. This vegetation type occurs on a variety of
substrates and under various environmental regimes.
312 Beach Grassland-Strands of beach or dune grasses
closely associated with sandy or cobbled substrates ;
partially protected from high winds, sail spray, and
sand blasting by drift log barriers. Dune grass
(Elymus moltis) and Mirram grass ( A mmophila are-
naria) are usually present in association with a wide
variety of other herbaceous plants. These areas are
considered upland hecause they are rarely inun-
dated.
313 Open Grassland-Usually natural grassland occur-
ring on deep soi l, frt:quently adjacent to rock
outcrops. Dominated by grasses and forbs, but may
have scattered low shrubs.
32 Shrub -Upland areas in which the dominant vegetative
cover consists of woody perennials up to 20 feet in
height. Shrub -dominated communities often represent a
stage in regenerati ng forest.
321 Successional Shrub -Disturbed areas undergoing a
series o f changes in plant types as they mature to-
ward their previous climax type of vegetation. This
process is referred to as plant succession. Transi-
tiona communities dominated by shruhs during this
succession are included in the category. Blackberry
(Rubus), currant or gooseberry (Ribes), Oregon
grape (Berberis), huckleberry (Vaccinium), ocean
spray (HolodisClIs), elderberry (Sam.buClAs), and
wild rose (Rosa) are often present.
322 Coastal Shrub-Shrub communities restricted to the
Sitka spruce (Picea sitchensis) zone , usually forming
a border between the upper level of drill logs and
the spruce canopy_ The substrate is typ ically sandy.
Salal (Gaultheria shallon) and huckleberry are typi-
cal co mponents o f the vegetation.
33 Riparian-Delineates those upland types which are adja-
cent to and directly influenced by streams o r standing wa-
ter. The associated vegetation is dominated by willow
(Salix spp.), coLlonwood (Populus triciJocarpa), alder
(Alnus ruura), western red cedar (Thuja plicata), red
stem dogwood (Comus sioionifera), and snowberry (Sym-
phoricarpos alba).
331 Shrub-Refer to class No. 32.
34 Bluff-Steep to moderate slopes of varying substrate are
classified as bluff. Other bluff classifications are fo und
under the appropriate land cover types, e.g., a forested
bluff (47) is typed under Forested Uplands; a nonvege-
tated bluff is typed under Bluff (76).
341 Grass-Refer to class !\o. 31.
342 Shrub-Refer to class No. 32.
4
Forested Uplands-All upland areas in which tree species
form a complete or partial canopy or arc dominant in a ma-
trix of grass, shrub, or exposed rock.
41 Coniferous Forest-Forested lands in wbich the canopy is
composed of at least 70 percent coniferous species. This
vegetative cover type is extremely diverse in the Pacific
Northwest and contains a complex of constituent plant
communities. Species commonly encountered in the ca -
nopy of a coastal coniferous forest include DOLlgias Fir
(Pseudotsuga menzi esii), western hemlock (Tsuga hetero-
phylla), western red cedar (Thuja plicata), Sitka spruce
(['icea sitciJensis), and grand fir (Abies grandis). Depend-
ing on the age of the stand, there is usually a rather defin-
itive subcanopy, shrub layer, and ground cover associated
with coniferous forest. This is climax vegetation in the
Pacific Northwest.
411 Coniferous Forest-Regeneration-A regenerating
forest in very early stages; individual trees [[Jay be
up to fourteen years of age. Introduced herbaceous
species are often interspersed with the conifer sa-
plings because of the open canopy.
412 Coniferous Forest-Pole Stage-A class following the
regeneration stage and preceding the second growth
s tage (4 13). The tree age and size may vary between
sites.
4121 Pole Stage/Successional Shrub-A mixture of
pole stage conifers with successional shrub, a
transitional phase.
413 ConiferolJs Forest-Second Growth-An age class fol -
lowing t he pole stage and preceding old growth
(414); usually characterized by an open canopy,
dense subcanopy and understory.
414 Coniferous Forest-Old Growth-An age class in
which individual trees are approximately 1')0 years
or more; characterized by unevenly aged stands and
high species diversity.
42 Broadleaf Forest-This forest typc consists primarily of
broadleaf species (70 percent or more of the canopy).
Regenerating conifers in the subeanopy are typical of the
broadleaf forest. A diverse ground cover may be present.
Characteristic species of this vegetative type include
alder, black cottonwood, willow, maple (Acer spp.),
choke cherry (Prunus emarginata), and Pacific dogwood
(Comus fwltallii).
421 Young Broadleaf-An age class consisting of decidu-
ous tree species less than or equal to 40 feet in
height.
422 Mahlfe Broadleaf-A forest age class greater than 40
feet in height with a well-developed subcanopy and
ground cover present.
43 Mixed Forest-Areas in which both broadleaf and coni-
ferous species are present but neither dominates is re-
ferred to as mixed. Constituent species are those typical
of both coniferous and broadleaf forests.
431 Immature Mixed-Comprised of individual trees
forty feet or less in height.
432 Mature Broadlear/Old Grow1h Conifer-Both vege-
tative types are present but neither dominates.
433 Second Growth Mixed-A canopy of second growth
conifers and broadleaf species , usually with a dense
subcanopy, shrub layer, and ground cover.
44 Open Woodland-Contains a variety of trees with scat-
tered individual plants not forming a eanopy _ These areas
usually support a diverse ground cover of grasses and
other herbaceous plants. Open woodland types often oc -
cur on dry, ex po sed sites.
443 Conifer/Exposed Rock-Individual trees are usually
scattered among a rocky matrix with as much as 30
percent exposed rock present. This combination is
characteristic of shoreline promontories where se-
vere weather conditions and irregular contours pre-
vent the rapid accumulation of soil.
445 Mixed Forest/Exposed Rock-Similar to 433 above
but trees arc not as dense; both coniferous and broad-
leaf species present but neither dominates .
45 Disturbed Forest-Forested areas which have been
severely altered or destroyed by natural events or human
activities and have not had sufficient time to regenerate
are considered disturbed. This classification excludes ur-
ban wooded areas and farm woodlots.
451 Clearcut-F o rmerly forested land which has been
logged with none of the original fores t remaining
and on which regeneration has not begun.
453 Selective Logging-A logging practice which results
in a thinned canopy and much disturbance to the
shrub layer and ground cover.
454 Grazed Forest-A canopy of no particular density
but with a rather uniform grass ground cover that is
gra7.ed by cattle on a regular basis.
46 Forested Riparian-Refer to 33.
461 Coniferous-Refer to 41.
462 Broadleaf-Refer to 42.
463 Mixed Forest-Refer to 43.
47 Forested B1uff-Refer to 34.
471 Coniferous-Refer to 41.
472 8roadleaf-Refer to 42.
473 Mixed-Refe r to 43.
5
Water-Both marine and freshwater habitats are considered
in those classifications in which water is the principal me-
dium.
51 River/Stream -Running water habitats are distinguished
by a definite current which varies greatly with valley
shape and other geohydraulic features in different
streams and in di ffere nt segments of the same stream
course. W o lf Bauer 's geohydraulic river zone classi f ica -
tion system has been followed to characterize stream se g-
ments. All streams distinguishable on aerial photographs
are included. No separations of stream types has been at-
tempted based on average or annual stream flow, except
for seasonally active streams. Map scale constraints often
prohibit accuratc depiction of stream course borders;
therefore, running water habitats are not always sepa-
rated from associated riparian habitat. When this occurs
the running water may not be identified separately.
511 Estuarine ZOlle-Strongly influenced by the marine
environment a nd can be distinguished by a branch -
ing channel pattern in a broad, flat valley. The
stream channel gradient is near zero feet per mile
with the result that weak currents deposit silt and
mud in the stream bed.
52 Lake/Pond-Permanent standing water habitats are nu -
merous in the recently glaciated Pacific -"Iorthwest. They
occur in local depressions of varying depth and mayor
may not contain emergent vegetation.
521 Lake-For mapping purposes, bodies of standing
water with a surface area greater than 20 acres.
Open water areas are relatively large compared to
nearshore zones and are the primary producing re-
gions for the la ke.
522 Inland Pond-Standing water with a surface area less
t han 20 acres situated at higher elevations than the
beach fringe or river delta. Ponds are typically shal-
low; therefore, the nearshore zone is an important
primary producing area.
524 Coastal Pond-Standing water of less than 20 acres
which is located along the beach fringe behind drift
logs and at the base o f shoreline bluffs. Coastal
ponds also form on river deltas when old stream
channels are b locked by levees or natural stream
course shifts.
526 Farm Pond-Created by damming a stream or
through excavation of basins by man. Stream water
is generally detoured around tbe pond or lhe pond is
formcd in a basin without permanent streamflow.
The intensity of management of these ponds will de-
termine their resemblance to natural lentic habitats
and the diversity of organisms present.
53 Reservoir-All manmade water storage areas identifiable
as sources o f water for domestic or industrial purposes
are included. These bodies of water will differ from natu-
ral lakes due to several factors, including basin geomor-
phology, controlled discharge and resultant fluctuating
water level.
54 Bay/Estuary-These moderately protected marine embay-
ments are commonly referred to as bays, harbors, inlets,
and coves. They have free connections with thc open sea;
wind and wave action is modified hy protective uplands
and freshwater inflow creates variable salinities. Bluffs,
beach substrates, marshes, eelgrass heds, and other inter-
tidal habitats associated with these emhayments are
greatly affected by upland, freshwater and marine influ-
ences and should be viewed as integrated communities,
not as individual habitat types. Examples include Dray-
ton Harbor, Skagit Bay, Skookum Inlet and Lynch Cove.
55 lmpoundment-Those portions of both marine and fresh-
water habitats isolated from marine waters by manmade
obstructions.
56 Lagooll-Highly protected brackish or freshwater embay-
ments formed when bars partially or completely close the
opening to shallow bays. Examples include portions of
Thorndyke and Vaughn Bays and Burley Lagoon.
561 Enclosed Lagoon-Completely enclosed lagoons
form when freshwater inflow is too weak to main-
tain a channel through the bar. Typical patterns in-
clude rapid siltation and vegetative succession,
which may lead to complete coverage by marsh
plants.
562 Open Lagoon-Partially enclosed lagoons are com-
mon, heing formed when freshwater inflow has
maintained a stream channel through bars formed
by alongshore deposition. Marsh and tidal Hats
cover much of the lagoon which is drained and filled
diurnally with tidal waters.
57 Slough-Blind channels along streams and narrow marine
inlets are included in this classification. They often result
from abandoned stream channels which, unlike oxbow
lakes and coastal ponds, have not been isolated from ad-
jacent water masses.
571 Freshwater Siough-Inlets along streams which re-
ceive back -up water from the main channel. They
arc similar to standing water habitats, but maintain
a more open connection with the parent stream.
Freshwater vegetation is typically associated with
the upland margin.
572 Marine Siough-Narrow inlets typically forming on
river deltas, which receive tidal back -up water and
very little freshwater runoff. Brackish and salt
marsh vegetation is common along the slough's mar-
gin.
58 Canal/Channel -Those waterways created and maintained
by dredging.
6
Wetlands-Designates those lands which are either covered by
water or strongly influenced by adjacent waters.
61 Forested Wetland -Lpland areas that have surface or
standing water during some portion of the year and are at
least partially forested.
611 Freshwater Swamp-Those areas which usually have
some open water (at least seasonally), relatively
dense, woody vegetation, and level terrain. Lateral
movement of water is impeded. Cedar and alder
swamps occur in the Sitka spruce zone. Snags occur
occasionally, and a dense shrub cover is associated
with the swamp margins.
612 Brackish Swamp-Areas with saturated soil or stand-
ing water, dominated by shrubs or trees, and subject
to occasional tidal inundation by salt or brackish
waters. Characteristic species include: Sitka spruce
(Picea sjlchensis), lodgepole pine (Pinus contorta),
red alder (Alnus rubra), sweet gale (Myrica gale),
and Nootka rose (Nosa nutkana).
62 Vegetated Wetland, Nonforested-That portion of the
wetlands which is nonforested but may be densel y vege-
tated, e.g., marshes, bogs, meadows, and intert idal areas.
621 Inland Freshwater Marsh-Low areas o r depressions
which contain standing water for all or a por tion of
the year, not under marine influence. Characteristic
vegetation consists of cattails (Typha spp.), sedges
(Carex spp.), bulrushes (Scirpus spp.), and other
marsh plants.
622 Coastal Freshwater Marsh-Similar in physical char-
acteristics to inland freshwater marsh except subject
to the more exposed, coastal environmental rcgime
and may be somewbat hrackish. The vegetation is
dominat ed by marsh plants.
623 Salt Marsh-A complex of plant comlllunities
strongly influenced by tidal ebb and 11 ow. Some of
the more prevalent plant species in Washington salt
marshes include picklewced (Salicornia spp.), salt
grass ({)islichlis spicata), arrow grass (Triglochin
maritimum), and jaumea (.laumea carnosa).
624 Bog-Composed of several plant communities asso-
ciated with a high water lab Ie and maintained by
high precipitation and low evaporation. Vegetative
cover is usually dense althe margins and may ex-
tend over the surface of standing water creating
"floating" vegetation. The standing water is o ften
acidic a nd usually has associated with it several spe-
cies of the heath family, such as labrador tea
(Ledum), salal (Gaultheria), and huckleberry (Vac-
cinium). Bog vegetation is usually sharply delimited
from surrounding vegetation.
625 Salt Meadow-Lsually adjacent to salt marshes hut
slightly higber in elevation. The vegetation receives
saline influence either from the presence of marine
sloughs or from salt spray. The greater soil depths of
the meadow supports taller marshes. A lkali grass
(Puccinellia), hair grass (Deschampsia), and creep -
ing bentgrass (Agroslis alba) are common salt -toler-
ant inhabitants of salt meadows.
626 Brackish Marsh-Characteristically forming at river
deltas, e.g., at the Nooksack, Nisqually, and Skagit
river deltas. The marine intluence is mediated by a
high volume of freshwater runoff. Dominant vegeta-
tion consists of sedges, cattails, bulrushes , and asso-
ciated grass species.
627 Seagrass -Vascular plants (i.e. related to terrestrial)
which grow in the marine environment. These
plants are more productive than many crops culti -
vated by man, and support a wide variety of marine
organisms. There are two major types of seagrass in
Washington , eelgrass (Zostera), and surfgrass (Phyl -
lospadix).
628 Kelp COllllllunity-The kelps are a group consisting
of any large brown algae (Phylum Phaeophyta)
which are often a conspicuous component of the
shoreline. Kelp is found where rock, cobble, or
coarse gravel substrates are present; and exists in
both the lower intertidal and shallow subtidal re-
gions. Due to its size it can easily be discerned from
aerial photographs and is mapped in both the inter-
tidal and shallow subtidal areas. The most conspicu-
ous are bull kelp (Nereocyslis), perennial kelp
(Macrocystis), and pompon kelp (PterygofJhora), al-
though honey ware kelp (Alaria), featber boa (Egre-
gia) and sugar wrack (Laminaria) may be included.
These latter kelps are more likely to be classed with
other algal associations. Refer to 629.
629 Other Algal Community-The numerous algal com-
munities present in intertidal areas are short bladed
and composed of green, brown, and red algal types.
Certain types may be separated on tbe basis of their
occurrence on selected substrate types and tidal
levels.
63 Beach Substrate-Beach substrates are a critIcal habitat
factor for marine plants and animals. More detailed de-
scriptions of various habitat classes will be produced as a
supplement to the the maps, and will discuss the biologi -
cal communities associated with the various substrate
types. Following the substrate number and classificatlOll
name is the letter designation ust:d in tht: Coastal Drift
maps to identify that particular substratc ty pc.
631 Rock (R)-Includes both sohd bedrock and boulders
which are too large to be constantly moved about by
wave or current action. Rock habitats are most
characteristic of high exposure areas (high degree of
wave or current action), although they also occur in
more protected environments. The occurrence of
tidepools in this habitat offers a unique microhabi-
tat. Rock habitats are generally characterized by an
abundant and diverse community.
632 Cobble (Cob)-Consists almost entirely of uniform -
sized cobbles (6.4-25.6 cm), with very little sand or
gravel present. The absence of smaller particles dis-
tinguishes this substrate from the mixed coarse class
(633), and results from high energy wave conditions
capable of moving even the cobbles. This biological
community IS characterized by a low diversity and
low number of organisms.
633 Mixed Coarse (MC)-Consists of cobbles, gravel,
and sand. AssoClated with moderate energy condi-
tions, but is occasionally found in lower energy
areas; in this case, there is often some mud present.
High diversity and high numbers of organisms are
associated with thIS habitat.
634 Mixed Medium (MM)-Includes beaches comprised
of coarse gravel and sand occurring together and
Glossary
<l.blatioll lill LLlo s ely consolidated rock debriS , l ormerly contained
by d glaCier, that accum ulated In place as the surface Ice wa s lem oved
by ablation
<l.ccrction Natural accretio n is the b Uildup of land, so lely by the
actIon of t he fOI ces of natuI e. o n a beach by depOSitIOn of water hor ne
or airborne mate l ials. Artificial accretion is a similar butldup of la nd
by a n aC I of man, such as the accretion formed by a groin. breakwate r,
o r bea,'h ftll deposited b y mechanICal means
Advance outwash St r<l trfled detrlfus (ch iefly sand a nd g rave l) re
moved or "washed out" durrng an advanCing penod from a glaCier by
meltwater streams and deposited in front of or beyond the terminal
moraine or the mar gin at a n actIve glaelel The coarse r matenal IS de-
pOSited nearer to the ice.
Aggregate Any of several hard , Inert. construction matenals (such
as sa nd , gra,el, shells. slag. crushed stone , or other miner al matena)),
llsed for Illlxlng wlth;1 cernentlllg or hltllTrllllOl1S mdt e lnd to form con
crete. mortar. plaster, etc., o r used alone as In railI oad ballast 01 In val-
lOllS man ufacturrng process es.
<l.gricuUural soil Unconsolidated ear th mate nals comprising that
palt of the grolllHI whIch h.t s heell modified th r ough time hy climatiC
and b iologic agents. Its lower limit is h a rd rock or mlnel al mattel de-
VOid o f roots 0 1 ot hcr mar ks o f biologic activity.
<l.i1l1viation The process of aggrada tio n or 01 butlding up 01 s ed l
ments by a stream along It s COUIse , 01 ofcovellng 01 filling;) sllrfilce
With allu,ium
Alluvium C lay , slit, sand, gravel, or SI milar unconso lidated detI 1-
tal m a terial depOSi t ed dllllll g cOIllP.-ildtlve ly r ecen t geu loglc (ITn e by d
st ream as a sorted or sem lsorted se diment In the bed of the st re am or on
it s flood plain o r dclta.
<l.nglc 01 repose The maxrmum angle of s lope at which loose , cohe-
sioniess matell a l wrll come to I est on a pde of slIllrlal matellal I hi S an -
gie is somewhat less than the s lop e angle at w hich s liding wil l be
inItiated
Appendicularian A I elatl ..... ely common marine zoop lankton . most
common at depth s less than 100 metres.
Aquiclude A body uf r e Llt"ely Imrelmeable lock that IS capable
of abso lblng 'A a t e r s low ly but functions as an upper or lower boundary
of a n aquife r and does not transmit ground wate r I apidly enough to
supply a well or s pring.
Aquifer A body of rock lhal contall]S sullicient sallil ated perm e·
ahle m a lerral to conduct glound watel and to yield economically Slg·
nlficant quant ities o f ground water to we ll s a nd sprin gs
Argillaceous PertaInIng to , compo:::.ed of. or cuntilliling clay size
pdrtlcles or c1.-IY IIll11el al s, s uch as an "argillaceous ore" in which the
gangue is main ly clay; espeCially said of a se d i ment (such as marl ) 0 1 a
sedimentary rock (such as sha le) containing an appreciablc amount of
clay.
Argillite A compact Iud , de r Ived e lth el flom mudstone (clay-
stone 01 Siltstone) or shale. that has undergone a some"hat higher dc -
gree of hardening t han is pr esent In mudstone c)r shale bur that IS Ie "
clearly laminated than shale
Kackshure That zone o f the shol e or beac h lYi ng between the
fOI eshore and th e coastli ne and ac ted upon by waves o nl y dUring s ever e
stor ms. It comprises the ber m or bcrms
Bank failure .... radure 01 I uptllle of d steep slope or Its face, usu-
;lIly c(J ns ls tlng oful1consolldated m atellal , that has been stressed be-
yond Its ultimat e streng t h thu s lIlitlating potential mass \..\Ias t Ing
Barrier beach ;\ SIngle , nanoVv , elongated s dTHll Hlge r ising
slightly "hove the high tide leve l and extendll1g genel ally parallel With
the shore. but separated from It by a lagoon.
Bathymetry The meaSlll ement of occan depths an d the charting 0 1
t he topography of the ocean nom
Kayrnou(h bar A bal extending pal tl y or entirely across t he mouth
of a bay.
Beach The zone of unconsolidated materia l that extends landv..ald
trom the low walel Ime to t he place where the I e IS a rllarked change In
matenal or phYSi og raphic form , or to the li ne of permancnt vegetation,
approximately the h igh water line. A beach Includes foreshore alld
back shore
Beach face T he section of the beach normally exposed to th e aellon
of the wave up rus h. thc foresh ore of a beach
Hf.'lrrin~ ('apacHy The loa d pel unit of a l ea \\thlch the ground can
safely support without excess"e Yield.
Bedding plane A planar or nearly pl a nar bedding surra~e Iha t vrSl -
bly se parates each successive laye r of stl:ltlfled rock (of the same 0 1 dif-
ferent lithology ) flam ItS p leced ing or follo"ing layer; a plane of de po·
sition. It often marks changes In the circumstances of deposition , and IS
often marked by partings, color dlfTer ellces. or both
Kcdrnck A general term for the lock. usually solid , that underlies
soil o r other unconsolidated . s uperfiCial material.
Berm A low, Impe rma n e nt , nearly horrzontal o r landward ·sluplng
bench, s helf, ledge, 01 narr ow t ell ace on the backshore of a beach,
formed of matel ial thrown up and deposited by storm waves.
Bluck slide A transltlunallandsllde In which the sl ide mass re-
mams essentially intact. mOVIng outward and downward as a unn , most
often along a preexlstmg plane ot weakness, s lll:.h as beddIng, fullatl()n;
JOint s, faul ls , etc. In con l rast to rotat io nal landslides. the various p oi nts
Within a displaced block slide landslide have predominantly maintained
the same mutual difference III clevatton relation to pOints outSide the
sltde mass.
Boil A chur nlng ag itati o n of water; espeCially at the surface of a
water bud y , slIch dS d flyer, s pring, or the sea.
Boulder A detached rock mass lar gel than a cobble, having a diam-
eter greater than 10 Inches (250 mm), being somewhat roun ded.
Breaker A sea surface wave t hat has become too stee p so that the
crest outraces the body of t he wave and collapses into a turbulent m ass
on s hore or over a f eef Of rock.
Breakwater An offshor e stl ucture (such as a mole , mound , wa ll. or
jet ty) that, by breaking the force of the waves, protects a harbo r, anchor-
age, baslll, beach , or shore area.
Bulkhead A stone, mud. wood, or concrete wall-like structure Pri-
marily designed to resist earth or water pressure, as a retaining wall
holding back the ground from sliding Into a c hannel or to protect a
shore from wave er OSIDi1
Buttress A pier constructed at right angles tn a lestrallllng wall on
those beaches consisting of essentially pure coarse
gravel. Mixed medium beaches occur along high en-
ergy shorelines. As with a cobble beach, the biologi-
cal community has low numbers of individuals and
101'; diversity.
635 Mixed Fine (MF)-Composed of fine gravel, sa nd
and mud. Usually occurs in protected areas but oc-
casionally in moderate energy areas, and is associ-
ated with a rich diverse biological community.
636 Sand (S)-Occurs in clthcr highly or moderately ex-
posed beaches. As a rulc, the more protccted the
beach, the finer the sand particles. Coarseness of the
sand greatly affects the associated biological com-
munity.
637 Sand-Silt or Muddy-Sand (S-Mud)-Fine sand and
silt fOlm a characteristic habitat in protected areas
such as bays and estuaries. Contains a more diverse
and abundant biological community than eIthcr a
sand or mud habitat.
638 Silt/Clay or Mild (Mlld)-Made up of very fine parti-
cles. This substrate is extremely soft, and sometimes
dangerous to walk on. Mud oc<.:urs only in areas
where wave action and current energy are extremely
Jow, such as at the hcads of bays and estuaries. Due
to this location, mud is often associated with brack-
ish water.
7
Exposed and Other Lands-Includes phySIcal features which
are treated in greater detail in the geology maps. How eve r ,
the interrelationships between physical and biological com-
munities have been recognized and some significant forma-
tions which have important biological values or which may
the Side opposite to the rest rallled material, Increa ses the strength of thc
w a l l
Clay A loose. earthy extl emely fine -grained. natural sediment or
soft rock compoied p r im ar ily o f elay,slZe o r collOidal particles an d
chal actenLed by high plasticity and by cont a mlllg a conSiderable
amollnt of clay millel als
Cohesion Shea r strength In a sediment not related to Intel nal p a rtl '
c le friction
Cohesionless Said of a soil that has re lat ively low shear strc ngth
when all-dlled, 01 coheSion when wet
Competent rock A volul11e of rock which under a 'pec lflc set of
co ndit ions is a b le to SUppOI t a t ecto nic force.
Concretion A hard , compact. and rounded mass o r aggrega te of
ITII nel al matte l genel al I)' for m ed hy pr eCI pi! at Ion f I om aq ueUl!S soil!
tl0n in the pores of a sedimentary or fragmental volcaniC lock and usu-
ally o f a composition Widely differ ent from that of the lock III w hich It IS
found and fr om ",hlch It IS I a ther shal ply se p arated
Confined ground water CJlound wd tel unde r ple "i ~lIre s lgrll r lca ntl'y
greater than that of the atmosphere and whose upper su rfa ce is the bot·
tom ot an Impermeable bed or a bcd of distinctly lower permeabrlity
lh<lI1 the TlIalerldlln \.\hH,,:h t he watel occurs
Conglomerate A coarse·grarned, clastiC sedrm entary l ock COI11·
posed of round ed fragment s lar ger than 2 mm in diameter (granules.
pebbles, cobbles, boulders) set rn a fine -grained matrix of sand, s ilt, or
any of the common natul al cementing matel ials
Contact (geo ll A plane o r Irregul a r surface between two different
types or ages ot r oc ks
Continental ice sheet A g laclel of consider ab le thICkness COIll-
pl ete ly covering a large part of a continent or an area of at least 50.000
sq km, obscurtng the re l le f ol the underlYing surface, such as the Ice
s h eets coveflrlg AntdlcllUI dllli Greenland
Cross-bedding An tntel nal all angement of the l aye l s Il1 a st r a t if led
I od , charactellzed by minol beds or laminae inclrned more or le ss
I egularly In slo ping lines at varIOUS angles to the ongInal depOSItion
SUI face , or tD the dIp 01 contac t of the fO f [nation. I t IS ploduced t,y
SW Ift. changing cu rre n ts of alt or \\tater , and IS charactenst lc of gl anu lar
sed ll11entary rocks (espeCially san dstonc ) a nd sand depOSits (as In dune,
stJ eam channel , 01 delta )
Cross-stratification See cross·bedd I ng.
Debris flo" A mass 1110"l11ent involVing rapid tlowage of d eblls
o f var IOU S killds undel various co nditI o n s: s peclfl-.:a l ly d high denSity
mudflow con tallllng abundant coa l se-gl~uned matell a ls and lesulung
almos t inva riab ly fro m an unusually heavy ram.
Delta The low , nearly flat, allUVial tract 01 land deposIted a t 0 1
neal the mouth of d nver , commo nly fo r mmg a tflangu la r or l an-
shaped pial!) of conSi dera b le a l ea encl ose d and CI ossed bv m any diStn·
butaries of the main riv er. perhaps extendll1g beyond the'general tlend
of thc coast, and resulting f r om the accum u lation In a Wi der body of
...... .-.ter (Ilsually a sea 01 lak e) of sediment sll rplled hy a r Ivel III such
quantities that it IS not removed by t ides. "aves, and currents. M ost
deltas are partly subaer ia l and partly below water
nesicnltiulIlTack A '::Id ck III :-;edrrll e n l , p r odu(ed by dr Yin g
Dike (e ng) An artificial wall, embankment, I idg e, or mound. usu-
ally 01 earth, stones. or np ra p, built around a relatively flat, low -lying
alea lo plulectlt flum fl ood ing
Dip The angle that a st ructural su rface, e g ,a bedding o r fault
planc, makes With thc horizontal, mea s ured perpendicular to the stnke
01 the structure
Drift Roc k matenal (clay, sand. gravel. bouldelS) t ranspor ted by a
glaCier a nd depOSited d irect ly by or from the Ice. or by running wa te r
emanating from a glaCier Dr ift Includes unstratified matenal (ttll) that
ru r ITIS rno r d lll e:-;, drltl stT.illfl e d rlep()"l ls ()f g l.tclal urlgln
Drift sector A seellon of beach With perpendicular shore bounda-
nes in which littoral matenals movc o n and offshore 0 1 alongshore.
Dritt sector boundary, absolute A pomt beyond \.\hlch mSlgntfl
cant amounts of Ilttor al mate! lals move a long the shuf e 111 01 out of ad-
Jacent dnft sectors
Drift sector boundary, approximate The drift sector boundal y
moves updrift 01 downdl ift seasonally, and/ol a slglllflcant aillount o f
littoral mate r ial s can pass Into or from the adjacent dri ft sectors. The
maj or it y of the littoral matena ls remain Within the dnft sector.
Eurthnu\-\ A mass IIlOyem ent cha r <-lcteilled by downslope moye
ment of soil and weathered rock over a susceptible shear surface" rthin
well defincd lateral boundarie s . Earthfl ows grade Int o mudfl ows with
IIlcredsmg tluld lty
Embankment An a rtifiCia l structule, u s ually ofealth or gr a vel.
constructed above the natural ground su rfa ce and deSigned to hold back
water trom o vedlowlIlg leve l land, to retalll water In a I eservolt" or a
st leam III Its bed , 01 tu carry d r uadway 01 I a l lrod<.i; ega dike , a
seawall, and a fill
Erosion terrace A t e rra ce produced by erosion.
Estuary f he seawdrd elld or lhe wrdelled funnel-shaped li d a l
mouth ofa Ilvel valley where fleshwatel IlI lx es v.nth ,1n d me<1slIr<1hly di-
lutes seawater and where tidal effects are ev ident
Facies (stratlg) The s um ot all primary lithol og iC a nd paleontolo-
gic chalaclellstlcs exhibited by <-I sedlrnentdry lock alld frum w hich Its
ong in and environment of formation may be inferred.
Fault i\ surface or zone of roc k fracture along which there has
been disp laceme nt , trom a tew centImetres to a tew k il o me t re s III scale
Fault contact A s11100th o r il l egulal plane along whic h str ata o r
r ock unit s of d ifferent stratigraphic posItron are III contact by faulting.
Feeder beach An artlfrctally Widened beach se rv ing to nouri s h
downd r 1ft beaches hy nafural iItiural curre nls ur furce s .
Felch length rhe unob structed horizontal water distance (In the dl'
r tctlon of the Wind) over which <1 Wind gene rate~ waves.
Flow (mass move) A mass movement of uncon sol idated material
that exhibits a continuity of motion a nd a plasttc or sem ifluid behaVior
resemblmg that of a viscous flUid. W ateI IS u ~uall y leqlllred [o r most
types of flow movement.
Fold (struc geol) A curve or bend 01 a planar struc t ure such as
rock strata, heddlng planes, foliation, or cleavage. A fold IS' usually a
product of deformation, although its definition is deSCriptive and not
genetic and may Include primary structures
Folding The curving or bending of a planar stl ucture such as rock
serve as useful introductions to more detailed analyses have
been mapped.
71 Rock-Upland habitats in which exposed rock composes
approximately 30 percent or more of surface areas.
711 Rock Outcropping-Occur on gentle to steep slopes.
Shallow soil may occur in depressions supporting
grasses and low shrubs. Mosscs and lichens occur on
the rock faces. When along the shoreline, this type is
assOCIated wIth rocky , cobble, or mixed medIUm in-
tertidal habitats.
713 Rock Island, Islet -Arbitrarily defined for mapping
purposes as islands andiol islets I'; ith a surface area
less than fifty acres and includes both vegetated and
non vegetated islands. Uplands are generally limited
to grassland or shrub vegetation. however , I'; here
soil is more fully developed, tree species do occur.
A rocky or cobble intertidal area WIth offshorc kelp
beds is common on these important refuges for nest-
ing seabirds, marIne mammals and bald eagles.
7131 Grass -Grasses are the dominant vegetative
cover.
7133 Conifer-COlllferous trees are the dominant
vegetative cover.
714 Cliff-Stet:p slopes conSIsting of exposed rock. A
limited, rocky mtt:rtidal art:a IS typIcally assOCIated
with these rugged shorelmes.
72 Sand-Areas in which sand or aggregatt: comprises ap-
proximately 30 percent or more of exposed surface areas.
722 Sand Dune-Upland accumulations of wind blown
sand. Stabilized by dune grasses. An undIsturbed
st rata, foliation , o r elea,age by deformation. The term is generally used
for the compres>ion of s trata in the formation of fold structu res o n a
broad sca le , a nd some t imes has the COllllota l llHi or genera l d efo rmat ion
of w hich t he actual folding IS on l y d part.
Foredulle A coastal sand ridge onented parallel to the shoreline of
dl! ocean 01 large lake , occLlrflng at the landwa rd malgrn of the beach
(0 1 a long the s hOiewald face ofa beach Iidge ) or a t the landwald II1Ilrt
o f t he hlg he st t ide. and more or less completely stab ilized b y vege tation.
Foreset bed One of the inclrned, Internal. and systc matically ar·
I aTiged Idyers of a -.:ro~s -bedded Unlt speclflcall), Olle of the gently in -
clined layers of sand)' matel ial deposi ted upon 0 1 along an advanCIng
and relatively s teep frontal s lope , such as the outer margin of a delta or
t he lee slde ora dune , a nd plogresslvely cover In g the bo ttomset bed a nd
III turn belIlg cove led or tluncated h y the to pse t bed FOieset beds r e p
I esent the gl eate l part of the bulk of d delta.
Foreshore The zo ne regula r ly cove r ed and unco,ercd by the riSe
and fall of the t ide , ur the Lone IYlfl g between the 01 dinar y tide level s up
to t he limit o f wave lunup.
Formation The baSIC or fundamental rock·stratlgraphic unit In the
local c1asSillcation of roc k s
Fossil A Il)' I elll all1 S, tr ace, 01 Implll1t of a p ia lH 01 an Il11 a l that has
been preserved, by natur a l processes. In the earth's crust s ince some
past geologiC ti me
Foundation A term th et t IS some llme ~ applIed to the uppel part of
the sorl or rock Illass In contact With, and suppoltrng the load s of t he
subsoil.
Fracturl' plane r he smooth or I r l eguiclr surface along w hICh rrdC -
turing has taken p lace.
Friable (a) Said of a l ock or minera i t hat clumbles naturally or IS
easily broken , pulvenzed , o r reduced to powdel , such a, solt or poorly
cemented sandstone (b) Said of a sari consistency in which rnois t soil
material cru s h es easily under gentle to moderate" p r e s s ure (between
thumb and foreflngcr) and co heres when pressed together.
Geumurphi,' Perl .tlTlin g tllihe fOl11l of the earth 01 of ItS :-;llIface
featllIes, e g. a geomorphic plovince.
Glacial marine Said of manne sed imcnts that contain glacial
material S y n g la clOmal me
Glaciolacustrine Perta in ing to, d e r iv e d from , or depOSited In gla·
clal lakes. especially said of the deposits and landfol ms composed of
s u s pended material b rought by meltwater s tream s !l ow ing Into lakcs
bordering th e g laCier
GraHl An unconsolidated , na tura l acc umu lation of rounded rock
f r agmcnts rc su lting from eroSio n , conSISting predo min a ntly o f particle s
larg e r than sand (dldmetel grealer than 2 HHn , slich as houlder s. coh
bles , pebbles, g r anules, 01 'lny cOl1lhinat ion of Ihese fragments). the un·
conso lidated equivalent of conglomer ate.
Graywacke An o ld rock name that is now gcnel a ll y appllcd to a
dark and vcry hard, tough , an d fIrmly Indurated , coarse-graIned san d-
sto ne that conSIsts of poor I} sorted and s harp grains of quartz and feld-
spar with an abundant vanety of small, d a rk rock and mineral frag·
ments embedded in a compact, partly metamorphosed clayey matnx
havlIlg the ge ner al compo~ltlon or s idl e <lnct contallllng an a l-"llll dance of
ver y fille-gr alned rnJllel also
Groin A shore plotection strueturc usually built perpendicular to
the shorelinc. to trap littoral matenals or retard eroSion of the shore
Cully erosion r::rosl(H1 of soil 01 soft luck rnatellal by funnlllg wa-
te r that forms distinct. narrow channels that are larger a nd deeper than
r il ls and that usually carry water only during and Immediately alte r
hea,y rain s o r follOWing the melting of Ice or snow
Headland A hIgh . steep faced pi oillontory ex tending IIlto t he sea.
Hook A sandy or gravelly spi t o r narrow cape turned sharply land -
ward at t he outer end, and rcsembllng a hook m form; e .g. a l ow penln'
s ula or bar e nding 1I1 a r ecll rv ed Spit a nd formed ell the end of a bd)'
Ice-contact deposit Stratified drift deposited In contact With melt-
Ing glacier Ice, such as a n esker. kame. kame terrace, or a feature
ma rked by numelous kettles
Illdurated Said uf d co mp act lock o r SOil hardened by the action of
pI essure, cementatIOn. and especially heat.
Infiltration The movement of water SOILJtlOTl~, espeCially or e be,lI
II1g solutIons, Into a lock through Its IIlterstices or flac t ures o r Int o the
so il. from another area.
Inshore (zone) A zone ot variable" rdth extellds from lhe
Iuw \\Idtel IlTI e lhrough the l)Jeakel 70ne
Interbed A bed, Iyplcally thin. of one kind o f l oc k matel ial oceul-
ring between o r alternating w ith beds of anothel kind
Interstmie A \Val TrIe r s u bstage of a glaCial stage, mal ked by a tem -
porary retreat of the Ice. a climatic episode wlthll1 a glaCiation dunng
which a secondary recesSion or a stillstand of glaciers took place
Jctt,} A s tructu re extending In tu a hod y of ...... atel. and deSigned to
plevent shoa ling ofa channel by l itto ral m a tenal s . and to direct and
confme tidal or ,tream flows.
Knob-and-kettle topography An undulating morarnal landscape In
Vvhlch a llisordered dssemb lage of knolls. mounds , 01 I idges of glacial
dr ift is Interspersed with Irregular depressions, pi ts. o r kettles th a t are
common ly undrained a nd may contain swamps or ponds.
Leachate A sol uti o n obtained hy lea~hrrrg; e.g water that has per-
colated thlOUgh sorl containing soluble s ubstances and that contains
certain amounts of these substances in solution.
Lensing The thInnIng out ot a st ratum In one or more dlredlun",
e g rhe dlSappearlllg laterally of a lentil.
Levee An artrlicr,]1 e mbankment. burlt along Ihe bank of a water-
course or an arm of the sea and deSigned to protect land from inunda·
tion or to confine streamflow to Its channcl.
Litholog) The descnption of rock s, especially sed imentary clastics
a nd es p eC ially In hand spcelmen and In outcrop. o n the basIS of such
characteristics as color) structures, mIneralogIC compOSitIOn) and gram
sIze
Littoral current An ocean ~llrrent cau~ed by t he approach of waves
to a coast at an angle. It flows parallel to and near to the shore Syn
a longshore current.
Littoral drift The sedrmentarv mate rial moved in the littoral zone
under the influence of waves and currents
Littoral transport The movement of littoral dnft in the lit to ral
zo ne b y waves and currents. Inc lu des movement p ara lle l (a longs hore
sand dune community will establish a complex se-
ries of successional stages leading from the beach
margin to relatively stable forested uplands in back-
dune rea<.:hes.
723 Slide-A reas of sand and/or gravel substrates which
drop from steep slopes, leaving a scar at the source
and an accumulation of substrate at the base.
724 Sand and/or Gravel Bar-Intertidal deposits which
are covered at mean high water The substrate is
unstable and subject to movement by waves and cur-
rents.
74 Spit-Shoreforms created when sand and other fine sedi-
mt:nts t:roded from cliffs or bluffs arc carried by along-
shore drift and deposited at bay mouths or coastal
obstructions. Marsh and bcaeh grassland vegetation typi-
cally invade the upper portIOns of these Important resting
areas for gulls and shorehirds.
741 Vegetated Spit-Spits with a vegetated area smaller
than can be mapped.
742 "/onvegetated Spit-The non vegetated parts of larger
spits and smaller, nonvegetated spits.
76 Bluff-Nonvegetated, steep to moderate slopes of varying
substrate. BurroI'; nesting birds use exposed surfaces
along steeper bluffs for nest sites. Blu ffs often serve as
buffers between developed uplands and wetlands at their
bast:, creating important strips of coastal habitat for
many species, induding bald eagles and rivt:r otters.
Rock Island or Emergent Rock -Rock islands or emergent
rocks too small to be designated as a polygon. May be vege-
tated or nonvegetated. Important areas for seabirds and har-
bor seals. IndIcated by black asterisk on maps.
tl anspol t) a nd per pend Ic ul a r (un-offshore tl anspor t) to the shot e. Rate
is expressed In cubic yards per seasonal s ix·m o n th penod Synonymous
With alongshol e transport rate.
Littoral LOlle In beach lerTTlIllology. an rndeflnlte zone extending
seaward from t he shoreline tOjust beyond the breaker zone.
Mass wasting A genel al term for the dislodgement and downslope
tran spo rt of soil and rock material und e r the dll ect rnfluen ce of g l aVl ty
In ..::un t l ast [0 other erosion processes the dehlls Je llloved by mass
wastrng processes is not carried WIthIn, on, or under another medium
possessing contrastlllg properties (\vind, running \:vate r, Icel. It Includes
slow dr~placements such ciS creep and solIfluctIOn dnd rapid movements
Il1 the fO I n o f eal thfl ows. I ockslldes, ava lanch es , and falls.
Mean se a level T he average he ig ht of the surf ace of the sea for all
stages 01 the tide ov el a 19-year per io d . usu a lly determined fl om hourly
height observatiOns on £Ill open coast 01 III adjacent waters havlIlg free
access to the sea . the ass umed or actual sea leve l a t its mean position
midway between mean high water and mean lo w water. Abbrcv: MSL
Meltwater Water derived from the melting of snow o r ICC , espe·
clally the sllea m water flOWing In , undel, or from meltmg g laCie r Ice.
Metasediment (a) A sediment 'JI s edrmentar y rock which ,hows "'-
Idence of having been s ubjected to metamorphism. (b) A metamorphic
rock of sedimentary or igin.
l\1icrofossil A fOSSil tuo srnalltn be :-;fudled Without the aid of<l m i-
croscope It may be th e remams of d mIcroscopic organIsm or a part of
a larger olganism
IVllid trnar Ille geol) A stIcky, fl11e-g lall1ed , Jl1anne detlltal
sed iment. e it her of marine or terrestrial ongln . Muds are usually de-
sc ribed by color. blue mud , black mud; gray mud , g reen mud; re d mud
Mud [sed ) A sllTny .lnd sticky [)I sllppely lllixtule ofwatel and
f ine-grain ed particles (stlt Size or s ma ller) of solid or earthy material,
With a conSIstency varying from that 01 a semilluid to that 01 a soft and
plastic se(limen t
Mudstone An Indur ated mud haV ing the textUI e and compOSitiOn,
but lacking the fine l a mll1ation o f sha lc; a blocky or maSSive, Itne-
graincd sedimentary rock In which the proportions of cia} and Silt ar e
dppru;"IfII,ltely t he same .
NGVD Abbr eviat lon for '\Jatlonal Geodetic Verlieal Dat um For
definition, see mean sea leve l.
Nearshore (zone) An II1defll1lte zo ne extendtng seaward from the
shol eline well beyond the breaker zone. It defin es the ar ea of nearshore
currents
Nodal zoni.' An a rea III w hi c h Ihe pledoll1lna nt directIOn of l he
dlollgshol e tl ans pol t changes
~ourishment The process 01 replenIShIng a beach It may he
brought about naturally, by alongshore transpo rt . '" dttifielal ly by the
depuslllOIl of dl edged materials
Offshore Situated off or at a d IStance fr om the shore, spec llteally
said of thc r elati,ely flat , a lways submerged zone of varrahle wldtfr ex ·
t e nding flom the breaker lOne to the seaward edge of the continental
shelf whele substantial movement of material IS limited.
Outwash Stratified detritus [ch iefly sand and g r avel ) r emoveo or
"washed ou t" from d g laCier by m e ltw a tel Stl eams and deposited III
frunt of'li beyond the margin of an active glaCier. The coarser material
IS depOSited nearer to the Ice. Syn: glacial outwash
Oxide A mmeral compound chalacterlled hy the linkage ofoxy-
gen with one metalliC e lement.
Pebble A rock fr agment larger than a granule and smaller than d
cobble, haVing a diameter In the range of 4-64 mrn being somewhat
rounded ur uther wise modified by ab l aSiOn in the course of transport
Perched ground water Unconfined gr ound wate r separ ated fr o m
an underlying main body o f ground \},tater bv an unsaturated Lone.
Perched water table The watel tahle ofa body of perched ground
wilter
Permeability tgeol) The property 01 capacity of a porou s rock,
sed iment. or soli for t ransmlttlllg a flurd Without Impall ment hy the
.,t ructllr e ufthe medlllTTl It IS a m easure of the re l a tive ease offl uld
flow undel unequal pressu re.
Pleistocene An epoch of the Quaternary penod, after the P lrocene
01 t he Tertrary and befme rhe Holocene, also. the corresponding world-
Wide s elles of l ocks. When the Quaternary IS deSignated as an e ra, the
Pleistocene is conS idered t o be a p e riod Syn Ice Age
Plucking The proce ss of glaCial eloSton by which Sizable lock frag-
ments, such a~ blocks, ale loosened, detached, and borne away froIll
bedrock by t he freezing of water as the Ice advanced.
Pocket beaeh A small, narrow beach lormed Ilr " pocket,
commonl)1 u escenliC In plan and concave tOVvard the sea. and generally
displayrng well sorted sands. a bay head beach.
Promontory A h igh, prominent p rojection o r pornt of land , or cliff
of rock, jutling out boldly Into a body of watel beyond the coastline, a
headland.
Quaternary The second period of thc Ccnozolc era follOWing the
Tertiary, Ihought to cover thc last two or three million years It consISts
of two epochs' the Pleistocene and Holocene
Radio·carbon dating A me thod of determining an age in years by
measuring the concentratiOn ofcarbon-14 rcm a ll1mg 111 an organIc
material, usually form e rly irving matter The method rs useful rn detel '
mrnIng ages In the range of 500 to 40,000 years.
Ravelly ground Rock that breaks into small pieces when drillcd
a nd that tends either to slough or partly cave int o the d r d l hole when the
drill strlng IS pulled or to bind the drdl string becoming wedged be·
tween the drlll pipe and borehole wall.
Recessionaloutwash Stratified detritus (chiefly sand and gravel)
removed or 'Vvashed out" from a glaCier by meltwater streams and de
posIted In front of or beyond the terminal moraine dunng a temporary
bllt srgIllflc"nt halt or p a use rn the frnal retreat of a glaCier.
Revetment A facrng of stone, concrete, etc, b uilt to protcct a
scarp, embankment, or s hore structure against erOSIUTl by wave action
or currents.
Rhythmic bedding An indlvrdualuntt of a rhythmrc succeSS[(JIl or
of beds de,eloped by I hythmlc sedimentation. The term Implies no
Illlllt as to thickness or complexity of bedding and It carries no time or
seasonal connotation.
Riprap A layer, facing, or protecting mound of stones randomly
placed to prevent erosion. scour. or s loughing of a structure or cmbank-
ment: also the stone so used
8
Run up The advance of wat e r up t he foresh ore of a beach, fo llow-
:'1g the breaking of a wave.
Sand A rock fra gm e nt or det rita l particl e sm aller thall a gra nul e
::nd larger th a n a coarse s ilt g ra i n, having a diameter in th e ra nge of
'/16 to 2 mm. The mate ri a l is most commonly composed o f quartz
(·ra ins re s ul ting from rock d is in tegra tion , but the part ic le s may be of
:Iny miner a l com p os ition or m ix ture of rock o r min e r a l fragme nts. s uch
as "cor a l sand" co ns isting of l im estone fr ag ment s.
Sandstone A medium -g r a in ed, sedimentary rock composed of
a bundant a nd ro unded or a ngul a r fragment s of sa nd size set in a fi n e -
grained matrix (s ilt o r cl ay ) and more o r less firmly united by a ceme nt -
ing mat e r ia l (com monly s ili ca . ir o n oxide, o r calc ium carbon a t e); the
co nsolid ated equi valent of sa nd , interm ed iate in tex ture between co n ·
g lome ra te a nd s hal e.
Scarp A r elativel y slee p 'lIld stra ig h t, c li ff-l i ke fac e or sl ope o f con-
side r a ble lin ear ex tent. b r eak in g the general co ntinu it y of th e l and by
separating leve l or gent ly sl op ing s urfaces ly in g a t d iffe re nt le ve ls, as
a long the m a rgin of a plate au , te rrace. or be nc h. A scarp ma y be o f any
height.
Scour The pow e rful an d conce ntrated clear in g i1ll cl di gging aC Lion
o f fl ow in g ai r or wa te r , espec ia ll y t he d ownward erosion by stream wa -
ter in sweeping away mud a nd si lt on the ou ts ide c urve of a be nd. o r
du r ing tim e o f tlood.
Seawall A structure se parating land and wate r areas. primarily de-
signed to pr evenr erosion a nd othe r damage due to wave act ion .
Sediment Soli d fr ag m e nt a l m a teri a l, o r a m ass of slic h mater ia l.
e ith e r inorga ni c o r organic, t h at o riginates f rom we athering o f rocks
a nd is tra ns po rt ed by , s us p en ded in , or deposi te d by , a ir , wa ter, o r ice,
u r that is accumu lated by ot he r natura l agent s, s lI c h as chem ica l preci pi-
tatiun from so lut io n o r sec r et io n by o rg a ni sms, a nd that fo r ms in l aye rs
0 11 th e e.-n ih 's surface a t o rdi nary te mperatures in a loos e, un co nso l i-
date d fo rm; e.g . sa nd, gra v el, .. il t, mud , t ill , loess. alluvium.
Seismic wave A ge neral te rm f o r all sea waves produce d by eart h -
qu akes or ge n erat ed a rt if ic ia ll y by ex pl os ions.
Shale A fin e-gr a ined , hard . detri t a l sed ime nt a r y rod formed by
the consul id at iu n ofelay . silt , o r mud. and ch aracter ized by fin ely
stratifi ed (lam in Hted) structure that is approximate l y parall e l to t he
bedding (a long whi ch th e rock brea ks re a di ly in t o t hin la ye r s). A thinly
la minated o r f iss il e cl aysto n e. si l ts to ne, or rn ud stone.
Shear A st rain r es ulti ng fr OIll str esses th a t ca use o r l end to ca u se
co n t igll ous p a rt s o fa body to slid e relat i ve to eac h other in a direc t io n
p a rallel to th e ir plane of co nt act. It is a lso use d lo refer 10 surf a ces and
9
zones offa ilure by sh ea r , a nd to surfaces a lo n g w h ich differenti a l nw ve-
men t has t aken place.
Shear strength T h e inte rna l res is t a nce of a bod y to s h ear str ess .
Sheeted Sa id o f an ig neo us rock suc h as a g ran i t e t h a l has und cl -
gone pressure-release joi nti ng or scal in g, so met imes g iv ing it the ap -
pearance of be in g strati f ied.
Sheet erosion E ros ion in w hi c h t hin laye rs of surface materia l are
gradua ll y r em oved from a n extensive a re a of gentl y s lop ing land by
broad , continuous sheet s of running wate r , e.g. e ros ion th a t uccu rs
when rain washes aw ay a thin laye r o f t o psoil.
Shoreface Th e na rrow zo ne seaward from the low I id e s ho relin e
cove red by wa t e r o ver w hi c h be ac h sa nd s a nd gra ve ls aC li ve ly move
back and fo rI h w ith ch a ngi ng wave cond itions.
Shoreline The int er sec t iun of a sp eci fie d p la n e of wa ter w it h the
sho re o r beach. It a pprox imates t h e mean high \ova te I' line.
Silt Rock fr a gments or det rital particles sma ll er th an a very fin e
sand grain a nd la rger th a n coarse clay. It var ie s cons id erab ly in cornpo-
Si li on b ut com m o nl y has a hig h co n tent o f clay m inerals.
Siltstolle A hard o r som ew h at hard e ned s il t hav ing t h e texture a nd
composit ion, b u t lacking the fin e lam i n a ti o n of sh a le: a m ass iv e mud -
sto ne in w hi c h t he silt predomin ates ove r clay.
Slump A l andslide cha r ac te rized by a shea rin g and rotary m ove-
ment o f a genera ll y i ndepen den t mass of roc k or earth along a curvetl
s lip s urface and w it h backward ti lt i ng of the m ass wi th res p ec t to th a t
s lope so t h at t he s lump s u r face o ft e n ex hib its a re ve r sed slo pe fac in g
uphill.
Sorted Saiel o f an unconso li dated se diment o r of a cement ed detri -
tal roc k consist in g o f p art ic le s of essen ti a lly unifor m s ize .
Spalling Th e c hippin g, f ract uring, o r fragmenta t ion. a nd the u p -
wa rd a nd o utward heav i ng , of rock cause d by the i n terac t iun of a shock
(com press iona l) wave at a fr ee su r face.
Stade A substa ge of a glacia l stage marked by a g lacia l readvance.
Sirandline T he short -l iv ed lin e or level <1t w hi ch a bo d y o f sta nuin g
wate r , as t he sea. m ee ts t he la nd ; t h e sho reline , es p ec in l ly a fo rme t'
sh o r elin e n o w e leva te d above th e p rese nt \va te r lev e l .
Stndifiecl F o rm ed , a rr a nged , o r laid down i n layers or strata: es p e-
c ia ll y sa id of any laye red sed im e n ta ry rock o r d epos i t.
Stratified drifl fluvioglac ia l dr ift con sisting o f sort e d a nd layere d
materi a l depos it ed by a me lt wa te r stream o r se tt led f rom s usp ension in
a body o f q uiet wa t er adjoin in g the glac ier.
Stratigraphic (geologic) column Any sequ e nce o f roc k uni t s found
in a g iven regi o n eithe r a t th e su rface o r below it (as in a drilled we ll or
min e shaft); a local geo log ic co lumn.
Stratum A tabular o r sheet-li k e mass, or a si ngle a nd distinct l aye r ,
of the same sed imen ta r y material of any thic kness, vis ua ll y se p arab le
from other laye r s ahove and belo w; sedimentary bed .
Strike (strue. geoU The direct ion or tr e nd that a st ru ctu r a l surface,
C.g. a bedd i ng or fa ult plane . ta kes as it int ersects the h o ri zo n ta l.
Surf zone Th e area be t wee n the o ut e rm ost b reak e r and th e l imit or
wave upr us h .
Swash The rush of wa t e r up o nt o th e beac h face fo llowing t hc
break i ng o f a wave .
Talus Roc k fr agments o f a ny size o r sh ape (usu a lly coa r se and
a ngu lar ) de ri ved fr om a nd ly i ng at th e base o f a cl iff o r ve ry stee p .
rock y s lope.
Terrace (coast) (a) A n a r row , gent ly slo p ing, construc t ional
coastal s tr ip extend i ng seaward or la keward, a nd covered by a thin
sed im entary de p osit; (b) Loose ly. a stripped wavec u t p latform th a t has
been ex posed by upl ift o r by lower ing o f th e water levcl; an e levatcd
wavec u t be n c h.
Tidal na.s San d y or mudd y l and area s w hi c h are cnve r ed a nd 1111 -
c ov e r ed by the ri se and fa ll o f th e t id e.
Till U nso rt ed a nd un stra tified dr ift, ge ne r a ll y unconso li dated, de -
posited direc t ly by an d underneath a glacier w ithout s ubseq uent re-
wo rk ing by wa t e r f rom t h e glac ier , and consisting ofa heterogeneou s
m ixture of c lay , sa nd . gravel, an d bould e rs.
Tombolo A ba r or sp it that con nect s o r "ties" an isl and to th e
m a i n la nd or to ano th e r island.
Tsunami A g r av i tat iona l sea w ave prod uced by any la rge -sca le ,
short duration d is tu rbance of th e ucea n noor, p r incipa l l y by a shallow
subm a ri ne ea rthquake , bu t (l l so by a sudden su b ma ri ne ea rth move-
TTl e rll, subs id e nc e. or vo lca ni c erur>tion , c h a racteri zed by g r eat speed of
prop agat ion (LI p to 950 k m/hr). lo n g wave length (up to 200 km ). lo ng
peri od (varyi ng fr o m 5 minutes to a fe w h o urs, gene rall y 10-60 m in ),
and low obse r vable ampl itud e on the o pen sea. It m ay p il e up to g r eat
heights (30 m et r es or m o r e) and cau se considerab le dam age o n e nter ing
s hall ow wat e r a lo ng a n exposed coast, o ft e n th o us and s o f ki lo m etres
fr o m t h e so urce.
Type area An a rea contai nin g the type local it y, wit h in .
d iag nostic re lations of t he type sect ion a re w id ely r e pre se ~'t :dh l ~:l ~~
a r ea III wh tch good exposu re s (of weak ly consol ida te d roC t,s ) are eva ne -
sc ent.
Unsorted (poorly s orted) Said o f a granul a r sed iment tlr o f a ce-
me nted det r ita l rock t h at cons ists of particl es of many s iz es mixed to-
get he r in an un syste matic manner so th at no one s ize c lass
predom in a t es .
Updrift The di rection oppos ite that of the predominant movement
of litto ral ma ter ia ls.
lJprush The ru sh of wa t e ,' lip o nto [he heach fo ll ow ing th e break illg
of a wave.
Water table The s urface between the zone of saturat io n and the
zo n e of aera ti o n : th a t s urface of a body o f unc o nfin e d gro und wate r a t
w hich the pressure is eq u al to t h a t of t he atmosphere.
Wave height The vertical d is tance be tw een a crest a nd the preced-
ing trough.
Wavelength The horizo nt al d is t a nce between simi l a r points o n t wo
successi ve waves meas ured pe rp endi c ular to t he c r est.
Wave period Thc time fo r a wav e c re st to trave rse a di stanc e equa l
to o ne wave le ng th. The tim e fo r two succe ssive wave cres ts lO p ass a
fixed point.
Wal'e train A se ri es of wave s produced by the same di sturbanc e.
Wclilog A log obta in ed from a we ll , show in g such iTifo rm a tion as
r esis ti vity , radi oact ivi tYl acoustic ve loc it y, e tc'l as a fUllcl io n of depth ;
es pec iall y a li t ho log ic record o f the rocks penet ra t ed.
Zooplankton S m a ll an im a l members of th e m a r ine p lan kt on
community including eopepods, a rrow worm s, e uph a us id s.
and var iolls l a rvae.
BIBLIOGRAPHY
G a r y, M ., McAffee. R ., Jr., a nd Wolf, C. L., e dito r s. Glmsary of
G eo logy , American Geolog ica l I nstitute , Washin g ton , D.C., 19 72,
80S p.
L a pedes, D . N., E ditor in C hi e f, Dictionary of S c ienrific and T ecllni-
cal Terms , M cGraw-Hill . 19 7 6 , 1,634 p.