The Lincoln Creek Formation 

Grays Harbor Basin 

Southwestern Washington

By HELEN M. BEIKMAN, WELDON W. RAU, and HOLLY C. WAGNER

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1244-1
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

U.S. GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1967

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 15 cents
CONTENTS

Page

Abstract __________________________________________ H

Introduction __________________________________________ 1

Previous usage ______________________________________ 2

General features _____________________________________ 4

Type section ________________________________________ 5

Reference sections ____________________________________ 5

Canyon River section _______________________________ 5

Porter section ____________________________________ 7

Pe Ell-Doty section _________________________________ 7

Willapa Eiver section _______________________________ 8

Age and correlations __________________________________ 8

Geologic summary _ ____________________________________, 12

References ___________________________ ________________ ]4

ILLUSTRATIONS

Page 

FIGTTRE 1. Index map ____________________________________ 12

2. Geologic map showing area of outcrop ________________ .'5

3. Stratigraphic sections ___________________________ 6

4. Photograph of a typical outcrop ____________________ 7

5. Correlation chart ______________________________ 9

ITT

CONTRIBUTIONS TO STRATIGRAPHY

THE LINCOLN GREEK FORMATION, GRAYS 

HARBOR BASIN, SOUTHWESTERN WASHINGTON

BY HELEN M. BEIKMAN, WELDON W. RAU/ and HOLLY C. WAGNER

Abstract

The Lincoln Creek Formation, formerly called the Lincoln Formation, crops out 

in the Grays Harbor basin of southwestern Washington. It is principally an offshore marine deposit and consists of as much as 9,000 feet of tuffaceous siltstone 

and tuffaceous fine-grained sandstone. The formation is predominantly Oligocene in 

age but includes some rocks of late Eocene and early Miocene ages. Generally the 

Lincoln Creek Formation conformably overlies upper Eocene sedimentary rocks. 

However, in some places it overlaps older strata, and locally it rests unconformably 

on lower (?) and middle Eocene volcanic rocks. The formation is overlain by the 

Astoria(?) Formation of early to middle Miocene age.

The rocks in the Lincoln Creek Formation are included in three foraminiferal 

zones, which from oldest to youngest are the Sigmomorphina schencki zone, the 

CassiduUna galvinensis zone, and the Pseudoglandiilina aff. P. inflata zone.

INTRODUCTION

The Lincoln Creek Formation consists of 2,000 to 9,000 feet of 

tuffaceous siltstone and fine-grained sandstone, predominantly Oligocene in age, that crops out within or underlies about 1,500 square miles 

in the Grays Harbor basin in southwestern Washington (figs. 1 and 

2). The rocks here called the Lincoln Creek Formation were originally named the Lincoln Formation by Weaver in 1912. Because the 

name "Lincoln" was first used for the Lincoln Porphyry of Eocene 

age in Colorado (Emrnons, 1882), its use for the rock sequence in 

Washington is preempted according to rules that govern stratigraphic 

nomenclature. To solve this nornenclatural problem and still retain 

nomenclatural similarity to a term in common usage, the name Lincoln

1 Washington State Division of Mines and Geology.
CONTEIBUTIONS TO STEATIGEAPHY

117 C

W A SIR I N G T 0 N

MT 

mpia JRAINIER

FIGURE 1. Index map showing Grays Harbor basin area.

Creek Formation is here used to replace the name Lincoln Formation. 

The definition and description of the Lincoln Creek Formation presented here are based on detailed geologic studies, mainly by the U.S. 

Geological Survey, in the Grays Harbor basin. The stratigraphy of 

the formation was worked out mostly during the mapping of the 

Centralia-Chehalis coal district between ]948 and 1951 by Snavely, 

Brown, Roberts, and Rau (1958). Additional information was obtained during later studies by Pease and Hoover (1957), Rau (1958, 

1966), Gower and Pease (1965), and current work by H. C. Wagner.

PREVIOUS USAGE

Weaver (1912, p. 15-16) applied the name Lincoln Formation to 

a 1,000-foot-thick sequence of marine shale and sandy shale of Oligooene age exposed on Lincoln Creek near the boundary between Lewis 

and Thurston Counties. Later, Weaver (1937, p. 110-111) regarded 

the Lincoln Formation "as the equivalent of the entire middle Oligocene of Washington," and in 1944 he designated the type section of 

the formation as "a composite of numerous sections exposed in the 

banks of the Chehalis River between Centralia and Porter, Washington, and in the hills southwest of these towns" (Weaver and others, 

1944, p. 592).

More recent work by Snavely, Brown, Roberts, and Rau (1958, p. 

35-53) in the Centralia-Chehalis coal district on the east edge of the 

Grays Harbor basin and by Pease and Hoover (1957) in the
LINCOLN CREEK FORMATION, GRAYS HABOR BASIN, WASH. I 3

124 "00'

Rocks younger than the 

Lincoln Creek Formation

Lincoln Creek Formation

As shown includes partly equivalent 

rocks of the Toutle Formation 

south of the Cowlitz River

ir«^ fe w < § i- ^ s.

Rocks older than the Lincoln 

Creek Formation

Approximate contact

Queried where indefinite

Basaltic "basement" rocks of 

the Crescent Formation

c ^-.

> 

Measured section

Dashed where thickness to top of 

formation is estimated

FIGURE 2. Geologic map of area of outcrop and location of measured sections of 

the Lincoln Creek Formation in the Grays Harbor basin. Geology from Pease 

and Hoover (1957) ; Snavely, Brown, Roberts, and Eau (1958) ; Huntting, Bennett, Livingstone, and Moen (1961) ; Gower and Pease (1965) ; and H. C. Wagner 

(unpub. data, 1966).
T4 CONTEIBUTIONS TO STEATIGEAPHY

Doty-Minot Peak area in the central part of the basin has extended the 

age range of Weaver's Lincoln Formation to late Eocene to early 

Miocene. The mapping in the Centralia-Chehalis coal district also 

demonstrated that the formation consists of a lower basaltic sandstone 

member representing continental or near-shore deposition and an upper 

tuffaceous silty sandstone and siltstone unit representing shallow-water 

offshore marine deposition.

GENERAL FEATURES

Throughout most of the Grays Harbor basin the Lincoln Creek 

Formation consists predominantly of tuffaceous siltstone and tuffaceous very fine to fine-grained sandstone strata which in places contain thin units of basaltic or glauconitic sandstone and beds or zones 

of calcareous concretions. Along the east edge of the basin, however, 

the Lincoln Creek consists mainly of the basaltic sandstone member 

with interbeds of pyroclastic rocks (Snavely and others, 1958, p. 38). 

This basaltic sandstone member is about 1,500 feet thick in the area 

east of Chehalis (fig. 2) but thins to the south and west. Equivalent 

rocks of the Toutle Formation, consisting of basaltic conglomerate, 

sandstone, siltstone, clay, and lignite beds, are about 600 feet thick 

south of the Cowlitz River (Roberts, 1958).

The thickness of the Lincoln Creek Formation increases from east 

to west and from south to north in the Gray Harbor basin. The formation is about 2,000 feet thick immediately west of Chehalis, about 

3,500 feet thick west of the Doty Hills, about 4,500 feet thick south 

of Raymond, and 8,500 feet thick along the Canyon River at the north 

edge of the basin. The formation thins locally where it onlaps highs of 

older rocks that now form the Doty Hills, the Black Hills, and Minot 

Peak (Pease and Hoover, 1957). The thickness and extent of the 

formation to the west of its outcrop area (fig. 2) are not known 

because of the thick cover of younger rocks.

Throughout most of the Grays Harbor basin, the Lincoln Creek 

Formation conformably overlies sedimentary rocks of late Eocene age. 

In the eastern part, these older rocks are fine- to medium-grained 

marine and continental clastic rocks of the Skookumchuck Formation. 

In the western part, they are lateral equivalents of the Skookumchuck 

and consist of marine siltstone and sandstone strata. In areas of 

pre-Oligocene relief, the Lincoln Creek overlaps older sedimentary 

rocks and locally rests unconformably on volcanic rooks of the Crescent Formation of early (?) and middle Eocene age.

The Lincoln Creek Formation is overlain by brackish-water and 

marine sedimentary rocks of the Astoria(?) Formation of early to 

middle Miocene age except in the eastern and southern parts of the 

basin where it is overlain by nonmarine sedimentary rocks of the
LINCOLN CEEEK FORMATION, GRAYS HABOR BASIN, WASH. I 5

Miocene and Pliocene (?) age. The contact between the Lincoln Creek 

and the overlying rocks is unconformable in the eastern two-thirds of 

the basin and conformable in most of the western third.

TYPE SECTION

The name Lincoln Creek Formation is taken from Lincoln Creek 

in Lewis County, "Wash. Weathered outcrops of strata typical of the 

greater part of the formation are easily accessible in the south half 

of T. 15 N.. R. 3 W. along State Road IN, which is parallel to and 

north of Lincoln Creek (Snavely and others, 1958, pi. 1). However, 

because only a small part of the rock sequence is exposed along Lincoln Creek, the type section is designated as the rocks exposed along 

the Chehalis River from Galvin to Helsing Junction. This section is 

shown as C on figures 2 and 3 and consists of approximately 1,200 feet 

of offshore marine strata. The exposed rocks are generally massive 

greenish-gray to olive-gray tuffaceous siltstone and fine-grained sandstone, a few thin tuff beds (fig. 3), and some calcareous beds that 

form persistent ledges (fig. 4).

The total thickness of the Lincoln Creek Formation in the type 

section is estimated to be about 2,500 feet. As determined from cores 

and cuttings from a nearby test hole, the lowermost 400 feet is composed predominantly of tuffaceous siltstone and sandy siltstone which 

conformably overlies the Skookumchuck Formation of late Eocene age 

(Snavely and others, 1958, pi. 3). The formation is disconformably 

overlain by the Astoriaf?) Formation of early to middle Miocene age.

REFERENCE SECTIONS

Inasmuch as the Lincoln Creek Formation is not completely exposed in its type section, four reference sections Canyon River (Rau, 

1966); Porter (Rau, 1958); Pe Ell-Doty (Chehalis River of Rau, 

1958); and Willapa River (Rau, 1951 and H. C. Wagner, unpub. 

data, 1966) in other parts of the basin are shown as A, B, D, and 

E respectively, in figures 2 and 3.

Canyon River section. The Lincoln Creek Formation is thickest in 

the northern part of the Grays Harbor basin. Along the Canyon 

River, the formation consists of about 8,500 feet of siltstone, sandstone, 

conglomerate, and mudstone which is tuffaceous and contains some 

concretions. The basal part of the formation, a basaltic sandstone 

about 100 feet thick, rests with apparent conformity on micaceous 

well-bedded siltstone and sandstone of late Eocene age. The basaltic 

sandstone is overlain by 1,600 feet of massive tuffaceous siltstone containing scattered concretions and concretionary beds. Above the siltstone is 1,350 feet of poorly sorted, very tuffaceous, thick-bedded sandstone and conglomerate interbedded with siltstone. The sandstone and 

conglomerate beds are composed largely of altered glass shards or

256-760 O - 67 - 2
16 CONTEIBUTIONS TO STRATIGRAPHY

fragments of pumice, together with grit-sized particles of basalt and 

sedimentary clasts. The next higher 4,400 feet of strata is primarily 

fine-grained silty sandstone, siltstone, and mudstone, which is tuffaceous. Much of this part of the formation is massive, but in some 

places the strata are rudely bedded, and in a few places thin beds of 

tuffaceous sandstone are present in the massive siltstone. Several 

glauconite and a few concretionary beds occur in this part of the 

section. The uppermost 1,000 feet of the formation is massive

CANYON RIVER 

Tps.20-21 N.

Rs.6-7 W. 

(Rau, 1966)

EXPLANATION

&0

FEET 

- 0

- 1000

L 2000 

VERTICAL SCALE

Basalt

Conglomerate Thickness estimated, 

lithology inferred

Covered interval

WILLAPA RIVER 

T. 13 N..R.3 W. 

(Rau 1951. and 

Wagner, 1966)

\PORTER

T. 17 N., R.5 W.

(Rau,1958)

GALVIN TO 

HELSING JUNCTION

T. 15 N..R.3 W. 

[Snavely and others, 1958)

Eocene sedimentary and volcanic rocks 

FIGURE 3. Stratigraphic sections of the Lincoln Creek Formation.
LINCOLN CEEEK FOKMATION, GEAYS HABOE BASIN, WASH. T 7

tuffaceous siltstone with scattered concretions. The formation is overlain with apparent conformity by carbonaceous and micaceous siltstone 

and fine-grained sandstone of the Astoria(?) Formation.

Porter section. The Lincoln Creek Formation is estimated to be 

about 3,000 feet thick along Highway 9 in the vicinity of Porter. 

The lower 1,900 feet consists of tuffaceous siltstone and sandstone, 

sonic of which is calcareous and concretionary. The base of the formation rests unconformably on the Crescent Formation. The upper 

third of the formation is poorly exposed, but the contact with the 

overlying Astoria(?) Formation is probably uneon form able (Pease 

mid Hoover, 1957).

PC Ell-Doty section. More than 2,000 feet of tuffaceous and concretionary siltstone and sandstone constitutes the Lincoln Creek Formation along the Chehalis River, between Pe Ell and Doty, near the 

south margin of the Urays Harbor basin. The basal part of the formation is basaltic tuffaceous sandstone, about 60 feet thick, that rests 

on concretionary sandstone and siltstone of the upper Eocene 

Skookumchuek Formation. The uppermost part of the formation is 

nnconformably overlain by sandstone of the Astoria(?) Formation.

FIGURE 4. Massive tuffaceous siltstone and fine-grained sandstone of the Lincoln 

Creek Formation as exposed along the Chehalis Eiver, half a mile north of Galvin, 

Wash. Height of cliff is about 125 feet. Photograph by Parke D. Snavely, Jr.
T8 CONTRIBUTIONS TO STEATIGEAPHY

Willapa River section. The Lincoln Creek Formation is well exposed in the bed and banks of the Willapa Eiver from Holcomb to the 

town of Menlo, a distance along the river course of nearly 5 miles. 

The formation which overlies a laminated to finely crossbedded sandy 

siltstone sequence of late Eocene age is about 4,500 feet thick and is 

mainly tuffaceous siltstone that contains several thin units of basaltic 

or glauconitic sandstone and micaceous silty sandstone in its lower 

and upper parts. The foraminiferal fauna throughout the area was 

studied by Rau in 1951, but only general notes on the lithology were 

taken. More detailed lithologic data are embodied in the following 

description by H. C. Wagner.

The basal part of the formation is basaltic, glauconitic granule 

sandstone as much as 50 feet thick and is overlain by predominantly 

tuffaceous siltstone about 1,200 feet thick in which bedding is generally well developed. Calcareous concretions, many of which contain megafossils, occur sporadically in beds and zones throughout this 

siltstone. Between this bedded siltstone and the upper part of the 

formation is a unit that is as much as 500 feet thick and is composed 

of very fine to fine-grained fossiliferous slightly micaceous lenticular 

silty sandstone and sandy siltstone. The upper 3,000 feet of the formation is massive tuffaceous siltstone. Discontinuous beds of glauconite 

and zones of calcareous concretions occur throughout much of the 

lower part of this massive siltstone. The content of volcanic ash decreases in the upper part, and the uppermost few hundred feet contains much sand-sized material and is mainly a slightly micaceous 

tuffaceous sandy siltstone and silty sandstone. The formation is conformably (?) overlain by the basal member of the Astoria(?) Formation, a dark-medium-gray carbonaceous siltstone that generally has a 

thin glauconitic sandstone bed at its base.

AGE AND CORRELATIONS

Molluscan and foraminiferal collections indicate that the Lincoln 

Creek Formation ranges in age from late Eocene to early Miocene. 

The formation correlates in part with the Toutle Formation to the 

south in Cowlitz County and in part with the Twin River Formation 

to the north on the Olympic Peninsula (fig. 5).

Age determinations made on molluscan faunas collected from the 

Lincoln Creek strata indicate that the formation in the CentraliaChehalis area includes rocks of late Eocene and Oligocene age. These 

age determinations were made by H. E. Vokes (in Snavely and others, 

1958, p. 51-54) and are as follows: (1) A fauna from the lower part 

of the basaltic sandstone member is late (or latest) Eocene in age, 

(2) faunas from the middle part of the formation collected at scattered localities are middle Oligocene in age, and (3) a fauna collected
(Weaver and others, 1944)

Age

o>

a

0)

£0>

.1

0

.

01

01

o

,J*

0

A

0>

0>

o 

o 

W

i 3i

Stage

Saucesian of 

Kleinpell, (1938)

Zemorrian of

Kleinpell, (1938)

Refugian of

Schenck and

Kleinpell, (1936)

Upper part of 

Narizian of 

Mallory, (1959)

Foraminiferal

zone

Epistominella parva

Pseudoglandulina aff.

P. inflata

Cassidulina galvinensis

( formerly Eponides

kleinpelli)

Sigmomorphina

schencki

Bulimina schenckiPlectofrondicularia cf. 

P. jen kins i

GRAYS HARBOR 

This report

Astoria(?) 

Formation

Lincoln Creek

Formation

~=: >

<^'

>

^^

^> ^ ""

< Basaltic

^ -- sandstone

~> member

^> SkookumMarine siltstonV- ~- > 

and sandstone ^ ^

^Formation

Centralia-Cheh

coal distric

(Snavely and ot

1958)

Astoria(?) Form

9 Absent

Lincoln Format

of Weaver (19

<^

\,

^-^

"^ Basaltic

^- -^ sands

^"> mem

Skookumchu

Formation

FIGURE 5. Correlation chart of the Lincoln Creek 
110 CONTRIBUTIONS TO STRATIGRAPHY

from the uppermost part of the formation southeast of Helsing Junction is late Oligocene in age, and the rocks there correlate with a 

fauna from the type Blakeley Formation of Weaver (1912).

To the west in the Doty-Minot Peak area well-preserved megafossils, 

collected in the SWi/4 sec. 34, T. 17 N., R. 5 W. from strata equivalent 

to the tuffaceous siltstone member in the Centralia-Chehalis area, were 

tentatively correlated by Vokes (in Snavely and others, 1958, p. 52- 

53) with fauna from beds (Toutle Formation) at the Gries Ranch 

fossil locality (fig. 2). Megafossils collected from the upper part of 

the Lincoln Creek Formation were correlated with a fauna from the 

type Blakeley by Ellen J. Trumbull (in Pease and Hoover, 1957). 

who asigned an early Miocene age to the assemblage.

In the Willapa River exposures, a varied and abundant marine 

megafauna occurs in the basal part of the formation. Warren Addicott 

(written commun., December 1964 and March 1966) places the fauna 

in the Turcicula columbiana zone [= the Keasey Stage of Weaver and 

others (1944)] of late Eocene or early Oligocene age. In the CentraliaChehalis district, also, T. columbiana has been reported from the 

basaltic sandstone in the lower part of the Lincoln Creek Formation 

(Snavely and others, 1958, p. 51-52).

Age determinations based on Foraminifera place the strata of the 

Lincoln Creek Formation entirely in the Oligocene Series. Three 

foraminiferal zones were recognized by Rau in the Lincoln Creek Formation as a result of study of Foraminifera collected during the 

mapping of the Centralia-Chehalis area (Snavely and others, 1958, p. 

43-51; Rau, 1958). From oldest to youngest, these zones were: the 

Sigmomorphina schencki zone, the Eponides kleinpelli zone, and the 

Pseudoglandulina aff. P. inflata zone. A fourth zone, the Epistominella 

parva zone, was thought to be represented in the upper part of the 

Lincoln Creek Formation in the Willapa River section (Rau, 1951; 

1958). However, detailed mapping by Wagner along the Willapa River 

has shown that the section is repeated by faulting and that the strata 

containing E. parva forms are in the overlying Astoria(?) Formation. 

Based on recent determinative work, Rau redesignated the E. kleinpelli zone the Cassidulina galvinensis zone (fig. 5) and also slightly 

revised the lists of representative forms in the different zones.

The Sigmomorphina schencki zone ranges in thickness from 700 to 

1,700 feet and includes the basal basaltic sandstone of the Lincoln 

Creek Formation, where this sandstone is present, as well as tuffaceous siltstone and silty sandstone. The foraminiferal fauna of the 

basaltic sandstone corresponds closely with the fauna found in rocks 

of the Toutle Formation at the Gries Ranch locality (fig. 2). The 

basaltic sandstone and Toutle Formation are paleontologic and
LINCOLN CREEK FOEMATION, GKAYS HABOR BASIN, WASH. Ill

lithologic equivalents (Roberts, 1958, p. 24). Foraminifera from the 8. 

schencki zone also compare favorably with those from the Keasey 

Formation and the Bastendorff Shale (latest Eocene or earliest Oligocene) of western Oregon (Rau, in Snavely and others, 1958, p. 50) 

and with some from part of the Twin River Formation on the north 

flank of the Olympic Mountains (Rau, 1964). However, rocks of the 

Twin River Formation are nontuffaceous and do not correspond 

lithologically to the predominantly tuffaceous strata of the Lincoln 

Creek Formation (Brown and Gower, 1958, p. 2497). The zone 

represents a large part of the Refugian Stage and in accordance with 

the Standard Pacific Coast section is regarded as "Eo-Oligocene" in 

age (fig. 5).

Forms typical of the Sigmomorphina schencki zone include:

Cancris joaquinensis Smith

Ceratobulimina wasftburni Cushman and Schenck

Cibicides elmaensis Rau

hodgei Cushman and Schenck 

Dentalina duseribwyi Beck 

Nonion halTcyardi Cushman

Plectofrondicularia pacJcardi Cushman and Schenck 

Eobulus spp. (large in size) 

Sigmomorphina schencki Cushman and Ozawa 

Uvigerina atwilli Cushman and Simonson

cocoaensis Cushman

The Cassidulina galvinensis zone includes the beds in the middle 

part of the Lincoln Creek Formation. It was first called the Eponides 

kleinpelli zone (Snavely and others, 1958, p. 49-50) but E. kleinpelli 

has been found to have a limited geographic distribution. Therefore 

the zone is here renamed after C. galvinensis, a more widespread and 

useful species. The C. galvinensis zone is approximately 1,000 feet 

thick in most of the Grays Harbor basin but is more than 2,000 feet 

thick along the Middle Fork of the Satsop River in the northern part. 

The rocks included in the zone are lithologically uniform, consisting 

largely of tuffaceous sandy siltstone and silty sandstone. In the northern part of the basin, thick beds of coarse-grained tuff and other 

pyroclastic debris are common.

The Cassidulina galvinensis zone is believed to be represented in 

the middle part of the Twin River Formation of the northern part 

of the Olympic Peninsula (fig. 5). In Oregon an approximate equivalent of this zone is known in a part of the Toledo Formation. It may 

also be represented in the upper part of the Keasey Formation of 

Oregon. The zone represents the upper part of the Refugian Stage 

of Schenck and Kleinpell (1936) and is Oligocene in age.
F12 CONTRIBUTIONS TO STEATIGEAPHY

A typical assemblage from the Cassidulina galvinensis zone contains: 

Cassidulina galvinensis Cushman and Frizzell 

Ceratobulimina washburni Cushman and Sehenck 

Epistomina eocenica (Cushman and Hanna) 

Eponides Icleinpelli Cushman and Frizzell 

Guttulina hantkeni Cushman and Ozawa 

Karreriella washingtonensis Eau 

Quinqueloculina imperialis Hanna and Hanna

The Pseudoglandulina aff. P. inflata zone includes more than 5,000 

feet of strata where it is complete. Two general subdivisions of the 

zone can be recognized and are informally referred to as lower and 

upper parts. Foraminiferal assemblages most nearly like those of this 

zone are known from beds correlated with a part of the Twin Eiver 

Formation and all the Blakeley Formation of Weaver (1912). In 

Oregon, similar assemblages are known from an upper part of the 

Toledo Formation. The Pseudoglandulina aff. P. inflata zone is referred to Kleinpell's Zemorrian Stage which he has regarded as 

Oligocene in age (Kleinpell and Weaver, 1963).

Combinations of foraminiferal species typical of the lower and upper 

parts of the Pseiidoglnndulinn aff. P. inflata zone are:

Upper part:

Bulimina alligata Cushman and Laiming

subfusiformis Cushman

Cassidulina crassipunctata Cushman and Hobson 

Elphidium 1* cf. E. minutum Cushman

Eponides mansfieldi oregonensis Cushman and E. E. and K. C. Stewart 

Pseudoglandulina aff. P. inflata (Bornemann) 

Eobulus 'brevispinostis (Nuttall) 

Siphogenerina nodifera Cushman and Kleinpell 

Uvigerina gallowayi Cushman

Lower part:

Bolivina marginata adelaidana Cushman and Kleinpell 

Cassidulina crassipunctata Cushman and Hobson 

ElpMdiuml cf. E. minutum Cushman 

Eponides duprei Cushman and Sehenck

mansfieldi oregonensis Cushman and E. E. and K. C. Stewart 

Plectofrondicularia packardi multilineata Cushman and Simonson 

Pseudoglandulina aff. P. inflata (Bornemann") 

Quinqueloculina loeaveri Eau 

Uvigerina gallowayi Cushman

GEOLOGIC SUMMARY

The present area of the drays Harbor basin was a part of a eugeosyncline that occupied western Washington and Oregon throughout 

much of the Tertiary Period (Snavely and Wagner, 1963). At the 

beginning of late Eocene time, before deposition of the Lincoln Creek 

sediments began, active uplift and voleanism formed land areas on the
LINCOLN CEEEK FORMATION, GEAYS HABOE BASIN, WASH. T13

north, south, and east of the present Grays Harbor and made a 

separate basin within the eugeosyncline. Basaltic rocks of the Crescent Formation of early (?) and middle Eocene age were exposed as 

islands and as sea cliffs along the north margin of the basin. In the 

southern part, basaltic fragmental debris resulting from late Eocene 

volcanism as well as basaltic material of the Crescent Formation wras 

exposed to local erosion. Basaltic and andesitic rocks of the Northcraft and Hatchet Mountain Formations of late Eocene age formed 

the northward-trending east margin.

At the beginning of Lincoln Creek time, a great quantity of detritus 

was rapidly eroded from the volcanic highlands along the east margin 

and deposited in the adjacent part of the Grays Harbor basin. The 

eastern part of the basin fluctuated near sea level, and the resulting 

continental and near-shore strata constitute the lower basaltic sandstone unit of the Lincoln Creek Formation. Concurrent with deposition of this sandstone, coal-bearing strata of the Toutle Formation 

were being laid down on a swampy coastal plain at the southeast 

margin of the basin.

In the deeper parts of the basin to the west and north no major 

break occurred between deposition of older sedimentary rocks and 

the Lincoln Creek strata. However, a much greater quantity of airand water-transported volcanic ash which originated from subaqueous 

and subaerial explosions to the east in the area of the present Cascade 

Range was carried into the basin. The type of sediments deposited 

changed from essentially nontuffaceous siltstone and sandstone to the 

tuffaceous strata that characterize the Lincoln Creek. As the basin 

subsided, Lincoln Creek strata overlapped upper Eocene sedimentary 

rocks. Along the margins of the basin and adjacent to volcanic islands, 

Lincoln Creek sediments were deposited unconformably on the Crescent Formation. In most places where this overlap occurred, a basal 

basaltic sandstone derived from the underlying rocks was deposited.

Early in the middle Oligocene time, accelerated erosion due to uplift or greater transporting capacity of streams resulted in an incursion of very fine to fine sand-sized detritus into the southwestern part 

of the basin. Volcanic ash that continued to be supplied to the Lincoln 

Creek depositional environment forms a considerable part of the 

detritus and indicates that eruptive activity persisted throughout this 

part of Lincoln Creek time.

Deposition in middle and late Oligocene time possibly reflects a 

return to lowland conditions adjacent to the basin area. Continuous 

deposition of silt- and clay-sized debris in the marine environment 

formed a massive ash-filled clayey silt. Toward the end of Oligocene
114 CONTRIBUTIONS TO STEATIGEAPHY

time, somewhat coarser detritus was carried into the basin, and by 

the end of Oligocene time volcanic activity had apparently ceased and 

the basin was nearly filled. In early Miocene time the nearby lowlying land area was presumably covered with vegetation and supplied 

much silt, clay, and carbonaceous material to the near-shore marine 

environment of early Astoria time.

REFERENCES

Brown, E. D., Jr., and Gower, H. D., 1958, Twin Eiver formation (redefinition),

northern Olympic Peninsula, Washington: Am. Assoc. Petroleum Geologists

Bull., v. 42, no. 10, p. 2492-2512. 

Emmons, S. F., 1882, Geology and mining industry of Leadville, Lake County,

Colorado: U.S. Geol. Survey, 2d Ann. Eept., p. 210-290. 

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