Geology of the Renton, 

Auburn, and Black 

Diamond Quadrangles, 

King County, Washington

GEOLOGICAL SURVEY PROFESSIONAL PAPER 672
Geology of the Renton, 

Auburn, and Black 

Diamond Quadrangles, 

King County, Washington

By DONAL R. MULLINEAUX

GEOLOGICAL SURVEY PROFESSIONAL PAPER 672

A study of Cenoxoic bedrock and 

surficial deposits in the southeastern part 

of the Puget Sound lowland

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

Library of Congress catalog-card No. 78-607547

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

Washington, D.C. 20402 - Price $1. (paper cover)
CONTENTS

Page

Abstract-,___________________________________________ i

Introduction. ________________________________________ 3

Location, purpose, and scope.______________________ 3

Acknowledgments. _ _____________________________ 4

Other studies-__-_________________________________ 5

Geography___________________________________________ Q

Topography and drainage___--_____________________ 6

Climate.________________________________________ g

Vegetation.______________________________________ 9

Culture._________________________________________ 9

Tertiary rocks.-_---_--_---_-------___-_______________ 9

Lower Tertiary sedimentary rocks._________________ 10

Puget Group_____-____-________._____________ 10

Undifferentiated Puget Group near Black

Diamond_ ____________________________ n

Tukwila Formation_______________________ 15

Renton Formation._______________________ 17

Environment of the Puget Group.__________ 19

Lincoln Creek(?") Formation____________________ 19

Correlation of lower Tertiary formations.__ ______ 22

Intrusive rocks.__________________________________ 22

Upper Tertiary rocks Hammer Bluff Formation_____ 24

Pleistocene deposits.__________________________________ 27

Sources of detrital material._______________________ 27

Criteria used to establish stratigraphy.______________ 29

Provenance._________________________________ 29

Climate.____________________________________ 30

Weathering._________________________________ 30

Stratigraphic sequence..___________________________ 31

Orting(?) Drift____________________.______________ 31

Intermediate drift. _______________________________ 35

Puyallup(?) Formation,___________________________ 39

Salmon Springs Drift ___________________________ 41

Undifferentiated drift in the Cedar River valley______ 42

Vashon Drift-_-_-___-_____--____________-________ 43

Til-___-_- --- _ --._ _ _ 44

Topographic expression__________________ 45

Lithology_ __---___---___-_-_-__-_________ 45

Weathering. _____________________________ 45

Advance stratified drift..______________________ 46

Recessional stratified drift________-_-.-________ 46

Deposits of locally derived melt water. ______ 46

Deposits of the ice-marginal river.__________ 47

Age and correlation of Pleistocene deposits.__________ 49

P-ge

Postglacial deposits_________._______________________ 50

Lacustrine deposits____--__-------__---__-_-_-__ 51

Terrace alluvium_______________________________ 52

Colluvium. ____________________________________ 53

Osceola Mudflow_____--___-_--____-_______-_-__ 54

Flood-plain alluvium.___________________________ 56

Cedar River valley ______________________ 57

Green River valley.________________________ 57

White River valley_-_--_--___--_-_--_-__.__ 58

Duwamish Valley._______--_____--___-_-____ 59

Geomorphology _ ____-____--__-_----_--_----------_- 61

Origin of Duwamish Valley and adjacent drift plain_ 62

Development of the present drainage pattern ____ 63

Effects of the Vashon glacier_________________ 64

Postglacial changes____________-_-_- _____ 65

River characteristics.___--__-_-____-----__--___- 66

Green River._________-_______-_-_-_-_____- 66

White River...___._ _________ 66

In Duwamish Valley._______________________ 68

Flood-plain development ____________________ 68

Structure._________-__----__-------------.--------- 69

Lower Tertiary rocks____________________________ 69

Upper Tertiary rocks ________________________ 72

Pleistocene deposits._________--__-_--__________- 72

Summary of geologic history.________________________ 72

Tertiary Period __________--__-__--_____-_-_- 75

Quaternary Period.___________-__-___-___-_-_-_- 76

Economic geology.-______-_-____--.-----_-_-_-----_- 77

Engineering geology _____-_--.-____-_____----__ 77

Geologic conditions that influence land use __ 77

Overconsolidation of fine-grained sediments. 77

Ground water._________________________ 80

Heterogeneity of glacial till._-____-_-____ 80

Landslides- ____________________________ 81

Construction materials._____________________ 82

Sand and gravel.__----____-_-__--______ 82

Stone._______-___----------____------- 83

Silica sand.____-____-___-_-_-_-____-__--_---__- 83

Oil and gas.________________--.______-_-_-_-___- 84

Clay. ________________-______..____-_---_-_-_--- 84

Coal_ __-________-__--_ -__.--_-__-_---- 85

Peat and topsoil-____________-,.__-_______-_-_--- 85

References cited._________---__-__-_______-_--_-___- 86

Index______ _---_ ---, ---- - 91

rn
IV CONTENTS

ILLUSTRATIONS

FIGURES 1-7. Maps: Page

1. Index of Washington_______-______--_-__--__-_-__________________________________________ 4

2. Index of recent geologic quadrangle mapping by the U.S. Geological Survey._-_-_---____________ 5

3. Major physiographic elements in the southeastern part of the Puget Sound lowland._____________ 6

4. Principal physiographic units in the Renton, Auburn, Black Diamond, and Maple Valley quadrangles_-__-__---__-_-_-______--__-___----_---_______-__---__-____-________________ 7

5. Changes of course and nomenclature of rivers-__-_-___---_-_-__-__-___-_____________________ 8

6. Pattern of drainage on drift plain,_________________________________________________________ 9

7. Principal populated areas and centers of communities referred to in text ________________________ 10

8. Diagram showing generalized stratigraphic section of the Puget Group in the vicinity of Black Diamond - 11

9. Graph showing cumulative curves of Puget Group arkose samples.___________________________________ 13

10. Chart showing late Eocene and early Oligocene fossil stages and zones.________________________________ 14

11. Generalized column of stratigraphic sequence at Renton_______--_-_-__-_--___-____-__-______________ 15

12. Chart showing generalized lithologic correlation of Eocene and lower Oligocene formations.______________ 23

13. Diagram showing direction of movement of ice______-_____--____---_-__----___--___-________________ 27

14. Stratigraphic sections of Orting(?) Drift.____-____--____-_-___----__--__--______..-_-_-_-_________ _ 33

15. Photographs showing comparison of textures of representative till deposits____________________________ 34

16. Graph showing cumulative particle-size distribution curves of glacial till.______________________________ 35

17-19. Stratigraphic sections:

17. Intermediate drift.___________________________-_______-___---_-_-__--------_-_--______-_- 37

18. Salmon Springs Drift__________________________________________________________________ 42

19. Undifferentiated drift__________________________________________________________________ 44

20. Map showin-g distribution of the Osceola Mudflow___________________________ _____--___--_--_ ___ 55

21. Topographic map and section of upper part of postglacial fill_________________________________________ 60

22. Map showing location of abandoned segments of preglacial courses of Cedar and Green Rivers and postglacial pre-Osceola course of White River_ ___________________-______-_____-______-_-_-_--__----_ 64

23. Generalized profiles of segments of the White, Green, and Cedar Rivers-______________________________ 67

24. Map showing principal structural features in lower Tertiary rocks..___________________________________ 70

25. Summary of Tertiary stratigraphy and geologic history in the Puget Sound lowland southeast of Seattle, _ _ 73

TABLES

Page 

TABLE 1. Sequence of geologic-climate units recognized in the southeastern part of the Puget Sound lowland and the

probable correlative geologic units exposed in the Renton, Auburn, and Black Diamond quadrangles._ _ _ _ 27

2. Heavy-mineral suites in modern alluvium.__-____--______-________-_----____-___----____-_--_--_--- 28

3. Heavy-mineral suites in Pleistocene sediments__-----_--_--__-----_-------------_-_----------------- 29

4. Mineralogy of silt and clay fraction of tuls-----_--_-_-__---__--_-_---------__---------__----------- 36

5. Summary of Quaternary stratigraphy-and geologic history in the Puget Sound lowland southeast of Seattle.- _ _ 74

6. Generalized description of engineering properties of principal mapped units in the Renton, Auburn, and

Black Diamond quadrangles. _______-_______--_-_-__-__________---______--__-______-_____----- 78
GEOLOGY OF THE RENTON, AUBURN, AND BLACK DIAMOND 

QUADRANGLES, KING COUNTY, WASHINGTON

By DONAL E. MULLHSTEAUX

ABSTRACT

The Renton, Auburn, and Black Diamond quadrangles lie 

southeast of Seattle, Wash., in the southeastern part of the 

Puget Sound lowland. Largely rural only a few years ago, 

this area is being increasingly used for suburban and urban development. These three mapped quadrangles are dominated physiographically by a broad drift plain of low relief, 

which stands several hundred feet above sea level. The drift 

plain consists chiefly of Pleistocene deposits that are overlain 

locally by thin postglacial sediments; it forms the ground 

surface in more than three-fourths of the mapped area. Steepsided valleys subdivide it into several segments and bound 

it on the west. The narrow valleys of the Cedar, Green, and 

White Rivers, three master streams that rise in the Cascade 

Range to the east, cut west and northwest across it to reach 

the broader Duwamish Valley that lies along the boundaries 

of the two western quadrangles. Postglacial alluvium on 

these valley floors forms the surface in about a fifth of the 

mapped area.

Exposures of pre-Quaternary rocks are few. Formations 

older than Tertiary are not known, and Tertiary rocks crop 

out only in very limited areas in the northwestern and southeastern parts of the area, near the cities of Renton and Black 

Diamond.

Tertiary rocks consist of sedimentary rocks of early Tertiary age, a few small bodies of intrusive andesite, and poorly 

indurated sedimentary rocks of late Tertiary age. Most of 

the lower Tertiary rocks belong to the Puget Group which, 

in the Puget Sound lowland, consists of a thick sequence of 

brackish- to fresh-water arkosic rocks that locally encloses 

a formation of andesitic sedimentary rocks. Near Black Diamond, the Puget Group is represented only by arkosic rocks, 

but they are at least 6,000 feet thick. The sequence in that 

area consists chiefly of sandstone and shale but also includes 

thin layers of claystone and coal. The rocks in the lower part 

of the sequence are generally similar to those in the upper 

part, though minor differences are known; therefore, the 

Puget Group near Black Diamond is not subdivided into formations.

Near Renton, two formations of the Puget Group are recognized. The lower, more than 2,000 feet thick, is the Tukwila 

Formation. It consists mainly of sandstone, conglomerate, 

shale, and mudstone composed of fragments of volcanic rock, 

but it contains a middle member of arkosic sandstone and 

shale. The upper formation, about 2,500 feet thick, is the 

Renton Formation. The Renton consists of arkosic rocks much 

like the Puget Group rocks that are exposed near Black Diamond. Puget Group rocks of the Black Diamond and Renton 

districts are predominantly late Eocene in age.

The thick arkosic rocks of the Puget Group were laid down 

under generally uniform conditions over a wide, subsiding

coastal plain by westerly flowing, continuously aggrading rivers. Subsidence was equaled by aggradation and the surface 

of the plain remained near sea level. Locally, volcanic activity resulted in construction of broad uplands of volcanic 

materials that stood above the surface of the arkosic plain; 

one such upland, represented by the Tukwila Formation, extended over the site of Renton. Cessation of volcanic activity, 

but continuation of both subsidence and arkosic aggradation, led to burial of the Tukwila by the Renton Formation. 

Beyond the limits of any of the volcanic uplands, as at the 

site of Black Diamond, arkosic sedimentation was continuous.

Near the end of Eocene time, arkosic sedimentation ceased, 

the mapped area subsided, and deposition of volcanic detritus 

derived from the east began. About 1,600 feet of the resulting 

Lincoln Creek (?) Formation is exposed at Renton. The Lincoln Creek (?) is dominated by volcanic sandstone and pebble 

conglomerate partly cemented by calcite and zeolite. At Renton, the formation contains only minor amounts of finer 

grained marine rocks and no coal. These marine rocks nx ay 

be late Eocene or early Oligocene in age, or both.

A few small bodies of intrusive andesite that have been 

mapped intruded the Puget Group and are therefore younger, 

but their age is not closely known.

By late Miocene time, the Lincoln Creek (?) and older ro?ks 

had been folded, raised above sea level, and eroded to a surface of low relief. In late Miocene time, thin continertal 

sediments of the Hammer Bluff Formation were laid down 

on this low-relief surface near Black Diamond. The lov^er 

member of this formation is quartzose and kaolinitic and v?as 

derived from the arkosic rocks of the Puget Group. The up"»er 

member, however, consists chiefly of volcanic sandstone rnd 

conglomerate derived from farther east. The Hammer Bluff 

also contains volcanic ash and pumice similar to the pumiceous detritus that is characteristic of several other Miocene 

and Pliocene formations along both sides of the Cascade 

Range in Washington.

Repeated glaciation in the Puget Sound lowland during 

Pleistocene time is recorded by interbedding of glacial drift 

and nonglacial deposits; glacial deposits in the mapped quadrangles include drift sheets laid down during at least four 

major glaciations. Sediments of only one intervening interglaciation, however, were recognized. The Pleistocene glacial and 

interglacial formations of the mapped area are, from oldest to 

youngest, Orting(?) Drift, intermediate drift, Puyallup(?) 

Formation (interglacial), Salmon Springs Drift, and Vashon 

Drift. Each of the drift sheets was deposited by a tongue, 

the Puget lobe, of a continental glacier that originated in 

British Columbia the Puget lobe moved from there sovthward into and across the Puget Sound lowland. The d~ift 

sheets of the Puget lobe are recognized as having a northern 

origin because of the suite of rocks and minerals they con-
GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

tain. A significant proportion of the rocks and minerals is 

typical of the mountains of British Columbia and northern 

AVashington, but these rocks and minerals are sparse or absent from the parts of the Cascade Range drained by rivers 

that flow into the mapped area. No till of Cascade alpine 

glaciers was identified in the three quadrangles. The climate 

of the interglaciation represented by the Puyallup(?) Formation, according to included pollen and diatom remains, became at least as warm as the climate is today.

The Orting(?) Drift consists mainly of gravel and sand, 

with intercalated stony till layers that record at least three 

advances of the ice across the outcrop sites. Almost all these 

sediments are stained brown, and montmorillonite is the predominant clay mineral in the till. No interglacial deposits 

were found directly above the Orting(?). Instead, it is directly overlain, with a sharp erosional unconformity, by 

intermediate drift, which is very different from the Orting(?) 

in lithologic character. The intermediate drift is composed 

predominantly of sand, silt, and clay rather than gravel and 

sand. It includes two extensive till members, which are composed almost completely of silt and clay they contain few 

stones. Gray sediments are common though not predominant 

in the intermediate drift; and though montmorillonite is a 

major constituent of the tills, it is not as prevalent as in the 

Orting(?) Drift. The tills of the intermediate drift are similar to some glaciomarine "tills" and may have been deposited 

by ice that advanced into or even floated in proglacial lakes.

Locally, thin sediments of the Puyallup(?) Formation conformably overlie the intermediate drift; elsewhere they are 

disconformable. The Puyallup(?) sediments are characterized 

by reddish-gray volcanic sand probably derived from an ancestral Mount Rainier and also by volcanic ash and peat. In 

the mapped area they also contain at least one volcanic mudflow. The pollen and diatoms that are abundant in the peat 

and ash beds, respectively, indicate a deposition during a 

warm climatic interval.

The Salmon Springs Drift is composed of beds of sand and 

gravel that include interbeds of silt and clay, and of less extensive lenses or sheets of till that record at least two advances of the ice. It overlies the Puyallup(?) Formation with 

erosional disconformity. Locally, the mapped Salmon Springs 

includes gravel and sand derived from adjacent parts of the 

Cascade Range; this gravel and sand lies both below and 

above outwash and till of northern origin. The Salmon Springs 

Drift is several hundred feet thick along the Duwamish Valley in the Auburn quadrangle, yet it is less than 100 feet 

thick farther east under the drift plain along the Green 

and White Rivers. Sand and gravel in the formation typically 

is stained pale or yellowish brown; montmorillonite is an important clay mineral constituent, but it is not markedly less 

abundant in Salmon Springs till than in older tills of the intermediate drift, nor is it significantly more abundant than 

in the younger Vashon till.

Along the Cedar River valley, a succession of strata, consisting of several layers of till and interbedded glacial and 

nonglacial sediments, reaches several hundred feet in thickness. Yet no distinctive drift formations or till members and 

no sediments derived from Mount Rainier were recognized. 

Peat layers occur at several stratigraphic horizons, but pollen 

from several layers that were sampled indicated only generally cool moist conditions and no warm period such as is 

represented by the Puyallup(?) Formation. Because of the 

absence of distinctive marker units and absence of evidence 

that any warm-climate periods separated the various glacial

units, the sediments along the Cedar River were not subdivided.

Over most of the drift plain, either Vashon till or stratified 

drift covers the older Pleistocene formations. Till l'°s at the 

surface on about half the drift plain and probably underlies 

most of the younger deposits that locally form th-* surface. 

The till varies widely in thickness; it commonly is 10-20 feet 

thick, but locally it is as much as 70 feet thick. It consists 

of compact lodgment till generally the hardpan of local usage 

 and looser ablation till. These materials constitute the 

ground moraine, which forms an irregular surface with a local 

relief of about 100-200 feet. Closed depressions in the ground 

moraine are common, and locally the moraine shows strong 

drumlinization in a south-southeast direction.

Vashon stratified deposits, chiefly recessional, cover broad 

plains, terraces, and channel floors in the southeastern and 

central parts of the area, but farther northwest they occur 

only as small bodies along valleys. The more extensive deposits are products of a large melt-water river, composed of 

Puget lobe melt water and drainage from the Cascade Range, 

which flowed west and southwest across parts of the Black 

Diamond and Auburn quadrangles. The stratified drift consists chiefly of loose friable gravel and sand.

Only the youngest drift of the Pleistocene sediments can be 

closely dated and correlated. Vashon Drift in tl« mapped 

area, dated by radiocarbon methods, is between about 15,000 

and 13,500 years old. It is correlative with part of the "classical" or later part of the Wisconsin drift of midwesfc^rn United 

States. Older formations are not dated by radiometric methods, but some can be tentatively correlated with rridwestern 

formations. The Salmon Springs Drift and the Puyallup(?) 

Formation probably are correlative with part of tl ? Wisconsin drift and with deposits of the Sangamon Inte^glaciation 

of the midwest, respectively. For the older drifts, no specific 

correlations are -suggested.

Principal postglacial sediments are lacustrine deposits, terrace alluvium, colluvium, the Osceola Mudfiow, and modern 

flood-plain alluvium. Peat and other lacustrine sediments occur in small deposits on the drift plain and valley floors. 

Colluvium, ranging from large landslide blocks to thin slope 

wash, covers much of the valley walls of minor streams, as 

well as valley walls of the Cedar, Green, and White Rivers. 

The Osceola. a bouldery montmorillonite-rich mu^fiow that 

swept down the White River valley from Mount Rainier about 

5,000 years ago, flooded and now covers the topo.rrraphically 

lower parts of the drift plain south of the Green F'ver. Modern flood-plain alluvium is thin in tributary valleys and is 

also thin in valleys of the major rivers where they enter the 

mapped quadrangles. But lower in these valleys and in Duwamish Valley, the alluvium becomes progressively thicker 

and finer grained. In Duwamish Valley itself, postglacial alluvium is at least several hundred feet thick. Most of the 

upper 200-300 feet of that alluvium, and perhaps more, consists of detritus from Mount Rainier, deposited by the White 

River after the time of the Osceola Mudflow.

A thick, broad postglacial alluvial fill in Duwamish Valley 

shows that the Duwamish existed as a large valley at the 

time of the Vashon glacier retreat. Yet the possibility of its 

pre-Vashon existence, once generally accepted, is problematic. 

It is possible that the valley was formed before Vrshon time, 

by either fluvial or glacial erosion, and that it was only modifled by the Vashon ice, but it is also possible that it was 

formed entirely by ice scour during the Vashon Stade. In 

contrast, there seems no doubt that valleys of the Cedar and
INTRODUCTION

Green Rivers were cut in postglacial time, along consequent 

courses that were established on the drift plain during and 

shortly after ice retreat. The White also initially followed 

a consequent course over the drift plain in postglacial time, 

but it flowed south into the Puyallup River. The White entered the mapped quadrangles after the Osceola Mudflow, 

when the river established a course along the mudflow axis 

between the mountain front and Auburn. In its new position, 

it cut rapidly into the mudflow and drift plain, and became 

the principal supplier of sediment to the alluvial fill of the 

Duwamish Valley.

Though the White and Green Rivers are similar in size 

and formerly joined at Auburn, the White River has a notably 

steeper gradient and it carries a coarser and probably more 

abundant load. The White also swings fairly rapidly across 

its valley floor by migration of meanders, constantly reworking overbank deposits that have accumulated. As a consequence, its valley floor is covered mostly by channel deposits. 

The Green River, in contrast, migrates by meandering at a 

comparable rate only locally and within its own valley. Downstream, the Green migrates progressively less by meandering, 

and in the northern part of Duwamish Valley it shifts chiefly 

by avulsion. The Green does not rework the intervening overbank deposits as it shifts by avulsion and leaves the northern 

reaches of Duwamish Valley covered largely by overbank 

materials.

Structural features in the lower Tertiary bedrock include 

complex folds and faults produced before late Miocene time. 

Near Renton, many folds and faults are nearly alined with a 

regional west-northwest structural trend. Near Black Diamond, 

however, the major trend of folds is nearly north. Later widespread but relatively minor folding and faulting have affected 

upper Tertiary sediments and all but the youngest Pleistocene 

and Holocene sediments.

Of major economic importance in this area is the effect of 

geologic conditions on land use. The geologic deposits have 

highly diverse inherent engineering properties. Yet in a general way, values or ranges of values for some .engineering 

properties can be correlated with individual geologic formations or with groups of them. Thus, engineering behavior of 

geologic units, to a certain extent, can be anticipated on the 

basis of identity of the units. Special conditions that involve 

factors other than inherent properties, such as landslides, are 

also highly relevant to land utilization.

Mineral resources that are exploited include construction 

sand and gravel, which is widespread, abundant, and in 

many places of good quality. Construction stone is valuable 

but scarce. Silica sand and clay are also mined, though in recent years production has not been large. Coal mining, formerly 

economically important here, has been suspended.

INTRODUCTION 

LOCATION, PURPOSE, AND SCOPE

The Renton, Auburn, and Black Diamond T1/^- 

minute quadrangles are in the southeastern part of the 

Puget Sound lowland of Washington, southeast of 

and adjacent to Seattle (figs. 1, 2). The northwestern 

part of the Renton quadrangle is in the Seattle metropolitan area and only about 8 miles from Seattle's 

central business district. Southeastward, the Black

Diamond quadrangle reaches to within a few miles of 

the front of the Cascade Range (fig. 2). Except for a 

narrow strip in Pierce County along the south edge 

of the Auburn quadrangle, the entire mapped area is 

in King County (fig. 2).

These three quadrangles are part of a mapping 

project that encompasses eleven T1/^-minute quadrangles (fig. 2). The purpose of the project is to provide 

geologic maps and other basic geologic data for an 

area of present and future urban and industrial use. 

The project area covers the southern part of Seattle 

and extends southeastward across the lowland into the 

foothills of the Cascades (fig. 2). Geologic maps have 

been published separately for several of the quadrangles: Buckley (Crandell and Gard, 1959); Poverty 

Bay, Des Moines, and Duwamish Head (Waldron, 

1961,1962,1967); and Renton, Auburn, and Black Diamond (Mullineaux, 1965a, b, c). Final reports on the 

Lake Tapps 15-minute quadrangle (Crandell, 1963; 

Gard, 1968) include geologic maps of the Sumner, 

Buckley, Orting, and Wilkeson T^-minute quadrangles. In addition, a preliminary geologic map of Seattle and vicinity has been compiled (Waldron and 

others, 1962).

Mapping of three quadrangles east of the Renton 

and Black Diamond quadrangles (fig. 2) by the U.S. 

Geological Survey as part of a cooperative project 

with the State of Washington provides additioral 

data on the lowland area. Results of that investigation are contained in preliminary geologic maps (Vine, 

1962b; Gower and Wanek, 1963) and in a final report 

by Vine (1969).

The Renton, Auburn, and Black Diamond quadrangles were mapped from 1954 to 1959. Mapping 

was done on aerial photographs, and contacts wore 

transferred planimetrically to a topographic base, with 

generally only minor adjustments to fit the topography as shown on that base. Along the valley walls, 

however, the match between aerial photographs and 

topographic base locally is poor. There, the altitudes 

of the nearly horizontal contacts between Pleistocene 

formations were measured by altimeter, and the contacts are shown on the map at the altitudes determined.

A report containing the geologic maps has previously been released in open file (Mullineaux, 1961), 

and the maps were published separately in 1965 (Mullineaux, 1965a, b, c). That report was rewritten in 

1968 and some results of recent nearby investigations 

referred to, but no new fieldwork was done. Because 

the maps have been published separately, they are not 

included with this version of the report and can be 

obtained only as individual geologic quadrangle maps.
GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

124° 122° 120° 118°

N 0 G A N I PERRY

 p i-ea* 7 

Q:( C H E L A N

i ._._

' U-- <' ^, ' "\ /-X-U- v ' 

\ FRANKLIN^ p [GARFIELDl J

I / ..r-i^lT ¥T%«DT«W I >

I ' «^»r »^y* L, E, W 1 S y^

JSK"^r°clssrfi;K:ir~ r ~ ~ ~ "T J< ^ COWLITZ , - Q

46°

50 

I

100 MILES

FIGURE 1. Index map of Washington showing the location of the Renton, Auburn, and Black Diamond quadrangles 

(shaded), and approximate boundary of Puget Sound lowland (heavy line). Modified from Crandell (1963, fig. 1).

ACKNOWLEDGMENTS

The author was assisted in the field at various times 

by L. A. Palmer, Herman Ponder, C. F. McKillop, 

D. A. Kapphahn, D. A. Holmes, and P. W. Birkeland, 

all of whom were geologic field assistants with the 

U.S. Geological Survey. The author acknowledges the 

help of the late Dr. George B. Kigg, Professor Emeritus, University of Washington, who provided unpublished information on peat bogs; Ralph Clark and 

M. Kochanik, International Pipe and Ceramics Corp., 

for information on characteristics of local clays; and 

S. L. Glover, former director, Washington State Division of Mines and Geology, for unpublished information on the Hammer Bluff Formation. The late 

R. W. Brown of the U.S. Geological Survey helped 

collect and identified the plant fossils. The molluscan 

fossils were identified by E. J. Moore and the Foraminifera by R. M. Todd, both of the U.S. Geological 

Survey. E. B. Leopold of the U.S. Geological Survey 

helped collect and analyzed samples for pollen and

provided interpretation of climate during Pleistocene 

jtime. K. E. Lohman of the U.S. Geological Survey 

identified diatoms in samples submitted and also provided interpretations regarding the climate and physical environment in which they were deposited. Radiocarbon samples were analyzed in the U.S. Geological 

Survey radiocarbon laboratory under the direction of 

Meyer Rubin.

Sedimentary rock samples were analyzed for grain 

size and were prepared for heavy- and light-mineral 

studies in U.S. Geological Survey laboratories under 

the direction of Dorothy Carroll, J. C. Hathaway, 

J. A. Sharps, and T. C. Nichols. In additior, identification of some heavy-mineral samples was carried 

out under the direction of Carroll and Hathaway. 

X-ray analyses of clay and silt were made by and under the direction of T. C. Nichols, Julius S^hlocker, 

J. C. Hathaway, and L. G. Schultz of the U.S. Geological Survey.

The present study was at least partly concurrent 

with several other Geological Survey projects in ad-
123°00'

INTRODUCTION

122*00' 121-00'

^Mountain Front 

- (Approximate)

Newcastle Hills - 

promontory z 

Snoqualmie

 47"00'

FIGURE 2. Index of recent geologic quadrangle mapping by the U.S. Geological Survey in the southeastern part of the 

Puget Sound lowland. The project of which this work is a part includes the Duwamish Head, Seattle South, D~<: 

Moines, Poverty Bay, Renton, Auburn, Black Diamond, Sunnier, Buckley, Orting, and Wilkeson 7^-minute quadrangles. The last-named four compose the Lake Tapps 15-minute quadrangle. The Maple Valley, Hobart, and Cumberland quadrangles were mapped as part of another project, in cooperation with the State of Washington.

jacent areas, and the author has benefited greatly from 

information made available by the geologists responsible: D. R. Crandell, H. H. Waldron, L. M. Gard, 

Jr., J. D. Vine, H. D. Gower, A. A. Wanek, and J. E. 

Luzier. The late Dr. J. Hoover Mackiii, formerly Professor at the University of Washington and the University of Texas, contributed significantly to the investigation through discussion, field conferences, and 

review of the text. Reviews of the text were also provided by Professors J. D. Barksdale, V. S. Mallory, 

and Peter Misch of the University of Washington, 

and by Crandell, Waldron, and Vine.

OTHER STUDIES

The discovery of coal near Renton shortly after 

1850 and later at Black Diamond stimulated interest 

in the geology of the area, but most of the early reports and references to the coal and bedrock contained 

little discussion of areal geology. The first published 

results of areal geologic studies are those of Willis 

(1886; 1898a, c) and Willis and Smith (1899); the 

stratigraphic divisions of bedrock and surficial deposits established in these reports have been followed 

since then with surprisingly little change. Willis' 

studies and those of White (1888, 1889) established

380-731 O - 70 - 2
6 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

the use, for example, of the name Puget Group for 

the arkosic nonmarine rocks in the Puget Sound lowland. Willis (1898c) also established the name Vashoii 

Drift for the youngest drift sheet in the area, and 

recognized the future necessity of subdividing his preVashon drift unit.

Bedrock of this area has been discussed in many 

reports since the early reports of Willis. In 1912, 

Evans described in detail the bedrock and coal beds 

in King County and divided the rocks exposed along 

the Green River into three useries." Weaver (1916, 

1937) published detailed descriptions of sections measured along the Green River during the study with 

Evans and further described the bedrock near Renton. 

Glover (1941) described previously unknown but economically important upper Tertiary clay and sand 

along the Green River, distinguishing them from the 

bedrock and less weathered Pleistocene deposits. In 

1945, Warren, Norbisrath, Grivetti, and Brown published a detailed map of the bedrock and, locally, the 

depth to rock under the cover of drift. More recently, 

Gard (in Crandell and Gard, 1959; Gard, 1968) redescribed the bedrock in the area where Willis originally subdivided the Puget Group. Waldron (1962) 

and Vine (1962a), as a result of mapping west and 

east, respectively, of the Renton, Auburn, and Black 

Diamond quadrangles, defined and named lithologically distinguishable subdivisions of the Puget Group. 

Vine (1969) restudied the Puget rocks in the Maple 

Valley, Hobart, and Cumberland quadrangles (fig. 2) 

and with Gower and Wolfe (Wolfe, Gower, and Vine, 

1961; Wolfe, 1968) established a stratigraphic column 

of Puget Group rocks based on floral zones.

Prior to this study, the Pleistocene deposits of the 

three quadrangles had not been mapped since Willis' 

time, though a soils map of King County by Poulson, 

Miller, Fowler, and Flannery (1952) shows the approximate outlines of some surficial geologic units, and 

many other studies in the lowland dealt in part with 

the area. Bretz (1913) made an extensive reconnaissance of glaciation in the Puget Sound lowland. His 

major contribution, the recessional history of the 

Vashon glacial episode, describes events near Renton 

and Auburn. Mackin (1941) studied the relation between continental and alpine glaciers along the west 

flank of the Cascades and described a major drainage 

diversion that brought great volumes of water across 

the Black Diamond and Auburn quadrangles. Later, 

Hansen and Mackin (1949) showed that there are at 

least two pre-Vashon drift sheets in the Puget Sound 

lowland and that the pollen content of sediments can 

be used to separate pre-Vashon drifts. In 1958, Crandell, Mullineaux, and Waldron established the sequence of three pre-Vashon drift units that is used 

in this report, and, in 1963, Crandell published a comprehensive study of surficial geology and geomorphology in the Lake Tapps quadrangle to the south. Recently, the geologic maps of the Renton, Auburn, and 

Black Diamond quadrangles have been incorporated 

into a smaller scale geologic map and report that 

covers all of southwestern King County (Luzier, 

1969).

GEOGRAPHY

TOPOGRAPHY AND DRAINAGE

The Renton, Auburn, and Black Diamond quadrangles lie in the broad lowland between the Olympic 

Mountains and the Cascade Range (fig. 2), where the 

terrain is dominated by a broad drift plain that stands 

several hundred feet above the floors of valleys cut 

into it. Though subdivided into many segrreiits by 

troughs and valleys, this drift plain extends from the 

Olympics across the entire lowland to the Cascades. 

Segments of it are the features called plateaus or 

islands by Willis (1898c) and later by Newcomb 

(1952), and Liesch, Price, and Walters (1963). In 

the vicinity of the mapped area, the drift plain is 

bounded on the north by a large bedrock ridge herein 

called the Newcastle Hills promontory (fig. 3), which

; i '///"I-''? ^ 

Renton '///''""Tiger Mountain

U/

DRIFT 

PLAIN

47M5'

47°00'

10

I

20

I

30 MILES

FIGURE 3. Major physiographic elements in the southeastern 

part of the Puget Sound lowland (Renton-Auburn-Black 

Diamond area outlined), showing troughs and highlands that 

bound the drift plain of that area.
GEOGRAPHY

is a northwest-trending highland that projects far out 

into the lowland from the Cascade Range. On the 

east and south, the drift plain is bordered by the 

southwest-trending front of the Cascades (fig. 3). It 

is separated from other parts of the drift plain farther 

west by the trough of the Duwamish Valley.

The drift plain constitutes about 80 percent of the 

mapped area; its surface is gently rolling, with a relief of 100-200 feet, and is underlain chiefly by ground 

moraine. The average altitude increases southeastward, 

from about 400 feet near the city of Renton to about 

600 feet in the southeast corner of the area. The highest point, in the southeast corner of the Black Diamond quadrangle, is slightly more than 850 feet. Steepsided valleys of the Cedar, Green, and White Rivers 

subdivide the drift plain in this area, and the largest 

of the resulting segments is nearly bisected by a meltwater trench that will be termed the "Covington 

channel" (fig. 4). The drift plain between the Green 

and White River valleys is similar to that in other

122-15' 7'30" 122-00'

47*30'

22'30"

47°15'

5 MILES

FIGURE 4. Principal physiographic units in the Renton, Auburn, Black Diamond, and Maple Valley quadrangles. Shaded 

area is drift plain.

parts of the area, except that its lower parts have b^-en 

covered by the Osceola Mudflow, which forms a flatfish 

surface that slopes gently northwestward.

The principal valleys that border and subdivide the 

drift plain locally are the Cedar, Green, and WHte 

River valleys and the trough of the Duwamish Valley 

(fig. 4). The largest is the Duwamish Valley, which 

trends northward along the west side of the Renton 

and Auburn quadrangles. It is wide, about 2 miles 

across, and is characterized by gently sloping valley 

walls. This valley, or trough, is part of an extensive 

system of troughs in this part of the lowland. To the 

south, it merges with a similar trough that contrins 

the Puyallup River (fig. 3). To the north, it divides 

at Renton; one arm extends northwest to the Puget 

Sound at Seattle, and the other continues north, where 

it contains Lake Washington. These troughs are not 

valleys cut by postglacial rivers; instead they are 

former extensions of the Puget Sound waterway that 

have become partly filled to above sea level with lacustrine and alluvial deposits. The part of the trough 

system herein called the Duwamish Valley (after 

Willis, 1898c) was occasionally called the White River 

valley when the White River flowed north to Seattle 

before 1906, and was called the Green River valley 

after diversion of the White. But these terms involve 

a name change and also suggest that the wide trough 

was cut by one or both of the rivers. The Duwamish 

Valley is herein regarded as extending from the junction with the Puyallup Valley at Sumner, north to 

Renton, and thence northwest to Seattle (fig. 3).

In contrast to the Duwamish Valley, the valleyp of 

the Cedar, Green, and White Rivers, which have been 

cut in postglacial time, are narrow and steep walled.

The lowest altitude in the mapped area, about 10-15 

feet above mean sea level, is on the Duwamish Valley 

floor west of Renton. From there, the altitude of the 

valley floor increases gradually southward to at out 

100 feet at the mouth of the White River valley, then 

decreases southward. The valley floors of the Cedar, 

Green, and White Rivers rise somewhat more steeply 

and reach altitudes of more than 100, 225, and 275 

feet, respectively, at the quadrangle boundaries.

The three master streams, the Cedar, Green, and 

White Rivers, all head in the Cascade Range and 

flow in well-defined valleys across the mapped area 

to the Duwamish Valley (figs. 2, 4). Both the Ceiar 

and the White Rivers form fans on the floor of the 

Duwamish Valley and in the past have established 

north- and south-flowing distributaries on these fans. 

Within this century, the courses of both rivers have 

been shifted, that of the White River chiefly by natural change and that of the Cedar by artificial change.
8 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

These drainage changes have been accompanied by 

several changes in the names applied to various parts 

of the river system in the Duwamish Valley in the 

last 60 years (Dart, 1952). Figure 5 shows the river 

system and the names applied in 1899, when the Tacoma 30-minute quadrangle map was published, and 

also the river system and the names applied in 1959. 

As of 1899, the main distributary of the White Eiver 

flowed northward to join the Green Eiver near Auburn and the Black River near Kenton and to enter 

the Puget Sound at Seattle. A smaller distributary 

flowed southward to join the Puyallup River and enter the Puget Sound at Tacoma. The north-flowing 

distributary was known as the White River as far as 

its junction with the Black, and as the Duwamish 

River from the junction to the Sound. The smaller 

distributary was known as the Stuck River down to 

its junction with the Puyallup River. During a flood

122'15' 122°15'

4 7° 30'

FIGURE 5. Changes of course and nomenclature of rivers in 

the Duwamish Valley, 1899-1959.

in 1906, most of the White River discharge shifted 

southward and occupied the Stuck River channel. 

Shortly thereafter the White River was artificially 

confined to the Stuck channel, and only the Green 

River occupied the channel from Auburn north to the 

junction with the Black River.

The Cedar River has been prevented froir joining 

the Green by way of the Black River since 1917, when 

a ship canal was dug connecting Lake Washington 

to Puget Sound. The lake was lowered several feet, 

the Cedar River was artificially directed into the lake, 

and the lake outflow was controlled by navigation 

locks. The Black River, which formerly contrined the 

discharge of both Lake Washington and Cedar River, 

was then reduced to a small brook. The name Duwamish is still usually applied to the river in the 

Duwamish Valley north of the former junction of the 

Green and Black Rivers, although the river is now 

merely the lower reach of the Green River.

In contrast to the master streams, most tributary 

streams head on the drift plain, where drrinage is 

only partly integrated. Lakes and bogs are abundant, 

and many smaller streams flow from swamp to swamp 

across the plain; only the larger streams r,nd even 

those only near their mouths have cut well-defined 

valleys. Northwest of the Coviiigton channel, streams 

are controlled by a topographic alinement that trends 

slightly east of south, in the direction of last ice movement (fig. 6). As a result, many small streams that 

head just east of the Duwamish Valley do not flow 

westward into that valley, but instead flow southeastward. Big Soos Creek, for example, originates only a 

mile or two from the Duwamish Valley near Renton, 

then flows south-southeastward nearly parallel to the 

valley for about 8 miles, and enters the Covington 

channel leading to the Green River. Southeast of the 

Covington channel and north of the Green River, most 

streams flow in abandoned melt-water channels that 

lead westward and northwestward to the Covington 

channel or southward to the Green River valley (fig. 

6). South of the Green, much of the flattish surface 

of the Osceola Mudflow is artificially drrlned by 

ditches. The largest stream, Newaukum Cre°<k, flows 

northward across the mudflow to the Green River 

valley.

CLIMATE

The climate of the Puget Sound lowland is mild, 

with wet winters and dry summers. The mean annual 

temperature at Seattle and at Kent, in Duwamish 

Valley between Renton and Auburn, is about 52°F 

(U.S. Weather Bureau, 1961). The highest mean 

monthly temperature in Seattle, about 65°F, occurs 

in July, and the lowest mean, about 40 °F, occurs in
TERTIARY ROCKS 9

122-15' 7'30"

47°15'

FIGURE 6. Pattern of drainage on drift plain (shaded) in 

Renton, Auburn, and Black Diamond quadrangles, and in 

Maple Valley quadrangle southwest of Cedar River Valley.

January. Extreme annual temperatures are usually 

well within limits of 0° and 100°F.

Precipitation is concentrated in the winter months, 

and it increases from west to east across this part of 

the Puget Sound lowland. Seattle and Kent, which are 

typical of the western part of the mapped area, receive about 30 35 inches of precipitation annually. 

Buckley, Snoqualmie Falls, and Landsburg, all of 

which lie along the east side of the lowland near the 

Cascade mountain front, receive about 50-60 inches; 

Cedar Lake, on the western slope of the Cascade 

Range, receives more than 100 inches annually. About 

75 percent of the rainfall occurs in the 6-month period 

from October through March; the peak rainfall is in 

December, when rainfall is frequent although usually 

not heavy.

VEGETATION

The mild and moist climate of the lowland results 

in a luxuriant growth of vegetation. The natural forest, which at one time consisted principally of large

conifers (Hansen, 1947), has been logged off and only 

the second growth remains. The second growth is 

composed of closely spaced smaller trees, chiefly bigleaf maple, alder, Douglas-fir, lowland hemlock, and 

vine maple. A dense tangle of shrubs and smaller 

plants grows under the second-growth trees and on 

cutover land.

Plants grow virtually everywhere except on ve^y 

rapidly eroded slopes, but the plant types differ markedly from place to place. These differences are strongly 

influenced by soil moisture, which in turn is influenced by the character of the underlying deposit. As 

a result, the distribution of certain plants locally 

indicates the identity and distribution of certain geologic deposits. For example, large deciduous treQ,s 

rarely grow on terraces of well-drained, gravelly glacial out wash; stands of Douglas-fir and sparse underbrush characterize such deposits. In contrast, abundant 

deciduous trees and much brushy undergrowth characterize more clay-rich deposits such as glacial till. 

Few large trees of any kind grow on deep peat bogs; 

as a result, in wooded areas the bogs can be recognized 

readily on the ground or on aerial photographs. On 

valley walls, plants that prefer very wet ground, such 

as devilsclub, skunkcabbage, and nettles, suggest the 

presence of springs or landslide deposits.

CULTURE

In 1960, most of the population of the area was in 

cities and towns in the Duwamish Valley, along the 

west edge of the area. Renton, the largest city, with 

about 18,500 people in 1960, adjoins Seattle on the 

south. Kent, with about 9,000 people in 1960, and Auburii, with about 12,000, as well as several smaller 

cities, are situated farther south along the valley (frg. 

7). The largest city east of the Duwamish Valley is 

Black Diamond, a former coal-mining center at the 

east edge of the Black Diamond quadrangle.

TERTIARY ROCKS

Tertiary rocks exposed in the Renton, Auburn, and 

Black Diamond quadrangles are the bedrock, which 

consists of sedimentary rocks of early Tertiary age 

and some intrusive rocks, and poorly indurated sedimentary rocks of late Tertiary age. Rocks older than 

Tertiary are not known in the mapped area; the nearest 

outcrops of pre-Tertiary rocks are in the Cascade 

Range about 20 miles east of Renton (Weaver, 1937). 

The lower Tertiary sedimentary rocks consist chiefly 

of the Puget Group of Eocene and Oligocene age, 

which is several thousand feet thick and which crops 

out in the northwestern and southeastern parts of the
10 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

122-15' 122°00'

47-30'

Maple 

Valley

Covington

Black Diamo^cl^//; 

'////

22'30"

5 MILES

FIGURE 7. Principal populated areas and centers of communities referred to in text.

area near the cities of Renton and Black Diamond 

(Miillineaux, 1965a, c). The Puget Group is overlain 

by the Lincoln Creek (?) Formation which is possibly 

of Eocene or Oligocene age or of both ages; this 

formation is more than 1,000 feet thick along the 

Cedar River east of Renton (Miillineaux, 1965a). 

South and west of Renton, the lower Tertiary rocks 

have been intruded by small bodies of andesite. The 

upper Tertiary rocks, the Hammer Bluff Formation, 

are but a few tens of feet thick and crop out only in 

a limited area along the Green River near Black Diamond (Miillineaux, 1965c).

LOWER TERTIARY SEDIMENTARY ROCKS

PUGET GROUP

The Puget Group in this area consists of a thick 

sequence of arkosic sandstone and interbedded shale 

and coal, which locally includes a formation of sedimentary rocks composed almost entirely of fragments 

of volcanic rock. The Puget probably underlies the 

entire area, but it crops out only in valley walls and

in a few hills that stand above the surface of the drift 

plain.

Rocks of the Puget Group were first described by 

Willis (1886), who referred to them as tK "Coal 

measures of the Puget Sound basin." A study of molluscan fossils from these beds led White (1888) to 

conclude that although the rocks enclosing th*, fossils 

were equivalent in age to the Laramie Formation, 

they had been deposited in a separate basin and deserved a different name. Accordingly, he proposed the 

name Puget Group (White, 1888, p. 446-447). Since 

then, the name Puget has been used consistently to 

refer to the coal-bearing brackish- and fresh-water 

arkosic sandstone and shale of Eocene and locally 

younger age in the Puget Sound lowland (Willis, 

1898a; Landes, 1902; Smith, 1902; Evan?,, 1912; 

Weaver, 1916, 1937; Warren and others, 1945; Crandell and Gard, 1959; Waldron, 1962; Vine, 1962a). 

Most writers have followed White's usage of the name 

Puget Group, but some (Willis, 1898a; Evans, 1912) 

have referred to these rocks as the Puget Formation 

and Puget Series.

Willis and Smith (1899, p. 8) subdivided the Puget 

Group near Carbonado (in the Lake Tapps quadrangle) into three formations of arkosic rocks: the Carbonado (oldest), the Wilkeson, and the Burnett 

(youngest). Evans (1912, p. 42) subdivided the Puget 

near Black Diamond into three "series," all arkosic, 

that he called the Bayne (oldest), the FranHin, and 

the Kiimmer (youngest). These subdivisions ^ere useful locally, but Willis and Evans (Willis, 1886, p. 

759; Evans, 1912, p. 49) pointed out that, owing to 

such characteristics as the lack of marker h^ds, the 

similarity of strata from bottom to top, and the lenticular nature of the beds, projection of these subdivisions from one locality to another was not generally 

possible.

In some places, however, the Puget Group can be 

subdivided and correlated on the basis of lithology, 

because it contains a formation composed chiefly of 

andesitic sedimentary rocks between the arkoric rocks. 

Such an andesitic formation lies within the Puget 

Group from west of Renton eastward to tl x ?, Tiger 

Mountain area near Issaquah. In this region, the group 

has been subdivided into three formations. They are, 

from oldest to youngest, the Tiger Mountain Formation (Vine, 1962a), which is typically arkosic; the 

Tukwila Formation (Waldron, 1962), composed mostly of volcanic materials; and the Renton Formation 

(Waldron, 1962), composed of arkosic strata. The upper two of these formations crop out in the Renton 

quadrangle. The Tukwila Formation does not extend 

southward to the exposures in the Black Diamond
TERTIARY ROCKS 11

district, however, and in that area the arkosic Puget 

Group was not subdivided for mapping purposes. Because of the marked difference in the lithologic sequences that make up the Puget Group in the Black 

Diamond and Renton districts, the rocks in the two 

areas are described separately.

UNDIFFERENT1ATED PUGET GROUP NEAR BLACK DIAMOND

Arkosic rocks of the Puget Group are well exposed 

in the canyon walls of the Green River in sees. 26, 

27, and 28, T. 21 N., R. 6 E., and are sparsely exposed 

in the town of Black Diamond. Coal-mine maps show 

that these rocks are present also under a thin cover of 

Quaternary deposits throughout an area of several 

square miles near Black Diamond (Warren and others, 

1945).

The exposures along the Green River extend northeastward into the Cumberland quadrangle for many 

miles (Gower and Wanek, 1963); these extensive outcrops provide one of the best exposed and most studied 

sequences of Puget Group rocks in this region. Willis 

(1886, p. 759) first reported the Puget Group of this 

area to be, not including the top or bottom beds, 6,200- 

8,200 feet thick; he later reported that measured sections in the area, though they did not represent the 

complete sequence, totaled 5,800 feet (Willis, 1898b, 

p. 5). Evans (1912, p. 42) and Weaver (1937, p. 56- 

61) measured more than 8,300 feet of Puget Group 

rocks, and Warren, Norbisrath, Grivetti, and Brown 

(1945) reported the thickness to be at least 6,500 feet. 

This great variation in reported thickness probably 

arises from variations in tentative correlations across 

several anticlines and synclines as well as across covered zones. Vine (1969) recently restudied the section; 

he reported that though the measurements of Evans 

and Weaver were accurate for the upper part of the 

sequence, they were too great for the lower part. Vine 

estimated the total exposed thickness along the Green 

River near Black Diamond to be about 6,200 feet (fig. 

8; Vine, 1969).

The thickest exposed sequence of the Puget Group 

within the mapped area, about 1,600 feet thick, crops 

out along the Green River from the east boundary of 

the Black Diamond quadrangle westward for 1-2 miles 

(Mullineaux, 1965c). These beds, which are exposed in 

the limbs of the Black Diamond anticline of Evans 

(1912), include parts of the Franklin and Kummer 

Series of Evans (1912; fig. 8, this report). The 1,600 

feet that is exposed within the quadrangle, however, 

is a small part of the total thickness known in this 

particular locality. Nearly 1,300 feet of strata that are 

higher in the Kummer Series crop out between the 

quadrangle boundary and the axis of the Kummer

syncline of Evans (1912) about half a mile farther 

east. In addition, drilling records suggest that' at least 

4,200 feet of older Puget rocks lie below those exposed

E

Kummer No. 0* a

Flintclay 

Kummer sandstone

 Harris* -

-Gem* 

-McKay*-

Is0 =

o

ll

 y C

JS n 

OlQ

£ o ** (o

82 

I-4) 3

£ 

O

ll

,-! (0 

1-

* O

c jo 

!I«n

£

n o 

o>

FEET 

0

-1COO

FIGURE 8. Generalized stratigraphic section of the Puget 

Group in the vicinity of Black Diamond, showing app~oximate stratigraphic intervals exposed and penetrated1 by 

drilling, positions of the Bayne, Franklin, and Kummer 

Series of Evans (1912), and of several key strata. Data 

in part from Evans (1912), Anderson (1959), and T7ine 

(1969). * indicates coal bed.
12 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

in the Black Diamond anticline; one of several deep 

wells drilled near the crest of the anticline reached a 

depth of 6,023 feet in Puget Group strata that dip 

less than 45° (Livingston, 1958; Anderson, 1959). The 

thickness suggested by drill records and exposures is 

thus about 7,000 feet, without the base of the group 

being reached.

In the part of the town of Black Diamond within 

the quadrangle, the Puget strata that are intermittently exposed represent a stratigraphic interval of 

about 1,000 feet of the Franklin Series that is strati - 

graphically lower than the rocks exposed along the 

Green Eiver to the south (fig. 8). These older rocks, 

reach the surface in the town because the Black Diamond anticline rises north of the Green Eiver. The 

anticline is also offset to the east; consequently, the 

Puget strata exposed at Black Diamond within the 

quadrangle are on the west limb of the anticline.

LlTHOLOGY

Rocks in the Black Diamond district are mostly 

light-gray to light-brown sandstone and interbedded 

shale. The sandstone encloses at least one thin bed of 

granule conglomerate and an intraformational conglomerate. The latter is composed of shale fragments, 

ranging from pebble to boulder size, in a matrix of 

fine-grained sandstone and is exposed in the Green 

River valley at the east edge of the quadrangle. Highalumina claystone, the Kummer flint clay of Glover 

(1941), which is associated with coal and carbonaceous 

shale, lies a few feet below the intraformational conglomerate. Carbonaceous beds are numerous. More than 

10 coal and carbonaceous shale zones, including the 

Gem, Harris, and Kummer No. 0 coal beds (fig. 8; 

Evans, 1912; Beikman and others, 1961, p. 52), are 

present in the strata exposed along the Green River 

within the quadrangle. At Black Diamond, strata that 

reach the surface include the McKay coal bed and another economic coal bed about 300 feet above the McKay (Evans, 1912, p. 151).

The sandstones are mostly medium to very fine 

grained. Coarser deposits are typically crossbedded, 

but bedding commonly is obscure except where it is accentuated by concentrations of carbonaceous material 

or iron oxide. Some fine-grained rocks are crossbedded; others are flat bedded. Sandstone samples analyzed for grain size range from well sorted to normally sorted in the terminology of Trask (1932, p. 72), 

with sorting coefficient values of about 2.1 to 3.5. 

Trask's sorting coefficient is based on the central half 

of the particle-size distribution curve, and fairly well 

sorted sand grains represent that part of the curve for 

these rocks. All the samples of sandstones that were

examined, however, contained 20 percent or more of 

silt and clay (fig. 9). Some other sorting values, such 

as those of Folk and Ward (1957), which ar°, based 

on a larger portion of the distribution curve, take into 

account part of the silt and clay in these reel's. As a 

result, the sandstones are, in the terminology of Folk 

and Ward, poorly sorted to very poorly sorted. Individual sand grains in the Puget rocks are mostly subangular to subrounded, but every sample that we examined contained a few well-rounded grains.

Most of the sandstone is poorly cemented, micaceous, 

salt-and-pepper arkose, whose predominant minerals 

are quartz and feldspar. Judged from examinations of 

one thin section and stained grain mounts from seven 

samples, quartz constitutes about 50 percent of the 

grains; potassium feldspar, 20-35 percent; and plagioclase, 5-20 percent. In stratigraphically lower rocks 

of the Puget Group nearby, however, plagioclase is 

reported to be more abundant than potassium feldspar 

(Vine, 1969). Chert, quartzite, and other rock fragments make up less than 10 percent of the grains. 

Muscovite, biotite, and chlorite are distributed throughout the sandstones; the micas are conspicuous in hand 

specimens, yet they probably compose less than 5 percent of the grains. Suites of heavy minerals (specific 

gravity > 2.8) generally are dominated by mica, 

opaque minerals, and brown, earthy aggregates that 

an X-ray diffraction analysis indicates are composed 

largely of kaolinite, siderite, and limonite (L. G. 

Schultz, oral commun., 1960). Other heavy minerals 

are sparse but consist of a wide variety of species; 

garnet and zircon are the most common, but tourmaline, staurolite, kyanite, rutile, pyroxene, and epidote 

are also common. In the Kummer Series along the 

Green River, just east of the quadrangle boundary, 

garnet is more abundant than zircon; ratios of garnet 

to zircon in three samples ranged from 2:1 to 5:1. 

Ratios of these two minerals in Kummer rocks reported by Bond (1959) are similar. In the Franklin 

Series within the quadrangle, in contrast, garnet is 

generally only about half as abundant as zircon.

Coarse and fine silt- and clay-size detritus (fig. 9), 

plus varying amounts of chemical cement, makes up 

the matrix of the sandstones. The principal clay minerals identified in the matrix of silty sandstone from 

the Kummer Series are kaolinite and smaller amounts 

of illite. Kaolinite and lesser amounts of mica (illite), 

mixed-layer minerals, and montmorillonite are reported to' be the clay minerals typical of the upper part 

of the Puget Group farther east along the Green River 

(Vine, 1969). The cement is largely calcite. The calcite is widely but very unevenly distributed r.nd typ-
TERTIARY ROCKS 13

0.01

SIZE OF PARTICLES, IN MILLIMETERS 

0.1 1.0 10.0

CLAY GRANULES PEBBLES

FIGURE 9. Cumulative curves of Puget Group arkose samples. Numbers 1-8 are from the undifferentiated 

Puget Group in Black Diamond area. Numbers 9-12 are from the Renton Formation at Renton.

ically forms bulbous concretions or lenticular concretionary lenses. Locally, it composes as much as a third 

of the rock, not only filling intergranular spaces, but 

also replacing parts of grains along their margins.

Shale probably makes up less than a third of the 

Puget strata exposed in the quadrangle, forming less 

of the rocks in the upper part of the Puget Group 

along the Green River than it does in the lower part 

(Weaver, 1937; Vine, 1969). Siltstone is predominant 

over claystone, and both locally are carbonaceous. One 

of the claystones, the Kummer flint clay, is a highalumina deposit, containing as much as 51 percent 

ALO3 (Glover, 1941); it consists mostly of kaolinite, 

gibbsite, and boehmite (Nichols, 1946).

WEATHERING

The Puget Group locally has undergone severe 

weathering. One locality of deep weathering is at 

Hammer Bluff, on the north side of the Green River 

in the NWi/4 sec. 28, T. 21 N., R. 6 E. In that area, 

arkose in the Puget is weathered and leached to a 

depth of as much as 30 feet and is now a light-gray 

friable sand composed mostly of quartz and kaolinitic 

clay. For an additional few tens of feet downward, 

in less weathered rocks, iron oxide has stained the arkose to brown or greenish-brown. Enough feldspar has 

been altered to clay and enough cement and iron oxide 

have been leached away so that the weathered arkose 

at Hammer Bluff has been used as a source of silica 

sand.

STRATIGRAPHIG RELATIONS

The Puget Group is the oldest rock unit exposed in 

the Black Diamond district; it is overlain by andesitic 

sedimentary rocks of Oligocene age (Warren and 

others, 1945; Wolfe, Gower, and Vine, 1961). NeitHr 

the lower nor the upper contact of the group is exposed 

in the mapped area; .the approximate position of the 

upper contact is known just east of the Black Diamond 

quadrangle in the Kummer syncline, but it is hidden 

beneath a large landslide. The attitudes of the Puget 

Group and the andesitic sedimentary rocks indicate 

little if any angular unconformity between the t^o 

formations. The andesitic sedimentary rocks are not 

exposed within the Black Diamond quadrangle; here, 

the Puget Group is unconformably overlain by the 

upper Miocene Hammer Bluff Formation.

FOSSILS AND AGE

Fossil leaves and fragments of petrified wood occur 

at many horizons in the Puget Group. According to

380-731 O - 70 - 3
14 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

Willis (1898a), the fossil flora represented was correlated by Newberry with that of the Laramie Formation, and the Puget was dated as Late Cretaceous or 

early Eocene. F. H. Knowlton (in Willis and Smith, 

1899, p. 3) noted that many species are represented 

and that there are well-marked differences between 

plants from the lower beds of the Puget and those 

from the upper beds at such places as the Kummer 

flint clay mine along the Green Kiver. Willis (1898a, 

p. 403) stated that Knowlton, on the basis of a preliminary examination, reported the lower beds to be 

Eocene in age and the upper beds to be possibly 

younger than Eocene. As a result of a study of fossil 

leaves collected recently, Wolfe (in Wolfe, Gower, and 

Vine, 1961; Wolfe, 1968) recognized several biostratigraphic subdivisions in the Puget Group near Black 

Diamond. He (1968) assigned most of that part of the 

sequence exposed along the Green Kiver within the 

Black Diamond quadrangle to the upper part of his 

Eavenian Stage, which he regards as of late Eocene 

age and approximately equivalent to the Tejon and 

lowermost part of the Keasey Stages of the standard 

Pacific Coast section (fig. 10; Weaver and others, 

1944).

A few pelecypods have been recovered from the 

Puget in the Green Kiver valley,, mostly from or near 

the old Kummer clay mine, wT hich is near the east edge 

of the Black Diamond quadrangle. The only fossils 

identified are a species of Corbicula, a genus reported 

to inhabit brackish and fresh water (White, 1889), 

and Batissa new'be-rryi White (F. S. McNeil, written 

comniun., 1962), which also inhabits fresh w?,ter, and 

perhaps brackish water.

SOURCE

Angularity and abundance of quartz and feldspar 

grains as compared with lithic fragments are regarded 

as suggesting that the rocks of the Puget Group were 

derived chiefly from silicic, plutonic igneous, or metamorphic rocks (Petti John, 1957, p. 512). The few wellrounded sand-sized grains of quartz, garnet, and zircon indicate that a small part of the material was 

derived from preexisting sediments. An abundance of 

feldspar grains indicates also that the source of the 

grains either was subject to a rigorous climate or had 

a high relief (PettiJohn, 1957, p. 328). F. H. Knowlton (in Willis and Smith, 1899, p. 3) pointed out that 

the climate in both eastern and western Washington

Wolfe

v i yooy

Age

OLIGOCENE

EOCENE

Stages

Kummerian

Ravenian

Informal 

substages

Lower

Upper

Standard Pacific Coast section

(Weaver and others, 1944)

Based on marine

megafossils

Stages

"Lincoln"

"Keasey"

"Tejon"

Age

OLIGOCENE

EOCENE

Based on marine

microfossils

Age

OLIGOCENE

"EOOLIGOCENE"

EOCENE

Stages

Refugian

Unnamed

Rau (1958, 1966); Beikman

Stages

Refugian 

of

Schenck

Kleinpell 

(1936)

Upper

part of 

Narizian 

of

Mallory 

(1959)

Zones

Cassadulina 

galvinensis

(Formerly

Eponides

kleinpelli)

Sigmomorphina 

schencki

Bulimina

schencki 

Plectofrondicularia 

cf . P. jenkinsi

Age

OLIGOCENE

"EOOLIGOCENE"

EOCENE

FIGURE 10. Late Eocene and early Oligocene fossil stages and zones, based on studies of plants by Wolfe (196:7 ) and of 

Foraminifera by Rau (1966) and on correlations suggested by Wolfe and Rau with the standard Pacific Coast section.
TERTIARY ROCKS 15

during Eocene time was mild; thus, high relief probably was the controlling factor.

Heavy-mineral suites show distinct changes from the 

lower to the upper parts of the Puget Group. Progressive upward change also occurs in types of clay minerals and feldspars present (Vine, 1969). Hence, the 

character or location of the source changed somewhat 

during deposition of the Puget rocks. Perhaps erosion 

uncovered different rock types in the same source area, 

or one or more streams from a different source entered 

the depositional basin.

Weaver (1937, p. 9, 67) suggested that the sources 

of the Puget Group lay generally east of the Puget 

Sound lowland in northeastern Washington, British 

Columbia, and Idaho. Bressler (1957), however, named 

the source of the Roslyn Formation, regarded by 

Weaver as an upstream equivalent of at least part- of 

the Puget, as the Mount Stuart batholith of central 

Washington. The problem of source is complicated by 

the fact that not only the suggested source rocks, but 

also the probable sedimentary correlatives of the Puget 

Group and the Puget Group itself, show considerable 

variations in mineral content. There is general agreement that the Puget rocks were derived from somewhere to the east, but a specific source has not been 

located.

TUKWILA FORMATION

The Tukwila Formation, which underlies the Renton 

Formation in the Renton district, was named for the 

city of that name on the west side of the Duwamish 

Valley about 2 miles southwest of Renton (Waldron, 

1962). The Tukwila crops out extensively in northwest 

Renton, and sparsely just south of the city. These rocks 

are part of the "tuffs and breccias" described by Warren, Norbisrath, Grivetti, and Brown (1945) as the 

"Eocene volcanic series,11 and have been described by 

others (Willis and Smith, 1899; Weaver, 1937) to include aiiclesitic flows, tuffs, breccias, and dikes.

The thickest, section of the formation known in 

this district is in the hill in northwest Renton, where 

the rocks of the Tukwila Formation crop out intermittently along the strike of the beds for about a mile. 

Dips here range from slightly less than 20° to about 

40°; the exposed thickness is inferred to be between 

2,000 and 3,000 feet, and the total thickness is not 

known. The Tukwila Formation probably thickens 

toward the east; it is estimated to be nearly 7,000 feet 

thick about 10 miles east of Renton (Warren and 

others, 1945; Vine, 1969).

Three members can be distinguished in the Tukwila 

Formation in the Renton district (fig. 11) : a lower 

member composed chiefly of andesitic sedimentary 

rocks, which constitutes most of the formation; an

Top not 

exposed

Lincoln

Creek(?)

Formation

No. 1*-

No. 2*- 

No. 3*-

 Sunbeam*-

Upper 

member

Middle 

member

Lower 

member

Base not 

exposed

FEET 

0

L 2000

FIGURE 11. Generalized column of stratigraphic sequence at 

Renton, and position of several coal beds (shown by *) in 

the Renton Formation. Data in part from Evans (1912), 

Warren, Norbisrath, Grivetti, and Brown (1945), and B<nkman, Gower, and Dana '(1961).

upper member of similar andesitic sedimentary ro°.ks 

about 300-400 feet thick; and a middle member of 

arkosic sandstone, shale, and coal about 250 feet thick. 

The middle member is similar lithologically to the 

Renton Formation and will not be described separately.

LlTHOLOGY

The upper and lower members of the Tukvdla 

Formation are composed chiefly of greenish-gray to 

brown sedimentary rocks that have a wide range in
16 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

texture. Poorly sorted, locally conglomeratic and tuffaceous sandstone apparently is predominant, and conglomerate, mudstone, shale, and tuff are common. A 

boulder conglomerate that includes subangular as well 

as rounded fragments crops out in the middle of the 

upper member along State Highway 900 about a mile 

west of the center of Renton, and bouldery poorly 

sorted volcanic mudstones that probably are mudflows 

are exposed in both members. Small outcrops of lava 

occur in a few places in the Tukwila, but it is notevident whether these rocks are parts of flows or intrusions. Several beds of fine-grahied silicified tuff lie 

about 500 feet below the top of the lower member. Coal 

is uncommon, although a layer of soft brown coal 1-2 

feet thick was temporarily exposed in the upper part 

of the lower member west of Renton.

Most sandstones, conglomerates, and mudstones are 

poorly sorted and are poorly stratified or massive. 

Many of these rocks are intensely fractured in an irregular pattern. Only in the upper parts of the lower 

and upper members do normally sorted and clearly 

stratified sandstones seem to be common.

Boulders, cobbles, pebbles, and most sand grains of 

the upper and lower members are fragments of porphyritic andesite or basalt, and most other readily 

identifiable grains are plagioclase. Altered mafic, minerals and opaque iron minerals are common, and quartz 

and apatite are accessory minerals. Nearly all the sandstone and conglomerate beds contain a considerable 

proportion of silt and clay, which consists chiefly of 

rock and plagioclase fragments in a matrix of green 

and brown minerals that include moiitmorillonite, zeolite, and iron oxides. Calcium moiitmorillonite is the 

dominant clay mineral in several mudstone samples 

analyzed by X-ray diffraction. Yellowish-brown to 

dark-brown iron oxide is widely scattered throughout 

both the lower and the upper members. Organic material is common, as coatings on grains and as particles 

ranging from silt size to more than G inches in diameter. Most of the larger fragments of organic material 

are partly replaced by iron oxide and silica.

Tukwila rocks are mostly moderately to poorly indurated. Some, however, especially a few breccias and 

tuffs, are hard and resistant. Clay minerals, and perhaps iron oxide, apparently provide the coherence for 

most of the rocks, though chemical cement also is common. Calcite probably is the most abundant cement, 

although silica and zeolite may cement some rocks. 

Thin siliceous tuff beds probably are the hardest rocks 

in the formation. Along Highway 900 west of Renton, 

in the NWVi sec. 13, the upper member of the Tukwila 

is cut by numerous veins composed chiefly of calcite

and quartz. The veins are similar to those in an intrusive body that is exposed half a mile farther south, 

and they probably were deposited from solutions derived from the intrusive body.

ALTERATION

Tukwila rocks are noticeably altered, as seen both 

in outcrop and under the microscope. Many exposures 

exhibit soft brown nearly unidentifiable rock in which 

structure and texture are obscure. Grains as well as 

matrix are strongly affected and are changed mostly 

to moiitmorillonite, calcite, chlorite, and zeolite. Alteration is relatively strong near the large intrusive body 

2 miles west of the center of Renton, and it probably 

is due to hydrothermal action. In other places, nirficial 

weathering has changed sandstone and conglomerate 

to clay in which little granular texture is retained. 

Most of this weathering probably occurred after deposition and deformation of the Puget Group. However, 

a buried weathering profile that formed at the top of 

the lower member during Tukwila time is exposed in 

Renton along Renton Avenue in the SWi/iNW1/^ sec. 

18. At this locality, hard and relatively unweT.thered 

volcanic sandstone grades upward into softer deeply 

weathered sandstone in which the sedimentary texture 

is only faintly preserved and most grains are altered 

to clay. This weathered volcanic sandstone is cverlain 

by and appears to grade upward into a gray kaolinitic 

claystone, which is overlain by coal at the base of the 

middle member. How the bed of kaolinitic claystone 

was formed is not clear. It could hare been formed by 

weathering of the sandstone before deposition of the 

coal, but it could instead have been formed by ill-place 

alteration beneath the coal or even simply by deposition of a bed of kaolinitic clay. If formed by weathering, a pause in deposition would be indicated that 

would be much longer than that shown by weathering 

of the still-recognizable volcanic sandstone, which in 

itself records a considerable pause in deposition during 

Tukwila time.

STRATIGRAPHIC RELATIONS

Neither the base of the Tukwila Formation nor the 

rocks directly underlying it are exposed in this area. 

At a locality 3 miles northwest of Renton, the Tukwila 

is in apparent fault contact with older marine sedimentary rocks (Waldron, 1962). About 10-15 miles 

east of Renton, near Tiger Mountain, the Tukwila 

conformably overlies and iiiterfingers with the Tiger 

Mountain Formation (Vine, 1962a). In northwest and 

south Renton the apparently conformable contact of 

the Tukwila with the overlying Renton Formation,
TERTIARY ROCKS 17

though it is not exposed, can be located within a few 

feet.

The contact between the lower and middle members 

of the Tukwila Formation is exposed in Renton. along 

Renton Avenue in sec. 18. The lower member here is 

strongly weathered, which indicates a time break between deposition of the two members; no evidence of 

erosion or angular unconformity, however, is exposed. 

The arkosic middle member contains volcanic rock 

fragments near its top, and its upper contact, which is 

not exposed, may be gradational.

FOSSILS AND AGE

Plant fragments were the only fossils found in the 

Tukwila Formation during this investigation. They 

occur throughout almost all the fine-grained andesitic 

sedimentary rocks and are especially abundant and 

well preserved in a zone about 200 feet thick in the 

upper part of the lower member. In 1958, these fossiliferous rocks were well exposed in many excavations in 

the NWViNWi/i sec. 13, T. 23 K, R. 4 E. Fossil leaves 

collected from the NWi/iNW1/^ sec. 13 during this investigation were identified by R. W. BrowTn (written 

commun., 1957) of the U.S. Geological Survey as Lastrea, fischeri Heer, Woodivardia sp., Equisetum sp., 

FmUax sp., Sabal sp., Carya or Aescidus sp., Tetracera 

sp., Phttanophyttum angustilobum (Lesquereux) MacGinitie, and Cercldipliyllum sp. The fossiliferous zone 

is exposed intermittently westward to the wall of the 

Duwamish Valley in the Des Moines quadrangle at 

the south boundary of sec. 11, T. 23 N., R. 4 E., where 

several fossil collections have been made at a site 

known as the Steels Crossing locality (F. H. Knowlton, in Willis and Smith, 1899). Fossil leaves collected 

by H. H. Waldron at the Steels Crossing locality were 

also identified by R. W. Brown, who reported the following forms not found in sec. 13 (written commun., 

1958) : Allantodiopsis erosa (Lesquereux) Knowlton 

and Maxon, Chaetoptelea sp., Platanus sp., Cinnamomuin dttleri Knowlton, (Jastanea castaneaefolia (Unger) Knowton, and Alangium sp. According to Brown, 

the assemblage of leaves from this zone indicates that 

the enclosing rocks date from the latter half of the 

Eocene, J. A. Wolfe (written commun., 1964) stated 

that the assemblage from sec. 13 could represent either 

the lower or the upper part of the Ravenian Stage; 

both zones are regarded as late Eocene in age (fig. 10; 

Wolfe, 1968). The assemblage from Steels Crossing 

was assigned by Wolfe (written commun., 1964) to the 

lower part of the Ravenian. The Tukwila Formation 

of the Tiger Mountain area was assigned a late Eocene 

age by Vine (1962a) and a late Eocene and early 

Oligocene age by Wolfe (1968).

SOURCE

The coarse texture and volcanic detritus of the Tukwila Formation suggest that the formation was derived mostly from a nearby volcanic center. Typically 

poor sorting, angularity of even coarse detritus, and 

tuff beds as much as 2 feet thick also indicate that the 

source was not far distant. Interbeddiiig of arkosic 

and volcanic material in the formation suggests further that the lithologic character of detritus supplied 

to the depositing rivers changed rapidly. This and the 

evidence of contemporaneous volcanism indicate that 

newly erupted material rather than older voles -nic 

rocks provided the volcanic detritus for the Tukwila 

Formation.

Evidence for location of the source of the Tukvnla 

comes largely from outside the mapped area. Warren, 

Norbisrath, Grivetti, and Brown (1945) concluded 

that the source of rocks here described as Tukvila 

probably was near Issaquah, where the greatest thickness of the rocks was found. From there, the Tukvila 

thins southward and interfingers with arkosic rockr of 

the Puget Group (Warren and others, 1945; Vine, 

1962a). The volcanic formation is missing farther 

south in the Green River gorge, where volcanic detritus 

was found in only a few thin beds within the Puget 

Group (Vine, 1962a). Thinning of the formation 

toward Renton is probable but cannot be demonstrated, 

but the more abundant coarse breccias and lava flows 

near Issaquah Mountain indicate that the source was 

nearer that locality than it was to Renton.

RENTON FORMATION

The Renton Formation consists of the arkosic sandstone, shale, mudstone, and coal that make up the upper part of the Puget Group in the Renton distrct; 

the formation was named for the city of Renton by 

Waldron (1962). It crops out typically in valley wr.lls 

in Renton in sees. 17, 18, and 19 and also crops out in 

sec. 30, 23, and 24 south and west of Renton. It has 

been regarded as part of the Puget Group since the 

Puget was first described by Willis (Willis, 189°a; 

Evans, 1912; Weaver, 1937; Warren and others, 1945).

The thickness of the formation near Renton apparently is about 2,500 feet, Along the Cedar River, about 

1,000 feet of the upper part of the formation overlies 

the Renton No. 1 coal bed (fig. 11). Along the Duwamish Valley wall, intermittent exposures indicate 

that the thickness under the same coal bed is about 

1,500 feet. The Renton Formation in the Tiger Mountain area east of Renton is reported to be at least 2,250 

feet thick (Vine, 1962a), and near Issaquah, northeast 

of Renton, it is 3,000-3,200 feet thick (Warren and 

others, 1945).
18 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

LlTHOLOGY

The Rentoii Formation is composed mostly of arkosic sandstone and shale. In the upper third of the 

formation, probably a little more than half the rock 

is sandstone, but scattered exposures and one drill record suggest that the lower two-thirds is mainly fineand medium-grained sandstone. The formation also 

locally contains thin beds of sandy granule conglomerate and layers of mudstone. Several intraf ormational 

conglomerates, composed of fragments of shale in a 

sandstone matrix, are exposed in a commercial claypit 

in Renton on the south side of the Cedar River. Three 

coal beds that were mined for many years at Renton, 

known as the Renton No. 1, Renton No. 2, and Renton 

No. 3 (fig. 11; Evans, 1912, p. 110), lie just above the 

middle of the formation. Several other coal beds that 

have been mined occasionally, notably the Sunbeam 

bed (fig. 11; Warren and others, 1945), lie a short distance above the base of the formation. In addition, 

thin coal and carbonaceous shale beds are distributed 

throughout most of the formation.

The overall composition, grain size (fig. 9), structure, and texture of rocks of the Renton Formation 

are similar to those of the rocks of the undifferentiated 

Puget Group exposed in the Black Diamond district. 

The Renton Formation consists mainly of quartz and 

feldspar and contains virtually the same accessory 

minerals as the rocks in the Black Diamond district. 

However, plagioclase appears to be as abundant as 

potassium feldspar in the Renton Formation, garnet is 

the dominant nonmicaceous nonopaque heavy mineral 

in all samples examined, and siderite is much less 

abundant than in the undifferentiated Puget Group at 

Black Diamond. Kaolinite, mica (illite), montmorillonite, and chlorite are the most common clay minerals 

in the formation at Renton.

STRATIGRAPHIC RELATIONS

The Renton Formation conformably overlies the 

Tukwila Formation and is overlain with at least minor 

clisconforniity by andesitic sedimentary rocks of the 

Lincoln Creek(?) Formation. About a mile east of 

the center of the city of Renton, the upper contact of 

the Renton Formation is exposed in a railroad cutbank on the south side of the Cedar River in the SE^- 

SEi/4 sec, 17, and in a highway cutbaiik 011 the north 

side of the river in the SW^SW^ sec. 16. In the exposure along the railroad, the base of a volcanic conglomerate truncates bedding planes in the Renton at 

angles of 10°-15°. This crosscutting relation apparently was interpreted by Warren, Norbisrath, Grivetti, 

and Brown (1945) as a slight angular unconformity. 

The relation is not clear because the attitude of the

conglomerate is obscure, and because dips in the Renton and the overlying formation vary by several degrees even in single exposures. Overall, however, strata 

in the two formations appear to be parallel, and the 

contact probably represents a disconformity rather 

than an angular unconformity. Even the disconformity 

may be local, for the contact in the highway exposure 

011 the north side of the river appears to be conformable.

Locally, arkosic strata crop out apparently stratigraphically above the upper contact of the Renton 

Formation. Along the railroad in sec. 17, a 30- to 40- 

foot-thick sequence of arkosic rocks crops out apparently more than 50 feet stratigraphically above the 

contact. Arkosic strata also occur in several smaller 

exposures above the contact, Stratification in the largest exposure is parallel to that in the Renton Formation, and the arkosic rocks at first appear to be an 

interbed in the overlying andesitic sedimentary rocks. 

The attitudes in most of these small exporures of 

arkosic rocks, however, differ markedly from the attitude in the Renton Formation, and in some erposures 

these arkosic rocks can be seen bounded by faults. 

Willis (1898a) described an exposure at this locality 

in which a sequence of thin-bedded sandstone with an 

attitude much different from that of Renton Formation strata was bounded 011 top and bottom b7 faults. 

Furthermore, faults mapped in coal mines at Renton 

a mile to the west strike directly toward these outcrops 

(Evans, 1912). Although the arkosic strata above the 

upper contact of the Renton Formation might be interbedded in the andesitic sedimentary formation, they 

presently are regarded as fault slices of Renton strata.

FOSSILS AND AGE

No fossils were found in the Renton Formation near 

Rentoii, thus its age assignment depends on ages determined for underlying and overlying rocks. Plant 

fossils in the Tukwila Formation west of Renton are 

assigned to the late Eocene lower part of the Kavenian 

Stage by J. A. Wolfe (written commim., 1964; fig. 10, 

this report). The few Foraminifera identified from the 

overlying Lincoln Creek (?) Formation at Renton do 

not distinguish between a late Eocene or early Oligoceiie age for the Lincoln Creek(?). A more definitive 

assemblage of forams from similar Lincoln Cv>eek(?) 

rocks about 5 miles to the northwest in Seattle, however, are assigned to the boundary-straddling "EoOligocene1 '' age (W. W. Ran, written commun., 1967, 

H. H. Waldroii, unpub. data, 1967). Therefore, the 

author regards the underlying Rentoii Formation at 

Renton as late Eocene in age as defined by forams. 

The formation is considered by Wolfe (1968), on the
TERTIARY ROCKS 19

basis of plant fossils found east of the Renton quadrangle near Tiger Mountain to extend into the Oligocene.

SOURCE

Composition and texture indicate that the Renton 

Formation, like the undifferentiated Puget Group in 

the Black Diamond district, was derived chiefly from 

silicic, plutoiiic igneous, or metamorphic rocks. The 

Renton probably was also derived from somewhere to 

the east. Small differences in composition between it 

and the rocks near Black Diamond may be owing to 

small lithologic differences within one large source 

area and to transportation to the two lowland districts 

by separate rivers.

ENVIRONMENT OF THE PUGET GROUP

The environment of deposition of the Puget Group 

has attracted special attention since the first studies of 

Willis (1886). The sequence of rocks is thick, it is variable in detail but generally similar from bottom to 

top, and brackish- to fresh-water conditions were apparently maintained during deposition of the entire 

sequence. The studies of Willis (1886, 1898a), White 

(1888, 1889), and Weaver (1937,1945) produced a picture of a broad coastal plain representing a transitional environment reaching from wide valley floors 

on the east across coalescing deltas to an estuary or 

marine gulf on the west. Subsidence in this region was 

equaled by accumulation as conditions remained remarkably uniform. Subsidence was laterally unequal, 

however; thickness of sediments varied from place to 

place, and embayments were produced, including a 

marine embayment that extended several tens of miles 

eastward from Seattle. According to F. H. Knowlton 

(in Willis and Smith, 1899), the climate was warm 

and possibly subtropical during deposition of the lower 

sediments, and more temperate during deposition of 

the upper.

The arkosic sandstone and shale and the coal in the 

Puget Group in the mapped area appear to be wholly 

continental and typical products of fluctuating deltaic 

conditions as described by Willis, White, and Weaver. 

Marine fossils and other evidence of marine conditions, 

even deposits such as well-rounded sand that might 

represent beach environments, have not been found. 

Marine strata a few miles northwest of Renton, once 

thought to be interbedcled with or correlative with the 

arkosic rocks near Renton (Weaver, 1916, p. 100), are 

now regarded as older and in fault contact with the 

Puget Group (Waldron, 1962).

The Tukwila Formation was deposited under conditions somewhat different than those under which arkosic Puget strata were deposited. The volcanic materials, probably because of rapid accumulation, built 

broad uplands that rose above the aggradational le^el 

of the plain of arkosic sediments. On the uplands, 

slopes and stream gradients were steeper than those on 

the plain below. The upland areas were sites of deposition of coarse-grained rnudflows and breccias, and fluvial sediments were poorly sorted as well as coarse 

grained. The land probably was significantly better 

drained, and coal swamps must have been uncommon. 

Building of these highlands, however, was not continuous. Overall subsidence continued during the pauses in 

accumulation of volcanic materials, and the flanks of 

the highlands were overlapped by continuously aggrading arkosic sediments. Renewed accumulation of 

volcanic materials again caused the highlands to be 

built out again over the arkosic materials at sites such 

as the Renton district. Then, eventual diminution or 

cessation of Tukwila volcanism allowed the Renton 

Formation to entirely bury the Tukwila in the Renton 

district. In contrast, the Black Diamond district lay 

between highlands of volcanic material and remained 

an arkosic plain.

LINCOLN GREEK(?) FORMATION

Marine and perhaps partly continental volcmic 

sandstone, conglomerate, mudstone, and shale overlie 

the Puget Group at Renton. These rocks are tentatively 

correlated with part of the Lincoln Formation of 

Weaver (1912), which has been redefined as the Lincoln Creek Formation of late Eocene to early Miocene 

age (Beikman and others, 1967). The rocks at Renton 

were previously mapped as part of an undifferentiated 

assemblage of Oligocene and Miocene beds (Warren 

and others, 1945). On the geologic map of the Renton 

quadrangle (Mullineaux, 1965a), they are shown as an 

unnamed formation of sedimentary rocks. Andes itic 

sedimentary rocks which are similar to those at Renton 

but somewhat coarser grained and which are apparently wholly nonmarine overlie the Puget Group south 

of Black Diamond in sees. 35 and 36, T. 21 N., R. 6 E., 

just east of the Black Diamond quadrangle boundary 

(Warren and others, 1945; Gower and Wanek, 196").

The Lincoln Creek(?) Formation is exposed along 

the Cedar River in and east of Renton. North of the 

river, it crops out only in a readout that shows the 

basal contact. Along the south side of the river, however, it crops out nearly continuously from its basal 

contact eastward for about three-fourths of a mile, and 

in a small isolated exposure about a fourth of a nile 

farther upriver. From 1,000 to 1,100 feet of strata, 

largely sandstone and conglomerate that dip 20°-30° 

E., are exposed between the basal contact and a point
20 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

half a mile farther east. There, steeply dipping beds 

that may be faulted break the continuity. From that 

point still farther east, 500-600 feet of strata, which 

consist mostly of mudstoiie and fine-grained sandstone 

that dip 20°-40° E., are well exposed. The rocks east 

of the steeply dipping beds are finer grained than the 

lower strata farther west, and they probably are not 

merely the lower beds repeated by faulting. Strata in 

the isolated exposure on the south side of the river, 

however, dip west, and their stratigraphic position is 

not known. On the assumption that there is no repetition by faulting in the east-dipping strata, the total 

thickness of the Lincoln Creek ( ?) exposed here is at 

least 1,600 feet.

LITHOLOGY

The Lincoln Creek ( ?) Formation is composed 

mostly of greenish-gray to brown sandstone. The lower 

900 feet consists largely of coarse-grained conglomeratic sandstone. Pebble conglomerate constitutes the base 

of the formation, and conglomerate also prevails in a 

zone about 50 feet thick that is nearly 900 feet stratigraphically above the base. The upper 600-700 feet of 

the exposed east-dipping strata is chiefly mudstone and 

shale alternating with beds of sandstone, but it also 

includes a small amount of conglomerate. Rocks in the 

isolated exposure on the south side of the river are 

chiefly sandstone and conglomerate.

Strata in the Lincoln Creek(?) are predominantly 

flat or plane bedded. In the lower part of the formation, stratification is usually obscure and the sandstones are thick bedded or massive. In the upper part, 

bedding typically is more distinct; the sandstone and 

shale are thick to thin bedded and are interlayered 

with mudstone. Lenticular bedding and cut-and-fill 

structure, however, are characteristic of the conglomeratic rocks. Both sandstones and conglomerates are 

poorly to normally sorted in the terminology of Trask 

(1932) and consist chiefly of rounded and subrounded 

clasts. No boulclery mudstones or strata characterized 

by angular fragments were seen in this formation.

Mafic volcanic rock fragments of sand and gravel 

size make up most of the formation. However, fragments of coal, shale, and arkose derived from the 

underlying Rent on Formation are common in the lower 

part of the Lincoln Creek(?), and pebbles of lightgray vitric tuff are characteristic of the conglomerate 

about 900 feet above the base. Most pebbles consist of 

andesite or basalt in which plagioclase phenocrysts 

occur in a felted mass of tiny feldspar laths and either 

glass or alteration products. Volcanic glass in some 

pebbles apparently is fresh, but it is partly or wholly 

altered in most. Some pebbles are so altered that they

consist only of a few feldspar phenocrysts set in a turbid matrix that consists chiefly of clay, iron oride, calcite, and zeolite. The only abundant grains other than 

rock fragments are plagioclase, which constitute as 

much as 20 percent of the grains in sandstones; quartz 

grains occur sparsely throughout the formation. Mafic 

minerals, including those as discrete grains and those 

in rock fragments, generally are altered beyond recognition. Heavy-mineral suites, consist chiefly of opaque 

iron oxides, a few amphiboles and pyroxenes, and 

sparse apatite.

The matrix of these rocks consists chiefly of silt- and 

clay-sized .fragments of feldspar, quartz, montmorillonite with some mixed layering, heulandite, crirtobalite, 

amorphous material that includes iron oxide, and 

chemical cement. Chemical cement is more abundant 

than detrital silt and clay in some sandstones and conglomerates, and in one sample it makes up about 35 

percent of the rock. Calcite is the dominant cement in 

the lower part of the formation; it not only fills interstices but also invades many grains. In the conglomerate near the middle of the sequence, however, zeolite 

cement is at places more common than calcite. Some 

beds are firmly cemented, but most are poorly cemented 

or friable.

ALTERATION

Most rocks in the Lincoln Creek(?) appear moderately weathered in outcrop and also show much 

alteration under the microscope. No gradational zones 

of any deep weathering profiles were recognized, but a 

wide range of alteration is present from place to place. 

Some individual clasts are almost completely altered 

to iron oxide and clay minerals, others show only 

weathered rinds, and still others are glassy r,nd relatively unweathered. The most common alteration products seem to be montmorillonite and chlorite.

STRATIGRAPHIC POSITION

The basal contact of the Lincoln Creek(?) Formation is seen in two exposures. In one, the andesitic 

sedimentary rocks cut across bedding in the UB derlying 

Renton Formation, yet average dips and strikes in the 

two formations at this locality are approximately the 

same. The contact in that exposure apparently is disconformable, but not angularly discordant. In the 

other exposure, the basal contact appears to be conformable. It seems likely that the Lincoln Creek(?) 

conformably overlies the Renton except where it occupies channels cut into the underlying formation. At 

Renton the outcrops of the Lincoln Creek (?) are overlain only by Quaternary deposits. A few miles northeast and northwest of Renton, however, sequences of
TERTIARY ROCKS 21

chiefly Oligocene andesitic sedimentary rocks that 

overlie the Renton are several thousand feet thick 

(Weaver, 1937; Warren and others, 1945; H. H. Waldron, unpub. data, 1967). These sequences suggest that 

the part of the Lincoln Creek(?) exposed at Renton 

represents only the basal part of a thick section of 

Lincoln Creek( ?) rocks that were once present in that 

general area.

FOSSILS AND AGE

Marine mollusks, Foraminifera, and fragments of 

fossil leaves have been collected about 1,000 feet above 

the base of the formation along the 'Cedar River about 

200-400 feet east of the railroad bridge in the SEi/iSWi/4 sec. 16, T. 23 N., R. 5 E. The fossils are poorly 

preserved; only a few species of Foraminifera and one 

mollusk have been identified, and most of these identifications are tentative. The single mollusk was identified by E. J. Moore (written commun., 1959) of the 

U.S. Geological Survey as "Nuculana" sp. cf. 'W." 

washingtonensis (Weaver). "AV washingtonensis 

(Weaver) generally is considered to be Oligocene in 

age (Durham, 1944, p. 135; Weaver, 1942, p. 38). However, Snavely, Brown, Roberts, and Ran (1958, p. 52) 

reported 'W.' 1 waxhingtonemis (Weaver) n. subsp. in 

the lower part of the Lincoln Formation of Weaver in 

the Centralia-Chehalis district of Washington, where 

that part of the formation was assigned a late Eocene 

age.

The following Foraminifera from the Cedar River 

locality were identified by Ruth Todd of the U.S. Geological Survey (written commun., 1959) : Cyclaftntnina, 

paciftca Beck, Robulus sp. (rel. to R. inornatus}, 

Plectofrondicularia sp. (rel. to P. miocenica and P. 

searsi}, Nonionl. sp. (rel. to N. soldanii), and Sigmomorphina sp. (rel. to 8. jacksonensis]. According to 

Miss Todd, these Foraminifera are marine, and the 

depth of water during deposition of the enclosing rocks 

was on the order of at least 100 fathoms. As the identifications are not certain, no definite age assignment 

can be made. If they could be confirmed, stratigraphic 

ranges reported elsewhere along the Pacific Coast for 

these fossils (Kleinpell, 1938, p. 221-222; Rau, 1958; 

Mallory, 1959, p. 61, 89) would suggest that the Lincoln Creek(?) rocks near Renton are either late Eocene or early Oligocene in age or both.

Two assemblages of Foraminifera that are more 

varied and better preserved have been collected from 

the lower though not basal part of the Lincoln 

Creek(?) Formation in Seattle by H. H. Waldron. 

One has been assigned to either the Narizian Stage of 

Mallory (1959) or the Refugian Stage of Schenck and 

Kleinpell (1936), and the other to the lower Refugian

Rigmomorpliina schencki zone of Rau (1958) (M. C. 

Israelsky, written commun., 1964; W. W. Rau, written 

commun., 1967; fig. 10, this report). These assemblages 

indicate that Lincoln Creek(?) deposition in the general area began during either late Eocene or Eocene to 

Oligocene time, as defined by studies of Foraminifera 

(fig. 10).

SOURCE

The volcanic rock fragments that compose mos^ of 

the Lincoln Creek(?) prove that the formation was 

derived chiefly from a volcanic terrane. However, neither the Tukwila Formation nor other older volcanic 

rocks are thought to be the principal source. The lithologic change from the underlying arkosic Renton Formation to andesitic sedimentary rocks is abrupt and 

suggests that the change was not due simply to gradual 

uncovering of volcanic rocks by erosion in the drainage basin. The change in lithology probably records 

eruption of abundant volcanic material in the source 

area of the Puget Group, or between that source area 

and the depositional basin. Eruptions could have produced such a change either by burying the rocks that 

yielded arkose or by overloading or blocking rivers 

that carried arkosic material.

Near Black Diamond, rocks that overlie the Puget 

Group are similar to the Lincoln Creek (?) at Renton 

but are coarser grained and continental. Farther east 

in the Cascades, correlative formations are largely 

flows, breccias, and tuffs. Thus the source volcanoes for 

the Lincoln Creek (?) probably were in the position of 

the present Cascade Range.

ENVIRONMENT

The Lincoln Creek (?) and correlative continental 

formations apparently were deposited in a marine gulf 

and on an adjacent coastal plain in a subsiding basin. 

Volcanic and andesitic sedimentary continental and 

marine formations of about the same stratigraphic 

position and age as the Lincoln Creek (?) are widespread along the west side of the Cascade Range (Warren and others, 1945; Snavely and others, 1958; F.oberts, 1958; Fisher, 1961; Gard, 1968; Vine, 1969). At 

Renton, the Lincoln Creek ( ?) Formation seem? to 

record at least two notable changes in environment. 

First, transporting streams probably became either 

swifter or larger, bringing coarser detrital material 

into the basin. Second, the rate of subsidence merersed 

enough to submerge the area near Renton despite the 

probably more rapid deposition. No coal was seer in 

the Lincoln Creek (?) ; any swamps that existed probably were ephemeral, and any peat that was formed 

probably was reworked by rapidly migrating streams.

380-731 O - 70 - 4
22 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

CORRELATION OF LOWER TERTIARY FORMATIONS

On the basis of the lithologic sequence, formations 

in the Renton district can be correlated with those in 

several other localities in and near the Puget Sound 

lowland (fig. 12). To the west and northwest, outcrops 

of the Tukwila and Renton Formations continue into 

the Des Moines and Seattle South quadrangles (Waldron, 1962; unpub. data, 1967). The Seattle South 

quadrangle also contains a middle Eocene marine formation, as well as rocks assigned to lower and upper 

parts of the Lincoln Creek(?) Formation (Waldron, 

1962; unpub. data, 1967). To the east, the Tukwila, 

Renton, and Lincoln Creek ( ?) Formations can be correlated readily with lithologically similar formations 

that crop out in the Newcastle Hills promontory near 

Tiger Mountain (Warren and others, 1945; Vine, 

1962a) ; in that area the Tukwila is underlain conformably by the arkosic Tiger Mountain Formation, 

which is underlain in turn by the marine Raging River 

Formation of middle Eocene age (Vine, 1962a). There 

is little doubt of the lithologic correlation of rock units 

from one of these districts to the other, but the age of 

contacts may differ from place to place. For example, 

interpretation of Foraminifera in the Seattle-Rentoii 

area indicates that rocks overlying the Puget Group 

are as old as late Eocene, but fossil plants in the Tiger 

Mountain district suggest that the upper part of the 

Puget Group in that area is Oligocene in age (Wolfe 

and others, 1961; Vine, 1962a). Thus the upper contact of the Puget may be significantly time-transgressive in this area. However, the time difference may be 

only apparent, resulting from dating by marine Foraminifera at one place and by fossil plants at another.

The sequence of lithologic units of the Renton, Seattle, and Tiger Mountain area also correlates well with 

the rock sequence in the Carbonado district in the Lake 

Tapps quadrangle (Gard, 1968) farther south. The 

rock units in the Lake Tapps quadrangle differ somewhat in that the basal formation, the Carbonado, is 

arkosic and is middle(?) Eocene in age (Gard, 1968). 

Andesitic sedimentary rocks that overlie the Puget 

Group, the Ohaiiapecosh Formation, are also coarser 

and more angular than the Lincoln Creek(?) Formation at Renton. Like the andesitic sedimentary rocks 

near Black Diamond, the Ohanapecosh at Carbonado 

is regarded as an onshore equivalent of the marine 

Lincoln Creek(?) rocks at Renton.

In the Black Diamond district between Renton and 

Carbonado, the Puget Group includes no mappable volcanic formation (Gower and Wanek, 1963; Vine, 

1969). According to interpretations of fossil leaves 

(Wolfe and others, 1961), the arkosic Puget Group in

the Black Diamond district spans the stratigrapliic 

interval of the Tukwila Formation. Thus the Tukwila 

and Northcraft Formations probably were not coextensive but were derived from different sources.

Major Eocene and lower Oligocene formations in the 

Grays Harbor basin near Ceiitralia (fig. 12; Suavely 

and others, 1958; Beikman and others, 19*37) are 

also comparable in lithology to those in the Renton-Seattle area. Correlations are supported by the ages 

of the Mcliitosh, Skookumcliuck, and Lincoln 

Creek( ?)^Formations that were determined from marine Foraminifera (Ran, 1958). Comparisons made by 

means of Foraminifera content also allow the sequence 

near Ceiitralia to be correlated with several other rock 

sequences in western Washington (Rau, 1958; Beikman and others, 1967), but the other sequences generally contain additional major rock formations.

Arkose similar to and correlated with th°, Puget 

Group occurs at several other places in western and 

central Washington. East of the mapped area, the Roslyn and similar formations have been interpreted as 

upstream equivalents of the Puget Group (Weaver, 

1937; Bressler, 1957). To the north, the Chuckanut 

Formation of McLellan (1927) was first regarded as 

part of the Puget (Willis, 1886), but now it is generally judged to be older than the Puget Group 

(Suavely and Wagner, 1963). To the west, in the 

Olympic Peninsula, rocks comparable in age to the 

Puget are not arkosic (Weaver, 1937; Brown and 

others, 1960). Sediments typical of the Puget apparently did not extend west beyond the position of the 

present lowland.

Deposition of arkosic sediments was extensive in 

western Washington during late Eocene time but was 

supplanted fairly abruptly by deposition of volcanic 

detritus and volcanic rocks. The change from arkosic 

to volcanic materials provides a widespread datum at 

the top of the Puget Group and correlative arkosic 

rocks. This change is dated by studies of Foraminifera 

as before the end o*f Eocene time in the Centralia, 

Castle Rock, and Seattle areas (Suavely and others, 

1958; Roberts, 1958; H. H. Waldron, unpub. data, 

1967), but by studies of plants as after the beginning 

of Oligocene time in the Tiger Mountain area (Wolfe 

and others, 1961; Vine, 1962a).

INTRUSIVE ROCKS

A few porphyritic andesite bodies crop out in the 

Puget Group in the northwestern part of the Rentoii 

quadrangle. The largest of these is extensively exposed 

in a large quarry in sees. 13 and 14, T. 23 N., R. 4 E., 

about 2 miles west of Renton. Its contacts are covered,
TERTIARY ROCKS 23

RENTONSOUTH SEATTLE

Waldron (1962); 

this study

Lincoln

Creek(?)

Formation

(volcanic,

marine)

Renton 

Formation 

(arkosic, 

continental)

Tukwila

Formation 

( volcanic, 

continental)

 

FAULTED

Part of

section

missing

Raging River

Formation 

(arkosic and

volcanic,

marine)

ISSAQUAHTIGER MOUNTAIN

Warren and 

others (1945); 

Vine (1962a)

Unnamed

(volcanic,

marine)

Renton 

Formation 

( arkosic, 

continental)

^^____j^^STukwila 

Formation 

( volcanic, 

continental)

~~^^__^

Tiger Mountain

Formation

( arkosic,

continental)

Raging River 

Formation

(arkosic and 

volcanic,

marine)

BLACK

DIAMOND

Grower and 

Wanek (1963); 

Vine (1969); 

this study

Unnamed

(volcanic,

continental)

Puget

Group

(arkosic,

continental)

LAKE TAPPS

QUADRANGLE

Gard (1968)

Ohanapecosh

Formation

(volcanic,

continental)

Spiketon 

Formation 

(arkosic, 

continental)

_- - 

Northcraft 

Formation 

(volcanic, 

continental)

Carbonado 

Formation 

(arkosic, 

continental)

GRAYS HARBOR

BASIN

Snavely and 

others (1958); 

Beikman and 

others (1967)

Lincoln Creek

Formation (part)

(volcanic,

marine)

Skookumchuck 

Formation 

(arkosic, 

marine and 

continental) ~~^_

Northcraft 

Formation 

(volcanic, 

continental)

Mclntosh 

Formation 

(arkosic and 

volcanic, 

marine)

FIGURE 12. Generalized lithologic correlation of Eocene and lower Oligocene formations in the Puget Sound lowland 

and adjacent areas. Age of contacts probably varies somewhat from place to place. Units termed "volcanic" include 

some which are composed chiefly of andesitic sedimentary rocks.

but the quarry shows a mass at least 1,000 feet long, 

TOO feet wide, and 150 feet thick. It is regarded as 

intrusive because no flow contacts, columnar joints, or 

vesicular zones have been found. Other probably intrusive rocks crop out in the city of Tukwila about a 

mile south of the large quarry, and about a mile south 

of Renton along the Duwamish Valley wall. A few 

smaller outcrops of similar rock were seen elsewhere

within the Tukwila Formation but were not mapioed 

separately.

The quarry rock in sees. 13 and 14 is mostly gray, 

dense, and porphyritic, although it is altered to green 

and brown in bands and irregular patches and is cut 

by numerous greenish-gray and white veins. Conjugate 

joints several feet apart separate most of the body into 

large blocks. The rock consists of white to pale-g^een
24 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

feldspar and dark greenish-gray mafic phenocrysts set 

in a medium-gray to greenish-gray dense groundmass. 

The feldspars, some of which are as long as 5 mm, 

typically are strongly zoned and twinned andesine or 

labradorite. The mafic phenocrysts, some, of which are 

as long as 7 mm, are slightly to strongly altered. All 

appear to have been pyroxenes, with clinopyroxene 

more abundant than orthopyroxene. The groundmass 

consists of small feldspar crystals interspersed with 

pyroxene, opaque iron minerals, glass, calcite, and 

alteration products.

Both phenocrysts and groundmass are altered. The 

most common alteration product is a brown to brownish-green clay, identified as moiitmorillonite from 

X-ray diffraction patterns by Julius Schlocker of the 

U.S. Geological Survey. It has replaced glass, mafic 

minerals, feldspar and, locally, the complete rock. The 

colors of the montmorillonite suggest that it is iron 

rich, but its index of refraction is lower than that of 

nontronite. Calcite and chlorite are also common in 

both phenocrysts and groundmass.

Montmorillonite, calcite, and quartz are common 

vein minerals. Veins of montmorillonite are as much as 

6 inches wide in places, and veins of calcite and quartz 

are as wide as 8 inches. Pyrite is disseminated throughout the veins, and the presence of native coppec was 

reported by the quarry operator.

A single sample of quarry rock that appeared representative was analyzed by rapid chemical methods, 

giving the following results:

K2O_ ______________ 0.62

H2O-_______________ 1.4

H2 0+_-------------- 1.0

TiO2 _.._.--_.._..,__. .17

P2 O8 ----------------- .19

MnO- _______________ . 10

CO________ _________ .95

The rock is classified as andesite according to silica 

content (Williams and others 1954) or according to a 

comparison of silica content with several other constituents (Rit tin ami, 1952). However, the rock locally 

is dark and frequently is called basalt for commercial 

purposes.

The andesite intrudes and is younger than the Eocene and Oligocene Puget Group but is overlain only 

by Pleistocene deposits. Presence of glass in the matrix 

suggests that the mass was intruded near the surface, 

but the shape of the mass is not known.

UPPER TERTIARY ROCKS HAMMER BLUFF 

FORMATION

The Hammer Bluff Formation is the only upper Tertiary rock unit known in the mapped area. The Hammer Bluff was described and named by Glover (1936; 

1941, p. 137, 144) for a truncated spur on the north

Si02 _. _______

A12 03 _________

Fe2 03 --_---__

FeO._. _-.-_.

MgO_________

CaO.__...._

Na,O________

- - _ _ _ _ 56. 2

--__-__ 17. 2

_______ 4 1

_______ 3.6

________ 7. 4

________ 3.4

side of the Green River in the NE*4 sec. 28, T. 21 1ST., 

R. 6 E. Glover described the formation as composed 

of quartzose sand and distinctive plastic buff-firing 

clay that were derived chiefly from arkosic sandstones 

of the Puget Group and that are characterized by 

woody lignite. Residually weathered arkose of the 

Puget Group at Hammer Bluff apparently has been 

considered part of the Hammer Bluff Formation in 

some reports, but it is not included in the formation as 

described herein. As used here, the Hammer Bluff 

contains two members: a lower member that mainly 

contains the clayey, quartzose sediments described by 

Glover, and an upper member that consists mostly of 

volcanic sand and gravel.

The Hammer Bluff Formation crops out in streambanks and artificial excavations in the Green River 

valley in sees. 21, 27, and 28, T. 21 N., R. 6 E., in the 

southeastern part of the Black Diamond quadrangle. 

Exposures are few because colluvium covers much of 

the formation. The formation is well exposed in three 

places: on the south side of the river across from Hammer Bluff in the SE1/^ sec. 28, where it crops out in a 

meander scarp for about half a mile; on the north side 

of the river in commercial sandpits at Hammer Bluff; 

and in a meander scarp half a mile northeast of Hammer Bluff. The formation probably also underlies the 

wide undulating terrace on the north valley wall in 

sees. 21 and 28. Landslides that cover the northwestern 

part of the terrace appear to be as much as several 

tens of feet thick, and the formation has not been 

mapped in that area; it has been mapped, however, in 

the southeastern part of the terrace because prospect 

pits indicate in that part of the terrace the formation 

is within a few feet of the surface. Although the Hammer Bluff Formation is exposed intermittently along 

the valley for about 2 miles, the thickest observed 

stratigraphic section was across the river from Hammer Bluff, where it is only about 60 feet thick. Additional nearby exposures indicate that the formation is 

at least 100 feet thick.

LITHOLOGY

Both members are typically cohesive and compact, 

because they are clayey and have been compressed by 

thick Pleistocene sediments and ice, but they have not 

been consolidated into firm rock. The lower member is 

composed mostly of light-gray poorly sorted and 

poorly stratified clayey sand and sandy clay, which are 

at least 28 feet thick (Glover, 1941, p. 138). West and 

northwest of Hammer Bluff, however, it contains some 

fairly well sorted and stratified sand. The sr.nd consists mostly of quartz, but it also contains feldspar,
TERTIAKY ROCKS 25

chert, and quartzite; some basalt fragments were reported in it by Glover (1941, p. 143). The heavymineral suite of the lower member consists largely of 

epidote, zircon, garnet, tourmaline, amphiboles, and 

opaque iron oxide minerals. The clay minerals, as determined by X-ray diffraction methods, are almost entirely kaolinite. Lignitic wood is distributed sparsely 

throughout the lower member except in one bed 2-3 

feet thick, which consists mostly of flattened fragments 

of limbs and stems.

The upper member consists of brownish-green to 

brown sand, clay, and pebble gravel, some of which is 

crossbedded. Pebbles are mostly rounded porphyritic 

andesite or basalt, and sand grains are chiefly fragments of similar volcanic rock, quartz, and feldspar. 

About equal parts of kaolinite and montmorillonite are 

the only clay minerals identified in the single sample 

examined by X-ray methods. Lignitic wood is distributed throughout and is abundant near the base. 

Some wood fragments are as large as 15 feet in length 

and iy2 feet in diameter. Light-gray pumiceous sand 

beds that are rich in green hornblende crop out in landslide blocks of the formation a mile northwest of 

Hammer Bluff, and volcanic ash beds were reported in 

the formation by Glover (1941, p. 138).

WEATHERING

The Hammer Bluff Formation is conspicuously 

weathered. The quartz sand and kaolinitic clay in the 

lower member probably are products of weathering of 

Puget Group arkose. Much of that weathering, however, presumably occurred in place within the Puget 

rocks, and still more weathering might have occurred 

during transportation. How much weathering took 

place after deposition of the materials in the Hammer 

Bluff Formation is not known. The upper member, 

however, clearly has been weathered in place, for most 

constituent rock fragments are now soft and altered, 

partly to clay. About 60 percent of the pebbles in one 

pebbly sand exposed in the commercial sandpit at 

Hammer Bluff are weathered enough to be broken by 

a gentle blow of a hammer. In some sand layers in the 

upper member, sand grains are soft, ugreasy,v and 

altered almost completely to clay, even though the texture of sand is retained.

STRATIGRAPHIC RELATIONS

The Hammer Bluff Formation is underlain by the 

Puget Group and is overlain by Pleistocene sediments. 

Both contacts are angular unconformities. In 1960, 

both were exposed in the commercial sandpit at Hammer Bluff and in a meander scarp to the south across

the river. On the south side of the river, the Hammer 

Bluff Formation dips about 10° SW. and overlies 

sandstone of the Puget Group that dips 20°-25° S. 

In some exposures, iron-stained Hammer Bluff sediments of the upper member overlie Puget Group sandstone that is weathered and leached of iron oxide. Thus 

the Puget must have been leached before the Hamrier 

Bluff was deposited. Nearly flat-lying Orting( ?) Drft, 

the oldest glacial drift in the area, unconformably 

overlies the Hammer Bluff Formation. A much higher 

percentage of volcanic pebbles in the Hammer Bluff 

are soft than in the Orting( ?) ; presumably a period of 

weathering occurred between deposition of the two 

formations.

SOURCE AND ENVIRONMENT

The source rocks of the Hammer Bluff Formation 

probably were the arkosic rocks of the Puget Group 

and later the widespread Tertiary volcanic rocks, 

which were largely in the position of the present Cascade Range. Features such as the thinness and discontinuity of beds, the uniform composition, and the 

abundance of wood in the lower member of the Hammer Bluff, and the lithologic similarity of the lower 

member to Puget Group rocks, led Glover (1941; 

unpub. data, 1956) to suggest that it was derived 

locally from the Puget Group, which is the only nearby 

source for such abundant quartz. The upper member 

was derived mostly from preexisting volcanic rocks; 

older volcanic rocks underlie most of the area nQ-ar 

Hammer Bluff that is not underlain by the Puget 

Group. The abundance of volcanic material in the upper member could have resulted either from uplift of 

the older volcanic rocks or from renewed volcanic activity in the area of the present Cascade Range. The volcanic ash, reported by Glover, and the pumiceous sediments in the formation show that eruptions did oc^ur 

during Hammer Bluff time.

Crossbedding and channeling in the sand and gravel 

suggest that part of the formation is fluvial, but the 

woody silt and clay and lignite indicate that much of 

it is lacustrine, as suggested by Glover (1936). The 

presence of poorly sorted, thin, and interbedded fluvial 

and lacustrine sediments suggests that the Hammer 

Bluff Formation was deposited on a piedmont surface 

of low relief, which was characterized by flood plains 

and lakes. At the time of deposition of the Hammer 

Bluff, the Puget Sound lowland was bounded on the 

east by a low range at the position of Cascade Range 

that was not high and continuous enough to form a 

major moisture barrier (Chaney, 1938, p. 641).
26 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

AGE AND CORRELATION

Glover (1936; 1941, p. 137) assigned the Hammer 

Bluff Formation to the Pliocene or preglacial Pleistocene; and Warren, Norbisrath, Grivetti, and Brown 

(1945) assigned it to the early Pleistocene. Each of 

these age assignments was based not on fossil evidence 

but on interpretation of physical evidence the Hammer Bluff is more like Pleistocene deposits than lower 

Tertiary bedrock. Fossil leaves collected during this 

investigation suggest that the Hammer Bluff is late 

Miocene in age (R. W. Brown, written commun., 

1956). The leaves were collected in the NW^SEi/i sec. 

28, T. 21 N., E. 6 E., across the Green Kiver from 

Hammer Bluff, where they occur in lenses of silt and 

clay near the base of the upper member. The following 

species were identified by R. W. Brown of the U.S. 

Geological Survey (written commun., 1956) : Ghamaecyparis sp., Fagus washoeitsis LaMotte, Uhnus sp., 

Gary a egregia (Lesquereux) LaMotte now called 

Gary a bendirei (Lesquereux) Chaney and Axelrod (J. 

A. Wolfe, written commun., 1969) ?/Sassafras sp., 

and Acer sp. Samples from the same strata were 

analyzed for pollen by E. B. Leopold of the U.S. Geological Survey, and the following pollen were identified: Garya, Pinus, Pterocarya, TJlmus or Zelkova, 

Polypodiaceae, Alnus, Picea, Quercus, and fungal 

spores. According to Brown, the assemblage of plant 

fossils indicates a middle to late Tertiary age, and 

Fagus 'washoensis LaMotte is not known to have survived the Miocene in this area. On the basis of plant 

fossils from the Hammer Bluff and apparently correlative formations 10-15 miles farther south (Mullineaux 

and others, 1959), the formation is assigned a late 

Miocene age.

Sand and clay that contains woody lignite recovered 

from holes drilled for the Kent water system along 

Rock Creek in the NE^SEi/i sec. 26, T. 22 N., R. 6 E. 

(Ross Ellis, oral commun., 1957) probably is correlative with the Hammer Bluff Formation. These sediments, which are covered by drift of late Pleistocene 

age, are lithologically similar to those of the lower 

member of the Hammer Bluff Formation and are very 

different from recognized Pleistocene deposits in the 

area.

The Hammer Bluff Formation was correlated by 

Glover (1941) and by Warren, Norbisrath, Grivetti, 

and Brown (1945) with similar sand and clay in the 

Green River valley near Palmer, about 8 miles northeast of Hammer Bluff. Gower and Wanek (1963) tentatively assigned the late Miocene age determined for 

the Hammer Bluff Formation by Brown to the Palmer 

deposit, but they did not use the same name because

they did not believe the two deposits were coertensive. 

A preliminary evaluation of seeds and pollen from the 

sediments at Palmer led R. W. Brown (written 

commun., 1957) to suggest that the Palmer deposit is 

younger than the deposit at Hammer Bluff. However, 

no sufficient further study could be made to confirm or 

deny this possibility.

On the basis of contained volcanic detritus and fossil leaves, some lacustrine and fluvial sediments exposed in the Lake Tapps quadrangle are also correlated 

with the Hammer Bluff Formation (Mullineaux and 

others, 1959; Gard, 1968). These sediments crop out 

along Voight and Wilkeson (Gale) Creeks 10-15 miles 

south of the Hammer Bluff locality. They cl aracteristically are mudflows and alluvium that contain 

abundant pumice in some beds. The pumice is unusual 

in this area, because it contains abundant green hornblende and virtually no other ferromagnesian mineral. 

In contrast, most other Tertiary and Quaternary volcanic rocks in this area contain abundant pyroxene. 

Hornblende pumice is sparse but is also present in the 

Hammer Bluff Formation, and it probably was derived 

from the same general source as was the pumice in the 

deposits along Voight and Wilkeson Creeks.

Similar sediments of probable late Miocene age that 

also are characterized by content of hornblende pumice 

are exposed farther south along the west sid0. of the 

Cascade Range. Near Eatonville, the pumiceou^ Mashel 

Formation (Walters, 1965) is a fluvial and Ir^ustrine 

deposit of middle to late Miocene age. Farther south 

near Castle Rock, the locally pumiceous fluvial and 

lacustrine Wilkes Formation is also considered to be 

late Miocene in age (Roberts, 1958).

The hornblende pumice in the Hammer Bluff and 

correlative formations is similar to the volcanic detritus 

in part of the Ellensburg Formation, which h of late 

Miocene and early Pliocene age. The Ellensburg crops 

out along the east flank of the Cascade Range from 

near Wenatchee (fig. 1) south to the Columbia River 

(Smith, 1903; Laval, 1956). Coombs (1941) noted that 

green hornblende and magnetite were virtually the 

only heavy minerals characteristic of the Ellensburg 

and suggested use of the distinctive mineralogic character for correlation. Later, J. E. Sceva of the U.S. 

Geological Survey (oral commun., 1954) mapped the 

Mashel Formation on the west side of the Cascades 

and proposed that it was equivalent to the Ellensburg 

Formation on the east side. The similarity of pumice 

in widespread formations on both sides of the Cascade 

Range suggests that the volcanic material waf derived 

from widely distributed volcanic vents in the position 

of the present Cascades (Gard, 1960; Fiske and others, 

1963).
GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON 27

PLEISTOCENE DEPOSITS

Repeated glaciation in the Puget Sound lowland 

during Pleistocene time is recorded by the interbedding of glacial drift sheets and nonglacial deposits 

(table 1). The climate of some nonglacial episodes that 

separated the various glaciations was as warm as the 

climate is today, and the entire lowland probably was 

free of ice. The youngest glacial episode recorded in 

the mapped area and that of which the record is by 

far the most complete is the Vashon. Its drift mantles 

the surface over much of the Puget Sound lowland 

and has been traced northward into British Columbia. 

Distribution and character of the Vashon Drift show 

that the Vashon glacier originated in British Columbia and moved southward over the lowland, covering 

the entire area of this report and extending several 

tens of miles -farther south (fig. 13; Bretz, 1913; Mackin, 1941). The northern origin of the glacier is shown 

by the content of the Vashon Drift. It contains numerous rocks and minerals that are sparse in or absent 

from the part of the Cascade Range that is drained by 

rivers that normally cross this part of the lowland, but 

that are common in ranges in British Columbia and 

the northern Cascades of Washington. Pre-Vashon 

drift sheets also contain a significant proportion of 

rocks and minerals from British Columbia and the 

northern Cascades. By analogy to the Vashon, the 

pre-Vashon drift sheets probably were also deposited 

by southward-moving ice from British Columbia. The 

lobe of ice that is inferred to have moved repeatedly 

into the lowland from the north is referred to as the 

"Puget glacial lobe" or "Puget lobe" (Bretz, 1913; 

Mackin, 1941; Crandell, 1963).

All the glacial-till deposits found in the mapped area 

contain typical northern rocks and minerals. Apparently glaciers from the adjacent Cascade Range did not 

reach that far out into the lowland. Therefore, the 

sediments termed "nonglacial" in the area include all 

those that are not derived from the Puget lobe. Some 

of these nonglacial sediments were deposited during

TABLE 1. Sequence of geologic-climate units recognized in the 

southeastern part of the Puget Sound lowland (on the left) and 

the -probable correlative geologic units exposed in the Renton, 

Auburn, and Black Diamond quadrangles (on the right)

Crandell and others (1958) 

Armstrong and others (1965) This report

Vashon Stade of the Eraser Glaciation,_________ Vashon Drift

Olympia Interglaciation. _______________ (No unit recognized)

Salmon Springs Glaciatioii_____________ Salmon Springs Drift

Puyallup Interglaciation._____________ Puyallup(?) Formation

Stuck Glaciation_ ______________________ Intermediate drift

Alderton Interglaciation..______________ (No unit recognized)

Orting Glaciation ---------.______________ Orting(?) Drift

__BRITISH COLUMPT A 

-~r A100 MILES

_J

APPROXIMATE

FIGURE 13. Direction of movement of ice (Puget lobe) 

in the Puget Sound lowland of western Washington 

during the Vashon Stade. Adapted from Mackin and 

Cary (1965, fig. 8).

cool climates and others during warm climates. Seme, 

because they are like outwash in physical characteristics, are mapped with drift formations, whereas others 

are mapped as separate nonglacial units.

SOURCES OF DETRITAL MATERIAL

Pleistocene deposits of this part of the Puget So^ind 

lowland consist of detrital material derived from tl^ree 

principal source areas: (1) the part of the central Cascade Range that is south of Snoqualmie Pass and that 

is drained by the Cedar, Green, and White Rivers; (2) 

Mount Rainier; and (3) British Columbia and the 

northern part of the Cascade Range of Washington. In 

the discussions to follow, detrital material and deposits 

derived chiefly from the first two areas are referred to 

as being of Cascade provenance, and those derived 

from the third are referred to as being of nortHrn 

provenance. Where it is desirable to distinguish between the first two sources, they are termed "central 

Cascade" and "Mount Rainier," respectively.

Sediments of central Cascade provenance are exemplified by alluvium of the modern Cedar and Green 

Rivers where the river deposits have not been con-
28 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

taminated by drift from the Puget lobe. Alluvium of 

the White Kiver, though the White also drains the 

central Cascades, consists chiefly of material from 

Mount Rainier. The Cedar and Green Kiver deposits 

are dominated by fragments of Tertiary volcanic rocks, 

which consist of a wide variety of greenish-gray and 

light- to dark-gray andesitic, dacitic, and basaltic 

rocks, both porphyritic and dense. In alluvium from 

the Cedar River, light-gray granodiorite from the Snoqualmie Granodiorite or similar intrusive bodies is also 

abundant. Heavy minerals in alluvium from the Cedar 

and Green Rivers are chiefly hypersthene, hornblende, 

and opaque iron minerals. Every heavy-mineral suite 

studied, however, contains a significant proportion, up 

to about 50 percent, of rock fragments and altered 

unidentified grains (table 2). When the lowland is not 

occupied by ice, such detritus from the central Cascades is brought into the mapped area from the east. 

It is then carried across the area and beyond it to the 

north and west, for the riverflow reaches the ocean by 

way of the Puget Sound and the Strait of Juan de 

Fuca north of Seattle.

Modern sediments of Mount Rainier provenance are 

represented by alluvium of the White River. Older 

sediments from Mount Rainier, however, are better 

exemplified by Pleistocene volcanic mudflows and other 

volcanic sediments that are exposed directly northwest 

of the volcano in the Lake Tapps quadrangle (Crandell, 1963). Modern alluvium along the White Piver is 

characterized by sand and gravel composed of reddishgray to grayish-red and light-gray to black pyroxene 

andesite. Heavy-mineral suites consist chiefly of hypersthene but also include a very small proportion of 

hornblende plus opaque iron minerals, altered grains, 

and rock fragments (table 2). Older deposits of Mount 

Rainier provenance are characterized by light-gray to 

black and reddish-gray hypersthene-hornblende andesite; their heavy-mineral suites are similar to those 

from modern sediments but contain a larger proportion 

of hornblende (Crandell, 1963). Like the Cedar and 

Green Rivers, the White carries its sediments across 

and northwestward beyond the limits of the mapped 

area.

The typical example of sediments of northern provenance is the Vashon Drift. Only part of the material 

in the drift, however, can be identified as northern. 

The drift contains abundant andesitic and grarodioritic stones, for example, that could have been derived 

either from the northern or from the central parts of 

the Cascade Range. Furthermore, the drift contains 

detritus of Cascade provenance that was carried north 

of the mapped area during nonglacial time, then picked 

up by the southward-moving Puget lobe. Th0- drift 

does, however, include a significant proportion cf rocks 

and minerals that can be recognized as having a 

northern source. Usually from 5 to 15 percent of the

TABLE 2. Heavy-mineral suites in modern alluvium of the Cedar, Green, and White Rivers

[Based on counts of approximately 100 grains. All samples separated in bromoform (specific gravity approximately 2.86); magnetic grains removed with hand nagnet. 

Abbreviations: R, seen in slide, but not in 100-grain count; NC, not counted. Analysts: H designates J. C. Hathaway and H. C. Starkey; M designates author]

Sample Content (grain count)

Source 

river

Grain

Locality No. size 

(mm)

Pyroxene Altered Amnhibole

(chiefly Fe-Mgmin- (cHiefly Garnet 

hypersthene) erals and rock hornblende)

fragments

Opaque 

minerals

Other 

minerals

Analyst

Upvalley segments beyond the area covered by the Puget lobe drift

Cedar.............. NWM sec. 26, T. 22 N., R. 9 E. ............. C 

Bex ...... ........... SE^sec. 29, T. 22 N., R. 9E...... . ......

Green......---.- NWM sec. 1, T. 20 N., E. 8 E. ............. .

White--_.....-_..._ SWM sec. 33, T. 20 N., R. 8 E..

!L-2 

12

9-1

9-2 

16

1/4-1/8 

1/8-1/16 

1/4-1/8

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/8-1/16 

1/4-1/8

1/8-1/16

23 

31 

71

71 

62 

73 

45

70

88

51 

37 

16

17 

9 

10 

17

6

14 

22

7

4 

9 

3 

10 

R

R

0 

2 

0

0 

0 

0 

1 

0

0

12 

6

7

8 

20 

14 

21 

12

6

0 H 

1 H

C H

C H 

1 H 

0 H

6 M 

C H

1 H

Downvalley segments in the area covered by the Puget lobe drift

Cedar.......

Green _ _.

White......

.---.-- NEM sec. 19, T. 21 N

SWM sec. 25, T. 21 N.

------ SEM sec. 30, T. 21 N. 

SEM sec. 34, T. 21 N.

,, R. 5E.._... _..

, R.5E. .............

, R.5E-. _-_...- 

434

435 

436 

437 

262-4 

CL 17

865-35-1

916-2-9 

691

1/4-1/8

1/8-1/16 

1/8-1/16 

1/8-1/16 

1/8-1/16

1/4-1/8

1/8-1/16 

1/4-1/16 

1/8-1/16

1/4-1/8 

1/8-1/16 

1/8-1/16

23

18 

28 

32 

25 

45

53 

55 

38

84 

84 

85

51

47 

42 

40 

24 

27

21 

21 

24

11 

5 

5

17

18 

14 

17 

23 

6

8 

19 

22

1 

R 

3

R

R

2

1 

4

4

1 

3

R 

R 

0

6

11 

12 

9 

17 

17

15

NC 

11

4 

10 

6

3

? 

5 

1 

7 

I

\

4

2

0 

2

1

M

M 

M 

M 

M 

H

H 

M 

M

H 

H 

M

1 Tributary of Cedar River.
PLEISTOCENE DEPOSITS 29

stones are gneiss, schist, coarse-grained biotite granite, 

quartzite, and marble rock types that are sparse in or 

absent from the alluvium of rivers that flow across the 

area in nonglacial time. Heavy-mineral suites in Vashon Drift consist largely of the same minerals as are 

present in alluvium of Cascade provenance, but they in 

addition contain abundant garnet and a wide variety 

of other minerals (table 3). That the abundant garnet 

was derived from the north is apparent from a comparison of heavy-mineral suites from sand of modern 

Cascade Rivers beyond the limits of the Puget lobe 

with those from Vashon Drift (tables 2, 3). In samples 

of sands from the Cedar, Green, and White Rivers that

are uncontaminated by northern drift, garnet is sparse. 

Only one such sample contained as much as 2 percent 

of that mineral in any counted fraction. In samples 

from Vashon Drift, in contrast, garnet generally makes 

up several percent of the heavy-mineral suites, and in 

many samples it makes up at least 10 percent.

CRITERIA USED TO ESTABLISH STRATIGRAPHY

PROVENANCE

The composition of Pleistocene deposits, to a certain 

extent, indicates their source and consequently whether 

they were deposited during glacial or nonglacial episodes. Sediments clearly of northern provenance idenTABLE 3. Heavy-mineral suites in Pleistocene sediments

[Based on visual estimates, in percent (F, 10-25; A, 70-90; S, <5; R, <1), and on counts of approximately 100 grains. All samples separated in bromoform (specific 

gravity approximately 2.86); magnetic grains removed with hand magnet. Abbreviations: ...., not determined; NI, present in sample but not included in count. 

Analysts: H designates J.C. Hathaway and H.C. Starkey; M designates author]

Sample

Locality Sample 

No.

Measured sec. A;<- SEJ£ sec. 28, T. 21 N., R. 6 E 862-22-17

862-25^1 

Measured sec. B;i NWJ£ sec. 29, T. 21 N., R. 6 E. ... 863- 4-3

Content

Size 

(mm)

Till

1/4-1/8 

1/8-1/16 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/4-1/8 

1/8-1/16

Pyroxene 

(chiefly hypersthene)

Altered FeMg minerals 

and rock 

fragments

Amphibole 

(chiefly 

hornblende)

Garnet Opaque 

minerals

Siderite 

aggregates

Other 

minerals

Analyst

, Orting(?) Drift

F 

F 

15 

F 

F 

35 

F 

F

27

35 

F

F 

F 

13 

F 

F 

15 

S 

-J F

F

S 

1 

F 

S 

4 

F 

S

F 

F

9 

F 

F 

6

S

S

F 

F 

31 

F 

F 

NI

R 

3

F 

5

S 

S

H 

H 

M 

H 

H 

M 

H 

H

Intermediate drift

Measured sec 

sec. 21, T. :

. D;2 SWMSEM sec. 16 and NW^NEM 

21 N., R. 5 E.. ...... . . 863- 4-1 

867- 5-1 

867- 6-1

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16

F 

F 

F

S 

F

S

F 

F 

F 

F 

F 

F

F 

F 

F 

F

A

F

F 

F

S

F

F 

F ....

S ....

S ....

S ....

s ....

S s 

s 

s

F

s

s

H 

H 

H 

H 

H 

H

Salmon Springs Drift

NEM sec. 2, 

SEH sec. 17,

T. 20 N., R. 5 E

T.21N., R.5E. ...... ........ .

920- 7-6 

845-16-5

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16 .

F .........

F .........

F A

F

F 

F 

F 

A

F

S ....

S

s ....

F

F ....

S R

S 

F

H 

H 

H 

H

Vashon Drift

Measured sec . A;i 8EH sec. 28, T. 21 N., R. 6 E 845-16-6 

862-25-2

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16

F 

F .........

F 

F

F

F .....

F

F ...

F

F

F 

F 

F ....

R 

F .....

F ....

S S 

F 

S 

F

H 

H 

H 

H

Outwash, Vashon Drift

SWJi sec. 14, 

NWJ4 sec. 34:

NEHsec. 16, 

NWH sec. 21, 

SEJ4 sec. 26, 

SWH sec. 17,

T.23N., R.5E-. ...... .....

, T. 22 N., R. 6E

T. 21 N., R. 6 E.. .........

, T. 21 N., R. 6E

T. 22 N., R. 5E

T. 21 N., R. 5E...

261-11-1 

792- 1-1

852- 1-1

852- 2-1 

787-18-1 

845-43-1

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16 

1/4-1/8 

1/8-1/16

22 

31 

29 

44 

30 

36 

47 

31 

24 

27 

23 

29 

29

52 

25 

51 

34 

39 

46 

31 

43 

48 

48 

47 

41 

36

9 

27 

10 

9 

11 

5

7 

19 

5 

23

24

10 

5 

2 

NI 

6 

7 

6 

5 

3 

5 

3 

5 

3

7 

9 

8 

9 

10 

7 

13 

15 

6 

16 

3 

13 

7

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0

0 

3 

0 

3

4 

0 

1 

0 

0 

0 

2

0

1

H 

H 

H 

H 

M 

H 

H 

H 

H 

H 

H 

H 

H

See figure 14. 2 See figure 17.

380-731 O - 70 - 5
30 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

tify stratigraphic units of glacial drift. They record 

presence of the Puget lobe in the lowland, even where 

the sediments do not include till. Sediments wholly of 

Cascade provenance, on the other hand, identify nonglacial stratigraphic units. During their deposition, 

the Puget lobe was distant enough that it did not contribute material to them. A succession of glacial and 

nonglacial episodes, with respect to the Puget lobe, 

can thus be determined by examining the lithology of 

sediments in a stratigraphic sequence.

The provenance of many coarse sediments can be determined by identification of constituent stones. For 

deposits in which pebbles are sparse, the proportion of 

garnet among heavy minerals can be substituted. Like 

pebble counts, estimates of garnet proportions are useful in the field; in gold-pan concentrates from coarse 

or medium sand, garnet typically is readily seen with 

a hand lens because of its prevalent red and orange 

colors. For concentrates from finer sand, however, it 

commonly is necessary to examine the minerals under 

a microscope.

Counts and estimates of garnet proportions encounter some problems that are not involved in pebble 

counts. Interpretation of both pebble and mineral proportions must allow for an apparent gradation of types 

from certainly northern to certainly Cascade sediments, probably resulting from mingling of Puget lobe 

melt water and Cascade rivers, and because of some 

reworking of drift by the Cascade rivers. But use of 

heavy-mineral proportions must also allow for variations resulting from handling of the sample. Handling 

causes variety in heavy-mineral proportions because of 

such factors as shape, density, and size of minerals. 

Garnet, for example, is nonimiformly discarded from 

a gold pan with the lightweight fraction, whereas tabular minerals are relatively concentrated (Theobald, 

1957). Even laboratory separation by heavy liquids 

may produce variable results, for the garnets tend to 

roll and congregate irregularly in a sample.

In spite of limitations of the garnet-proportion 

method, the determined proportion of garnet seemed 

to be adequate to distinguish many strata as either of 

northern or of Cascade provenance. In this study, 

sediments in which garnet was absent or sparse were 

regarded as clearly of Cascade provenance and therefore nonglacial. Those in which garnet made up only 

a few percent of the heavy-mineral fraction were regarded as not identifiable on the mineral proportions 

alone, and of doubtful provenance in the absence of 

other evidence. Only those sediments in which garnet 

made up more than about 5 percent of the heavy fraction were regarded as of northern provenance and 

therefore glacial on the basis of mineral proportions.

CLIMATE

Evidence of past climates not only is useful in distinguishing nonglacial from glacial sediments, but also 

in indicating, for times of nonglacial sedimentation, 

whether the glacier had made a major or a minor retreat. The climate that existed during deposition of 

many nonglacial deposits is recorded by the t;Tpes of 

pollen and diatom fragments they contain.

Hansen and Mackin (1949) showed that pollen 

analyses could be used to determine the climste that 

existed during deposition of some stratigraphic units 

in the Puget Sound lowland. Further, they showed 

that pollen and stratigraphic studies together could be 

used to demonstrate a succession of pre-Vashon glacial 

and nonglacial episodes. Pollen analyses and resulting 

paleoclimatic interpretations applied to this study were 

made by E. B. Leopold of the U.S. Geological Survey. 

The interpretations are based on comparison of counts 

of tree pollen from pre-Vashon sediments from the 

mapped area with tree-pollen counts from the uppermost deposits in modern peat bogs at various altitudes 

in the Pacific Northwest (Hansen, 1947). Fossil pollen 

assemblages that indicate a forest similar to the.t existing today in the lowland, for example, are used to infer 

a comparably mild climate in the lowland at the time 

the pollen-bearing sediments were laid down. Similarly, pollen that indicate a forest like that abo^e 5,000 

feet in the Cascades today suggest cool and moist conditions in the lowland during deposition of the enclosing sediments.

Identifications of diatoms and interpretations of 

their depositional environments were made by K. E. 

Loliman of the U.S. Geological Survey. Fossil assemblages that consist of species living in water with 

a temperature range like that in the Puget Sound lowland today (termed "moderate" or "temperate") or 

warmer are regarded as indicating that the climate in 

the lowland during their deposition was as warm as it

is now.

WEATHERING

Weathering that has been recognized in the mapped 

area consists chiefly of iron staining and decomposition of pebbles. No well-developed pre-Vashon soil 

profiles, and only one probable profile, have been 

found. Some of the oxidation zones that are common, 

however, probably represent parts of expanded soil 

profiles. Nearby, weathering profiles have beer recognized in the Lake Tapps quadrangle (Crandell, 1963), 

in Seattle (Mullineaux and others, 1964), and in a few 

other places in the Puget Sound lowland (Bretz, 

1913).
PLEISTOCENE DEPOSITS 31

Iron oxide stains Pleistocene deposits various shades 

of brown the deposits are then termed "oxidized" 

or it stains them bluish to greenish gray they are 

then termed "reduced." Most pre-Vashon formations 

are deeply stained, and an intense color due to staining 

that is spread throughout a formation is regarded as 

evidence of pre-Vashon age. Permeable sediments are 

most strongly stained. Well borings suggest that the 

sediments are in a reduced state at depth, but they 

typically are oxidized to brown near the surface. Sediments containing abundant disseminated peat or wood 

are commonly gray even at the surface, or if the organic material is scattered, are mottled in gray and 

brown. Relatively impermeable sediments such as clay 

and till generally are stained along fractures and 

around stones mainly by concentrations of iron oxide. 

Sediments from Mount Rainier differ from most other 

deposits in that they typically are not iron stained 

even where permeable. .

Vashon Drift generally is stained in only the uppermost few feet. Till at the ground surface typically is 

oxidized to a light yellowish brown to depths of 2-4 

feet, depending on permeability. Below the surface 

zone, it is nearly uniformly olive gray and does not 

contain notable concentrations of iron oxide along 

fractures or around pebbles. Permeable Vashon outwash commonly is oxidized to depths of 6-8 feet, though 

zones of oxidation occur irregularly at greater depths. 

Locally, the Vashon sediments are strongly stained by 

iron oxide, but overall oxidation of the formation was 

not seen anywhere.

Decomposition of stones can be used to differentiate 

some pre-Vashon sediments from Vashon Drift. Partly 

decomposed stones are common in many older sediments, but are sparse in Vashon deposits. Where such 

stones are abundant, they indicate a pre-Vashon age.

STRATIGRAPHIC SEQUENCE

Pleistocene deposits in the Puget Sound lowland in 

and southeast of Seattle record at least four glaciations separated by interglacial intervals (table 1; Mullineaux and others, 1957; Crandell and others, 1958). 

The, three pre-Vashon glacial and the two intervening 

interglacial episodes are named for formations that 

crop out in the Puyallup Valley; they are the Orting 

Glaciation (oldest), Alderton Interglaciation, Stuck 

Glaciatioii, Puyallup Interglaciation, and Salmon 

Springs Glaciation (Crandell and others, 1958). 

Vashon Drift lies on Salmon Springs Drift in the 

Puyallup Valley, but deposits of another interglaciation, the Olympia, separate the two drifts in some 

other parts of the lowland (Armstrong and others,

1965). The stratigraphic sequence in the mapped r.rea 

is the Ortiiig(?) Drift, an unnamed intermediate 

drift, the interglacial Puyallup (?) Formation, Salmon Springs Drift, and Vashon Drift.

ORTING (?) DRIFT

The oldest deposits recognized as Pleistocene are 

stony till and outwash that lie on Tertiary fonaations along the Green River southwest of Black Diamond (Mullineaux, 1965c). These deposits are similar 

in lithology and stratigraphic position to the Orting 

Drift of the Puyallup Valley and are tentatively correlated with it. The name Orting was first assigned 

by Willis (1898c) to gravel that is typically exposed 

near the town of Orting in the Puyallup Valley. Because till is interbedded with the gravel, the Orting 

Gravel as used by Willis has been redefined as Orting 

Drift (Crandell and others, 1958, p. 387).

LITHOLOGY

The Orting (?) Drift along the Green River consists 

predominantly of brown sand and gravel that contains 

lenses and sheets of till, silt, and clay. Locally, deposits of probably lacustrine gray to brown sand, silt, 

and clay are thick. Sections A and B are composite sections that illustrate the lithology of the formation 

where it is well exposed.

Section A. South valley wall of the Green River in 

T. 21 N., R. 6 E.

sec. 28,

{Lower three units of Orting(?) Drift measured about a quarter of a mile northwest 

of main exposure]

Tliick-

(feet)

15

Vashon Drift:

Sand, pebbly, gray to yellowish-gray, friable___.

Till, stony, gray, compact; contains gravel and clay 

lenses (sample 862-25-2)...____________________ 70

Gravel, sandy, gray.__________---__--_-__----__- 5

Orting(?) Drift:

Sand, medium and fine, grayish-brown, horizontally

stratified . _ ________-______--_-------___--__- 95

Gravel, pebble-ands-cobble, reddish-brown to grayishbrown. _____________-_---__---_--------___-_- 30-35

Till, stony, mottled gray to reddish-brown; darkreddish-brown iron oxide concentrated along 

joints and around pebbles (sample 862-25-1)._ _ __ . 15

Gravel, cobble, bouldery, reddish-brown; lies in 

channels and contains blocks of underlying sand__ 5-15

Sand, medium to coarse, reddish-brown..__________ 35

Covered._ _______________________________.about 30

Gravel, boulder, reddish-brown.__________________ 5

Sand, coarse to medium, reddish-brown to grayishbrown; upper 3-5 ft strongly iron stained________ 15

Till, stony, mottled gray to reddish-brown; darkreddish-brown iron oxide concentrated along joints 

and around pebbles (sample 862-22-17)_________ 15-20

Hammer Bluff Formation._______-____-______-_------ 15
32 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

Section B. South side of the Green River in cutoff spur, 

sec. 29, T. 21 N., R. 6 E.

[Lower three units of Orting(?) Drift measured about 600 feet east of upper part of

section]

ThickVashon Drift: $% 

Till, stony, gray________________________________ 35

Gravel, pebble, olive-gray....____________________ 15

Salmon Springs Drift:

Sand, medium, yellowish-brown_________________ 13

Gravel, pebble-and-cobble, brown.._______________ 8

Sand, coarse, brown. ____________________________ 8

Intermediate drift:

Till, mostly silt and clay, olive-gray_______________ 10

Gravel, pebble-and-cobble, sandy, brown.._________ 15-20

Sand and silt, yellowish-gray.____________________ 10-15

Till, mostly silt and clay, olive-gray; increases in 

thickness westward to more than 100 ft (sample 

863-4-1)_.___.___- -_---__.___-_._-_---__.____ 10

Orting(?) Drift:

Till, stony, mottled olive-gray to reddish-brown, 

iron oxide coatings around stones and along fractures (sample 863-4-3) ________________________ 10-15

Gravel, pebble-and-cobble, yellowish-brown to 

reddish-brown; contains stones probably derived 

from an ancestral Mount Rainier, and lenses of 

bluish- to greenish-gray silt and clay____________ 50

Sand, medium to coarse, yellowish- to reddishbrown. ______________________________________ 15

Break in continuous exposure.

Sand, fine to medium, light-brown, horizontally

bedded.__-__---_--------_-__-_---------__--. 200

Silt and sand, clayey, horizontally laminated; grades

upward into fine and medium sand.-_______-___- 20-30

Till, stony, mottled olive-gray to redd;sh-brown; iron

oxide coatings around stones and along fractures. _ _ 15

At least two and probably three till sheets or lenses 

in the Orting (?) Drift are exposed in the map area. 

Till strata lie at two stratigraphic horizons below 

thick sand of probable lacustrine origin at section A 

(fig. 14). In addition, a lens of till that probably also 

is Orting (?) in age lies above the same sand in a 

nearby exposure. Till also lies both above and below 

a similar probably correlative thick sand at section B 

(fig. 14). Typically, the Orting(?) till is very compact 

and stony; it consists of pebbles, cobbles, and a few 

widely separated boulders in a clayey sand and silt 

matrix (figs. 15, 16). The till contains rocks and heavy 

minerals of northern provenance (table 3), showing 

that it was deposited by the Puget lobe. The heavymineral suites, however, contain in addition to the minerals usually found in northern drift a large percentage of siderite and aggregates of siderite and clay. 

X-ray analyses of three samples of matrix material 

show that almost all the clay minerals in the till are 

montmorillonite. Chlorite in small amounts is the only 

other clay mineral identified (table 4).

Roughly half the stratified drift that is well exposed 

011 the south side of the Green River is sand of probable lacustrine origin; most of the remainder is fluvial 

sand and gravel. At measured section B (fig. 14), 

clayey silt and sand overlie till and grade upward 

into fine and medium sand that is uniformly well 

sorted, horizontally bedded, and about 200 feet thick. 

The thick sand is overlain by crossbedded coarse sand 

and gravel that is, in turn, overlain by till. At measured section A (fig. 14), thick and uniform horizontally bedded fine and medium sand overlies till and 

gravel at an altitude higher than at section B and the 

sand is only 95 feet thick. The thick horizontally 

bedded sand and the underlying silt and clay are interpreted as deposits of a proglacial lake that formed 

in a depression in Orting(?) till and gravel.

Medium to coarse sand and pebble-and-cobble gravel 

prevail in the fluvial deposits that are well erposed. 

Boulder gravel, however, crops out in one expensive 

layer several feet thick in the lower part of the formation at measured section A. Silt and clay layerr occur 

within the sand and gravel, but only as thin lenses. 

The sands and gravels typically are crossbedded and 

lenticular; individual lenses vary greatly in thickness 

and horizontal extent. Channeling of underlying beds 

and cut-and-fill structural features are commor.

Like the till, the stratified drift contains roc^s and 

minerals of northern provenance. The lacustrine sand, 

however, contains fewer identifiable northern minerals; the sand probably contains a considerable a.mount 

of detritus brought in by Cascade rivers that flowed 

along the east margin of the Puget lobe during Orting 

time.

Organic material is not common in the Ort: iig(?) 

except in one general locality on the south side of the 

Green River in the west half of sec. 28 and in the east 

half of sec. 29, T. 21 K, R. 6 E. Wood fragments, some 

of which are logs more than a foot in diameter, are 

abundant in gravel and sand along Newaukum Creek 

in sec. 29 that is mapped as part of the Ort: ng(?) 

Drift. Wood fragments are also abundant in a single 

exposure of Orting(?) till in sec. 28 along Whitney 

Hill Road in 1956, but these wood fragments are small, 

generally less than an inch across.

WEATHERING

The Orting (?) contains some decomposed stones, 

and it is stained and weakly cemented in places by 

iron oxide. It also contains abundant, probably secondary siderite and niontmorillonite clay minerals. It 

is the most weathered of the Pleistocene formations 

but is distinctly less weathered than the underlying 

Hammer Bluff Formation. Nearly all the Ortmg(?) 

is stained by iron oxide. The permeable gravel or sand
PLEISTOCENE DEPOSITS 33

EAST WEST

SECTION A

550'

SECTION B

350'

300'

250'

200'

Sample discussed 

in text

Correlation 

line

Gravel Sand Silt and clay Clayey till Stony till

FIGURE 14. Sketch of sections A and B in south valley wall, showing Orting(?) Drift. Section A is in SE}4 sec. 28, T. 21 N.,

R. 6 E., and section B in NW1^ sec. 29, T. 21 N., R. 6 E.

typically is various shades of yellowish or reddish 

brown. The silt and clay, however, typically is bluish 

to brownish gray. The till generally is stained brownish gray or mottled brown and gray, and almost all 

stones and fractures are coated with dark-brown iron 

oxide. Some of the constituent montmorillonite clay 

minerals probably were picked up by the glacier from 

the underlying, deeply weathered materials. However, 

montmorillonite is prevalent in till layers that are high 

in the formation (table 4, sample 862-25-1) and that 

probably represent readvances of the ice over fresh

drift. It seems likely that much of the montmorillonite 

was formed in place by weathering.

DISTRIBUTION AND THICKNESS

Orting( ?) Drift has been recognized only along the 

valley walls of the Green River and Newaukum Creek 

in the eastern part of the Black Diamond quadrangle. 

The entire formation dips westward slightly, but more 

steeply than the slope of the Green River valley floor 

or of the drift plain. Between measured sections A and 

B. the oldest till and fluvial deposits pass out of sight 

beneath the flood plain, and apparently successively
34 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

c D

FIGURE 15. Comparison of textures of representative till deposits in A, Vashon Drift; B, Salmon Springs Drift; C, intermediate drift; and D, Orting(?) Drift.

younger strata are exposed in the upper part of the 

drift (fig. 14).

The thickest section of Orting(?) Drift exposed is 

at section B, where lacustrine silt and clay crop out at

river level. Because fluvial sediments and till underlie 

the lacustrine deposits elsewhere, the formation probably is considerably thicker than the 230 feet exposed 

at section B.
PLEISTOCENE DEPOSITS 35

100

90

Q

id 80

70

60

50

I I I I 

EXPLANATION

Vashon Drift

Salmon Springs Drift

Intermediate drift

Orting (?) Drift

100

PARTICLE-SIZE DIAMETER, IN MILLIMETERS

FIGURE 16. Cumulative particle-size distribution curves of glacial till samples from Vashon Drift, Salmon Springs Drift, intermediate drift, and Orting(?) Drift.

STRATIGRAPHIC RELATIONS

The Orting(?) Drift overlies the Hammer Bluff 

Formation with a slight angular unconformity. In 

1956, the contact was well exposed in the commercial 

sandpit at Hammer Bluff and in natural exposures 

across the river to the south. In most exposures, the 

Orting (?) is overlain directly by Vashon Drift, but at 

measured section B (fig. 1-t), it is overlain with sharp 

erosional unconformity by intermediate drift. No profile of weathering was recognized in the Orting(?), but 

there is an overall difference in montmorillonite clay 

content between it and the intermediate drift (table 

4) that suggests an interval of weathering between 

the deposition of the two drifts.

INTERMEDIATE DRIFT

The formation next younger than the Orting(?) in 

the mapped area is an unnamed drift here informally

termed "intermediate." This stratigraphic unit, which 

consists mostly of two fine-grained clay-rich till members separated by 50-175 feet of stratified sediments, 

crops out along the Green and White River valley 

walls. The intermediate drift lies between formations 

that are tentatively correlated with the Orting Drift 

and Puyallup Formation of the Puyallup Valley. Its 

position thus suggests equivalence with drift of the 

Stuck Glaciation (table 1), but it cannot be traced to 

that formation. The intermediate drift, furthermore, 

is strikingly dissimilar to the type Stuck Drift that is 

only about 8 miles to the southwest. The type Stuck 

is thin and contains only a single till member that is 

coarse grained and stony. Because of the lithologic 

difference, it does not seem likely that the intermediate 

drift is an extension of the Stuck Drift exposed in the 

Puyallup Valley. It does seem likely that the intermediate drift was deposited at some time during the
36 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

TABLE 4. Mineralogy of silt and day fraction of tills

[Tr., trace. Analysts: Dorothy Carroll, P. D. Blackmon, J. C. Hathaway, H. C. 

Starkey, and Gillison Chloe]

Sample Mineralogy

Locality No. Size i Minerals

Estimated 

content 

(parts in 10)

Vashon Drift

Measured sec. E; 2 

center sec. 17, T. 21 

N., E. 5E.

Measured sec. A; ' SEM 

sec. 28, T. 21 N., E. 

6E.

Mica.. ....... ......

Chlorite(7). ..........

4 

2 

1 

1 

1 

5 

4 

Tr. 

3 

2 

2 

2 

Tr. 

5 

4

Salmon Springs Drift

Measured sec. E; 2 

center sec. 17, T. 21 

N., E. 5 E.

NEM sec. 2, T. 20 N., 

E. 5E.

Mica..- -..-----.---

Silt. ...... Quartz................

Mixed-layer chloritemontmorillonite _ . .

5 

o

1 

1 

Tr. 

6 

3 

Tr. 

4

1 

1

1 

Tr. 

4 

4

Intermediate drift

Measured sec. B; 3 

NWJi sec. 29, T. 21 

N., E. 6E.

Measured sec. D; 4 

SWJiSEK sec. 16 and 

NW^NEM sec. 21, 

T. 21 N., E. 5E.

Mica..................

867- 5-1 Clay...... Montmorillonite..- _-._

Chlorite _ ...........

Silt....... Quartz...-.-.-.... _._

Plagioclase. .......... _

Chlorite (?)...., .._--. -

Mica..................

Chlorite (?).... ........

4 

3 

1 

1 

Tr. 

5 

4 

4 

o

1 

1

1 

4 

3 

2 

5 

2(?) 

1 

1 

Tr. 

5 

4 

Tr.

Orting(?) Drift

Measured sec. B; 3 

NWJi sec. 29, T. 21 

N., E. 6E.

Measured sec. A; 3 

SE}£ sec. 28, T. 21 

N., E. 6E.

i Clay, <0.002 mm; silt, 

3 See figure 18.

863-4-3 Clay...... Montmorillonite.. ....

Chlorite...............

Mica.. ................

Chlorite(?)_ ...........

Montmorillonite (?).... 

862-22-17 Clay.--.__ Montmorillonite. . .

Chlorite ........ _._

Quartz ................

Plagioclase .........

0.002-0.05 mm. 3 See figure 14.

5 

2 

1 

1 

Tr. 

4 

4 

7 

2(1) 

Tr. 

6 

o

1(?)

8

K?) 

Tr. 

Tr. 

6 

3

Stuck Glaciation, yet it is possible that it resulted 

instead from a glaciation not represented in the Puyallup Valley sequence. For that reason, and because of 

the lithologic difference, the term "Stuck" is not applied to the intermediate drift of this report. 

The upper part of the intermediate drift of this report is correlative with the lower of two drift sheets 

first described as intermediate in the Buckley quadrangle (CrandeU and Gard, 1959). The low-,r drift 

sheet there was later assigned to the Stuck Drift by 

Crandell (1963). 

LITHOLOGY

The intermediate drift consists of fine-grained till, 

lacustrine silt, clay, and sand, fluvial sand, and minor 

amounts of gravel. Deposits exposed on the scuth and 

north walls of the Green Kiver valley east of Auburn 

(sections C and D; fig. 17) are typical of the formation.

Section C. South wall of Green River valley in sees. 25 and 36, 

T. 21 N., R. 5 E.

[Main section measured in SW^SW}^ sec. 25; Puyallup(?) Formation measured in 

NEj£NW}^ sec. 36, about a quarter of a mile farther southeast] Thickness 

(feet)

Vashon Drift: 

Sand, pebbly, light-brown. __ __ _ _ _ 10

Till, stony, olive-gray _ __ ___ __ _- 25

Gravel, pebble, sandy, olive-gray. _ ___ - 15-20 

Salmon Springs Drift: 

Gravel, pebble-and-cobble, sandy, yellowish- to

Puyallup(?) Formation:

Sand, medium, ashy, pale-yellowish-gray-- _ 5-10

Intermediate drift: 

Till, mostly silt and clay, olive-gray. ______ _ _ _ 10-30

Sand, and pebble gravel. _______-_--__---_---__-- 10

Till(?), mostly silt and clay, olive-gray __ __.__.__ 2

Sand, medium and coarse, with some pebble gravel-- 100 

Silt and clay, pebbly, laminated, bluish-gray to

Till, mostly silt and clay, olive-gray __ ______ 45

Section D. North wall of Green River valley

[Section measured in SW^SEM sec. 16 and NWJiNEM sec. 21, T. 21 N., E. 5 E.. 

in cutbank of Green Eiver and along Lake Holm Eoad] Thickness 

Vashon Drift: (feet)

Gravel, pebble-and-cobble, sandy, yellowish-brown . _ 25 

Salmon Springs Drift: 

Gravel, pebble, sandy, brown; lenticular, locally 

contains blocks of clay and glacial till. ___ ._. 10

Sand, medium to coarse, brown (not continuously 

exposed) _ _ _ 35

Intermediate drift: 

Silt and clay, thinly laminated, bluish-gray _ _ _ 20-25

Till, mostly silt and clay, olive-gray (sample 8^7- 

5-1) " _ ____________-_____-- --__- 20-25
PLEISTOCENE DEPOSITS 37

Section D. North watt of Green River valley Continued

ThkkIntermediate drift Continued (feet) 

Sand, fine to medium, gray to brown; crossbedded in

part, contains interbeds of silt__________________ 40

Silt and clay, thinly laminated, yellowish-gray to

brown-______________________________________ 10

Till, chiefly silt and clay, olive-gray (sample 867-

6-1).________._.______.__.____._____.___._.__ 65

Till occurs in the intermediate drift throughout almost all its mapped distribution. Both major till members appear to be extensive and to be nearly continuous sheets. No other thick or extensive till deposits 

are known in the formation, but local thin unstratified 

clayey silt layers containing scattered stones may tflso 

be till.

The tills consist of widely separated stones in an

SOUTHEAST EXPLANATION

500' SECTION C

400'

Puyallup (? 

Formation

350'

300'

200'

100'

Covered

Covered

-Osceola 

Mudflowv

o o.o- o

o A

1300 - -

NORTHWEST

3 miles - 867-5-1

867-6-1

_ A ~_ A

Stony till

867-5-1

Sample discussed 

in text

FIGURE 17. Sketch of sections C and D, showing intermediate drift. Section C is in sees. 25 and 36, 

T. 21 N., B. 5 E., and section D is in SW^SE^ sec. 16 and NW^iNE^i sec. 21, T. 21 N., B. 5 E.

380-731 O - 70 - 6
38 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

unsorted olive-gray to bluish-gray matrix of silt, sand, 

and clay. Overall, they are much less stony than most 

deposits of till in this region. Pebble- and granulesized material, which makes up large parts of till in 

other formations in the mapped area, constitutes only 

a few percent of samples of intermediate till (fig. 

16). Locally, however, till in the intermediate drift is 

relatively coarse, especially at the tops of the two principal till members, and is somewhat similar in texture 

to other till deposits. Although the fine-grained tills 

contain thin lenses and blocks of stratified sand and 

silt, they are unstratified. They are also compact and 

cohesive, and fracture in a typically blocky pattern 

(fig. 15).

The fine-grained tills contain a slightly higher percentage of stones of northern provenance but otherwise are similar in composition to other glacial tills 

in the area. White marble and quartz pebbles are especially noticeable, because they are readily visible 

against the fairly uniform gray matrix. Clay minerals 

are chiefly montmorillonite and chlorite, but small 

amounts of fine-grained mica or illite are also found 

(table 4).

Exposed stratified drift consists mainly of sand, 

silt, and clay. Gravel is present but is sparse. Horizontally stratified, laminated, and thin-bedded silt and 

clay from a few feet to 50 feet thick generally overlies 

the lower till. Similar but thinner deposits also commonly overlie the upper till. Most of the other sediments are flat-bedded sands that probably also are 

lacustrine. Crossbedded coarse pebbly fluvial sand and 

even some gravel, characterized by cut-and-fill structures, occur, mainly in the middle and upper parts of 

the strata between the two till deposits. The stratified 

drift contains rocks and heavy minerals of northern 

provenance, but the proportion locally is low, especially 

in the fluvial materials. Between the two ice advances, 

which are represented by fine-grained till, the Puget 

lobe retreated enough to permit draining of the proglacial lake in which the lacustrine sediments were 

deposited. Fluvial sediments laid down next probably 

were derived in part from rivers heading in the Cascade Range.

WEATHERING

The intermediate drift appears considerably less 

weathered than the underlying Orting(?) Drift. Few 

stones in it are decomposed, and iron staining is less 

strong than in the Orting(?). The relatively weak 

iron staining probably is partly but not wholly due 

to the abundance of fine-grained strata. The finegrained tills generally are gray and show only small 

amounts of iron oxide accumulation around stones and 

along fractures. The abundant silt and clay strata are

also generally gray; they show minor oxidation except 

for concentrations at the top where they are overlain 

by sand. Even some sand deposits are not noticeably 

oxidized. Overall, however, the sand is lightly stained 

to yellowish brown, and locally to a strong' brown 

color. Along the White River, a thin zone of greenishbrown probably weathered clay occurs in th°- top of 

the formation below the Salmon Springs Drft. The 

weathered clay is at the same horizon at which a thin 

humified zone occurs in the Lake Tapps quadrangle 

(Crandell, 1963, p. A24).

DISTRIBUTION AND THICKNESS

The intermediate drift crops out in both valley walls 

of the Green River from about 1 mile east of Auburn 

to the middle of the Black Diamond quadrangle. The 

two fine-grained tills crop out along most of this distance and increase in altitude from west to e^st (fig. 

IT). The formation is well exposed at measured section O and also at section D (fig. IT). The drift also 

crops out along Big Soos Creek valley, but its extent 

there is poorly known because exposures are poor and 

distinctive fine-grained tills were not found more than 

a few hundred feet above the valley mouth.

The intermediate drift is also exposed in the White 

River valley. Outcrops of the drift are nearly continuous from about 1 mile from Auburn southeastward 

into the Lake Tapps quadrangle. The formation there 

dips less steeply than the gradient of the White River. 

Although both fine-grained tills crop out in downvalley exposures, upvalley the lower till passes below 

the flood-plain level before the quadrangle boundary 

is reached.

A mile north of Auburn, gray lacustrine clay, silt, 

and sand crop out in small exposures along the Duwamish Valley wall. Although typical fine-grained till 

is not exposed there, the sediments are mapped as intermediate drift, because lithologically they are similar 

to and only 2 miles from well-exposed intermediate 

drift at measured section D.

The maximum exposed thickness of intermediate 

drift is about 225 feet, in the Green River valley 

(measured section C; fig. IT). The upper till is generally from 10 to 35 feet thick, but the lower till is 

more variable in thickness. It commonly is about 40 

feet thick, but is more than 60 feet thick ir several 

exposures, and apparently is nearly 200 feet thick at 

the east margin of the drift (fig. 14).

STRATIGRAPHIC RELATIONS

The intermediate drift overlies the Orting(?) Drift 

with a sharp erosional disconformity. Locally it is con-
PLEISTOCENE DEPOSITS 39

formably overlain by the Puyallup (?) Formation, but 

in most places it is overlain and channeled by Salmon 

Springs Drift. The conformable contact at its top is 

exposed in the south valley wall of the Green River at 

section O.

ENVIRONMENT

Lakes seemingly were widespread during the glaciation that produced the intermediate drift. That ponding was common in the Green River area is shown by 

abundant lacustrine sediments in the drift. Moreover, 

lakes apparently were widespread farther north in the 

lowland, where the Puget lobe must have picked up 

much of its load. Both the abundance of silt and clay 

and the low proportion of Cascade stones in intermediate tills suggest that, north of the Green River, 

the Puget lobe overrode more lake deposits and less 

coarse alluvium of Cascade Rivers during the intermediate glacial episode than during other glaciations.

The fine-grained tills typical of the intermediate 

drift are very similar in texture and structure to marine "tills" in British Columbia (Armstrong and 

Brown, 1954, p. 353) and in northern Washington 

(Easterbrook, 1963). No marine fossils, however, were 

found in the tills in the intermediate drift. Nor have 

exchangeable sodium cations, which suggest a marine 

origin for some similar deposits in Seattle (Mullineaux, 1967), been recognized in several analyzed 

samples. The textural similarity of the fine-grained 

tills to the marine "tills," as well as the abundant lacustrine sediments, suggests that the Puget lobe of the 

intermediate glacial episode advanced into and perhaps even floated in a proglacial lake.

PUYALLUP (?) FORMATION

Thin beds of sand of central Cascade and Mount 

Rainier provenance, and silt, clay, and peat lie above 

the intermediate drift and below Salmon Springs 

Drift. These sediments contain climatic evidence of interglacial conditions, but they could not be traced into 

either the Alderton or the Puyallup interglacial deposits of the Puyallup Valley. They are tentatively 

correlated with the Puyallup Formation because they 

directly underlie Salmon Springs Drift.

The name Puyallup Sand was established by Willis 

(1898c), who applied it to the compact gray sand of 

Mount Rainier provenance that is exposed along the 

Puyallup Valley, and to the interglacial episode represented by the sand. The name has since been changed 

to Puyallup Formation because the sand at the type 

locality is a facies of an assemblage of sand, gravel,

and mudflow deposits of Mount Rainier provenr.nce 

(Crandell and others, 1958).

LITHOLOGY

The Puyallup (?) Formation consists chiefly of sand, 

silt, clay, and peat but also contains volcanic ash and 

a volcanic mudflow. The deposits are characterized by 

reddish-gray sand from Mount Rainier, by volcanic 

ash, and by peat deposits; peat is present in all deposits mapped as Puyallup (?). Peat exposed in the 

formation at the mouth of the Green River valley durkig this investigation is thin and mixed with silt and 

clay. Thicker, purer beds, however, from which blacksmiths regularly obtained "coke" many years ago, v^ere 

reported at that locality by local residents. In the 

Green River valley east of Auburn, peat in the formation ranges in thickness from a few inches to 4 feet. 

It is highly compressed, breaks with a distinct shaly 

fracture, and is classed as lignite (Cooper and Abernethy, 1941, p. 36). Several of these peat or lignite 

beds on the south wall of the valley have been prospected in the belief that they were coal beds in the 

Puget Group (Geer, 1941, p. 41). The deposits are 

high in inorganic material, however, and in the natural state contain more than 50 percent moisture 

(Cooper and Abernethy, 1941, p. 38).

Volcanic ash crops out in the Puyallup (?) Formation at the mouth of the White River valley south of 

Auburn (Mullineaux, 1965b) and on the south wall of 

the Green River valley in sees. 25 and 36 about 6 miles 

east of Auburn (Mullineaux, 1965c). At the first locality, ash associated with peat, silt, and clay occur*' in 

several beds from river level to about 15 feet higher. 

The ash bed at river level is as much as 3 feet tlick. 

At the second locality, several ash beds, one of which 

is 21/2 feet thick, are also exposed; here the ash is also 

associated with peat, silt, and clay. Diatom remains 

are abundant in the ash at both places.

Sand of Mount Rainier provenance, comparable to 

that in the type locality of the Puyallup Formation 

(Crandell and others, 1958), crops out along the Duwamish Valley north of Auburn, and along the White 

River valley. Similar sand, shown by augering to be 

more than 40 feet thick, underlies exposed Pryallup(?) deposits at the mouth of the Green River valley. It is a purplish-gray medium to coarse sand that 

is characterized by abundant red and gray and?.site 

fragments and hypersthene.

Puyallup(?) deposits at the mouth of the Green 

River valley include a lens or sheet of till-like material 

interpreted as a volcanic mudflow from Mount Rainier. 

The mudflow is a hard, compact, and unsorted and
40 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

unstratified stony mixture of sand, silt, and clay. It is 

distinguished from till by an abundance of angular 

mineral grains and stones, an abundance of material of 

Mount Rainier provenance, and its association with 

peat-bearing sediments.

WEATHERING

The Puyallup (?) Formation generally is light to 

dark gray, is not iron stained, and appears fresh. Few 

dense stones are soft, but many light-gray open-textured volcanic rocks are at least partly decomposed. 

No weathering profile on Puyallup (?) deposits has 

been found in the mapped area, though the top of the 

Puyallup Formation in the Lake Tapps quadrangle is 

locally weathered to the clay mineral halloysite to 

depths of about 10 inches * (Crandell, 1963). The 

weathering profile in the Lake Tapps quadrangle 

probably represents a period of weathering of several 

tens of thousands of years, for not even rinds have 

formed on stones in the Vashon Drift, which has been 

exposed to weathering for about 14,000 years (Waldron and others, 1957; Mullineaux and others, 1965).

DISTRIBUTION AND THICKNESS

Deposits assigned to the Puyallup (?) are thin and 

discontinuous and are exposed in only the southwestern part, of the mapped area. In the Lake Tapps quadrangle 10 miles south of Auburn, the Puyallup Formation is about 135 feet thick, and its top is at an altitude of 175 feet (Crandell, 1963). It thins and decreases in altitude northward to less than 100 feet in 

altitude about 1 mile south of the Auburn quadrangle 

boundary. In the Auburn quadrangle, Puyallup(?) 

deposits are exposed near flood-plain level at the mouth 

of the White River valley and intermittently farther 

north nearly to Kent. A thin unmapped lens of ashy 

sand, clay, and peat that crops out half a mile southeast of Kent may be the northernmost Puyallup(?) 

exposed in the mapped area. In the Green River valley, the only deposits continuous enough to be mapped 

crop out about 6 miles east of Auburn on the south 

valley wall (Mullineaux, 1965b, c). In the White River 

valley east of its mouth, the only deposits discovered, 

near the south boundary of the Auburn quadrangle, 

are thin and discontinuous and were not mapped.

The maximum known thickness of the Puyallup(?) 

in the mapped area is about 55 feet, at the mouth of 

the Green River valley. Fifteen feet of the formation 

is exposed at that locality, and another 40 feet is 

known from angering. Along the Green and White 

River valleys, the formation probably is not more than 

25 feet thick.

STRATIGRAPHIC RELATIONS

The Puyallup(?) Formation conformably overlies 

intermediate drift and is disconformably overlain by 

Salmon Springs Drift. Both the upper and lower contacts of the Puyallup (?) are exposed along the Green 

River valley at section C (fig. 17). There the formation lies conformably 011 fine-grained till of thQ, intermediate drift and is overlain and channeled by gravel 

of the Salmon Springs Drift. In the Duwamish Valley, Puyallup(?) sediments generally extend below 

flooci-plain level. They are overlain and channeled by 

sand and gravel of Cascade provenance that is mapped 

as part of the Salmon Springs Drift. Although weathering that probably represents tens of thousands of 

years and erosional relief of about 100 feet occurs on 

the Puyallup Formation in the Lake Tapps quadrangle (Crandell, 1963), the channeling of the, top of 

the Puyallup (?) is the predominant evidence seen of 

the time break in the mapped area.

FOSSILS AND ENVIRONMENT

The Puyallup(?) contains pollen and diatoms that 

indicate at least part of the formation was deposited 

during a warm inter glacial period. Pollen in a sequence of samples of Puyallup (?) sediments from 

the Green River valley, studied by E. B. Leopold, 

indicate that the climate became as warm as that of 

the Puget Sound lowland at present. Miss Leopold 

reported (written comniun., 1958) that a prevalence 

of lowland hemlock pollen in the middle of the sequence reflects lowland wet conditions similar to those 

now in parts of the Puget Sound lowland where rainfall is more than 40 inches annually. A predominance 

of lowland hemlock over mountain hemlock in this 

phase of the sequence implies warm growing seasons 

with an average July temperature of at least 60°F, 

as is true of the Puget Sound lowland now. Shifts 

from dominance of Douglas-fir to lowland hemlock 

and back to Douglas-fir in the sequence are attributed 

to changes of rainfall during the clepositioiial interval.

Diatoms from the sequence along the Green River 

valley, and also from ashy Puyallup (?) beds exposed 

at the mouth of the White River valley, ^ere examined by Mr. Lohman. Diatoms from both localities 

are fresh-water forms. Bottom-dwelling types are common at both localities, indicating that the lake or lakes 

in which they lived were shallow. The Green River 

valley samples contained a few warm-water and a few 

cold-water forms, but most are types that live now in 

a temperate climate comparable to that of tH Puget 

Sound lowland at present. The White River valley 

samples contain only types now living in temperate
PLEISTOCENE DEPOSITS 41

or wanner climates. According to Lohman, the diatom 

assemblage from each locality indicates interglacial, 

temperate conditions as warm as those in the Puget 

Sound lowland now.

Puyallup (?) sediments exposed along the Duwamish 

Valley are chiefly alluvium similar to that now being 

deposited on the Duwamish Valley floor, and they include water-laid ash and a volcanic mudflow. These 

deposits probably were laid down on the wide flood 

plain of a river that headed on Mount Rainier. Puyallup (?) deposits exposed along the Green River valley 

are thin, lenticular, and characterized by at least partly 

lacustrine sediments that were slowly accumulated. 

They probably were laid down on an undulating interfluvial plain of intermediate drift very like the surface 

of the Vashon drift plain of the present. Beds of volcanic ash in all the deposits show that a volcano, presumably Mount Rainier, was active during Puyallup (?) time.

SALMON SPRINGS DRIFT

Stony till and outwash sand and gravel assigned to 

the Salmon Springs Drift overlie Puyallup(?) deposits and underlie Vashon Drift along the Green 

River, White River, and Duwamish Valleys. Along the 

Duwamish Valley walls, these deposits can be traced 

into the type Salmon Springs Drift in the Lake Tapps 

quadrangle. The Salmon Springs Drift is named for 

springs on the east wall of the Duwamish Valley about 

6 miles south of Auburn (Craiidell and others, 1958).

Fluvial sand and gravel of Cascade provenance 

locally underlies and overlies Salmon Springs outwash 

gravel and locally is iiiterbedded with northern outwash along the Duwamish Valley wall near Auburn. 

These Cascade-derived sediments are closely associated 

with and are similar in grain size to the Salmon 

Springs stratified drift, and they are mapped and described as part of the Salmon Springs deposits.

LITHOLOGY

The Salmon Springs Drift consists chiefly of fluvial 

sand and gravel. The formation locally includes one or 

two till layers, and in places its lowermost and uppermost beds are fluvial sand and gravel mainly of Cascade provenance. The formation is well exposed in 

northeast Auburn in the Duwamish and Green River 

valley walls. There, the formation consists of thick 

sand and gravel of Cascade or mixed Cascade and 

northern provenance at the base; this sand and gravel 

is overlain by northern sand and gravel that includes 

two layers of till, which in turn is overlain by sand and 

gravel of Cascade provenance (section E, fig. 18).

Section E. Composite section in center sec.. 17, T. 21 N., R. 5 E., 

in Green River and Duwamish Valley walls

ThickVashon Drift: (ffef) 

Sand and pebble gravel, gray to light-brown, friable.-- ______________________________________ >40

Till, stony, gray (sample 845-16-6)_______________ 30

Gravel, pebble and sand, gray____________________ 15

Salmon Springs Drift:

Sand and pebble gravel, reddish-gray to gray; Mount

Rainier provenance,__________________________ >20

Sand and gravel, olive-gray to brown; northern

provenance-____-----_----__----_____________ 5-10

Till, stony, olive- to brownish-gray (sample 845-

16-5)________________________________________ 15

Sand and pebble gravel, brown; northern provenance. 40

Till, stony, olive-to brownish-gray______________ .__ 5-10

Sand and gravel, brown; northern provenance.----- 5-10

Gravel, pebble-and-cobble, and pale-yellowishbrown to brown sand; Cascade or mixed Cascade 

and northern provenance; grades into overlying 

northern sand and gravel- ________-___-___-_-_- 20

Silt and clay, peaty; contains scattered stones__--__ 3

Gravel, pebble-and-cobble, and pale-yellowish-brown, 

light-brown, and brownish-gray sand; Cascade or 

mixed Cascade and northern provenance- ____-__- 50

Sand and silt, blusish-gray to reddish-brown; contains

wood and peat____-_______--__-____-_-____-_- 5

Sand and pebble gravel, reddish-brown____________ 5

Puyallup (?) Formation:

Silt and sand, peaty, reddish-gray to brown; Mount

Rainier provenance.________________---_--_--- 5-10

Mudflow, hard, compact stony silt and sand_ ________ > 5

Till is common in the formation only in the vicriity 

of Auburn, where at least two separate layers are exposed. From section E, till is intermittently exposed 

northward for about 3 miles in the Duwamish Valley 

wall. It is also exposed eastward from the Duwamish 

Valley wall for about a quarter of a mile in the Green 

River valley wall. In the White River valley, till is 

exposed intermittently from the south boundary of the 

quadrangle northwestward for about a mile and a 1 alf. 

Elsewhere along Duwamish Valley and the valleys of 

the Green and White Rivers, however, till was fcmid 

either sparsely or not at all.

The till generally is olive gray to yellowish brown, 

hard and compact, and unsorted and unstratifieci. It 

consists of numerous stones in a silty sand matrix; 

the stones and heavy minerals indicate a northern provenance. The till is similar in texture and composition 

to Vashon till and is distinctly more stony than typical 

tills of the underlying intermediate drift (figs. 15, 16).

Stratified drift from the Puget lobe at section E is 

mostly brown sandy gravel and coarse sand. It is loose 

and well sorted in a few places, but generally it is compact and has a matrix of grayish-yellow silt and clay.
42 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

350'

300'

250'

150'

100'

50 J

o- o- o o o 

o-o o . o o .

O . o . o o . o

 o o . o o 

o o o . o . o

 o o-o- o t

o o . o o o 

. o . o . o o.

O O O o O-O

EXPLANATION

Vashon

Drift 

845-16-6

845-16-5

Salmon

Springs

Drift

Silt and clay

A o 

o

o 

A

Till

Mudflow

845-16-6

Sample discussed 

in text

Puyallup (?) 

Formation

FIGURE 18. Sketch of section E, showing Salmon Springs 

Drift. Section E is in center sec. 17, T. 21 N., B. 5 E.

A few fragments of wood have been found in it between the two tills. Cascade-derived fluvial sediments 

and those of mixed Cascade and northern origin are 

sandy pebble-and-cobble gravel that contains lenses of 

sand and even of clayey silt. Most of this fluvial detritus is of central Cascade origin, but pebbles derived 

from Mount Rainier are common, and several lenses of 

sand are largely of Mount Rainier provenance. Peat 

and flattened wood fragments are common in clayey 

silt and sand near the base of the Salmon Springs 

sequence at section E, and organic material occurs 

sparsely in a lens of clayey silt about 55 feet higher. 

Pollen samples from these organic sediments, analyzed 

by Miss Leopold, are dominated by pine and spruce; 

the pollen are suggestive of but not diagnostic of a 

cool climate.

Salmon Springs stratified sediments along Duwamish Valley north and south of Auburn appear to 

be mostly interbedded gravels and sands similar to 

those at section E. Stratified drift exposed in the Green 

and White River valleys is chiefly brown sand and 

pebble-and-cobble gravel.

WEATHERING

The Salmon Springs Drift is somewhat iron 

stained, and a few stones in it are decomposed. Stratified sediments, even those along Duwamish Valley that 

have a silt and clay matrix, generally are stained yellowish brown. Although some deposits in the Salmon 

Springs are gray and appear fresh, iron staining is 

widespread enough to be useful in differertiating 

Salmon Springs from Vashon Drift. The staining suggests that the Salmon Springs Drift was weathered 

before Vashon time, but no weathering profile has 

been found on it.

DISTRIBUTION AND THICKNESS

Salmon Springs Drift is inferred to compose most 

of the east wall of Duwamish Valley from Kent to the 

south boundary of the Auburn quadrangle, where it 

extends on into the Lake Tapps quadrangle. At section 

E in Auburn, the formation is about 200 fee4: thick. 

Near the south boundary of the Auburn quadra ngle, it 

is intermittently exposed from near flood-plain level 

up to about 450 feet above sea level; thus it miM be at 

least 400 feet thick in that vicinity. It also crops out 

for several miles in the Green and White River valleys 

upstream from Auburn. In the Green River valley, it 

generally is less than 100 feet thick; and in the White 

River valley, it is less than 50 feet thick.

STRATIGRAPHIC RELATIONS

The Salmon Springs Drift lies unconformably on 

the Puyallup (?) Formation or the intermediate drift 

and is unconformably overlain by Vashon Dr'ft. The 

base of the Salmon Springs is exposed at sections C 

and E, where the formation lies in channels cut into 

the underlying Puyallup (?) and intermediate drift 

formations. The base of the Salmon Springs is more 

than a hundred feet lower along Duwamish Valley 

than it is along the Green and White River valleys a 

few miles to the east. A north-trending valley, whose 

east wall was a short distance east of Auburn, may 

have been filled by Salmon Springs Drift.

Along the Green River valley east of Auburn, 

brown Salmon Springs Drift locally is overlain by 

gray gravel and stony till that underlie Vashon till. 

This gray drift has been mapped as part of the Salmon 

Springs, though it may be younger.

UNDIFFERENTIATED DRIFT IN THE CEDAR RIVER 

VALLEY

Several layers of till and intervening stratified sediments including peat underlie the Vashon Drift along 

the Cedar River east of Renton. In this strati graphic
PLEISTOCENE DEPOSITS 43

sequence, no till layers were found with markedly different textural or weathering characteristics, comparable to, for example, the fine-grained tills in intermediate drift or the weathered Orting(?). Neither 

were distinctive sediments from Mount Rainier found 

anywhere to serve as marker layers. Consequently, no 

stratigraphic sequence similar to that in the Green 

River valley and in Duwamish Valley was recognized. 

Because the Cedar River valley strata could not be 

traced to the other valleys, they are not correlated with 

or described as part of the named formations mapped 

farther south. Not only were no distinctive marker 

layers recognized in the Cedar River valley sequence, 

but analyses of pollen layers from three different horizons in the sequence failed to show evidence of a distinctly warm climate separating episodes of till deposition. As a result, the entire sequence has been mapped 

as and will be described as undiffereiitiated.

LITHOLOGY

At least three layers of pre-Vashon till, separated 

by fluvial sand and gravel and lacustrine sand of predominantly northern provenance and by silt and clay, 

are exposed in the Cedar River valley walls. The 

stratigraphy of these deposits is illustrated by sections 

F, G, and ZT, in figure 19. Composite section F at Renton includes at least three, and perhaps four, layers of 

pre-Vashon till. Two of the layers are exposed nearly 

as far east as the quadrangle boundary. Each of the 

layers that clearly is till is gray and not noticeably 

oxidized; the one other layer that may be till, which 

directly overlies a woody silt and peat deposit, is grayish brown.

The pre-Vashon tills of the Cedar River valley area 

are generally similar in texture and composition to the 

Vashon till and were deposited by the Puget lobe. 

Overall, they are somewhat finer grained than Vashon 

till, but they are not as fine grained, nor do they show 

the fractures typical of till in the intermediate drift.

The prevalent stratified deposits along the Cedar 

River valley are sand. Uniform horizontally bedded 

lacustrine sand with silt and clay is widespread and as 

much as 100 feet thick in exposures on the north side 

of the valley (fig. 19). Probable lacustrine sand at the 

base of section H is of central Cascade provenance and 

is nonglacial. Till and varved clay and silt at higher 

altitudes, however, show that a considerable part of the 

sequence is glacial. Fluvial deposits include sand, pebble gravel, and locally boulder gravel. One bouldery 

cobble gravel 15-20 feet thick occurs in channels at the 

top of thick lacustrine deposits at sections G and H 

(fig. 19).

WEATHERING

The drift along the Cedar River valley shows little 

weathering other than partial iron oxide staining of 

permeable sediments. Tills, with the possible exception 

of one, are not notably more oxidized than the Vashon 

till. Near Renton, iron staining generally is limited to 

a few beds, and even some very coarse and permeable 

gravels are not stained. However, farther east, the 

staining is more intense and more widespread. Part of 

the more strongly stained deposits in the eastern part 

of the quadrangle may be equivalent to unstained strata 

nearer Renton, but the basal strata to the east certainly 

underlie the beds exposed at Renton. No weathering 

profiles have been found either within or on top of the 

undifferentiated drift in the Cedar River valley.

DISTRIBUTION AND THICKNESS

Pre-Vashon drift makes up most of the Cedar River 

valley walls from Renton eastward to the quadrargle 

boundary. The deposits dip as much as 350 feet per 

mile to the northwest, thus progressively older strata 

are exposed upvalley. The pre-Vashon beds are irore 

than 200 feet thick about 3 miles east of Renton. Unoxidized drift like that in the Cedar River valley also 

crops out in a few places along Duwamish Valley in 

and slightly south of Renton.

FOSSILS AND ENVIRONMENT

The undifferentiated deposits include peat in two, 

and probably three, stratigraphic horizons. The warmest climate indicated by pollen in several samples from 

the peat beds is definitely cooler than the present climate in the Puget Sound lowland. Pollen has been 

examined from peat at the top of the pre-Vashon 

sequence at section H and across the valley from section F, and from peat at 75-90 feet above sea level at 

section F. According to Miss Leopold, pollen from section H indicates that the climate was cool, similar to 

that which now characterizes altitudes of 4,000-5,000 

feet on the west flank of the Cascade Range in Washington. Pollen from peat across the valley from section 

F is almost entirely pine, so no climatic interpretation 

can be made. Pollen from section F is largely comparable to pollen in modern peat at altitudes of 3,000- 

4,000 feet in the Cascade Range. The assemblage contains a few species typical of the present Puget Sound 

lowland, however, which may indicate the climate was 

somewhat warmer than that now at 3,000-4,000 feet.

VASHON DRIFT

Till or stratified drift of Vashon age lies at the surface of the drift plain in almost all of the area mapped. 

The name Vashon was first used by Willis (1898c, p.
44 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

NORTHWEST SOUTHEAST 

SECTION H

350'

300'

250'

200'

150'

SECTION F

Woody f" 

and < 

peaty I

 Peat

EXPLANATION

o O 0

o

Gravel

Till

Correlation 

line

FIGURE 19. Sketch of sections of undifferentiated drift exposed on the north side of the Cedar River valley near 

Renton. Section F is in SWy4NE% and NW%SE% sec. 17, T. 23 N., R. 5 E.; section G, in NE^NWi/i sec. 22; and 

section H, in NE^4NEi4 sec. 22, T. 23 N., R. 5 E.

126) for "the episode represented by the latest occupation of the Puget Sound basin by the northern ice 

tongue and its deposits." The term is derived from 

Vashon Island in Puget Sound southwest of Seattle, 

where according to Willis (1898c, p. 126), characteristic gravelly till occurs "typically, although not heavily." The Vashon Drift as used by Willis is still called 

Vashon Drift, but his Vashon Glaciation is now known 

as the Vashon Stade of the Fraser Glaciation (Armstrong and others, 1965).

The Vashon Drift extends entirely across the mapped 

area, and as much as 25 miles farther south (Bretz, 

1913; Crandell, 1963). Twelve miles east of Kenton, 

the glacier rose to a height of about 3,000 feet on Tiger 

Mountain (also known as Mount Issaquah) (Bretz, 

1913, p. 36; Vine, 1969). In the Lake Tapps quadrangle south of Black Diamond, the glacier rose to altitudes of 1,600-1,800 feet along the Cascade mountain 

front (Crandell, 1963). Thus the ice probably was at 

least 2,500 feet thick over the drift-plain surface near 

Renton, and at least 1,500 feet thick over that surface 

even in the southernmost part of the mapped area.

TILL

Vashon till forms the present surface of about half 

the drift plain, and probably extends under most other 

deposits that lie at the surface. It is the most widely 

exposed unit in the mapped area. In thickness, it is 

highly variable; the maximum exposed is about 70 feet, 

but the average thickness probably is 110 more than 20 

feet, and exposures in which it is less than 5 feet thick 

are common. It is generally thinner on north-facing
PLEISTOCENE DEPOSITS 45

than on comparably steep south-facing slopes. Locally, 

the Vashon Drift appears to contain two layers or 

zones of lodgment till, but in most places it contains 

only a single layer.

TOPOGRAPHIC EXPRESSION

Vashon till mantles rather than forms major topographic units. It veneers almost all the drift plain 

(though it is covered itself in places), and it laps up 

over bedrock highlands as well as over some valley 

walls, such as those in Duwamish Valley. On a minor 

scale, however, the Vashon till forms the characteristic 

topography of undulating ground moraine. On that 

scale, the ground moraine has a rolling surface that is 

characterized by a relief of a few tens of feet and by 

numerous closed depressions. On a larger scale, the 

surface displays a rough south to south-southeast 

elongation of hills and swales; locally, the hills are 

very elongate, cigar shaped, and closely alined in drumlinized topography. Such an alinement is formed by 

actively flowing ice (Flint, 1957, p. 72) and indicates 

the direction of ice movement. Most of the hills in the 

drumlinized ground moraine appear to be only veiieered by till, but some small hills probably are drumlins constructed entirely of Vashon till. The relief and 

alinement probably result from scour and fill by the 

glacier.

The surface of the till has been very little modified 

except where it has been eroded by large melt-water 

rivers on the drift plain and by postglacial rivers that 

have cut valleys down through it. On most of the 

ground moraine, postglacial change has been limited to 

minor erosion by small streams.

LITHOLOGY

Vashon till consists of an unstratified, nearly unsorted 

mixture of pebbles and cobbles in a clayey silt and sand 

matrix (figs. 15, 16), and it contains scattered boulders 

as large as several feet across. Till that is often regarded as typical is compact, hard, and coherent. Silt 

and clay particles are tightly packed into spaces between grains of sand and gravel, and as a result the 

till is highly impermeable. This tight, dense till is regarded as lodgment till, deposited at the base of and 

compacted by the weight of the glacier. It generally 

is the "harclpan" of local well drillers and construction workers. A second f acies can be recognized almost 

everywhere the till lies at the surface. This facies is 

less compact, less coherent, locally somewhat sorted, 

and usually only a few feet thick. The looser material 

probably is chiefly ablation till, let down from the surface of the glacier as the ice melted, and is not appreciably compressed by ice. The less compact material

may also include some lodgment till that has been 

loosened by frost, root, and animal action. Locally, it 

grades into thin stratified drift.

Although the till is unstratified, it does contain rome 

blocks and lenses of stratified drift. In addition, lodgment till commonly shows thin partings, close to and 

approximately parallel to the ground surface; the resulting structure is called fissility by Flint (1957, p. 

113). In places, Vashon till also shows horizontal or 

gently dipping partings that are spaced several feet 

apart.

The till everywhere in the mapped area is a mixture 

that is characterized by a substantial amount of material in each of many size grades (fig. 16). It differs 

significantly in average grain size and in degree of 

sorting, however, from place to place in the mapped 

area. Just north of the Cedar River, for example, the 

till consists mostly of silty sand. Over most of the rest 

of the area, however, as Willis (1898c) noted, it typically is gravelly. Most of the pebbles and cobbler are 

rounded rather than angular, and only a few are 

strongly faceted or striated. The roimding of the stones 

probably resulted from a pre-Vashon history of stream 

abrasion, and perhaps short transport by the Vashon 

Puget lobe. Most constituent pebbles, though their ultimate source was the mountains of Washington, probably were transported first by rivers into the part of 

the lowland north of the mapped area. These stones, 

rounded by rolling along streambeds, were later picked 

up by the Puget lobe and incorporated into its deposits.

Generally about 5-15 percent of the rocks and minerals in Vashon till can be identified as of northern 

provenance, but the rest are of Cascade or of doubtful 

origin. Locally, especially in till just south of Puget 

Group outcrops near Renton, the till also contains 

abundant fragments of soft sandstone and shale. Garnet commonly makes up at least 5 percent of the sandsize heavy-mineral grains. Clay-size particles, smaller 

than 2/i, (microns), are approximately half norclay 

minerals and half clay minerals; the clay minerals are 

mostly montmorillonite and chlorite (table 4).

WEATHERING

Weathering generally is limited to oxidation ir the 

upper few feet and to development of a weak brown 

podzolic soil profile (Poulson and others, 1952; C andell, 1963). Where the ablation till is more than 3 feet 

thick, oxidation commonly extends to a depth of about 

30-36 inches. In relatively permeable ablation till, it 

may extend a foot or two deeper. Where the ablation 

till is only a foot or two thick, the oxidized zone extends down through it and a few inches beyond into
46 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

compact lodgment till. A thin rim of accretionary iron 

oxide occurs on stones within the oxidized zone; but 

lower in the till, iron oxide is generally not concentrated around stones or along fractures.

ADVANCE STRATIFIED DRIFT

Advance stratified drift occurs in all parts of the 

mapped area but generally is thin and discontinuous 

and covered by Vashon till. The advance deposits are 

especially well exposed along the major river valleys 

that were cut in postglacial time. Advance drift is similar in texture and composition to recessional stratified 

deposits and in general can be distinguished from recessional drift only where it is overlain by Vashon till. 

A few deposits, however, can be recognized as probable 

advance drift, because their surfaces apparently have 

been modeled by overriding ice.

Advance drift locally fills depressions in the preVashon topography and is highly variable in thickness. The thickest exposed deposits crop out along Big 

Soos Creek and Duwamish Valley, where they locally 

are more than 100 feet thick. However, advance drift 

generally is less than 50 feet thick and probably averages less than 30 feet in thickness. The variations from 

place to place suggest a few features of the pre-Vashon 

topography, but exposures are not adequate to outline 

the older drainage pattern. Thin widespread sand and 

gravel under Vashon till along the Cedar, Green, and 

White River valleys suggests that the pre-Vashon drift 

plain in those areas was broad and similar to the 

present one. Thick deposits that suggest former deep 

valleys are sparse; at only two sites, along the Big 

Soos Creek and Duwamish Valleys, do advance sediments show the existence of depressions of 100 feet or 

more in the pre-Vashon surface. Thus neither an extensive nor a deep pre-Vashon valley system is indicated by the exposed advance stratified drift.

Advance sediments consist chiefly of gray unoxidized pebble-and-cobble gravel and pebbly sand. The 

gravel is typically compact and indistinctly stratified, 

and in places it contains substantial amounts of interstitial silt and clay. Although such a matrix is not universal in the mapped area, it appears to be more common in advance gravels than in recessional deposits. 

Sand is also common in the advance drift, which locally 

also includes lenses of silt and clay. No oxidized zone 

characterizes the top of the advance drift, because it 

was immediately covered by Vashon till. Brown, oxidized layers, however, are present within it in a few 

localities.

RECESSIONAL STRATIFIED DRIFT

Stratified drift laid down as the glacier retreated is 

composed of a wide variety of deposits, which are

divided into two groups on the basis of inferred origin. 

One group consists of small deposits laid dovm by 

melt-water streams that probably issued directly from 

the nearby ice front. These are the generally small and 

discontinuous bodies of recessional outwash that lie in 

the Renton quadrangle and in the part of the Auburn 

quadrangle that is northwest of the Covington channel. The second group, representing a much larger 

volume of sediments, was deposited by a large icemarginal river that originated not locally but much 

farther north along the Puget lobe. This river flowed 

southward along the east flank of the lobe to the ice 

front, then southwest ward along the front and across 

the mapped area. It included, besides Puget lob^ melt 

water, considerable drainage from the Cascade Kange, 

which flowed west to the Puget lobe and joined the 

ice-marginal stream flowing along the flank. The icemarginal river laid down broad, continuous deposits 

over much of the Black Diamond quadrangle, along 

the Covington channel, and, to a lesser extent, along 

the Cedar River valley.

DEPOSITS OF LOCALLY DERIVED MELT WATER

Recessional stratified drift deposited by melt water 

from the local ice front consists of scattered kames 

and small valley trains on the drift plain, and kame 

terraces and glaciolacustrine deposits along th?. Duwamish Valley.

KAME DEPOSITS

The kames are few in number and widely separated. 

The largest is a low ridge of sand about 1 mil0, long 

but less than a quarter of a mile wide that is located 

about 1 mile east of Kent. Four other kam^s are 

mapped 011 the drift plain between Renton anc1 Lake 

Youngs south of the Cedar River (Mullineaux, 

1965a) ; all consist chiefly of pebbly sand. A single 

small kame in the northeast corner of the Auburn 

quadrangle consists of sandy pebble-and-cobble gravel.

VALLEY-TRAIN DEPOSITS

Small valley trains, composed chiefly of sand and 

pebble gravel, were formed in some shallow troughs 

that led from the ice front southward over the drift 

plain. The valley-train deposits are terrace remnants 

and collapsed masses of sand and gravel, mostly in the 

trough of Big Soos Creek and in a trough between the 

Cedar River valley and Lake Youngs. The deposits 

indicate that irregular masses of stagnant ice lay in 

parts of these depressions during formation of the valley trains. Melting of the ice resulted in collapse of 

parts of these deposits and destruction of their constructional surfaces. Recent peat and alluvium now 

cover some of the collapsed sediments.
PLEISTOCENE DEPOSITS 47

The least collapsed valley-train deposit probably 

records a temporary stillstand of the ice front in the 

shallow trough of the drift plain in which Big Soos 

Creek now flows. The deposit forms a continuous pair 

of terraces in the trough from the Covington channel 

northward for about a mile and a half. For the next 

2 miles farther north, however, deposits at the surface 

along the creek are chiefly lacustrine silt, clay, and 

peat. Ice apparently filled the part of the trough now 

floored by lacustrine sediments while the valley train 

leading to the Covington channel was deposited. The 

ice then retreated rapidly from that position, and silt 

and clay were laid down in a temporary lake formed 

in the trough behind the valley-train deposits.

KAME-TERRACE DEPOSITS

Many small kame terraces were formed along Duwamish Valley north of Auburn, adjacent to a tongue 

of ice that lay in the Duwamish Valley after the 

glacier had retreated from the drift plain. Streams 

from the drift plain descended to the ice margin, and 

there joined melt water flowing between the valley 

wall and the ice. Deposits of these streams include 

some relatively undisturbed cut-and-fill terraces and 

some extensively collapsed fill terraces.

Directly east of Auburn, two kame terraces cover 

about a quarter of a section each in sees. 8, 9, and 17. 

They are high on the valley wall, at about 350 feet 

above sea level, and may have been formed while the 

Puget lobe still covered part of the drift plain nearby. 

Both appear to be composed of well-sorted gravelly 

sand and pebble gravel from about 15 to 40 feet thick.

In Kent, several small terraces were cut across a 

spur on the Duwamish Valley wall while ice in the 

valley served as the northwest bank of a channel. The 

sand and pebble gravel that underlies these terraces 

probably is only about 10-20 feet thick.

Several kame-terrace deposits that collapsed extensively are located along the valley wall north of 

Kent. The highest and largest of these, composed of 

well-sorted sand and pebbly sand, is about a mile and 

a half northeast of Kent. Collapsed deposits on the 

valley wall below the high terrace generally consist of 

less well sorted material, and near the valley floor they 

grade into mixtures of clayey sand and bouldery gravel 

that may represent lateral moraines. The "moraines" 

and some of the adjacent extensively collapsed kameterrace deposits have been mapped together as undifferentiated Vashon Drift (Mullineaux, 1965a).

LACUSTRINE DEPOSITS

Two lacustrine sand and silt deposits crop out in 

Kenton. These were laid down in a lake in Duwamish

Valley that stood at least 25 feet above the level of the 

present flood plain. One deposit is a fan-shaped bcdy 

at the mouth of a small stream south of the business 

district of Kenton. It grades from pebbly sand near 

its apex to clayey silt and sand at its distal edge. The 

second is a mass of horizontally bedded sand and silt 

exposed in sec. 18, from about 20 to 40 feet above sea 

level. Although these deposits were laid down ir a 

lake ponded by the Puget lobe, they are free of kettles 

or any other evidence that they were deposited against 

ice.

DEPOSITS OF THE ICE-MARGINAL RIVER

A large ice-marginal river, fed by melt water is^iing directly from the east flank of the Puget lobe, by 

large and small streams draining the adjacent Cascade 

Kange, and by combined melt water and Cascade 

drainage from farther north by way of the Cedar Spillway of Mackin (1941, p. 465; see fig. 22, this report), 

formed along the east flank of the Puget lobe during 

the retreat of the lobe. The river occupied many successively lower and more northerly channels as the ice 

retreated across the lowland southeast of Seattle 

(Bretz, 1913; Crandell, 1963). Owing to variation of 

the overall slope of the drift plain in the mapped ar^a, 

the melt-water river occupied many closely spaced, 

poorly defined channels southeast of the Covington 

channel but crossed the northwestern part of the 

mapped area only along the route of the present Cedar 

Kiver. The part of the drift plain southeast of Covington decreases in overall altitude to the northwest to a 

broad shallow sag that trends northeast from Auburn. 

Farther northwest, the overall altitude of the drift 

plain increases again. As the Puget lobe retreated north 

and northwest, the ice-marginal river occupied successively lower, southwest-trending courses, mortly 

along the ice front but locally over ice, until it reached 

the broad sag. The glacier continued its northwestward 

retreat, but the river remained in the sag, which became the Covington channel, until it shifted to the 

position of the Cedar Kiver.

Large volumes of stratified drift were deposited by 

the ice-marginal river in kames, a broad pitted mtwash plain, valley trains, a kame terrace, and a delta. 

Although some of the sediments were laid down in 

contact with ice, they are almost entirely channel deposits of a large river. Consequently, they are typicrlly 

coarse, well sorted, and well stratified.

KAME DEPOSITS

The kames are irregularly shaped mounds of stratified drift that owe their shape to collapse caused by 

melting of underlying or adjacent ice. They occur in
48 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

three groups or fields in the Black Diamond quadrangle. Each field is characterized by the hummocky 

shape of mounds and intermound depressions that is 

called kame-and-kettle topography. Two of the kame 

fields grade, by decrease in proportion of collapsed 

surface, into the adjacent pitted outwash plain. Because of their formation adjacent to or on ice, these 

kame deposits are more variable in texture and structure than most other outwash deposits. Horizontal continuity of individual strata locally is limited, and beds 

of markedly different grain size are interbedded. Scattered boulders are common, and, locally, sorting is 

poor. Thickness is highly variable from place to place 

in the kame deposits; a minimum thickness can be 

estimated from the height of the kames.

The largest of the three kame fields, about 2 square 

miles, is south of the Green River, in the southeast 

corner of the quadrangle. It is partly covered by the 

Osceola Mudflow, and one kame is separated at the 

surface from the remainder of the field by lacustrine 

and terrace deposits. Apparently, pebbly medium to 

coarse sand predominates in the southern and western 

parts of this field, and pebble-and-cobble gravel in 

the northern part. A smaller field, composed chiefly of 

pebbly sand, covers about half a square mile just west 

of the town of Black Diamond. A third, poorly defined 

kame field, which grades into the surrounding outwash 

plain on all sides, lies 4 miles farther west, mostly in 

sec. 18, T. 21 K, E. 6 E. Kames in this field probably 

consist largely of pebble-and-cobble gravel, but they 

also include medium and coarse sand.

OUTWASH-PLAIN DEPOSITS

Pitted outwash terraces and channels that form a 

broad low-relief surface over much of the Black Diamond quadrangle are mapped together as an outwash 

plain. Locally, topographic units of that plain are well 

defined, but over most of the plain they are indistinct 

or discontinuous. Furthermore, surfaces that formed 

during a single stream-flow regime even those that 

can be traced southwestward in the direction of flow 

are commonly now preserved as terraces at one place 

and channel floors at another. The drift-plain surface 

itself decreases gradually in altitude to the southwest 

along these channels and terraces. It also decreases in 

altitude to the northwest, by steps, from one set of 

surfaces to the next. In places, scarps-separating the 

steps are several tens of feet high and are sharp and 

long. More commonly, however, they are low, indistinct, 

and laterally discontinuous.

Outwash-plain gravel occurs in about half the Black 

Diamond quadrangle. It is prevalent at the surface 

from the Covington channel to the Green River, surrounding nearly all the hills of ground moraine and 

kame deposits. It also extends southward beyond the 

quadrangle boundaries, but south of the Green River 

it is covered by the Osceola Mudflow. Deep kettles and 

high scarps show that the gravel locally is more than 50 

feet thick and commonly is more than 20 fee* thick. 

Gravel-pit exposures in an area west of Lake Sawyer, 

however, show that the gravel there, at least loyally, is 

only 10-20 feet thick. Gravel of similar thickness underlies a wide terrace in sec. 1, T. 21 N., R. 5 E.

Well-sorted and stratified pebble-and-cobble gravel 

make up most of the upper 10-20 feet of the ontwashplain deposits, though pebbly sand and bouldery cobble gravel are locally present. Below the upper 10-20 

feet, there appears to be a greater variation in grain 

size. The lower deposits may represent, at least in part, 

kame or kame-terrace deposits of which the upper part 

was reworked later by the ice-marginal river.

Most of the outwash-plain sand and gravel was 

deposited as the ice-marginal river ran in a chute which 

had been formed between the glacier front and the 

sloping drift plain. On the northwest, the river channels were bounded partly by ice and partly by groundmoraine hills. The highest terrace gravels in th?/ southeastern part of the outwash plain were deposited first. 

When they were laid down, the site of the northwestern part of the outwash plain was still largely covered 

by ice. Frequent small changes in the positior of the 

ice front allowed concurrent small shifts of tlie river 

into successive channels, each of which was only 

slightly lower and farther northwest than the previous 

one. Such frequent shifts could account for the many 

closely spaced channels and terraces, which differ only 

slightly in altitude, that characterize the outwash 

plain.

VALLEY-TRAIN DEPOSITS

Valley trains were formed along the Covington 

channel as higher ground to the northwest prevented 

continuation of progressive northward shifting of the 

ice-marginal river. The principal valley train ranges 

in width from about half a mile to 2 miles and lies in 

the Covington channel from Maple Valley southwest 

to Duwamish Valley at Auburn. Terraces along the 

channel suggest that the melt-water river first formed 

a gravel fill at high level. It then cut into the fill, 

pausing enough during the cutting to form other broad 

flood plains at levels below the fill surface. Th<v upper 

fill terraces appear to consist of pebble-and-cobble 

gravel'as much as 50 feet thick. At lower levels, cut 

terraces consist mostly of pebble gravel that probably 

is only 10-20 feet thick. In the northeastern part of the 

channel, the channel floor is covered with sand. The
PLEISTOCENE DEPOSITS 49

sand, by its size, records a decrease in carrying capacity of the ice-marginal river and probably was laid 

down after part and perhaps most of the river had 

shifted its flow to a channel farther north.

Formation of the valley-train fill resulted in the 

blocking of some small tributary valleys along the 

Covington channel. Foresets in valley-train gravel, 

exposed in borrow pits in the SE. cor. sec. 26 and in 

the NE. cor. sec. 35, T. 22 N., R. 5 E., dip across and 

up the Big Soos Creek valley, suggesting that the 

gravel at least partly blocked the trough of Big Soos 

Creek. In sees. 3 and 10, T. 21 N., R. 5 E. the valleytrain surface slopes from the Covington channel across 

and slightly up another small tributary valley. Grain 

size of the valley-train deposit decreases up the tributary valley, from pebble-and-cobble gravel in the main 

channel to sand half a mile to the north. Farther north, 

lacustrine sediments were laid down behind the dam 

of sand and gravel. Silt and clay more than 18 feet 

thick were penetrated by angering in a branch of the 

tributary near the center of sec. 34, T. 22 N., R. 5 E.

KAME-TERRACE DEPOSITS

One large kame terrace was formed by the icemarginal river in an embayment of Duwamish Valley 

wall in sees. 28, 29, 32, and 33, T. 21 N., R, 5 E. The 

kame terrace has been partly eroded by the White 

River, but it still covers about 1 square mile on the 

south side of the White River valley. Gravel is exposed 

intermittently from the level of the White River, which 

is less than 125 feet above sea level, up to about 425 

feet in the valley wall. Gravel and sand nearly 200 feet 

thick crop out in a single exposure in the western part 

of the terrace. The terrace deposits are largely wellsorted and stratified pebble-and-cobble gravel, with 

lesser amounts of sand. In the westernmost, extensively 

collapsed, part of the terrace, however, the prevalent 

material at the surface is well-sorted medium and 

coarse sand.

DELTA

The Auburn delta (Bretz, 1913, p. 134) was built 

into an ice-dammed and partly ice-filled lake in Duwamish Valley at Auburn at the end of the Covington 

channel. At least one large iceblock was buried in the 

delta; melting of the iceblock formed the kettle now 

occupied by White Lake. Gravel of the Auburn delta 

forms most of the wall of Duwamish Valley between 

the Green and White Rivers. The gravel crops out for 

about a mile and a half in a north-south direction but 

extends, as a thick deposit, only about a quarter of a 

mile east of the delta face. The part of the delta west 

of White Lake stands about 150 feet above the adjacent

Duwamish Valley floor, and gravel is exposed from the 

top to the level of the valley floor. Thus, the gravel is 

at least 150 feet thick. Furthermore, because the floor 

of the Duwamish trough was several hundred feet 

lower during late glacial time than it is now, the 

deposit probably extends several hundred feet farther 

down the old valley wall and is now buried by alluvium. The surface of the delta east of the White Lr.ke 

kettle merges smoothly with the surface of the valleytrain deposits of the Covington channel.

The delta gravel is chiefly well-sorted, well-stratif <xl 

pebble-and-cobble gravel. Topset and foreset beds are 

well exposed in a gravel-pit wall nearly 125 feet high 

southwest of White Lake. The topset beds are about 20 

feet thick, and long unbroken foreset beds make up the 

rest of the exposed deposit. Similar foreset beds w^re 

exposed in 1959 along a railroad spur west of White 

Lake and along the railroad and highway north of the 

lake. In the high pit wall southwest of the lake, the 

foreset beds dip west; northward their dip swings 

progressively more toward the north so that in the 

northernmost exposure along the delta face the dip is 

northwest. Topset and long foreset beds were also w^ll 

exposed in 1959 in a gravel pit in the southwesternmost 

part of the delta.

The principal surface of the delta terminates along 

its west margin at altitudes of slightly more than 250 

feet. Bretz (1913) recognized a 260-foot level as wQll 

as a level at 235 feet, and he proposed that the Auburn 

delta was deposited in an arm of Lake Tacoma. Lake 

Tacoma, according to Bretz (1913, p. 133, 134), occupied the Duwamish and Puyallup troughs south of 

Auburn and spilled through a channel in South 

Tacoma.

AGE AND CORRELATION OF PLEISTOCENE DEPOSITS

Although at least four episodes of glaciation are recorded by the Pleistocene deposits, only the youngest 

drift, the Vashon, can be dated closely or correlated 

with confidence with Pleistocene deposits outside the 

lowland. The Vashon can be dated the most accurately 

because it is young enough to fall within the range of 

radiocarbon dating methods used to measure ages back 

to about 38,000 years. Recognized p re-Vashon formations in the mapped area, in contrast, are all older than 

38,000 years. The age of these older formations is estimated on the basis of the number of events that separate them from the Vashon, and the probable timespans of the events. Estimates of time spans, in turn, 

are based on such factors as overall weathering or 

existence of weathering profiles, periods of erosion, 

and evidence of significant changes of climate.
50 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

The Vashon Drift was deposited during the Fraser 

Glaciation (Armstrong and others, 1965) ; the Vashon 

was the only stade of that glaciation in which the 

Puget lobe extended into the southeastern part of the 

lowland. The Vashon Drift has been most closely dated 

at, Seattle. A sequence of nonglacial beds below the 

drift, at Seattle contains wood fragments ranging in 

age from about 24,000 to about 15,000 years old (Mullineaux and others, 1965). Radiocarbon dates from 

material overlying the drift are as old as 13,500 years 

(Rigg and Gould, 195T). Thus the Puget lobe of 

Vashon age did not reach Seattle (or Renton) until 

after 15,000 years ago, and it had retreated by 13,500 

years ago. The Vashon Stade, then, represents only a 

brief glacier advance that occurred late in the Fraser 

Glaciation.

The youngest glaciation of the Puget Sound lowland has, since early investigations, generally been regarded as equivalent to the Wisconsin Glaciation in 

central United States, because the Vashon Drift has 

undergone only slight weathering or other modification. Radiocarbon dates show that the Fraser Glaciation is approximately equivalent to the "classical" Wisconsin of Flint (1957) and the Woodfordian Substage 

of the Wiscoiisinan Stage (Frye and Willman, 1960). 

The first few radiocarbon dates from above the Vashon 

Drift in the Puget Sound lowland suggested that the 

Vashon advance was approximately contemporaneous 

with the maximum (Tazewell Stade) advance of continental ice into central United States (Waldron and 

others, 1957; Rigg and Gould, 1957; Crandell and 

others, 1958). The dates obtained later from below the 

drift at Seattle, however, show that the Vashon advance did not occur until well after the time of the 

Tazewell maximum of central United States.

The Salmon Springs Glaciation is older than 

the classical Wisconsin of Flint, but it may not be 

older than the earliest parts of the Wisconsin Glaciation of central United States. A sample of peat 

(W-672) from between two drift members of the 

Salmon Springs Drift at the type section has been 

dated as more than 38,000 years old (Crandell, 1963). 

Another sample from the same peat bed has been dated 

definitely as at least 50,000 years old, and possibly no 

older than about that age, by Dr. J. C. Vogel of the 

Natuurkundig Laboratorium of the Rijks-Universiteit 

at Groningen (J. C. Vogel, written conimun., 1965; 

and reported in Easter brook and others, 1967). No 

strong weathering of the Salmon Springs Drift is 

known that would record a long interglacial interval 

comparable to the Saiigamon Interglaciation of central 

United States. Neither is there evidence of a climate as 

warm as that of Sangamon time in nonglacial sediments that separate members of the Salmon Springs 

Drift (Crandell and others, 1958) or that separate the 

Salmon Springs from Vashon Drift (Mullineaux and 

others, 1965; Armstrong and others, 1965). Consequently, the Salmon Springs Drift is regarded as 

younger than the Sangamon Interglaciation. If that is 

correct, the Salmon Springs Glaciation is correlative 

with some older part of the Wisconsin Glaciation. Such 

an episode is the Altonian Substage of the Wisconsinan Stage (Frye and Willman, 1960). The Altonian 

may have included more than one glacier advance, according to Frye and Willman (1960, p. 6), jurt as did 

the Salmon Springs.

The Puyallup Interglaciation is interpreted to be a 

major interglacial episode because of (1) the fairly 

warm climate recorded by pollen and diatoms in the 

Puyallup Formation and the probably correlative formation in the mapped area, (2) the amount of weathering in the top of the formation, and (3) the occurrence 

of a period of erosion between deposition of the formation and the Salmon Springs Glaciation (Crandell 

and others, 1958). The Puyallup Interglaciation is 

tentatively correlated with the Sangamon Interglaciation, but it may be as old as the Yarmouth Interglaciation of central United States.

The Orting (?) Drift and the intermediate drift appear to be middle (?) Pleistocene in age and older, but 

both their ages and their correlations with glaciations 

elsewhere are uncertain. A nonglacial interval (Alderton Interglaciation) in which the climate was as warm 

as present, as well as another glacial episode, is recorded between Orting and Puyallup time in the Lake 

Tapps quadrangle (Crandell, 1963). In the mapped 

area, both Orting (?) and intermediate drifts record 

more than one glacier advance. The multiple advances 

in each glaciation, the Alderton warm episode that 

probably intervened between the glaciations, and the 

fact that the Orting(?) is the oldest known drift in 

the area suggest that the'Orting(?) may be as old as 

the earliest glaciation (Nebraskan) of the central 

United States.

POSTGLACIAL DEPOSITS

Deposits termed "postglacial" are postglacial in a 

local sense and are not necessarily all post-Pleistocene 

in age. At any particular locality, postglacial sedimentation began as the Puget lobe retreated to a point 

where it no longer contributed sediment to tl x at locality. But for a considerable time after such sedimentation began in the mapped area, glaciation continued in 

the northern part of the lowland, during parts of the
POSTGLACIAL DEPOSITS 51

Vashon and Sumas Stades of the Fraser Glaciation 

(Armstrong and others, 1965; Crandell, 1965). Consequently, a few postglacial deposits of the mapped 

area may be late Pleistocene in age. More, however, are 

partly late Pleistocene but mostly Holocene in age, and 

some are entirely Holocene in age.

LACUSTRINE DEPOSITS

Lacustrine deposits that consist of peat and lesser 

amounts of silt, clay, and sand occupy closed depressions and other poorly drained areas on the glacial 

drift plain and on the floors of the major valleys. Those 

on the drift plain occur chiefly in ice-scoured basins in 

ground moraine, in kettles in outwash, and along small 

stream courses. Two small bogs that lie in shallow 

swales on the drift plain south of the Green River are 

dammed by the Osceola Mudflow. On the valley floors, 

lacustrine sediments generally occur in broad thin layers in flood-plain basins. A few other small peat bogs 

lie on the valley walls in depressions behind landslide 

blocks.

The constituent that is typical of the lacustrine deposits is the organic material. According to Rigg (1958, 

p. 5), the organic material in local peat bogs is chiefly 

woody, fibrous, sedimentary, and moss peat. Woody 

peat contains all sizes of plant material from large logs 

to small fragments. Fibrous peat consists chiefly of the 

remains of small sedges; logs and other wood fragments do occur but are much less common than in 

woody peat. Sedimentary peat consists of the remains 

of small aquatic plants and animals, and moss peat 

consists mainly of small fragments of leaves and stems 

of sphagnum mosses. Most shallow bogs and the upper 

parts of deeper ones consist of fibrous or woody peat; 

but in a few, moss peat is extensive. Sedimentary peat 

generally is confined to the lower part of thick lacustrine deposits. Rifle, Mukilteo, and Greenwood bog or 

peat soils are composed chiefly of woody, fibrous, and 

moss peats, respectively (Poulson and others, 1952, p. 

102; Rigg, 1958, p. 9).

Lacustrine deposits on the drift plain are largely 

peat and are relatively low in mineral material except 

along permanent streams such as Big Soos Creek. In 

bogs that lie on ground moraine, the peat generally is 

underlain by thin deposits of lacustrine silt, clay, or 

sand; in bogs on permeable outwash, organic material 

more commonly overlies gravel or sand directly. 

Locally, silt and clay was deposited in ponds formed 

temporarily by ice. Marl occurs in some peat deposits 

(Rigg, 1958, p. 10), as does diatomite. A single volcanic ash layer i/4-2 inches thick, which extends over 

much of the Puget Sound lowland, occurs persistently

in the peat bogs (Hansen, 1947; Rigg, 1958). The ages 

of peat samples from just below this ash layer in one 

bog in sec. 32, T. 22 N., R. 6 E., about 2 miles east 

of Covington, and in another at Arrow Lake about 13 

miles farther west, have been determined by radiocarbon analyses to be about 6,500 and 6,600 years, reflectively (Rigg and Gould, 1957, p. 354; Rubin and Alexander, 1960, p. 164). Until recently, the ash of this 

layer was believed to have come from Glacier Peak 

volcano in northern Washington (Hansen, 1947; Rigg 

and Gould, 1957). Subsequent work, however, that included comparison of analyses of pumice and ash from 

Glacier Peak and from Mount Mazama at Crater Lake, 

Oreg., and more detailed petrographic examination of 

the ash layer in the Puget Sound lowland has shown 

that the ash layer of the peat bogs originated at Mount 

Mazama (Powers and Wilcox, 1964). Ash samples 

from the Covington and the Arrow Lake bogs are 

among those identified as part of the Mazama ash 

layer (R. E. Wilcox, oral commun., 1966).

Three drift-plain peat bogs in the mapped area were 

studied in detail by Rigg (1958) as a part of ar inventory of peat deposits in Washington. Two ar^. on 

outwash in the Black Diamond quadrangle, and another is on ground moraine in the Renton quadrangle. 

Each bog is isolated from large drift-plain streams, is 

fairly free from silt and clay, and contains the Mazama ash layer. The thinnest of the three deposits- lies 

on ground moraine at Panther Lake in sec. 4, T. 22 1ST., 

R. 5 E.; its maximum known thickness is about 23 feet 

(Rigg, 1958, p. 84). Peat is about 32 feet thick in a 

kettle bog in sees. 2 and 3, T. 21 K, R. 6 E., about 2 

miles north of Black Diamond (Rigg, 1958, p. 88). The 

thickest peat found by Rigg (1958, p. 77) in the P+ate 

is in the Covington bog in sec. 32, T. 22 N., R. 6 E., 

which is also in a kettle; this peat is at least 63 feet 

thick. Other thick peat deposits on the drift plain 

probably are similar to those examined by Rigg. The 

numerous peat layers along Big Soos Creek and other 

smaller creeks generally are much thinner and contain 

relatively abundant mineral matter.

Two silt and clay deposits that contain very little 

peat lie on the ground moraine northeast of AuHirn, 

one in sec. 4, T. 21 N., R. 5 E., and another in s?.c. 3 

of that township and in sec. 34 of T. 22 N., R. 5 E. The 

former was laid down in a short-lived ice-dairmed 

lake, and the latter in a temporary basin dammed by 

outwash sand and gravel.

Valley-floor lacustrine sediments occur mostly in Duwamish Valley; in other major valleys, lacustrine deposits have not been separated from fine-grained overbank alluvium. The lacustrine sediments are chiefly
52 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

thin peat deposits, which lie at the surface along the 

edge of the flood plain and which also are interbedded 

in the upper few feet of alluvium. Only one peat deposit within the mapped quadrangles is large; this one 

is about 2 miles south of Kenton on the east side of the 

valley floor. Typically, peat in that area is much mixed 

with inorganic material, and it grades laterally to 

organic-rich silt and clay. This bog was also examined 

by Eigg (1958, p. 74), but he drew no profile, probably because of the large proportion of mineral matter. Although the peat contains much silt and clay, it 

is still soft enough so that in places it can be penetrated readily as much as 15 feet deep by a peat auger.

Pollen is abundant in lacustrine sediments, as are 

diatom fragments just above the Mazama ash layer, 

and mollusks have been recovered from a few bogs. 

Pollen from a peat bog in sees. 2 and 3, T. 21 N., E. 6 

E., about 2 miles north of Black Diamond, has been 

studied by Hansen (1941). He concluded that the pollen profile there records the change from a cool to the 

warmer climate of the present, but not other fluctuations that are indicated by evidence elsewhere in the 

Pacific Northwest (Hansen, 1947). Mollusks recovered 

from marl at the bottom of the Covington bog have 

been identified by D. W. Taylor of the U.S. Geological 

Survey as follows: Pisidiwn casertanum (Poli), Valvata* Lymtutea palustrls (MiUler), and GyrauTus par- 

 vus (Say). According to Taylor, all these are restricted 

to fresh-water environments.

Although two lacustrine silt and clay deposits probably are late Pleistocene in age, most of the postglacial 

lacustrine deposits are of late Pleistocene and Holocene age. A few deposits, notably those on the valley 

floors and the two adjacent to the Osceola Mudflow, are 

entirely Holocene in age. The postglacial sedimentation in. the area started shortly after retreat of the 

Puget lobe; postglacial peat samples from Lake Washington and a bog 60 miles farther north have been 

dated as approximately 13,600 and 12,900 years old, respectively (Eigg and Gould, 1957; Eubin and Alexander, 1958, p. 1476). Eigg and Gould (1957) also 

attempted to date the start of peat formation in the 

deep Covington bog, but a sample of basal peat from 

a depth of 63 feet at the deepest probed site in the bog 

was dated as only about 10,200 years old. It is possible 

that the material sampled was not the oldest peat in 

the bog or that contamination during deep sampling 

resulted in an anomalously young date. But it is also 

known that the site of the Covington bog was occupied 

by a thick block of stagnant ice, and a considerable 

amount of time must have passed before it melted and 

allowed peat formation to begin.

TERRACE ALLUVIUM

Alluvium deposited on flood plains by the White, 

Green, and Cedar Eivers as they cut down into the 

drift plain is preserved locally on terraces along the 

present valley walls. Flood-plain remnants regarded 

herein as terraces include only those standing distinctly above the present valley floors; even relatively 

high parts of the present valley floors that only occasionally are flooded are regarded as part of the nodern 

flood plain.

Within the mapped area, extensive postglacial terraces occur only along the Green Eiver in the Black 

Diamond quadrangle. Elsewhere, they are small or 

ha\Te been so disturbed by landsliding that the deposits 

are described as part of the colluvium. The most extensive terraces occur high on both walls of the Green 

Eiver valley at the east edge of the Black Diamond 

quadrangle. Farther west along the north side of the 

river, a flight of rock-defended terraces is preserved in 

sec. 27, T. 21 N., E. 6 E., and a single broad terrace is 

preserved in sec. 25, T. 21 N., E. 5 E., near tre west 

edge of the quadrangle. In sec. 27, terraces form a 

series of steps from nearly the top to the bottom of 

the north valley wall, which is underlain by bedrock. 

In contrast, only one questionable river terrace is preserved on the opposite side of the valley, where the 

valley wall is underlain chiefly by Pleistocene sediments. Smaller, mostly unmapped terraces occur elsewhere along the Green Eiver valley and along the valleys of the White and Cedar Eivers, but they are not 

abundant. Sandy gravel, probably derived from a postglacial terrace, occurs on slump blocks halfway up the 

south valley wall of the Green Eiver in sec. 30, T. 21 

N., E. 6 E., but no terrace landform is evidert now. 

Probable terrace sand and gravel also occurs on landslide blocks along the southwest side of the White 

Eiver valley in sec. 34, T. 21 N., E. 5 E. Very likely, 

terraces were once much more extensive along each of 

the major valleys, but they have been removed as the 

valley walls retreated by landsliding.

Terrace alluvium along the Green Eiver occurs in 

sheets of gravel and sand only about 15-30 feet thick 

rather than in thick fill deposits. In the easternmost 

group of terraces, the alluvium consists chiefly of wellsorted sandy pebble-and-cobble gravel. In the fl; ?ht of 

rock-defended terraces farther west, the terrace deposits also consist of sand and gravel but exhibit a 

wide range in grain size. The upper terraces, at altitudes of about 350-400 feet, are capped chiefly by 

sandy pebble-and-cobble gravel and only a fe^ boulders. An extensive intermediate terrace at about 325 

feet, however, is veneered mostly by boulder-and-cob-
POSTGLACIAL DEPOSITS 53

ble gravel, and the lower terraces are covered chiefly 

by sand and pebble-and-cobble gravel. On the single 

broad terrace at the west edge of the Black Diamond 

quadrangle, the alluvium is mostly well-sorted sand 

and pebble gravel.

The terraces were formed by lateral swinging of the 

various rivers against their valley walls as they cut 

downward through the drift plain in postglacial time. 

Along the Green and Cedar Rivers, terrace formation 

started soon after retreat of the glacier and continued 

into Holocene time. A remnant of the 5,000-year-old 

Osceola Mudflow that lies at about the level of the 

present flood plain in the Green River valley proves 

that in this valley the river had cut clown to at least 

its present altitude by that time. Consequently, terraces 

along the Green must be between about 14,000 and 

5,000 years old. In contrast, terrace remnants in the 

White River valley in the Auburn quadrangle are less 

than 5,000 years old, because the river was emplaced 

along that course by the Osceola Mudflow (Crandell, 

1963, p. A68).

COLLUVIUM

Deposits mapped as colluvium consist chiefly of 

landslide debris but also include slope wash and even 

some alluvium on valley walls. The landslides are of 

widely varying types, but can be separated into two 

groups (see Sharpe, 1938, or Varnes, 1958, for landslide 

classifications) : slides, which move mostly as discrete 

blocks; and flows, which move with much internal deformation and take a form resembling that of a viscous 

fluid (Varnes, 1958, p. 32). All gradations between 

slides and flows occur, however, and individual landslides may exhibit both types of movement. Most large 

slides are slump blocks that are tilted backward as a 

result of rotation; downslope they often progressively 

break into smaller blocks and grade to earthflows. 

Smaller discrete slides are mostly slump blocks or 

debris slides. A particularly common type of small 

debris slide consists of one or of perhaps a few trees 

and the material in which they are rooted. Landslides 

classed as flows are very abundant, especially mudflows, debris avalanches and debris flows, earthflows, 

and creep. Flows commonly are interbedded with slope 

wash and alluvium and probably grade into those deposits. Material described as slope wash is intermediate 

between landslide debris and alluvium; it is defined as 

the material moved downslope predominantly by gravity assisted by running water that is not concentrated 

in channels (Stokes and Varnes, 1955). Alluvium 

treated as part of the colluvial deposits herein is that 

alluvium which is moved intermittently by small

streams on valley walls, where it is intimately associated with landslide debris and slope wash.

Nearly all steep slopes in the three mapped quadrangles are covered by a mantle of colluvium; this colluvium is thickest and most active on valley walls of 

streams that have cut deeply into the drift plain in 

postglacial time. Large block slides are especially extensive in the Black Diamond quadrangle along the 

Green River and Newaukum Creek, where locally most 

of the valley wall is laden with slumps as much as 

several hundred feet long. These slumps are surrounded by smaller blocks, flows, and slope wash. Large 

slumps are also common in the Auburn quadrangle 

along the southwest side of the White River and along 

Soos Creek in sec, 11, T. 21 N., R. 5 E. In the Cedar 

River valley, large slumps are less abundant, but one 

large feature in sec, 21 about 1 mile east of Renton 

(Mullineaux, 1965a) is interpreted to be an ancient 

slump block. Smaller block slides and other colluvium 

are widespread elsewhere along the White, Green, and 

Cedar Rivers and along Soos Creek, even where not 

shown on the geologic maps, for these deposits were 

mapped only where thick and continuous enough to 

prevent identification of the underlying strata.

Slopes modified by the Vashon ice, in contrast, carry 

considerably less colluvium. Along Duwamish Vr.lley, 

for example, colluvium other than a thin creep mantle 

is not extensive except where the Green River has recently cut against the valley wall, as it has about 1 mile 

north of Auburn. Similarly, colluvium on the drift 

plain is thick and abundant only where late glacial or 

postglacial streams have cut sharply into the drift, and 

generally only creep has aifected constructional slopes 

on ground moraine and outwash gravel.

Colluvium typically is represented by hummocky 

slide-block topography and the smoother profiles of 

flows and slope wash. Most landslide areas include 

slump blocks whose elongate upper surfaces arc approximately parallel to and tilted back toward the valley wall. Ponds and swamps commonly form ir the 

depressions behind the blocks. Locally, mudflows, slope 

wash, and alluvium between the blocks smooth mcst of 

the valley wall. The flow materials may make rather 

steep coalescing aprons along the base of a valley wall 

or extend as separate fans out onto the floor of the 

valley. In a few places, slide blocks also have ridden 

out onto the valley floor. Landslide topography that 

develops in the flat-lying Pleistocene deposits is well 

illustrated along the Green River valley in the Black 

Diamond quadrangle. Along the valley, the drift plain 

in several places is bounded abruptly by a steep arcuate scarp that leads down to a broad flatter slope
54 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

formed by a jumble of block slides seemingly afloat in 

mudflow and alluvial deposits.

Thickness of the colluvium is highly irregular, especially where it is composed partly of large slide blocks. 

The shapes of some large slumps in the Green River 

valley indicate that they are at least 50 feet and perhaps more than 100 feet thick, but blocks ranging in 

thickness from a few feet to probably 20 feet appear 

to be more common. Other colluvium also is locally 

thick; near the west edge of sec. 22, at the base of the 

south valley wall of the Cedar River, a colluvial sequence composed mostly of mudflows is at least 30 feet 

thick. However, the landslide flow deposits and associated slope wash and alluvium probably are generally 

thinner than the slide blocks that they encompass.

Both the composition and the texture of colluvial deposits are widely variable, reflecting the variation of 

source sediments and amount of disturbance. Colluvium exhibits as much diversity as the geologic formations that crop out in the valley walls, for part is derived from each older formation. Because most is derived from nonindurated Pleistocene deposits that consist largely of clay, silt, and sand, colluvium typically 

is fine grained. Locally, however, debris flows heading 

in thick gravels have spread deposits of the gravel far 

down valley walls and even onto flood plains. Disturbance of component strata is minor in large slide 

blocks, which may retain structural features of the 

source beds with little change, but materials in flow 

deposits generally are much reworked. In the latter, 

beds of clay, sand, and gravel commonly are broken 

and juxtaposed or intimately mixed. Changes in grain 

size and sorting are abrupt, a silty or clayey matrix is 

almost universal, and bedding is usually crude or 

absent.

Weak Pleistocene formations, vertical and lateral 

river erosion, man's activities, and rainfall are the most 

important of the many factors that cause landslides in 

the mapped area. (See Sharpe, 1938; and Varnes, 1958, 

and references therein for discussions of landslide 

causes.) Some of the factors are nearly constant conditions that operate mostly to determine the location of 

slides; others change rapidly and tend to determine 

the timing. Lithologic factors such as weak formations, 

for example, are almost constant, and so their effect 

is to determine sites of abundant landslides. In the 

Green River valley, slides are sparse in the bedrock 

gorge but are abundant just down valley where the 

river has cut into weathered clay-rich Hammer Bluff 

Formation and Orting(?) Drift. Erosion that produces steep slopes occasionally is rapid enough to trigger slides, but generally it also only determines localities that are especially subject to landsliding. Man's

activities, particularly those that undercut or overload 

slopes, often produce slopes that are subject to sliding. 

But excavation and filling also commonly disturb slope 

conditions enough to set slides in motion. The triggering cause of most landslides here, however, probably is 

rainfall. The water adversely affects slope stability in 

many ways, and enough so that most landslides occur 

during the rainy season.

Most of the colluvium mapped is Holocene in age. 

Older colluvial materials very likely have beer completely reworked or removed, particularly in valleys 

that were widened and deepened in Holocene time. 

Locally, landslides are known to be younger than the 

5,000-year-old Osceola Mudflow, because they occur in 

the White River and Newaukum Creek valleys that 

themselves postdate the mudflow.

OSCEOLA MUDFLOW

The Osceola Mudflow is a mass of bouldery sandy 

clay that flowed down the White River valley from 

Mount Rainier and spread out as a digitate lot«, over 

at least 65 square miles of the Puget Sound lowland 

(fig. 20; Crandell and Waldron, 1954, 1956; Crmdell, 

1963). It was first described by Willis (1898c) as the 

Osceola Till, but it has since been redefined as the 

Osceola Mudflow (Crandell and Waldron, 1956, p. 

361).

Only a small thin part of the Osceola extends into 

the Black Diamond and Auburn quadrangles. South of 

the Green River in these two quadrangles, it covers 

parts of the drift plain over an area about 6 miles long 

and 2 miles wide (fig. 20; Mullineaux, 1965b, c). In 

addition, one small remnant forms a terrace 5-10 feet 

above the Green River flood plain in sec. 25 about 5 

miles east of Auburn. Another remnant has been identified by Luzier (1969) at a depth of 265 feet in r, water 

well in Duwamish Valley, 4 miles northwest of Auburn 

(fig. 20). The nmdflow generally lies at the surface; 

thus, its character is well exposed at the tops of valley 

walls and in drainage ditches. Near Enumclaw (fig. 

20), it is as thick as 75 feet (Crandell, 1963, p. A47), 

but in the mapped area the maximum observed thickness is about 15 feet, and the average probably is less 

than 10 feet.

The mudflow has a nearly flat surface, but locally it 

laps up onto hillocks of the rolling drift plain. The 

mudflow surface is poorly drained naturally, and 

drainage ditches have been dug in most cultivated 

areas. The average slope of the surface in the direction 

of flow is only about 25 feet per mile in the westernmost 4 miles of outcrop between the Green and White 

Rivers. On the flanks of Vashon Drift hills, tH thin
POSTGLACIAL DEPOSITS 55

122° 00'

47°30'

 47°00'

FIGURE 20. Distribution of the Osceola Mudflow (patterned area), location of Renton, Auburn, and Black Diamond quadrangles (outlined), and site of water well (DH) in the Duwatnish Valley northwest of Auburn in which mudflow was penetrated. Area shown as mudflow includes small areas of Vashon Drift and postmudflow alluvium. Within Cascade Range, 

pattern shows path of mudflow but does not show actual distribution. From Crandell and Waldron (1956), Crandell (19(33), 

and Luzier (1969).
56 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

mantle of mudflow generally rises only a few feet above 

the overall surface of the Osceola, but a thin layer may 

cover drift mounds that are only a few feet higher than 

the general mudflow surface. Thus, the top of the mudflow apparently was once higher than it is now. Its 

lowering probably resulted chiefly from compaction 

after emplacement, but it may have resulted partly 

from outflow of still mobile mud from under a stationary crust.

The Osceola is an unsorted and unstratified deposit 

that contains clay, silt, sand, and stones of all sizes up 

to large boulders. A sample collected by D. R. Crandell 

from the south valley wall of the Green River near 

Auburn, from which cobbles and boulders were excluded, consisted of 20 percent silt and clay, 36 percent 

sand, and 44 percent gravel. Cobbles are common; 

boulders are scattered only sparsely in and on top of 

the formation near the Green River but become more 

abundant southeastward toward the source. Most outcrops that expose both bottom and top of the mudflow 

show a distinct decrease in size of stones from bottom 

to top, a feature that is characteristic of this as well as 

other mudflows (Crandell and Waldron, 1956, p. 352; 

Crandell, 1957).

The mudflow is composed chiefly of volcanic material from Mount Rainier and from Tertiary andesitic 

rocks in the Cascade Range. Pebble counts at several 

Puget Sound localities, involving about 900 stones, indicate that from 1/3 to y2 the pebbles are derived from 

Mount Rainier and that most of the others are derived 

from Tertiary volcanic rocks (Crandell, 1963). The 

sand fraction consists largely of volcanic rock fragments, volcanic glass, feldspar, and heavy minerals, of 

which hyperstheiie constitutes as much as 95 percent. 

Montmorillonite is the predominant clay mineral in 

all samples examined; however, kaolinite, mica (illite), 

and mixed-layer clay minerals also occur, and in a few 

samples are nearly as abundant as montmorillonite. 

Wood is common and generally appears fresh.

The distribution of the Osceola in the lowland shows 

that it was emplaced as a fluid mass, flowing generally 

around rather than over obstacles; and its character 

indicates that it is a volcanic mudflow (Crandell and 

Waldron, 1956, p. 351). The mudflow has been traced 

up the White River valley to Mount Rainier, where its 

distribution indicates that it originated high on the 

northeast side of the volcano. Crandell and Waldron 

(1956, p. 360) originally suggested that the mudflow 

was initiated by partial collapse or explosive destruction of part of the volcano as a result of eruption. 

After studies of surficial deposits at Mount Rainier, 

Crandell (1963) proposed that the Osceola resulted

from one of several major avalanches that destroyed 

the former summit of the mountain. Phreatic explosions were regarded as the most likely cause, but initiation by earthquakes or slope failure after oversteepening by glacier erosion was considered possible. In contrast to these hypotheses, Fiske, Hopson, and Waters 

(1963) proposed that the mudflow was formed by the 

collapse and the flowing out of a thick fill of watersaturated sediments in the upper part of the White 

River valley. Distribution of remnants of the Osceola 

on the flanks of the volcano well above the White River 

valley, however, seems to show clearly that the mudflow originated somewhere 011 the volcano fr.r above 

the White River valley.

Discovery of a brown podzolic soil profile in Vashon 

Drift beneath the mudflow (Crandell and Yraldron, 

1956, p. 357) first showed that the Osceola was significantly younger than the Vashon Drift. Shortly 

thereafter, three wood samples from the mudflow in 

the lowland and along the edge of the Cascade Range 

were elated by radiocarbon methods as about 4,700, 4,- 

800 and 4,950 years old (Crandell, 1963, p. A49). Another wood sample, from the mudflow buried in alluvium in the Duwamish Valley northwest of Auburn, 

was determined to be about 5,000 years old (Luzier, 

1969). Consequently, the Osceola is regarded to be, in 

round figures, 5,000 years old.

FLOOD-PLAIN ALLUVIUM

Modern flood-plain alluvium includes some small deposits from creeks that head on the drift plain, but it 

consists mainly of alluvium from the Cedar, Green, 

and White Rivers. The topographically higher parts of 

alluvium on the major valley floors could be classified 

as terrace deposits according to an interpretation of 

Wohnan and Leopold (1957, p. 105), inasmucl as they 

stand above the level of annual or biennial flooding. 

However, definition according to flood frequency is not 

used herein. First, the deposits appear to be a lithologic unit that is continuous from the high, lQ-ast frequently flooded parts of the valley floors to tl>0* lower, 

more regularly inundated parts. Second, in a large 

part of Duwamish Valley, levees along the modern, 

channel are among the least frequently flooded parts 

of the valley floor. Perhaps more important, food frequency in these valleys has been altered by man's 

activities. The present flood frequency is net representative of that of the recent past, and additional 

river control might further protect the valley bottoms 

from flooding. Consequently, all the main-stream alluvium on the valley floors is considered to be modern 

flood-plain alluvium.
POSTGLACIAL DEPOSITS 57

Deposits of small streams that head on the drift 

plain are all small, and they vary widely in content, 

width, and thickness. Creeks that cross the surface of 

the drift plain necessarily have low gradients, and 

they have had to alternately cut and fill to attain their 

present profiles. Consequently, the deposits are highly 

diverse even along a single stream. Where such a creek 

has cut into the drift, its alluvium typically consists of 

only a thin and narrow band of sand and silt. Where 

it has filled instead, the deposit is broader and thicker, 

and the sand and silt are interlayered and flanked with 

clay and peat. Along the margins of the drift plain, 

a few of the larger drift-plain streams such as Newaukum and Soos Creeks have cut deep trenches that lead 

steeply down to the major valley floors. Along the 

deep reaches, alluvium of these creeks consists of thin 

and narrow strips of gravel and sand with little associated silt, clay, or peat. Alluvium of Newaukum 

Creek, for example, forms a continuous band of pebbleand-cobble gravel and sand only a few tens of feet 

wide except in its broader terminal fan on the Green 

River valley floor. Alluvium of Big Soos Creek is similar (though somewhat finer grained) except in the 

lower mile or two of its valley, where the deposit 

widens to about 500 feet and probably thickens to at 

least 50 feet. In that area, the deposits at the surface 

consist of gravel and sand 50-100 feet wide along the 

creek, and of sand and silt elsewhere on the surface 

of the flood plain.

Smallest of the alluvial deposits are those of streams 

flowing directly down the valley walls. They typically 

are not only narrow and thin but commonly grade into 

or are interbedded with colluvium. Generally such alluvium has not been mapped except where it broadens 

into a fan at the base of a valley wall. The deposits 

consist largely of sand and silt but locally are pebble 

or cobble gravel.

In contrast, deposits of the three major rivers in 

their own valleys and in Duwamish Valley are thick 

and widespread, covering about a fifth of the total area 

of the Renton, Auburn, and Black Diamond quadrangles.

CEDAR RIVER VALLEY

The major part of the Cedar River valley floor in 

the 4-mile-long segment in the Renton quadrangle is 

covered by alluvium, although colluvium and sidestream alluvium are proportionately more abundant 

there than on the floor of any other major valley. In 

the upvalley segment of about 3 miles, valley-bottom 

sediments are about a third of a mile wide; westward 

they narrow to about 400 feet in a bedrock gorge 1 

mile east of the center of Renton (Mullineaux, 1965a).

The depth of main-stream alluvium is not well 

along any part of the valley. A thick fill in Duwamish 

Valley at Renton suggests that alluvium is at least 300 

feet thick at the valley mouth, but the bedrock 1 mile 

upstream might have limited the downcutting so tl at 

the deposits farther up the valley are no more th'Mi 

20-30 feet thick.

Although the Cedar River heads high in the Cascade Range, most of its alluvium in the lower valley is 

derived from the lower part of the drainage basin, for 

Cedar Lake in the Cascades traps most material derived from the upper part. Constituent rock fragments 

and minerals are obtained principally from volcanic 

rocks of the Puget Group and younger Tertiary andesitic rocks, and to only a minor extent from the Snoqualmie Granodiorite and similar plutonic bodies and 

glacial drift. Gravel of the Cedar River at Renton, 

therefore, is composed chiefly of greenish-gray and 

gray volcanic rocks. Light-gray granitic rocks and 

metamorphic rocks from the drift are common, though 

they make up only a small proportion of the gravel. 

Heavy-mineral suites from sand consist largely of 

hypersthene, amphibole, clinopyroxene, altered lightgray and yellow minerals, small rock fragments, and 

opaque minerals (table 2).

Sediments on the floor of the Cedar River valley 

consist largely of narrow strips of pebble-and-cobble 

gravel and coarse sand in and near the river channel, 

and broader flanking deposits of finer sand and silt. In 

several places, however, the coarse channel materials 

widen to cover as much as half the breadth of the flood 

plain. Grain-size studies of channel deposits by L. A. 

Palmer (written commun., 1957) indicate that more 

than half a typical channel bar in the Renton quadrangle consists of pebble-size stones and that a third 

to a quarter of the bar consists of cobbles. The flank: ng 

silt and sand appears to be only a few feet thick over 

gravel in much of the valley, but locally, gravel-free 

deposits as much as 10 feet thick have been exposed in 

trenches.

GREEN RIVER VALLEY

Alluvium of the Green River that thickens progressively westward covers the floor of the Green Rrrer 

valley except for the parts covered by minor amounts 

of colluvium and side-stream deposits and for a small 

area at the valley mouth that is covered by WHte 

River deposits. In the bedrock gorge near the east 

margin of the Black Diamond quadrangle, flood-plain 

alluvium of the Green River is thin and as little as a 

few hundred feet wide. About 1 mile west, however, 

the alluvial floor widens to about a mile and, concurrently, the deposits thicken. A maximum thickness at
58 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

the valley mouth of more than 75 feet is probable, 

because the Green River must have aggraded at least 

that much in response to White River aggradation in 

Duwamish Valley. Records and logs of wells in sees. 

16 and 21, a mile up from the valley mouth, according 

to Luzier (1969), indicate that the Green River deposits there may be at least 120 feet thick.

Alluvium of the Green River is composed chiefly of 

greenish-gray and dark-gray volcanic rock and mineral fragments that were derived from Tertiary andesitic rocks in the Cascade Range. Although the Green 

River flows through a gorge cut into Puget Group 

arkose just east of the Black Diamond quadrangle, no 

more than a few percent of pebbles in the alluvium are 

derived from the Puget Group. Somewhat more material appears to have been derived from Pleistocene 

sediments, because pebbles of northern provenance are 

more common than those from the Puget. Heavy minerals from the Green River sediments are mostly hypersthene, amphibole, clinopyroxene, altered green and 

yellow minerals, rock fragments, and opaque minerals 

(table 2). Hypersthene and clinopyroxene are more 

abundant than in alluvium along the Cedar River, and 

light-gray altered minerals are much less common.

Channel gravel and sand, flanked by overbank sand 

and silt that grades laterally into flood-basin silt, clay, 

and peat, compose the valley-floor alluvium at the surface. Although coarse channel material appears only as 

narrow strips along much of the valley, it broadens 

greatly at two localities where the river has recently 

been migrating rapidly by cutting against the outside 

banks of meanders. For about 3 miles below the mouth 

of Newaukum Creek, the band of coarse channel deposits, though fluctuating greatly in width, probably 

averages about 1,000 feet in width and covers nearly a 

third of the flood-plain surface. Similarly, in the mile 

downvalley from the mouth of Big Soos Creek, gravel 

and coarse sand form the flood-plain surface in a band 

that averages about 500 feet in width.

Channel gravel of the Green River in the Auburn 

and Black Diamond quadrangles consists chiefly of 

pebbles, with lesser amounts of cobbles and sand. To 

determine the grain size of bedload being carried, 

samples were taken at low water from bars at several 

points along the river between the bedrock gorge on 

the east and the valley mouth near Auburn. After the 

lag pavement or armor (Straub, 1942) of stones was 

cleared from the bar surface, 40-50 pounds of material, excluding boulders, was dug and sieved at each 

sample site. In the sample from the easternmost site, 

near the mouth of the bedrock gorge, the mean diameter of all particles was about 4 cm, and about 30 percent of the sample was of cobble size (>6.4 cm). Boulders as large as 40 cm across are scattered over the bar, 

and several much larger ones, probably derived from 

the adjacent valley wall, lie on the surface of the bar. 

In the sample taken nearest the valley mouth, the 

mean diameter was slightly more than 2 cm, and only 

about 10 percent of the stones were of cobble size. 

Boulders as large as 20 cm across are present on the 

bar at this point, but noticeably larger boulders are 

absent, probably because any such boulders derived 

from valley walls here were buried during aggradation of this part of the flood plain.

Overbank sediments in the Green River v&lley include sand deposits similar to those called flood-plain 

splays by Happ, Rittenhouse, and Dobson (1940), and 

channel-fill and flood-basin deposits of sand, silt, clay, 

and peat. In the part of the valley in the Bk.ck Diamond quadrangle, overbank material appears to be 

chiefly sand in flood-plain splay and channel-fill deposits that apparently rapidly cover coarse channel 

sediments. Coarse channel deposits along sever?! meander segments cut off and abandoned since 1987 were 

largely covered by silty sand by 1959; several inches of 

overbank sand and silt were laid down in the same 

part of the valley during floods early in 195f. Exposures along the present channel show that, at least 

locally, these overbank deposits are no more than a 

few feet thick.

Flood-basin sediments are more abundant in the 

Auburn than in the Black Diamond quadrangle, 

although sand or" uncertain origin is a major constituent of the alluvium there. Sand without grr.vel, for 

example, was predominant in the walls of a pipeline 

trench excavated across the valley floor in sec. 22, T. 21 

N., R. 5 E., along nearly half its length. Sard interbedded with channel gravel was exposed along nearly 

a quarter of the trench, which also intersected one 

abandoned and filled channel that contained several 

buried logs. Flood-basin silt, clay, and intcrbedded 

peat as much as 10 feet thick formed the walls of the 

trench along approximately a third of its length. 

Nearer the valley mouth, fine-grained deposits may be 

even more abundant; in sees. 20 and 21, 10-20 feet of 

peaty silt and clay was penetrated in several auger 

holes. In addition, the log of a 70-foot well in-sec. 21 

shows only "peaty sand" (Luzier, 1969).

WHITE RIVER VALLEY

The valley floor is occupied by thin coarse alluvium 

and a little side-stream alluvium or colluvium. In the 

4-mile segment in the Auburn quadrangle, the valley 

floor is about half a mile wide, and the thi^Tiess of 

sediments probably is about equal only to the depth of 

scour of the river, perhaps 20-30 feet. This alluvium is
POSTGLACIAL DEPOSITS 59

inferred to be thin because the White River valley has 

been cut concurrently with, rather than before, the 

filling of Duwamish Valley. Hence, little or no aggradation in the White River valley would be expected in 

response to filling of the Duwamish Valley.

Alluvium of the White River is distinctive because 

of its high proportion of material derived from Mount 

Rainier. This proportion is far greater than would be 

expected from the small area of the drainage basin 

occupied by the volcano. Several factors probably contributed to this abundance of Mount Rainier detritus. 

Fragmental or weakly agglutinated pyroclastic rocks 

and breccias, for example, are abundant on the volcano (Russell, 1898; Coombs, 1936; Fiske and others, 

1963). Glaciers on the mountain contribute a large 

amount of detritus to the rivers. Mechanical weathering is probably more effective at the heights reached 

by the volcano than at the lower altitudes of the 

nearby Cascades, and the White River and its tributaries rework abundant mudflow and debris flow deposits that line their valleys between the volcano and 

the Puget Sound lowland (Crandell, 1963, p. A54). 

Pebbles and cobbles in the alluvium are mostly opentextured to dense dark-gray to brick-red andesite from 

Mount Rainier and greenish- to dark-gray volcanic 

rocks from older volcanic rocks in the Cascades. Heavy 

minerals are predominantly hypersthene, which composes as much as 90 percent of the heavy fraction of 

some samples. The remainder of heavy-mineral suites 

consists largely of clinopyroxene, amphibole, rock 

fragments, and opaque minerals (table 2). Many mineral grains are coated with red hematite(?); hence, 

sandbeds as well as gravel deposits have a reddish cast 

that distinguishes them from Cedar or Green River 

sediments.

Channel deposits of pebble-and-cobble gravel and 

sand cover nearly all the floor of the valley, and only 

discontinuous strips of medium and fine sand along 

the edges of the valley appear to be overbank material. 

Two samples of modern bar gravel along the White 

River were taken and sieved, in the same manner as 

those from Green River bars. One was taken approximately where the river enters the Auburn quadrangle, 

and the other where it leaves the quadrangle. In the 

upstream sample, the mean diameter was approximately 7 cm, and about half the stones were of cobble 

size. Boulders as much as 50 cm across were common at 

the site, and much larger ones derived from the Osceola Mudflow and from drift in the valley walls were 

evident on the flood plain nearby. In the downstream 

sample, the mean diameter was nearly 5 cm, and about 

30 percent of the stones were of cobble size. Boulders

as large as about 25 cm were fairly common, but significantly larger ones were absent. Large boulders 

would seldom be carried to the downstream site, which 

is near the center of Duwamish Valley, and those that 

were would soon be buried by aggradation there.

DUWAMISH VALLEY

Alluvium in the mapped part of Duwamish Valley 

forms a thick deposit that partly fills the deep, wide 

glacial trough that lies along the west side of the 

mapped area. Unconsolidated deposits underlying the 

valley floor are known from well borings to be at least 

several hundred feet thick (Luzier, 1969). In places, 

Vashon Drift, mantles the valley wall and passes down 

under the flood-plain sediments; lacustrine or fluvial 

stratified drift, as well as till, undoubtedly locally underlies the postglacial material at depth. The upper 

part of the postglacial sediments, of which about 100 

feet was penetrated by auger during this study, consists almost entirely of alluvium from the three major 

rivers of the area. Both White River and Cedar fiver 

alluvial sediments form extensive, distinct lithologic 

units in Duwamish Valley, although these units are 

interfingered and gradational along their margin"*. In 

contrast, alluvium of the Green River probably occurs 

only as a buried delta or fan that underlies YHiite 

River sediments at Auburn (fig. 21), as narrow tands 

of channel sediments along the modern river course, 

and as a minor constituent of the alluvium of the combined White and Green Rivers.

Alluvium of the Cedar River forms a distinct fan in 

Duwamish Valley at Renton. It slopes at about 15-20 

feet per mile from the mouth of Cedar River valley at 

the east edge of the city northward to and ber°-ath 

Lake Washington, westward to the opposite valley 

wall, and southwestward toward Tukwila. About 1^2 

miles southwest of the valley mouth, the fan passes 

under deposits of the White River. About 1 mile farther southwest at Longacres, Cedar River sediments 

underlie White River deposits at about 50 feet below 

the surface and extend to a depth of at least 90 feet. 

Logs of holes drilled in 1956 at the site of a Boeing 

Co. plant in the northern part of Renton, in the NW1^ 

sec. 8, T. 23 N., R. 5 E., show that the alluvium of the 

Cedar River there extends from the surface to a depth 

of at least 130 feet, about 100 feet below present sea 

level. The Cedar River fan consists largely of sand and 

gravel but includes interbedded layers of silt, clay, and 

peat and at least one layer of volcanic ash. With increasing distance from the mouth of the Cedar Piver 

valley, the gravel and sand not only become finer 

grained but are interbedded and overlapped by increasingly thicker deposits of sand and silt. Although
60 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

DRIFT PLAIN

13

100

A'

-100'

*-s Sand, 

~>CEDAR gravel, 

 ^ and peat 

RIVER

CAM V°ICaniC

FAN ash

_SEA 

LEVEL

h- 50'

-100'

FIGURE 21. Topographic map and section of upper part of postglacial fill in Duwamish Valley. Contours are in feet, sketched 

from U.S. Army Corps of Engineers map of Green and Duwamish Rivers, No. E-12-7-37; datum is mean lower low 

water. Hole 1 (black dot) is boring at Boeing Co. site; all others are U.S. Geological Survey auger holes.

largely covered by artificial fill now, peat formerly was 

fairly extensive at the surface along Duwamish Valley walls near Renton.

Most of the alluvium in Duwamish Valley, however, 

is included in a unit that is a fan of the White Kiver. 

The White Kiver fan forms the floor of the entire 

Duwamish Valley (except for that part formed by the 

Cedar River fan) from the Puyallup Valley northward 

to the Duwamish River mouth at Seattle (Willis, 

1898c). Lithologically, the fan consists dominantly of 

White River material, but north of the city of Auburn 

it contains a small proportion of detritus carried in by 

the Green River, which prior to 1906 joined the White 

at Auburn. Near its apex at the mouth of the White 

River valley, the fan is a smooth topographic feature 

that slopes outward at about 40 feet per mile. This distinct, relatively steep part of the fan is readily recognizable from the south boundary of the Auburn quadrangle northward to about the north edge of Auburn. 

Detailed contours of the valley floor (fig. 21) show that 

the White River fan even extends a few hundred yards 

up the Green River valley at Auburn. North of Auburn, the fan shape is much less distinct. The valley 

floor north of the city shows increasingly mor^ local 

relief and becomes characterized by multiple meandering channels, broad curved natural levees, and low 

flood-basin areas.

The main component of the White River fan is channel sand and gravel composed almost entirely of detritus from the White River. Where the river issues from 

its own valley, the channel deposits lie at the rurf ace, 

though farther down the fan .they become buried by a 

thickening wedge of overbank silt, sand, clay, ard peat. 

At the fan apex, the alluvium is chiefly coblxl e-andpebble gravel overlain by at most a few feet cf sand. 

The gravel becomes progressively smaller in size, and 

the overlying sand thickens with increasing distance 

from the apex. In three auger holes (nos. 9, 11, and 12, 

fig. 21), all between 2 and 3 miles from the apex, gravel 

was struck below 20-40 feet of sand; and in two 95- 

foot holes (nos. 13 and 8, fig. 21) in alluvium of the 

White River about 3 and 4 miles southwest anc1 northwest, respectively, from the apex, no gravel was encountered. North of Auburn, several other augor holes
GE OMORPHOLOGY 61

show that coarse to fine sand forms most of the alluvium under the thin wedge of finer overbank materials 

at the surface. From Auburn north to Tukwila, the 

sand unit was found to extend to at least 95 feet below 

the present surface (fig. 21). Clay and silt in minor 

amounts were recovered with the sand, but they apparently do not form thick layers. No peat layers were 

identified, though pieces of wood appeared to be distributed sparsely throughout the sand xmit.

Deposits at the surface from Auburn north consist 

chiefly of overbank silt, sand, and clay laid down 

partly by the Green River but mostly by the combined 

Green and White Rivers during times when the White 

flowed northward in Duwamish Valley. In the upper 

few tens of feet, channel gravel and sand apparently 

occurs only along present and abandoned channels of 

the main rivers; in abandoned channels, it probably is 

overlain by silt, clay, and peat. The overbank deposits 

generally range in thickness from a few feet to about 

40 feet. At a borrow-pit site in sec. 23, west of Kent, 

fine sand and clayey silt from 15 to 20 feet thick overlie 

coarse to medium sand, and in sec. 24 about 2 miles 

southwest of Renton, auger holes indicate that silt, 

clay, fine sand, and interbedded peat averaging about 

30 feet in thickness overlie coarse to medium sand. At 

the surface, material in natural levees consists mostly 

of fine sand and coarse silt, whereas finer silt, clay, and 

peat form the surface in flood basins between the levees 

and adjacent to the valley walls. Peat is especially 

abundant along the east and west sides of Duwamish 

Valley just south of Renton and Tukwila.

Fossils are widespread in Duwamish Valley fill and 

also in the Puyallup River valley fill to the south 

(Crandell, 1963). In Duwamish Valley, fossils have 

been recovered from an auger hole west of Kent at 

about 40 feet below mean sea level, from another auger 

hole near the Longacres race track southwest of Renton at about 40 feet to more than 50 feet below sea 

level, and from drill holes at a Boeing Co. plant site in 

northern Renton at about 75 feet below sea level (fig. 

21). Fossils from the Kent, Longacres, and Boeing 

plant holes, identified by E. J. Moore of the U.S. Geological Survey, were limpets (Acmaea), periwinkles 

(Littorina) , mussels (mytilid), Cryptomya, My a, barnacles, and a few echinoid spines, all of which are 

marine. According to Mrs. Moore, no fossils in these 

collections suggest a depth of water greater than a- few 

fathoms; and the limpets, periwinkles, mytilid mussels, and barnacles presumably lived where they were 

exposed at low tide. Hence, the fossils show that Duwamish Valley was an arm of Puget Sound during 

some parts of postglacial time. Furthermore, the presence of these tidal-range fossils at depths of as much 

as 75 feet below present sea level suggests that relative 

sea level during part of postglacial time was several 

tens of feet lower than at present.

Postglacial sediments have accumulated continuously in Duwamish Valley since retreat of the Vashon 

glacier. They began to form as the Cedar and Green 

Rivers built deltas or fans into the valley. The Ce'lar 

River continued to build its fan rapidly until the fan 

extended across the main valley and blocked off Lake 

Washington from Puget Sound. Studies of Lake Wrshington (Rigg and Gould, 1957; Gould and Budinger, 

1958) suggest that the lake was established by about 

13,500 years ago. Marine shells that may have t^en 

deposited while the lake was an arm of the sound are 

overlain by peat, two samples of which were dated as 

about 13,600 and 14,000 years old, respectively (Bi^g 

and Gould, 1957; Broecker and Kulp, 1957, samples 

L-330, L-346A). The layer of volcanic ash found in 

drill holes at the Boeing plant site in Renton may be 

part of the widespread Mazama ash that is about 6,600 

years old (Powers and Wilcox, 1964). If so, the 60 feet 

of alluvium of the Cedar River overlying the ash has 

been laid down at a rate of about 1 foot each hundred 

years.

However, most of the sediment in the valley in the 

White River fan was deposited in less than 5,000 ye^rs, 

or since the Osceola Mudflow diverted the lower segment of the river to Duwamish Valley at Auburn 

(Crandell, 1963). Deposition of White River material, 

as much as 300 feet thick (Luzier, 1969), thus occurred 

much more rapidly than deposition of the Cedar River 

sediments. Furthermore, deposition of the lower gravel 

and sand unit of the White River fan might have required only a small part of post-Osceola time.

GEOMORPHOLOGY

The dominant landscape features of the mapped 

area are the drift plain; the wide north-trending Duwamish Valley; and the narrower west- to northwesttrending Cedar, Green, and White River valleys. All 

these features originated during Quaternary time. The 

drift plain is part of a widespread, complex fill in the 

lowland that is composed largely of glacial sediments. 

The Duwamish Valley was excavated during or before 

the Vashon Stade the time and manner of origin of 

that and similar valleys (and the intervening driftplain segments) probably has been the most discussed 

geomorphic problem of the area. Most of the present 

drainage pattern was developed as the Vashon glacier 

retreated, though the White River was positioned Kter 

by the Osceola Mudflow. Entrenchment of the major
62 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

river valleys and aggradation of the Duwamish Valley 

floor have been effected chiefly or wholly by the Cedar, 

Green, and White Rivers in postglacial time.

ORIGIN OF DUWAMISH VALLEY AND ADJACENT DRIFT

PLAIN

Duwamish Valley ahd the adjacent segments of drift 

plain exhibit a relation typical of the Puget Sound 

lowland in that low-relief "plateaus" stand several hundred feet above wide northerly trending deep 

"troughs." Some of these troughs are arms of Puget 

Sound; others, like Duwamish Valley, formerly were 

arms of the sound but now are aggraded to above sea 

level.

The origin of the "troughs" and "plateaus" has been 

repeatedly discussed in the literature (LeConte, 1874; 

Kimball, 1897; Willis, 1898c; Bretz, 1913; Crandell 

and others, 1965). In most early reports, origin was 

attributed to either subaerial erosion of a preexisting 

plain by rivers or glaciers (LeConte, 1874) or preservation of preglacial valleys as the intervening divides 

were built up into plateaus (Willis, 1898c). Willis 

(1898c) first discussed the two ideas in detail, largely 

on the basis of his work in the Puyallup-Duwamish 

Valley. He referred to the first idea as the erosion 

hypothesis and to the second as the construction hypothesis. Willis noted that Vashon Drift not only 

mantled much of the Duwamish Valley wall, but also 

raised the adjacent drift-plain margins by deposition. 

Because he reasoned that the available evidence favored the construction hypothesis, he proposed that the 

Duwamish and similar valleys probably had been preserved through Pleistocene time by ice tongues that 

occupied preglacial valleys and had been maintained 

by them as ice-marginal outwash built up the adjacent 

divides into plateaus.

Later investigations, however, led to general acceptance of a version of the erosion hypothesis. Bretz 

(1913) noted that the plateaus were not constructed 

over bedrock divides and that continuity of some formations from plateau to plateau showed that they were 

parts of a continuous fill. According to Bretz, the fill 

formed during a single glaciation, the Admiralty. The 

troughs originated when rivers cut down into the fill 

as a result of as much as 1,000 feet of uplift during 

the interglacial interval prior to the Vashon advance. 

The valleys were then modified by the Vashon glacier 

and were drowned by submergence.

Hansen and Mackin (1949), Sceva (1957), and Crandell, Mullineaux, and Waldron (1958) confirmed that 

the valleys were cut into an overall fill, but they showed 

that the fill consisted of deposits of several different 

glacial and nonglacial episodes. No evidence was found

to negate Bretz' hypothesis of pre-Vashon origin by 

fluvial erosion caused by uplift, and of only modification of the valleys by the Vashon glacier.

As a result of recent detailed work in and near Seattle, however, Crandell, Mullineaux, and Waldron 

(1965) proposed that the Vashon Puget lobe formed 

at least one major trough in the lowland rather than 

merely modifying a preexisting valley into a trough. 

At Seattle, the deep Puget Sound trough is bounded 

by sea cliffs that expose a conformable sequence of 

nonglacial sediments of Olympia age and overlying 

Vashon advance outwash. Nonglacial sediments in the 

sea cliffs contain wood that ranges in age from 24,000 

to 18,000 years; elsewhere in the city, wood from the 

nonglacial sediments is as young as 15,000 years (Mullineaux and others, 1965). The stratigraphic sequence 

shows that the locality of the present Puget Sound 

trough was a site of aggradation as much as several 

tens of feet above present sea level thus near'y 1,000 

feet higher than the floor of the modern trough during the Olympia Interglaciation. Moreover, aggradation continued to several hundred feet higher before 

the site was overridden by the ice. But the, Puget 

Sound trough had already been fashioned in virtually 

its modern form when the glacier retreated; thus, the 

trough was formed under the ice and must lave resulted from ice scour. No regional uplift, fluvial erosion, or later submergence was required. Though the 

position of the modern Puget Sound trough might 

have been influenced by a previous valley, the trough 

was scoured by the Vashon glacier.

The manner of origin of the Puget Sound trough 

suggests that Duwamish Valley, once regarded as preserved from preglacial time and later as eroded by preVashon rivers, might alternately have been scoured by 

the Vashon Puget lobe. However, pertinent evidence 

along Duwamish Valley is meager and not adeauate to 

either prove or disprove such an origin. Some raising 

of the valley margins during Vashon time, as proposed 

by Willis, seems certain. But the troughs were not preserved from preglacial valleys, for remnants of the 

interglacial Puyallup Formation in both walls of the 

Puyallup-Duwamish trough show that the deep trough 

could not have persisted throughout Pleistocene time. 

Vashon Drift that was formerly thought to show that 

Duwamish Valley predated the Vashon advance is 

largely subglacial material that could have l^en deposited under the ice long after its first advance. Stratified drift deposited in front of the ice is very limited 

in size and distribution along the valley and does not 

prove existence of more than small, local depressions 

prior to the Vashon advance. Thus, no large Duwamish 

Valley formed by erosion can be shown to have existed
GEOMORPHOLOGY 63

during Olympia time. Finally, it cannot be demonstrated for Duwamish Valley (because of the absence 

of iionglacial sediments of Olympia age) that the site 

of the present valley was wholly or partly filled just 

before the ice advance, and that therefore the valley 

must have been produced by ice scour.

The available evidence does indicate that considerable ice erosion occurred. The very absence of nonglacial sediments of Olympia age suggests that any 

former valley along the same alinement must have 

been narrower than the present valley. If a former valley had been as wide, some remnants of iionglacial 

sediments should be found now in positions of former 

embayments or gullies in the valley walls. Second, 

aggradation to high levels along the Puget Sound at 

Seattle during noiiglacial time indicates that any preVashon Duwamish Valley would not have been as deep 

as the postglacial Duwamish trough. Aggradation at 

Seattle records a high local base level, and a preVashon Duwamish Valley should also have been aggraded to about the same level. Thus, a Duwamish Valley during Olympia time that was either as wide or 

deep as the one is now seems very unlikely. Ice scour, 

at the very least, must be responsible for much of the 

width and especially for the depth of the postglacial 

trough. The question of whether the valley was first 

or principally excavated by a river or by the Vashon 

glacier and, therefore, whether it originated during a 

pre-Vashon episode or during the Vashon Stade is still 

not answered. But similarity of the Duwamish to the 

Puget Sound trough suggests strongly that the valley 

was excavated chiefly by scouring by the Vashon Puget 

lobe.

DEVELOPMENT OF THE PRESENT DRAINAGE PATTERN

The modern drainage pattern within the mapped 

area developed almost completely in late Pleistocene 

and Holocene time, though the general system of 

major rivers formed much earlier. The river system 

began to develop during the Miocene, as rocks in the 

Cascade Range and the Puget Sound lowland were 

folded along north-northwest-trending axes (Weaver, 

1937). A new drainage system then became established 

along those structural trends (Mackin and Gary, 1965). 

By the end of Pliocene time, the Cedar, Green, and 

White Rivers probably all were flowing from the 

flanks of the rising Cascade Range northwestward 

across the Puget Sound lowland. The Cedar River at 

that time, however, was north of the bedrock barrier 

formed by the Newcastle Hills promontory (Mackin, 

1941). Later, in Pleistocene time, the Cedar River was 

diverted into the lowland south of that promontory by 

the Puget lobe (Mackin, 1941). The Puget lobe also

shifted the Green River so that it emerged from the 

Cascades several miles south of its preglacial exit (fig. 

22; Campbell and others, 1915). Mackin and Campbell 

presented evidence that initial diversion of each river 

occurred before Vashon time.

Thus, each of the major rivers had, before Vashon 

time, temporarily or permanently been directed into 

the lowland south of the Newcastle Hills promontory. 

Within the mapped quadrangles, coarse detritus of 

Mount Rainier origin clearly shows the presence of a 

river, presumably the White River, heading on the 

volcano. These sediments crop out along the east wall 

of Duwamish Valley north to about Kent and along 

the west wall to about Tukwila (H. H. Waldron, o~al 

cominun., 1966). Gravels of central Cascade provenance, which crop out along all the valleys east of the 

Duwamish, record the presence of one or both of the 

Cedar and Green Rivers.

Although deposits in the mapped quadrangles show 

the presence of the major rivers during at least parts 

of pre-Vashon Pleistocene time, distribution of what 

deposits are exposed gives little evidence of specific 

river courses. Only the sediments from Mount Rainier 

appear in a fairly linear distribution, which suggests 

a valley fill. These sediments are almost all along the 

western part of the area, a distribution that suggests 

early existence of a pre-Vashon north-south valley 

much like the Duwamish of today. Each of the other 

rivers probably flowed across many different parts of 

the area from time to time and at other times probably 

did not even enter the mapped area. Diversion of the 

Green River at the mountain front obviously required 

the river to find a new route at least once, and each 

river might have taken a virtually new course across 

the lowland after each glaciation.

It is possible that the Cedar, Green, or White Rivers 

did not cross the mapped area immediately prior to the 

Vashon advance. No extensive Vashon outwash and no 

sediments of Olympia age at all have been identified 

along the present valleys of those rivers. Absence of 

such deposits and continuity of pre-Vashon sediments 

along present valley walls suggest that the rivers are 

not now following courses established in pre-Vasl on 

time. In the Cedar River valley, a small deposit of 

stratified drift suggests the possibility that some depression existed there just prior to the Vashon advance, 

but no other similar deposits indicate that the depression was extensive. Thick Vashon stratified drift n°-ar 

Maple Valley and the low trough in the drift plain 

from there southwest to Auburn suggests a pre-Vashon 

depression along that route. However, fairly good exposures and apparent continuity of pre-Vashon formations in valley walls near Auburn indicate that the
64 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

122°00'

r rNewcastle Hills 

promontory

MILES

47°30'

47°00'

EXPLANATION

Abandoned preglacial courses of Cedar and Green Rivers near mountain front

Abandoned postglacial pre-Osceola course of White River

FIGURE 22. Location of abandoned segments of preglacial courses of Cedar and Green Rivers near front of Cs scade 

Range and of abandoned segment of postglacial pre-Osceola course of White River.

depression was not a major valley. That one or more 

rivers followed the route of the present Duwamish 

Valley seems possible, but supporting evidence is lacking.

EFFECTS OF THE VASHON GLACIER

Vashon Drift apparently smoothed over and concealed the drainage system over which the glacier advanced, and it constructed a new surface on which a 

consequent drainage developed. In general, the postglacial drainage was directed by the overall west to

northwest slope of the drift plain that characterizes 

this part of the lowland. In detail, the drainage was 

controlled somewhat by the alinement of groundmoraine ridges, but mostly by the pattern of late glacial 

melt-water channels. The positions of the melt-water 

channels were in turn controlled by successive positions 

and configurations of the receding ice front.

As the Vashon Puget lobe retreated, first th°> White 

River and then the Green and Cedar Rivers became 

established in consequent courses along melt-water
GE OMORPHOLOGY 65

channels in the lowland. The White flowed southwestward along the mountain front in a channel that led 

to the Puyallup Eiver by way of the present South 

Prairie Creek valley (fig. 22; Crandell, 1963). The 

White remained in that course until it was relocated 

by the Osceola Mudflow; thus, it did not flow into the 

mapped area in early postglacial time.

The Green Kiver joined an ice-marginal river at the 

mountain front and flowed with it southwest for several miles. For the first few miles, the combined melt 

water and Green River flowed in a broad spillway 

between bedrock hills that probably had been cut by 

repeated ice scour and melt-water erosion during the 

Pleistocene (fig. 22). Southwest of that spillway, the 

stream was held along or near the front of the Puget 

lobe by the overall northwest slope of the drift plain. 

As the lobe retreated, the combined flow occupied several successively lower and more northward courses. 

It occupied several different channels in the Lake 

Tapps quadrangle (Crandell, 1963) and several in the 

southern parts of the Black Diamond and Auburn 

quadrangles before reaching the present route of the 

Green River. Further retreat of the Puget lobe along 

the mountain front eventually allowed the melt water 

to find a more northern course, so that the ice-marginal 

stream on longer joined the Green River at the mountain front. The Green River, however, was prevented 

from taking a shorter, northwest- or west-trending 

course to the lowland by the combination of the southwestward gradient of the melt-water channel floor and 

the barriers formed by bedrock hills and stagnant iceblocks.

The Cedar River was deflected, along with abundant 

melt water, through the Cedar Spillway (Mackin, 

1941) into the lowland south of the Newcastle Hills 

promontory (fig. 22). The Cedar River and the melt 

water flowed from the spillway down the slope of the 

drift plain and across the Black Diamond quadrangle 

in front of the Puget lobe. The Cedar was probably 

only a small part of the large ice-marginal river that 

shifted gradually northwestward, forming, as it 

shifted, the broad outwash plain and later forming 

the valley train in the Covington channel. The 

Covington channel was abandoned when the river 

found a lower course to Duwamish Valley at Renton. By the time the river shifted to Renton, 

however, it may have consisted chiefly of the Cedar 

River itself rather than of ice-marginal melt water. At 

about the time of the shift, the ice-marginal river 

abandoned the Cedar Spillway to flow north of the 

Newcastle Hills promontory. Like the Green River, the 

Cedar was held in a southwest-trending spillway, even

after ice retreat allowed the melt water to reach the 

lowland by a shorter, lower route.

Many minor streams on the drift plain also followed 

melt-water channels, but others were controlled by the 

lineation of the Vashon ground moraine. Southeast of 

the Covington channel, the drift-plain streams almost 

all followed south- to west-trending melt-water channels that led away from the retreating ice front or 

laterally along it. Northwest of the Covington channel, 

the drainage is mostly consequent on drumlinized 

ground moraine. As a result, streams flow in a northnorthwest or south-southeast direction. The southeasttrending streams enter the Covington channel, wliere 

they join Big or Little Soos Creek and flow southwest 

to the Green River.

POSTGLACIAL CHANGES

Postglacial changes along the streams consist chiefly 

of entrenchment, distributary shifting on alluvial fr/iis, 

and relocations caused by the Osceola Mudflow. Both 

the Cedar and Green Rivers probably became quickly 

entrenched after retreat of the Vashon ice. As they did 

so, each built a fan and delta into the marine emtayment that then occupied the Duwamish Valley. The 

Cedar River probably blocked off Lake Washington 

from the Duwamish embayment very shortly after ice 

retreat (Gould and Budinger, 1958). The lake then 

drained to the^embayment by way of the Black River 

around the toe of the Cedar River fan. As the Ceiar 

continued to build its fan, it flowed at various times 

to Lake Washington, to the Black River, and directly 

to Duwamish Valley. Such shifting has been prevented 

since 1916, when Lake Washington was lowered and 

the Cedar River channeled artificially into the lake.

The principal change caused by the Osceola Mudflow was the deflection of the White River to Duwamish Valley at Auburn, evidence for which is found 

along both the old and new courses of the river (Crandell, 1963). Exposures along the modern White River 

valley southeast of Auburn indicate that no mp.jor 

valley existed there prior to inundation of the drift 

plain by the Osceola. No alluvium of the White River 

underlies the mudflow along that route, and the mudflow nowhere is seen as a thick valley fill. Instead, it 

occurs as a thin broad deposit over the surface of the 

drift plain. In the valley of South Prairie Creek, in 

contrast, the mudflow overlies coarse gravels of Meant 

Rainier provenance. The only possible source for the 

alluvium, according to Crandell (1963), was the White 

River, for South Prairie Creek does not head on the 

volcano. This and other evidence led Crandell to conclude that prior to Osceola time the White River flowed 

through the South Prairie Creek valley and that it
66 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

was later relocated to its present position by the mudflow.

After diversion to Duwamish Valley at Auburn, the 

White River entrenched itself and built a fan and 

delta in Duwamish Valley that rapidly raised the 

valley floor above sea level. As Willis (1898c) pointed 

out, the alluvial cone of the White River extended 

from the end of the Puyallup Valley at Tacoma to 

Elliott Bay at the end of Duwamish Valley at Seattle. 

The river flowed alternately north and south on its fan 

until 1906, when during a flood the main flow shifted 

from the northern to a southern > distributary. Since 

that time, the river has been held artificially in the 

southern part.

The Osceola not only relocated the White River but 

also diverted many small streams on the drift plain. 

One such stream, Newaukum Creek, enters the Lake 

Tapps quadrangle about 2 miles south of the Black 

Diamond quadrangle along a southwest-trending meltwater channel. The creek probably once continued to 

the Puyallup Valley in that channel. But the channel 

was overwhelmed by the Osceola, which directed 

Newaukum Creek north to flow down the gradient of 

the mudflow to the Green River in the Black Diamond 

quadrangle.

RIVER CHARACTERISTICS

Each of the three major rivers flows across the 

mapped area on a fairly smooth gradient, and each 

may be at or nearly at grade within the mapped quadrangles. The channel and flood-plain characteristics of 

the closely adjacent Green and White Rivers east of 

Duwamish Valley, however, are markedly different, 

even though these rivers formerly joined in Duwamish 

Valley at Auburn. The two rivers are similar in that 

they carry about the same discharge, they both rise in 

the Cascade Range and flow across the lowland in 

valleys cut into the drift plain, and until recently they 

both had a common local base level at their confluence. 

Yet above the former junction at Auburn, they differ 

conspicuously in size of bedload carried, gradient, channel patterns, migration habits, and flood-plain characteristics. There is also a conspicuous contrast between 

channel and flood-plain characteristics of the rivers 

east of Duwamish Valley and those in Duwamish Valley itself.

GREEN RIVER

Green River discharge as measured near Auburn 

averaged about 1,330 cfs (cubic feet per second) between 1936 and I960.1 The maximum recorded dis1 Data on river discharge used In discussion, unless otherwise stated, 

are taken from Water Supply Papers entitled "Surface Water Supply 

of the United States, Part 12, Pacific Slope Basins in Washington 

and upper Columbia River basin," published annually (to 1960) by 

the U.S. Geological Survey.

charge during the same period was 28,100 cfs in 1959. 

The gradient along the river from the east boundary 

of the Black Diamond quadrangle to Auburn decreases 

from about 20 to 5 feet per mile (fig. 23); the material 

that composes the bedload along the same stretch of the 

river decreases in median grain size from about 4 to 2 

cm. (Seep. 58.)

The Green River in its valley east of Auburn 

migrates primarily by cutting on the outside of meanders. Meander migration is rapid, and braiding is 

common along only two stretches of the river. These 

two are the localities where channel deposits are broad 

(p. 58), just down valley from the mouths of Newaukum and Big Soos Creeks. Below Newaukum Creek, 

comparison of the Auburn topographic map, made 

from aerial photographs taken in 1943, with field observations in 1957 shows shifting of the channel at one 

place as much as 1,500 feet in 14 years. Below Pig Soos 

Creek, comparison of the map with aerial photographs 

taken in 1953 shows migration of about 500 feet in 10 

years. Elsewhere on the valley floor, however, presence 

of large trees and old farms indicates that the river 

does not migrate nearly that rapidly over the flood 

plain as a whole.

WHITE RIVER

White River discharge measured at Buckley, 15 miles 

upstream from Auburn, averaged about 1,40C cfs for 

26 years of record before 1960, an average very close 

to that of the Green River. Some 600-900 cfs was 

diverted from the White River just below Buckley, 

however, and did not pass through the Auburn quadrangle. The average discharge at a station b?low the 

diversion over a period of 15 years was about 620 cfs. 

The maximum recorded discharge of the White between 1928 and 1960 was only about 17,000 cfs. However, an unrecorded maximum was estimated from 

flood marks at the gaging station to have reached about 

28,000 cfs in 1933, about the same as the maximum recorded flood along the Green River.

The southern distributary in which the White River 

now flows near Auburn has almost exactly the same 

length and gradient as did the northern distributary 

that formerly joined the Green River at Auburn; it is 

assumed that the White had approximately the same 

characteristics in both distributaries. The gradient of 

the White River from the point at which it eiters the 

Auburn quadrangle to where it leaves decreases from 

about 30 to 20 feet per mile (fig. 23). The median diameter of bar gravels along the same river reach decreases from about 7 to 5 cm. (See p. 59.) The White 

River thus carries a coarser load and maintains a 

steeper slope along a reach like the one above its former
mco 

<m 

m>

Cf &

e- W

(* 2

Elliott Bay (Puget Sound)

moo 

<m 

m>

 West edge of Renton quadrangle

moo 

<m

m>

Lake Washington (level varies slightly 

according to season)

 East edge of Renton quadrangle

Former junction of White and Green Rivers

 South edge of Auburn quadrangle

 East edge of Auburn quadrangle

 East edge of Black Diamond quadrangle

£|. 

P' 

vT 
68 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

meanders as well as by braiding. From the amount of 

the flood plain covered by fresh channel deposits that 

are nearly bare of vegetation, it seems certain that the 

White River moved across its flood plain as a whole 

much more rapidly than did the Green River. The 

more rapid migration may also be a result of the load 

supplied to the White River just upstream from 

Auburn quadrangle. A coarse load and high velocity 

are factors that lead to rapid lateral migration 

(Mackin, 1948).

IN DUWAMISH VALLEY

Stream gradient, bedload size, and rate of progressive channel migration along both the Green and White 

Rivers are distinctly less in Duwamish Valley than in 

the Green and White River valleys. Along the White 

River south of the Auburn quadrangle, natural changes 

are somewhat masked by several artificial factors, including the effect of reintroduction of diverted water 

to the river without bedload (Crandell, 1963, p. A55). 

North from Auburn, however, grain size and gradient 

decrease notably down the distinct White River fan 

and along the present channel of the Green River (fig. 

23). The size of most bedload particles has decreased to 

that of sand where the Green River leaves the mapped 

area at Tukwila, and the gradient of the river has 

decreased to about 1 foot per mile at. that point. The 

river does meander in Duwamish Valley north of 

Auburn, but cutting along the outside of the meanders, 

especially north of Kent, is slow. Levees that form on 

both sides of the river along the meanders, and peat 

layers interbedded in the overbank materials, provide 

evidence that the river does not shift rapidly by progressive migration of meanders. Another method of 

channel migration, that of avulsion or the shifting of 

whole segments of the channel at a time, appears to be 

much more important. Two long segments of 

abandoned channel that are similar in form to the 

present channel indicate that the river shifted extensive portions of its course at a single time rather than 

by progressive lateral migration.

FLOOD-PLAIN DEVELOPMENT

Flood plains of the Green and White Rivers within 

the mapped area are made up of widely varying proportions of the materials defined as channel deposits 

(deposits of lateral accretion) and of overbank material (deposits of vertical accretion) (Fenneman, 1906; 

Mackin, 1937; Jahns, 1947). The importance of overbank material in the formation of flood plains has been 

questioned by Wolman and Leopold (1957, p. 106), 

who concluded that for average flood plains "the proportion of overbank material appears to be small." The

flood plains of the Green and White Rivers in some 

places include very little overbank material; in other 

places they have more significant proportions cf overbank material, and in still other places they are composed largely of overbank deposits. The origin of the 

coarse channel gravel is easily recognizable, but, as 

Wolman and Leopold pointed out, the origin of the 

finer deposits may not be so evident. Deposits described 

as overbank sediments herein are identified by their 

occurrence on natural levees or by the presence c f interbedded peat material that should have been removed 

if the channel had migrated laterally past that site.

The flood plain of the White River east of Auburn 

serves as a local example of a flood plain with very 

little overbank material. The rate of channel migration 

there is rapid compared with the rate of overbank 

deposition; consequently, the flood plain consists 

largely of gravel or gravelly sand that clear1 y is a 

channel deposit.

The flood plain in the Green River valley contains 

considerably more fine material than that in the White 

River valley, but only a small proportion of it can be 

identified as overbank deposits. Channel migration 

over the whole flood plain is slower than along the 

White, and only a small part of the material at the 

surface is clearly channel gravel and sand. Finer materials that are probably of overbank origin, which are 

thin in the Black Diamond quadrangle, increase in 

thickness and volume westward toward Auburn. Although not certain, it seems likely that the trick silt 

and clay and peaty sands near Auburn are largely of 

overbank origin.

In Duwamish Valley, overbank material increases in 

proportion to channel deposits northward along the 

former course of the White River until, north of Kent, 

nearly the entire valley floor is formed of overbank 

sediments. Overbank materials are relatively tHck and 

extensive there because the river migrates mostly by 

avulsion, rather than by meandering, and thus it does 

not continuously rework the flood plain. Levees on both 

sides of the channel and presence of peat interbedded 

with fine-grained sediments between channels show 

that the active channel remains in place for long 

periods of time compared with the channels in the 

Green or White River valleys east of Auburn. Modern 

conditions in Duwamish Valley north of Kent apparently are similar to those in the Puyallup Valley 

in the Lake Tapps quadrangle, where remnants of 

volcanic mudflows on the flood plain show that the 

river has remained in a narrow course for at l°iast the 

last 500 years (Crandell, 1963, p. A55).

Thus, flood plains along the Green and White Rivers 

exhibit a wide variety in proportion of channel and
STRUCTURE 69

overbank materials, from one river to another and 

also along the same river over distances of as little as 

10 miles. Presumably all gradations eiist between 

flood plains composed predominantly of channel deposits and those consisting chiefly of overbank material, depending on local conditions that determine the 

rate and type of channel shifting (Mackin, 1948, p. 

503; 1956). Where the river migrates rapidly, the flood 

plain is composed mostly of channel deposits; where 

it shifts slowly and chiefly by occasional sudden diversion, the flood plain may be composed largely of overbank sediments. Locally, the flood plain in the White 

River valley east of Auburn illustrates the type composed mostly of channel deposits, and that in the 

northern part of Duwamish Valley illustrates the type 

dominated by overbank material.

STRUCTURE 

LOWER TERTIARY ROCKS

Regional deformation in the lower Tertiary bedrock 

produced major up warps and downwarps with axes 

10 miles or more apart (Weaver, 1916) and numerous 

smaller folds and faults. According to Weaver, the 

major structural features were developed along a 

regional west-northwest trend and extended acrqss 

what are now the Puget Sound lowland, the Olympic 

Mountains, and the Strait of Juan de Fuca. Mackin 

and Gary (1965) suggested that the west-northwest 

alinement of major streams in the Cascade Range 

indicates that the same regional trend extends virtually through the Cascades. Vine (1969) recently 

emphasized that a west-north west trend of gravity 

contours exists north and east of Renton. He also 

proposed that a hinge line having that same trend, 

which separates areas of markedly different thickness 

of Eocene sediments, was a major structural element 

as early as Eocene time, He pointed out, however, that 

in detail, structural elements do not faithfully follow 

a regional west-northwest trend. The Newcastle Hills 

promontory, which extends from the Cascade Range 

west-northwest into the Puget Sound lowland (fig. 22), 

is described as a major up warp by Weaver (1916). 

Rocks within this upland illustrate the many smaller 

folds and faults that are apparently related to the 

regional orogeny (Weaver, 1916; Warren and others, 

1945; Vine, 1969). These smaller folds and faults within 

the Newcastle Hills upland both parallel and diverge 

widely from Weaver's postulated regional trend.

In the report area, the principal structural features 

known are small anticlines and synclines whose axes 

are generally half a mile to a mile apart and a few 

faults. The presence of bedrock outcrops far out in

the lowland at Renton, in contrast to their absence to 

the south, is in accord with Weaver's hypothesis that 

this area lies along the flank of the Newcastle Fills 

upwarp. At Renton, the observed folds generally follow the postulated 'regional west-northwest trend but 

locally the strikes diverge considerably from it. Near 

Black Diamond, in contrast, the principal folds have 

a markedly different trend, slightly east of north. This 

northerly trend is not merely a local divergence from 

a regional trend, for similar folds trend north along 

the Cascade mountain front to the north, east, and 

south of Black Diamond (Weaver, 1916; Warren and 

others, 1945 ; Gard, 1968; Vine, 1969).

The bedrock structure in the Renton and Black 

Diamond districts has been studied repeatedly, chiefly 

in the search for coal. Detailed studies by Willis 

(1886, 1898a), Evans (1912), Weaver, (1916, 193T), 

and Warren, Norbisrath, Grivetti, and Brown (1945) 

all made use of exposures of bedrock in operating 

mines as well as those on the surface. Figure 24, which 

summarizes structure information in the Renton district, has been assembled largely from these earlier 

reports.

Most folds exposed near Renton are asymmetric 

anticlines and synclines whose limbs dip from about 

10° to 65°. They are somewhat irregular; either their 

axes curve or they are offset by faults, and some 

apparently die out along the strike. Correlation of 

features across even a mile or two of alluvium is 

uncertain. The principal folds are two anticlines and 

two synclines, the northernmost of which is the Renton 

anticline of Evans (1912) (fig. 24, this report). The 

Renton anticline extends from northwest to southeast 

Renton, plunging gently southeast; dips on its limbs 

range from a few degrees to about 30°. The adjacent 

syncline to the south, the Talbot syncline of Evans 

(1912), is exposed on the east wall of the Duwamish 

Valley. Its south limb dips about 65°, whereas its 

north limb dips only about 10°. East of sec. 19, its 

position is not known, but it may curve northeast and 

cross the Cedar River in sec. 21 (fig. 24). Northwestward, it is largely hidden under alluvium, but its 

probable position is indicated near the quadrangle 

boundary by exposures on a small hill in Duwamish 

Valley in sec. 24 (fig. 24). The crest of the next 

anticline south of the Talbot syncline, here called the 

Tukwila anticline, is hidden under alluvium, but its 

approximate location is indicated by exposures in the 

small hill in Duwamish Valley in sec. 24 and in the 

west wall of the valley at Tukwila in sees. 23 and 24. 

To the southeast, its north limb is exposed along the 

east wall of Duwamish Valley but its crest and south 

limb are not and apparently have been offset alorg a
70 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

R. 4 E. R. 5 E.

EXPLANATION

Selected contact in bedrock 

Approximately located Strike and dip of beds

65

Anticline, approximately located 

Shows crestline. Dashed where inferred

Strike and dip of beds underground in mine workings

Amount of dip shown when known

Horizontal beds

Syncline, approximately located 

Shows troughline. Dashed where inferred

U

Fault, approximately located

Dashed where inferred. U,upthrown side; D,downthrown 

side. Arrows show relative horizontal movement

FIGURE. 24. Principal structural features in lower Tertiary rocks of the Renton district, showing inferred correlation across 

Duwamish Valley. Data in part from Willis (1886, 1898a), Evans (1912), Weaver (1916, 1937), and Warren, Norbisratli 

Grivetti, and Brown (1945).
STRUCTURE 71

fault. Another syncline, here called the Springbrook 

syncline, lies south of this fault and is also exposed 

along the east valley wall.

The existence of another anticline, about 1,000 feet 

south of the Springbrook syncline (Warren and others, 

1945), could not be confirmed because the key outcrops 

along Panther Creek (fig.» 24) are so poor that the 

attitude of the beds there could not be determined. 

Willis (1898a), however, indicated that a lignite bed 

in the Panther Creek area dipped north rather than 

south as shown by Warren, Norbisrath, Grivetti, and 

Brown (1945). If the dip is actually to the north, no 

anticline is indicated just north of the Panther Creek 

exposures.

A few other folds are indicated by the outcrop pattern and by isolated outcrops. The curve of the outcrop 

of the middle member of the Tukwila Formation in 

northwest Renton suggests that in that locality a small 

syncline and anticline lie across the southwest limb 

of the Eenton anticline. Along the Cedar River east 

of Renton, reversal of dips in the Lincoln Creek(?) 

Formation indicates the presence of a northeast-trending syncline.

Two faults in the Renton district are large, but most 

known faults are small, with only a few feet displacement. The largest, here called the Sunbeam fault, 

trends eastward across the Duwamish Valley wall in 

sec. 30 (fig. 24; Warren and others, 1945). It brings 

the lower member of the Tukwila Formation up adjacent to the Renton Formation, separated from the 

Renton along the valley wall by only a small intrusive 

body. The fault apparently extends east-northeast, 

north of the outcrops of the Tukwila Formation in sec. 

29. This fault probably is responsible for the reversal 

of dip in the Tukwila Formation between sees. 30 and 

29; the axis of the Tukwila anticline south of the fault 

apparently has been shifted to the northeast. If so, the 

Sunbeam fault has at least 3,000 feet of left-lateral 

strike-slip displacement. Warren, Norbisrath, Grivetti, 

and Brown (1945) show a fault at the southeast end of 

the Sunbeam mine in sec. 29 as a part of this fault 

zone.

The second large east-trending fault has been inferred by Warren, Norbisrath, Grivetti, and Brown 

(1945) to underlie alluvium in the Cedar River valley. 

The Renton Formation strikes directly across the valley, yet the top of the formation on the north side is 

about 1,000 feet farther east than on the south side. A 

strike-slip fault with about 1,000 feet of the rightlateral displacement or a high-angle fault with the 

south block downthrown about 500 feet could account 

for the apparent displacement of the formation top.

Only one other fault, which is in northeast Eentcn, 

has been mapped in the Renton district in this investigation. The many small faults observed and shovm 

on mine maps and in earlier reports are typically highangle faults, and most are reported to be normal.

Near Black Diamond, the structure is dominated by 

a series of anticlines and synclines that trend generally 

north and are best exposed in the Green River valhy 

(Evans, 1912). The westernmost known anticline and 

syncline of this group lie about 1 mile apart in the 

Black Diamond quadrangle (Mullineaux, 1965c). T" 3 

anticline, the Black Diamond anticline of Evans 

(1912), is asymmetric and plunges north where it 

crosses the river; beds pn its east limb dip about 45°, 

and those on its west limb about 20°, indicating a westward dip of its axial surface. Between the Green River 

and the town of Black Diamond, this fold is interrupted by a small transverse syncline and by a fault 

(Willis, 1898a), which is the Franklin fault of Evans 

(1912). North of the fault the plunge reverses and 

the fold rises northward under the town; it then reverses again and plunges northeastward as the fcM 

axis curves just north of the town. At Black Diamord, 

the crest of the fold has been offset to the east and cut 

of the Black Diamond quadrangle. The rocks witliin 

the quadrangle lie on its west limb in a small we.itplunging transverse anticline whose core contains the 

oldest beds exposed within the quadrangle boundaries. 

A north-trending syncline west of the Black Diamond 

anticline is indicated in the Green River valley by reversal of dips between isolated exposures, which also 

indicate that the axis of the fold plunges south (Mullineaux, 1965c).

Exposures, drill records, and mine records show tl at 

the bedrock near Black Diamond is broken by many 

small faults, but only one major fault is known in the 

quadrangle. It is the Franklin fault or fault zone, 

which was discovered during early mining and geological explorations (Evans, 1912). The Franklin is 

a strike-slip fault that passes just south of the town of 

Black Diamond and shows about 1,000 feet of rightlateral displacement along a west-northwest tre^d 

(Warren and others, 1945; Vine, 1969). Most smaller 

faults observed and reported from the mines are high 

angle and normal. Anderson (1959), however, suggested by a cross section of the rocks near Black Diamond that reverse faults are also common.

From evidence in the mapped area, the major deformation can be dated only as younger than upper 

Eocene and lower Oligocene Puget Group rocks near 

Black Diamond and older than the overlying upper 

Miocene Hammer Bluff Formation. Major regional 

diastrophism in this region, according to Weaver
72 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

(1937), occurred in late Miocene time, after deposition 

of the Oligocene and Miocene rocks that crop out near 

Issaquah. Strong deformation, however, was not 

limited to one episode but occurred at several times 

during the Oligocene and Miocene and at various 

localities (Fiske and others, 1963; Gard, 1968; Vine 

1969). Thus, folding of the lower Tertiary rocks of 

the report area might have occurred at any time between early Oligocene and late Miocene time.

UPPER TERTIARY ROCKS

The upper Tertiary Hammer Bluff Formation shows 

minor deformation that occurred after the folding of 

the lower Tertiary bedrock. Exposed Hammer Bluff 

lacustrine clays and lignite show dips as high as 10°; 

dips as high as 25°-30° have been reported in the formation by Glover (1941). It is not certain how much 

of the steeper dips is due to deformation and how much 

represents initial dip. Attitudes in this formation vary 

considerably within individual exposures, and their 

determination is complicated by numerous landslides. 

However, near Hammer Bluff, observed dips were consistently to the north and northwest on the north side 

of the river and to the southwest on the south side. 

Half a mile east of Hammer Bluff, the formation dips 

gently eastward. Glover (1941), measured northwest 

dips at Hammer Bluff and a northeast dip only a 

quarter of a mile to the southeast. He pointed out that 

there apparently is a gentle arch or anticline in the 

formation at the Hammer Bluff locality (Glover, 1941, 

1936). Although faults have been found in deposits in 

the Lake Tapps quadrangle that are correlated with 

the Hammer Bluff Formation (Mullineaux and others, 

1959), none have been observed in the Hammer Bluff 

itself.

The deformation of the Hammer Bluff Formation 

apparently does not represent recurrent folding along 

the structural features shown in the bedrock, because 

the arch in the Hammer Bluff beds lies over a synclinal 

trough in the bedrock. Gentle dips are common in 

various deposits that have been correlated with the 

Hammer Bluff Formation (Glover, 1941; Mullineaux 

and others, 1959) ; thus, the deformation apparently 

was widespread.

PLEISTOCENE DEPOSITS

Pleistocene sediments generally are nearly flat lying 

and are little deformed, but they show an apparent 

gentle overall tilt to the west, a few small folds, and 

numerous small faults. The tilt to the west is best 

shown by the Pleistocene sediments exposed along the 

Green and Cedar River valleys. Along the Green River, 

the lower (?) Pleistocene Orting(?) Drift dips gently

west and passes under the middle (?) Pleistocene intermediate drift. At one place, Orting(?) lacustrine beds 

that dip 2°-3° W. are well exposed along the river for 

several hundred feet. The overlying intermediate drift 

also appears to dip gently west, but at only abcnt 30-40 

feet per mile. Along the Cedar River valley at Renton, 

thin nonglacial lacustrine beds that dip as much as 5° 

to the northwest can be traced for more than 1,000 feet. 

The general westward dip of Pleistocene sediments 

along the Green and Cedar Rivers is inferred to be a 

result of broad tilting associated with relative subsidence of the Puget Sound lowland, the central part 

of which is west of the mapped area. Along tlie Cedar 

River, the effects of local tectonic deformation or unequal compaction might have been superimposed on 

the overall gentle dip.

Small folds have been seen in all mapped Pleistocene 

formations except the Vashon Drift. Dips that exceed 

a few degrees occur mostly in foreset beds and collapsed 

strata in glacial drift. Elsewhere, dips are low, and 

very few exposures are large enough to show whether 

the dipping sediments occur in small folds or fault 

blocks. In a few places, series of small folds have been 

observed. Along the White River, well-exposed lacustrine beds in the intermediate drift are folded into a 

series of anticlines and synclines only a few tens of 

feet across. Although the origin of most dips in the 

Pleistocene sediments is obscure, it seems likely that 

one of the most common causes is differential settlement over irregular topography and that oth^r causes 

are subaqueous sliding and ice shove.

Faults that are common in the Pleistocene deposits 

typically are high angle and small. The largest known 

fault shows only about 30 feet of displacement, and 

most faults show only a few inches to a foo* or two. 

The largest fault, which is exposed along the Green 

River (Mullineaux, 1965c), is downthrown about 30 

feet on the east side. It cuts through 200 fee* of Orting (?) glaciolacustrine and fluvial sediments and is 

not associated with smaller faults. Most smaller faults 

occur in clusters in stratified drift, but some cut 

through peat-bearing nonglacial sediments. Probably 

ice shove or ice melting and subsequent collapse are 

responsible for most small faults in drift units, but 

larger faults that occur alone seem to indicate a tectonic 

origin. No faults were seen that cut entirely through 

the Vashon Drift.

SUMMARY OF GEOLOGIC HISTOPY

The stratigraphy and geologic history of tK area of 

the Renton, Auburn, and Black Diamond quadrangles 

and nearby parts of the Puget Sound lowland are summarized in figure 25 and table 5. The following inter-
H* S- 

'"I ff

O5 O

to OR

P 1-0 

B r?

Eocene v » J \

xi

Middle

v Oligocene

Late s x

\

Puget Group

fo

^^ - P

"1 9 *< ft! 3'

3£.g-|<*

(/) p 3 »-j

K ED ^

& & §

3 K rt*

§l: l

"-(

 -(1CO

o

85 ff ° §

rt o o ~.

uous deposition on subsiding 

tal plin.Submergence, locally 

?low sea level. Probable volcanis: 

>me places inlowland

3

n

n ^ HI-I

3 3 'B H 

3 § " |

3 S'o ° 

rt 3 C P 

ft^co 3^ 3

5"

>-( Oco_ rs'

37*

CO

Tukwila Formation

r

J 3 °

£*!* * 3 ~> 

1 !T 

£, ^

CO ft! O,

^30

111 S-'"

^ o' ^?

^ m"

l-j Jj

Q 3

£ s.

CO !

5J3

Hh

£!

g

^p 3 s:

e S. <B 0- 

5T 3 rT

1 IT P *<

> wo

2. S'

>-( on

9?

CO

pi!

1 sr P *<

>-< co 3 

C TO Uj

 a n. <B JiT' co

CO 3 ft

ft

HJ

V!

WTO3?S1 C 

ft!

5'

> w

g. n

*i On

7?

CO

Unbroken sequence of arkosic rocks in some places

Continuous aggradation of arkosic sediments

Formerly submerged area rj

above sea level

B.

CO

n.

Intermittent volcanism, at

more than one center on 

coastal plain

Volcanis] 3

Pause involcai surficial wea

ft ti 3*55

<B a

3.-3. 3

Arkosic aggra overlaps pai 

volcanic mo

g So-

^2,5' 3

Volcanism res volcanic ma spread over of arkosic p

 rt r-1 

ft! ^3 (fc 5

3 » I'-8?

Volcanism ceases. Arkosic aggi buries volcanic formation

B. Po"3

O

(B£

(B3

Hh 

S'

a.

Local erosion

r 

22^3'

Mfs.

3- <L3 3

£ 1 ' §' »

CO

rs a co 3 

O 3 & Q,

3- ^ &co

^' P' 3 ft"

(B <B g n'

^ n, i-J

e<<3rs-w

_ ..^ _ Q

ro IT <5 y.f

3 9 o fT

0 ^ P ft!

(g ^3 3.

p. 3 <B co

n in position ofCascade Range; volcanic detritus brought into

1; locally, subsidence rapid

to submerge area below sa leve

M

o3

51S

Hh

n.

O>-J O1x

ft!

g, C

"S.

Hh

W

rosion andsurficial weathering

r

2 1 3 *

0" 

(B

,O

r£

2.^

K N

3.8 £*-. (B

n C

^§

^ ^

3

£

:athflala

edimentation inlowland
74 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

TABLE 5. Summary of Quaternary stratigraphy and geologic history in Puget Sound lowland southeast of Seattle

[Modified from Crandell (1963, table 4)]

Time

HOLOCENE

MIDDLE(?) LATE PLEISTOCENE AND 

MIDDLE PLEISTOCENE AND EARLY(?) 

FRASER GLACIATION, VASHON STADE

OLYMPIA INTERGLACIATION

SALMON 

SPRINGS 

GLACIATION

PUYALLUP GLACI- INTER 

ATION

STUCK 

GLACIATION

ALDERTON 

INTER GLACIATION

O

Approximate age 

(years)

5,000 

6,600

13,500 

15,000

>38,000

Deposit

Postglacial fluvial andlacustrine deposits

Vashon Drift

Salmonprings 

Drift

Puyallup Formation

Intermediate drift; Stuck 

Drift in

Lake Tapps quadrangle

S3 3? 

o &

Ipri

n*

Alluvii

Osceols 

Volcan

Cedar

1-2-S

K

Till.-.

Advant

Nongla

Gravel 

Gravel 

Till...

Volcan 

Nongla 

Till...

Sand a

Peat-.

Volcan 

Volcan 

Alluvii

Silt am 

Till...

Fluvia 

Till...

Alluvii

Till...

Laeust 

Till...

Sand a 

Till...

,e drift.. ._..._..._-.__..__._......._..___

Event

Rise in relative sea level. 

§ Duwamish Valley fill emplaced.

'fcj

"jq O

J 3 White River emplaced in present course. 5 Eruption of Mount Mazama. 

 g i Relative sea level lower than at present.

-all

'> m Formation of Lake Washington.

3

Marine water invades Puget Sound.

Proglacial lakes formed in Puget Sound. 

Retreat of Puget lobe.

Occupation by Puget lobe.

Advance of Puget lobe.

Fluvial and lacustrine sedimentation. 

Surflcial weathering.

Reestablishment of northwesterly flowing streams. 

Retreat of Puget lobe. 

Occupation by Puget lobe. 

Eruption of Mount Rainier (?). 

Some climatic warming. 

Occupation by Puget lobe. 

Alluviation. 

Onset of glaciation(?).

2) o w S « Erosion and surficial weathering. 

.3 "S rt g § Lacustrine sedimentation in closed basins. 

'a S'-S J3 8 Volcanic eruptions of Mount Rainier(?). 

i ? 3 % o. Reestablishment of northwesterly flowing streams.

Formation of proglacial lake during retreat of Puget lobe. 

Occupation by Puget lobe. 

Retreat of Puget lobe. 

Occupation by Puget lobe.

Erosion (in Black Diamond district). 

Fluvial and mudflow accumulation in Lake Tapps quadrangle . 

Northwesterly flowing streams reestablished or established.

Occupation by Puget lobe. 

Retreat and formation of proglaeial lake. 

Occupation by Puget lobe. 

Retreat of Puget lobe. 

Occupation by Puget lobe.
SUMMARY OF GEOLOGIC HISTORY 75

pretation of history is based on geologic evidence in 

the three mapped quadrangles, 011 the literature cited 

previously, and in part on as-yet-impublished results 

of U.S. Geological Survey investigations in adjacent 

areas. The known history of the area starts in the 

Tertiary with the oldest rocks exposed in this part of 

the lowland, which are of middle Eocene age.

TERTIARY PERIOD

In middle and late Eocene time, the Puget Sound 

lowland was part of a coastal plain in a subsiding basin 

or geosyncline. Sediments accumulated in the basin at 

about the same rate as it subsided. The basin fill consisted mostly of slowly and continuously deposited 

arkosic sediments of the Puget Group derived from the 

east and locally of more rapidly but intermittently 

deposited volcanic rocks and sediments of the Tukwila 

and similar formations derived from eruptive centers 

on the coastal plain. The plain extended from south of 

Washington north at least as far as Renton and Seattle; 

it extended east at least to the position of the present 

Cascade Range and locally farther, into what is now 

central Washington. No high mountain range like the 

Cascade Range of today existed in Eocene time, and 

the coastal plain may have covered a large part of the 

area of the present central Cascades. The climate during middle and late Eocene time was subtropical or 

temperate.

During part of the middle Eocene, a marine embay - 

ment in western Washington reached north as far as 

Seattle and, at that latitude, east as far as Tiger 

Mountain. Twenty-five miles south of Tiger Mountain, 

however, it apparently did not extend as far east and 

did not reach Carbonado. Andesitic and arkosic sediments were deposited in the marine embayment in the 

vicinity of Seattle and Tiger Mountain. Subsequently, 

the sea retreated and continental sediments of the 

Puget Group were deposited on the marine sediments.

In late Eocene time, volcanic activity either began or 

became more intense at eruptive centers on the coastal 

plain, one of which was somewhere east of Renton near 

Issaquah. Volcanic rocks and sediments, the Tukwila 

Formation, derived from this center, accumulated 

rapidly. These deposits raised the surface of the coastal 

plain near Renton higher than the aggradational surface of the arkosic sediments. Rocks in the Tukwila 

Formation record both explosive and quiet eruptions 

during this part of the period. Deposition of the volcanic detritus was intermittent; during pauses in deposition, exposed sediments in some places were weathered 

to clay and then were overlapped and covered by continuously aggrading arkosic sediments. Later, these

arkosic sediments were covered by more volcanic 

detritus during another episode of rapid accumulation 

of Tukwila volcanic material. Farther from the eruptive center, near Black Diamond, aggradation of 

arkosic sediments continued virtually undisturbed by 

the volcanic activity.

After volcanism ceased in Tukwila time, arkosic 

sediments of the Renton Formation overlapped and 

covered the Tukwila Formation. During depositior of 

the Renton, the area of the southeastern part of the 

Puget Sound lowland still was mostly a continental 

coastal plain of low relief near sea level. The plain 

probably was similar to the surface of large mocVrii 

deltas; bedloads of sand were carried by the rivers 

that crossed the plain, and the areas between the rivers 

were occupied by swamps, lakes, and lagoons. The 

rivers aggraded and shifted back and forth across the 

plain as it subsided, and they deposited a sequence of 

interbedded sand, silt, clay, and peat more than 2,000 

feet thick.

Near the end of Eocene time, volcanic activity and 

perhaps uplift in the position of the present Cascade 

Range cut off the area of the Puget Sound lowland 

from the source of arkosic sediments, and deposition 

of the Renton Formation ended. A volcanic mountain 

range formed east of the position of the present Jowlaiid. Volcanic detritus from this range was brorght 

into the basin, and deposition of the Lincoln Creek (?) 

and correlative continental formations began. Rivers 

became swifter or increased in volume enough to carry 

boulder gravel nearly to Black Diamond and pebble 

gravel as far west as Renton. At the same time, the 

rate of subsidence at Renton increased markedly; although the rate of deposition probably also increased, 

the Renton district was submerged to several hundred 

feet below sea level during deposition of part of the 

Lincoln Creek (?) Formation. At Black Diamond the 

coastal plain remained above sea level, but its character had changed from that of Renton time. During 

Lincoln Creek (?) time the coastal plain was narrower, 

it was crossed by swifter, more rapidly aggrading 

streams, and swamps on it were ephemeral or abrent.

Deposition of marine andesitic sediments like those 

of the Lincoln Creek (?) continued in the region near 

Renton, at least intermittently, through much of the 

Oligocene Epoch. In middle or late Miocene time, 

after rocks in western Washington had been folded 

and faulted, the area of the Puget Sound lowland was 

raised above sea level. After this deformation and 

before the end of Miocene time, the region was eroded 

to a surface of low relief, and the rocks were weathered 

and leached.
76 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

111 late Miocene time fluvial and lacustrine sediments of the Hammer Bluff Formation were deposited 

near Black Diamond. The lithologic change upward 

in the Hammer Bluff to andesitic sediments derived 

from Tertiary andesitic rocks of the Cascade Range 

from the sediments that were derived locally from 

arkose suggests that some uplift of a nearby range to 

the east occurred in late Miocene time. However, the 

range did -not become high enough or continuous 

enough to be a climatic barrier, as it is at present.

During Hammer Bluff time, volcanic eruptions in 

the Cascade Range produced andesitic rocks that are 

rich in green hornblende and notably different from 

most volcanic rocks in the Cascades. Detritus from 

these eruptive centers was deposited along both the 

east and the west flanks of the range. It forms much 

of the upper Miocene and lower Pliocene Ellensburg 

Formation in central Washington and occurs in several upper Miocene formations along the west side of 

the Cascade Range from Hammer Bluff southward.

During late Miocene or Pliocene time, the Hammer 

Bluff Formation was mildly folded. In addition, it 

was exposed to weathering during much of Pliocene

time.

QUATERNARY PERIOD

In Pleistocene time, the Puget Sound lowland repeatedly was occupied by a lobe of the Cordilleran 

glacier, which advanced southward from British Columbia. The oldest glaciation recognized in the lowland, the Orting, may have occurred in early Pleistocene time (table 5), but its precise age is not known. 

The Puget lobe of Orting age advanced to the front 

of the Cascade Range southeast of Seattle and probably extended several tens of miles south of Seattle. 

The glacier advanced across the Black Diamond district two or three times, retreating an unknown distance between advances. Gravel in the drift contains 

stones probably derived from an ancestral Mount 

Rainier, indicating that such a volcano would have 

been in existence before the end of the Orting 

Glaciation.

The Alderton Formation was deposited on the 

Orting Drift during the interglaciation that followed 

the deposition of the drift. Pollen studies show that 

the climate during part of Alderton time was as warm 

as it is in the Puget Sound lowland today. The Aiderton Formation attests to the fact that streams carried 

volcanic detritus derived from Mount Rainier more 

than 30 miles northwest of the volcano into the Lake 

Tapps quadrangle. However, no Alderton deposits are 

exposed in the Renton, Auburn, and Black Diamond 

quadrangles to show that the Alderton reached as far 

north as the mapped area.

The Stuck Glaciation followed the Alderton Interglaciation. Probably at some time during this episode, 

the drift formation termed "intermediate" was deposited in the area between Auburn and Black Diamond by the Puget lobe. The lobe advanced across the 

mapped area least twice and deposited two widespread sheets of clayey till and an intervening 100 feet 

of stratified sediments.

The climate during part of the succeeding Puyallup 

Interglaciation was again as warm as it is in the lowland now. Streams in the southeastern part of the 

lowland were reestablished in northwesterly courses, 

and they carried sediments derived from Mount 

Rainier at least as far as Kent, about 50 miles northwest of the mountain. Alluvium and mudflows derived 

from Mount Rainier, together with lacustrine silt and 

clay, volcanic ash, and peat, were deposited in the 

lowland during the Puyallup interval. In places these 

deposits were eroded and subjected to a long period 

of weathering during a later part of the long P lyallup 

Interglaciation.

Early in the Salmon Springs Glaciation, which followed the Puyallup interval, and before the Puget 

lobe reached the mapped area, much of the region near 

Auburn was covered with gravel and sand deposited 

by rivers heading in the Cascade Range. The Puget 

lobe then, during the Salmon Springs Glaciation, advanced south of Auburn at least twice. At Auburn, 

no significant time interval between the two advances 

is evident. A few miles farther south, however, a 

climate somewhat warmer than glacial, but still cool 

and moist, is recorded between the two S.almon, Springs 

advances. After the glacier retreated, streams were 

again established in northwesterly courses, bringing 

sediments of Mount Rainier provenance again about 

as far north as Kent.

In late Pleistocene time, the Puget lobe of Vashon 

age occupied the entire Puget Sound lowland, extending about 50 miles south of Renton. Virtually the 

entire mapped area was covered with ground noraine. 

The glacier probably was at least 3,000 feet thick at 

Renton; it rose to nearly 3,000 feet above sea level,on 

Tiger Mountain east of Renton and to about 1,500 feet 

against the Cascade Mountains southeast of Blrck Diamond. North-trending valleys were formed or deepened by scour during the glaciation, but most westtrending valleys were filled with drift.

As the Vashon glacier retreated across the mapped 

area about 14,000 years ago, a large ice-marginal river 

flowed along its east boundary, then flowed westward 

across the drift plain to Duwamish Valley. The Duwamish and similar valleys in the lowland then contained proglacial lakes, because the glacier still blocked
ECONOMIC GEOLOGY 77

drainage to the Strait of Juan de Fuca. One lake in 

Duwamish Valley stood more than 250 feet above 

present sea level when the ice-marginal river built a 

large delta into it at Auburn.

By 13,500 years ago, the glacier had retreated northward far enough to permit marine water to enter 

Puget Sound and Duwamish Valley. A short time 

after the sea invaded Duwamish Valley, alluvium of 

the Cedar River blocked the valley at Renton, and 

Lake Washington was formed north of the dam. 

Duwamish Valley began to fill slowly with sediment 

brought in by the Cedar and Green Rivers, but part of 

it remained an arm of Puget Sound until after 5,000 

years ago. About 6,600 years ago, volcanic ash was 

spread over the Puget Sound lowland, becoming interbedded with postglacial lacustrine and alluvial sediments over the entire area. During these times, the 

land stood several tens of feet higher, relative to the 

sea, than it does now, and it remained higher until 

some time after 5,000 years ago.

About 5,000 years ago, a large volcanic mudflow 

came down the White River valley from Mount 

Rainier. As it spread out in a digitate lobe on the 

drift plain, it partly filled the premudflow course of 

the White River, which was across the plain into the 

South Prairie Creek and Puyallup River valleys. The 

White River then became established in a consequent 

course down the axis of the mudflow lobe, emptying 

into Duwamish Valley at Auburn. The river cut into 

the mudflow and the underlying drift and carried the 

material derived from these deposits into Duwamish 

Valley. Heavily loaded, it built a broad fan in the 

valley, aggrading the valley to above sea level. Distributaries flowed alternately south and north along 

Duwamish Valley, the southern distributary extending 

the fan to the Puget Sound at Tacoma and the northern one extending it to the sound at Seattle. The river 

continued to flow alternately north and south until 

1906, when it shifted to the southern route during a 

flood. Since that time, the river has been artificially 

restricted to the southern channel.

ECONOMIC GEOLOGY

This description of economic geology treats engineering implications as well as rock and mineral resources. 

Application of geology to land use is even now an 

important aspect of the economic geology of the 

mapped area, and it will become more important as 

urbanization spreads southeast from Seattle. Natural 

resources being exploited are principally sand and 

gravel and construction stone. Mining of coal and clay 

formerly was important within the mapped area, but

by 1961, coal mining had ceased and clay mining tad 

dwindled to minor operations. Production of silica 

sand, however, was still maintained after 1961. Possibility of economic oil and gas resources in the Puget 

Group continued to attract attention, although no 

producing wells had been drilled. Peat and topsoil 

production was sporadic; only one operator was reported in production in 1960 by Thorsen (1961).

ENGINEERING GEOLOGY

GEOLOGIC CONDITIONS THAT INFLUENCE LAND USE 

Land use in glaciated areas such as the Puget Sound 

lowland is especially influenced by the character of 

underlying materials. To make the advantageous use 

of the land, availability of both generalized geologic 

information and site data is desirable. Geologic maps, 

resulting from this study (Mullineaux, 1965a, b, c) and 

table 6, which briefly summarizes principal engineering 

properties of map units, are intended to provide some 

generalized geologic data. Engineering properties of 

some widespread ground conditions have also been 

provided by McLerran and Krashevski (1954) in an 

engineering soils manual designed to be used with the 

soils map of King County (Poulson and others, 1952). 

None of the generalized data, however, should be 

considered a substitute for site studies for specific 

projects. Geologic formations in glaciated areas are 

characterized by a wide range of physical propert;<1 s. 

Generalized data can provide an idea of the range of 

properties or of an average, but local conditions can 

vary crucially from the average.

Besides providing a qualitative comparison of properties of various units, table 6 is intended to provide 

some warning of special geologic conditions that co^ld 

significantly affect engineering projects. Some of ttase 

conditions, and sources of further information regarding them, are treated in the following paragraphs.

OVERCONSOLIDATION OF BINE-GRAINED SEDIMENTS

A great difference in physical properties exists 

among the fine-grained deposits simply called silt, 

clay, and peat in this report. These differences, resulting chiefly from the compression of some deposits by 

thick glacier ice, are widely recognized by local geologists and engineers but should be emphasized nevertheless. For that reason, table 6 separates fine-grained 

sediments above the Vashon Drift from other such 

sediments in and below it. Postglacial silt, clay, r.nd 

peat deposits are, in general, normally consolidated in 

a soils engineering sense. Typically they are loose r.nd 

soft, have high water contents, and have low bear;ng 

and shear strengths. Heavily overconsolidated (or p^econsolidated) pre-Vashon silt, clay, and peat deposits,
78 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

TABLE 6. Generalized description of engineering properties of principal

[From Mullineaux (1965a, b, c). Soil groups

Units (Symbols used are from 

Mullineaux, 1965a, b, c)

Special features Drainage Ground water

Artiflcialflll (af)..------------------_--- Includes wide variety of natural and man- Highly variable, dependent on content Highly variable, dependent or content and

made inorganic and organic debris. and method of emplacement. method of emplacement.

Alluvium of major rivers (Qac) (Qag) 

(Qaw).

Material varies widely in size and charac- Infiltration slow to fast, dependent on Water table usually near surface. Permeteristics along various rivers. See text. grain size. Runoff generally poor be- ability greater horizontally than verticause of low surface slope. Susceptible cally because of interbedcJed layers of

to flooding. fine and coarse material.

Deposits of mass-wasting processes 

(Qmc) (Qms).

Includes intimately mixed material and 

discrete blocks from other mapped units. 

Movement as blocks and flows common.

Infiltration slow. Runoff locally good but 

in many places poor because of closed 

depressions. Springs common.

Water table often near 

ability generally low.

surface. PenneLacustrinepeat andmuck (Qlp) (Qlm)..

Lacustrine silt and clay (Qlc).

Consists mostly of flne-grained, highly 

compressible material with low shear 

strength. Locally thick. Some bogs contain abundant interlocked fibrous 

woody material especially in upper part; 

low pH typical.

Mostly mixtures of bedded silt, sand, and 

clay. Overlain in places by thin peat 

deposits.

Runofl poor, unit occupies closed depressions. Frequently flooded.

Infiltration slow. Runofl generally poor 

because unit has low surface slope.

Water table usually at or near surface. Permeability variable.

Water table generally near surface. Permeability low, probably greater horizontally 

than vertically.

Osceola Mudflow (Qom).

Ice-contact stratified drift of small meltwater streams (Qsr, Qiv, Qis; Qit 

and Qik north of Auburn).

Unsorted mixture of stones, sand, silt and Infiltration very slow. Runofl poor be- Water table may be very near surface. Perclay. Boulders common. Contains abun- cause of flattish surface. Generally meability low.

dant montmorillonite. drained by ditches.

Sand deposits, mostly gravelly except for Infiltration generally moderate to fast on Water table low where deposit lies on slope; 

silty fine sand (Qis). Collapsed strata natural surfaces; fast on stripped sur- high where it lies on valley floor or in 

common. Boulders and blocks tff till faces. Runoff generally poor to mod- drift-plain depression. Permeability genscattered, erate. erally high.

Proglacial stratified drift of large melt- Well-sorted (uniform) loose gravel and Infiltration generally moderate to fast on Water table generally low. Springs in basal

water rivers (Qpd, Qpo, Qpv, Qpa). sand. Deposits of large rivers in various natural surfaces; fast on stripped sur- zone common where it overlies till. Pertopographic positions. Locally thick. faces. Runoff generally poor because of meability generally high.

	infiltration and low surface slope.

Ice-contact stratified drift of large melt- Irregularly shaped, collapsed deposits of Infiltration moderate to fast on natural .... .do....--..-... -._-..- . 

water rivers (Qik in Black Diamond sand and gravel. Contain scattered surfaces, fast on stripped surfaces. Runquadrangle; Q it south of Auburn). boulders and blocks of till. off generally poor because of infiltration.

All deposits below have been overridden and compacted

Vashon Drift, ground-moraine deposits Intimately graded mixture of clay to Infiltration very slow. Runoff good on Generally above water table but perched

(Qgt). slopes, but undrained depressions are 

common.

water "common over till. Permeability 

low except locally in sani and gravel 

lenses.

gravel sizes. Contains local lenses of sand 

and gravel. Hardpan of common usage. 

Here refers to subglacial lodgment till 

which is overlain by a few feet of less

compact ablation till (see text). , .

Undifferentiated pre-Vashon deposits Interbedded strata of sand, silt, clay, Exposed only on valley walls. Runoff good Contains much water, locally percnea. 

'~ v ' < except where affected by landslides. Interbedding restricts vertical permeability. Springs abundant.

(Qu). gravel, and till.

Salmon Springs Drift (Qss).

Puyallup(?) Formation (Qpy)~

Chiefiy sand and gravel with interbedded 

stony till and minor silt and clay strata.

Chiefly volcanic sand. Contains some silt 

and clay, peat, and a compact volcanic 

mudflow.

Infiltration generally slow to moderate. 

Generally exposed only on slopes where 

runofl is good, except where affected by 

landslides.

Infiltration slow to moderate. Runoff generally good because formation exposed 

only on steep slope.

Contains much water, perched in places, 

and confined elsewhere. Permeability 

highly variable, even in sand and gravel 

because of localized occurrence of silt and 

clay matrix. Springs abundant.

Commonly contains some water. Permeability low to moderate. Interbedding 

restricts vertical penneabiTty.

Intermediate drift (Qid).

Ortlng(?) Drift (Qor).

Chiefly two fine-grained till sheets separated by interbedded sand, silt, and 

clay.

Mostly sand and gravel, but includes silt 

and clay beds and stony till.

Infiltration slow because exposed on 

slopes, and contains numerous finegrained beds. Runoff generally good 

because of slope, except where affected 

by landslides.

Infiltration slow to moderate. Runoff good 

because of slope except hi landslide areas.

Generally contains water, perched in 

places. Permeability locally high in 

gravel; low in till and clay. Interbedding 

restricts vertical permeability. Springs 

abundant.

Generally contains water, perched in 

places. Permeability moderate to high in 

gravelly and coarse sand; low in till and 

clay. Springs abundant.

Hammer Blufl Formation (Th). Lower member mostly quartz sand and Infiltration generally slow. Runoff fair,

kaolinitic clay. Upper member mostly Formation generally is exposed on

clayey weathered volcanic sand and slopes, but sliding produces numerous

gravel. undrained depressions.

Contains abundant water. Permeability 

generally low, but may bo moderate to 

high hi clean quartz sand beds near base.
ECONOMIC GEOLOGY 79

mapped units in the Renton, A uburn, and Black Diamond quadrangles 

from U.S. Army Corps of Engineers (1953)]

Ease of excavation Foundation stability Slope stability Reported or possible uses

Principal

soil groups

(Unified Soil

Classiflcat'on)

Highly variable, dependent on content 

and method of emplacement.

Generally easy to excavate with hand 

or power equipment. Much could be 

dredged.

Highly variable, dependent on content and method of emplacement. 

May contain high proportion of 

voids, and both rapidly compressible and slowly decaying, slowly 

compressible material.

Fair to excellent depending on grain 

size, In Duwamish Valley, locally 

contains compressible layers of organic material.

Highly variable, dependent on content and method of emplacement.

Generally fair to poor because loose 

and saturated to near surface. May 

stand in steep cuts where above 

water table.

Generally easy to excavate with hand Mostly subject to further movement. Both natural and cut slopes generally 

or power equipment. Locally con- Corrective measures needed. of limited or temporary stability, 

tains large stones. Commonly cohesive.

Fill, topsoil. Channel gravel is a Includes virtu 

major source of commercial sand ally all. 

and gravel. Alluvium in White 

River valley and Duwamish Valley contains porous glassy volcanic 

rocks that may be chemically reactive in high-alkali concrete.

Generally easy to excavate with hand Very poor. Low shear strength, and 

or power equipment; fibrous woody will settle significantly under load, 

material containing interwoven 

stems much more difficult. May conIncludes virtually all except GF.GW, 

SP, SW.

Topsoilbeneficiation, _.____-_-_._- Ft, OH, OL.

tain large crisscrossed logs.

Some shallow deposits could be removed prior to construction.

Easy to excavate with hand or power Generally fair to poor. Contains some 

equipment. May be cohesive. compressible strata.

Difficult to excavate with hand or light 

power equipment. Dense, tough and 

cohesive; lacks bedding, contains 

scattered large boulders.

Generally easy to excavate with hand 

or power equipment. Contains few 

boulders.

Generally easy to excavate with hand 

or power equipment. Noncohesive.

Generally easy to excavate with hand 

or power equipment. Contains 

scattered boulders and blocks of till.

Fair to good in crust near surface. Locally has low shear strength below 

water table in thick deposits. (See 

Crandell, 1963, p. A74-A75.)

Good to excellent....-.....-.--....-..

-do_

-do_

Not generally found on natural slopes. 

Cutbanks variable; fibrous peat in 

upper part of deposit may stand in 

steep cuts, yet lower peat runs 

freely.

Will stand in steep cuts where dry, but Topsoil-------- ...-- ----- ML, OL, CL.

much less stable where wet. Cut 

slopes are subject to gullying and 

landsliding

Stands in steep natural and cut slopes Fill.-.-.----...-.--- -.-. ...... GC, GM.

where moderately dry. Small 

amounts of water can decrease stability markedly.

Generally unstable in steep cuts because of lack of binder, but may 

stand for short periods. Failures 

generally extend only a few feet below surface. Cut slopes in sand subject to gullying.

Generally unstable in steep cuts because of lack of binder, but may 

stand for short periods. Failures generally extend only a few feet below 

surface. 

.....do.__------_ .. . - Fill. Commercial sand and gravel. GP, SP.

-do.....--.---.----..--..---..--- SP, SW, SM.

Fill. A major source of commercial GP, SP. 

sand and gravel.

by one or more glaciers at least 1,500 feet thick

Very difficult to excavate with hand or 

light power equipment. Stony, 

dense, tough, and coherent. Generally lacks bedding or extensive fracturing. Contains scattered large 

boulders.

Highly variable. Except till, generally 

can be excavated with hand or light 

power equipment. Till difficult to 

excavate.

Most sand and gravel strata can be excavated with hand or light power 

equipment, but locally they contain 

firm binder. Till similar to Vashon 

till, very difficult to excavate.

Generally can be excavated with hand 

or light power equipment except 

mudflow and compact peat beds, 

both of which are tough, coherent, 

and difficult to excavate.

Except till, generally can be excavated 

with hand or light power equipment. Till is tough and cohesive, but 

commonly fractured, and less difficult to excavate than stony till.

Sand and gravel generally can be excavated with hand or light power 

equipment. Stony till very difficult 

to excavate.

Clean quartz sand beds can be excavated by hand or light power 

equipment. Clay and clayey sand 

and gravel are tough, cohesive, and 

more difficult.

Excellent. No settlement expectable._. Stands in steep natural and artificial

cuts for long periods. Stability lessened locally by lenses of stratified 

material.

Fill..---------------------------- GC, GM.

Fair to poor. Crops out on slopes 

where water is abundant. Virtually 

no consolidation expectable, but 

subject to landsliding dependent on 

slope, moisture, and distribution of 

silt and clay.

Good to poor. Crops out on slopes 

where water is abundant. Virtually 

no consolidation expectable, but 

subject to landsliding dependent on 

slope, moisture, and distribution of 

silt and clay.

----do.-----------.--.---------....-.

Fair to poor. Crops out on slopes 

where water is abundant. Virtually 

no consolidation expectable, but 

subject to landsliding dependent on 

slope, moisture, and distribution of 

silt and clay.

Good to poor. Crops out on slopes 

where water is abundant. Virtually 

no consolidation expectable, but 

subject to landsliding dependent on 

slope, moisture, and distribution of 

silt and clay. Landsliding especially 

widespread where underlain by 

Hammer Bluff Formation.

Poor. Crops out on slopes; springs and 

landslides abound in nearly all areas 

underlain by formation.

Locally stands in steep natural and _.. ..do. 

artificial cuts. Landslides common.

Locally stands in relatively steep nat- Fill, common and select.. -..-...-- 

ural or cut slopes for long periods. 

Stony till forms ledges resistant to 

stream erosion and mass wasting. 

Locally subject to landsliding.

Locally stands in steep artificial and Fill. Sand contains some glassy volnatural slopes. Mudfiow and peat canic rocks that may be chemideposits form resistant ledges. cally reactive in high-alkali

concrete.

Locally stands in steep natural and cut Fill.'common clay products. _.-. -- 

slopes. Landslides common.

Locally stands in steep natural and cut Fill, common and selectslopes for long periods. Stony till 

forms ledges resistant to erosion. 

Landslides common.

Can stand in steep natural and cut Semirefractory and common clay 

slopes for short dry periods, but products. Silica sand, 

generally is wet. Landslides very 

common.
80 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

TABLE 6. Generalized description of engineering properties of principal mapped

[From Mullineaux (1965a, b, c) Soil groups

Units (Symbols used are from 

Mullineaux, 1965a, b, c)

Special features Drainage Ground water

All formations

Intrusive rocks (Ti).._--._..... 

Lincoln Creek(?) Formation (Ts).

Puget Group undifferentiated, Renton 

Formation, and middle member of 

Tukwila Formation (Tp, Tr, Tta).

Tukwila Formation upper and lower 

members (Ttu, Ttl).

Igneous rock cooled from melt. Numerous Infiltration slow. Runoff excellent.

crosscutting fractures. Contains clay

zones and veins. 

Partly cemented. Contains zeolite and .....do..-.-. .-------------------

glassy volcanic rocks. Fragments commonly altered, many are soft.

Partly cemented quartzose feldspathic .....do_.---..--....-.--.-...---..

sandstone. Cement generally is calcite. 

Locally friable.

Partly cemented, locally weathered sand- .....do...-.------...-..--.-.-------

stone, conglomerate, and mudstone 

composed of fragments of volcanic rock. 

Contains some bouldery beds.

Ground water occurs in fractures; Permeability very low except along fractures.

. Ground water meager. Permeability low.

.do.

.do.

however, are relatively compact and hard, have low 

water contents, and have high bearing and shear 

strengths. These are fairly "strong" sediments, but 

they present special problems of their own, among 

which are vertical and horizontal rebound on unloading. Horizontal rebound apparently is especially critical, and it has been credited with causing damaging 

landslides in Seattle (Wilson and Johnson, 1964).

GROUND WATER

Ground water, which can be expected to present 

problems for both light and heavy construction, is 

abundant, and the water table in the drift plain typically is high above the level of nearby valley floors. 

Ground water occurs at many different stratigraphic 

positions, some perched within the typically interbedded impervious and pervious layers of Pleistocene 

sediments. Moreover, artesian conditions are not uncommon. On the Duwamish Valley floor north of 

Kent, a drilled well that intersected Pleistocene sediments under the alluvium produced more than 1,700 

gallons per minute under pressure equivalent to a 

water surface 90 feet above the valley floor (Luzier, 

1969). These conditions obviously can be of major 

concern for developments that require cutting along 

valley walls or tunneling through the drift plain. 

Valley-floor sediments also include interbedded deposits that carry highly diverse amounts of water. One 

hazard involved in trenching or other excavation in the 

alluvium, for example, is the possibility of intersecting 

linear meandering deposits of channel gravel that can 

produce very large flows of water.

Extensive information on ground-water conditions 

in the mapped area, much of wrhich is pertinent to 

engineering projects, is included in the ground-water 

report by Luzier (1969).

HETEROGENEITY OF GLACIAL TILL

Knowledge of glacial till is important to engineering practice because the till is so widespreecl and so 

variable in physical properties and thickness. As 

mapped, glacial till includes all unsorted and unstratified material deposited by the glacier. It may be compact or loose and may be composed largely of silt and 

clay or largely of gravel and sand. The concretelike 

lodgment member of the Vashon till (commonly called 

hardpan) is widely recognized as till; but the looser 

ablation member is not so often recognized,'because it 

is so different from the "typical" lodgment till. Nor 

are the abrupt changes that characterize the till, or 

the great variety of grain sizes that compose it, always 

recognized. The objective of this discussion is to emphasize that (1) till, especially the Vashon, consists 

of two members that are very different ir physical 

properties, chiefly compactness and coherence; (2) 

either of these members can, at any one point, compose most or all of the till mapped; (3) till sheets as 

a whole (and the lodgment and ablation members 

individually) typically vary widely in thickness from 

place to place; and (4) even compact lodgment till 

contains weak zones. The importance of any one of 

these factors as compared with another factor probably depends mostly on the type of project, ^mall construction jobs in Vashon till, for example, might be 

much more affected by the diversity in compactness 

than large jobs would be.

The Vashon till, which covers about half tl <», mapped 

area, illustrates the great heterogeneity of till. Where 

mapped, it usually consists of thin ablation over lodgment till, but at any one place might consist mostly of 

either member. Important variable features of the 

lodgment member are thickness, amount of silt and 

clay "binder," and presence or absence of weak zones.
ECONOMIC GEOLOGY 81

units in the Renton, Auburn, and Black Diamond quadrangles Continued 

from U.S. Army Corps of Engineers (1953)]

Ease of excavation Foundation stability Slope stability Reported or possible uses

Principal

soil groups

(Unified SoU

Classification)

below are bedrock

Very difficult. Requires blasting. 

Breaks along cross joints.

Heavy power equipment or blasting 

generally required for excavation, 

although some zones are friable and 

more easily excavated.

--..do. -----------------------------

.do.

Excellent_-.-..-. --.-.--.-- ..-.- ExcellentGood, but subject to limitation of 

steep slopes on which formation 

crops out.

Generally very good; less so where 

relatively altered.

Excellent__------------------------- Generally very good.

Generally good to excellent but locally 

weathered partly to clay.

Generally very good; less so where 

weathered.

Riprap, fill, ballast, decorative 

stone. Crushed for road metal, 

concrete, and asphalt aggregate.

Fill, contains zeolite and glassy volcanic rocks that may react with 

some cement.

Fill, riprap (cemented strata). Coal. 

Refractory, semirefractory, and 

common clay products. Silica 

sand.

Riprap, fill__._-__...........

Thickness' commonly ranges from a few inches to about 

20 feet, though lodgment till as thick as 70 feet is exposed. In places, as in Renton north of the Cedar River, 

it is nearly all silty and gravelly sand; elsewhere it 

contains as much as 50 percent silt and clay. With low 

silt and clay content, it is friable enough that fragments can be crushed in the hand, yet even that material might require ripping before it could be removed 

effectively with large earthmoving equipment. With 

higher silt and clay content (for example, 20-40 percent), till is typically coherent, tough, hard and resistant to penetration, and nearly uniformly resistant 

to breaking. With still higher silt and clay content, 

the till tends to remain coherent but be less hard and 

more likely to contain fractures along which blocks 

can be separated from the main mass. In many places, 

lodgment till contains lenses of gravel or sand, but the 

location of such lenses cannot be predicted. The lenses 

are important, however; they can give up large amounts 

of water for short periods, and they are weaker zones 

that make the till easier to excavate but that reduce its 

ability to stand in opencuts.

Vashon ablation till is not as compact or as coherent 

as lodgment till, because it has not been heavily loaded 

by ice. Generally it is less than 5 feet thick, but it 

locally has been seen as thick as about 10 feet. It is 

mostly a poorly sorted clayey, gravelly sand. Locally 

it grades into better sorted gravel and sand that by increase in thickness and continuity grade into the 

mapped deposits of recessional outwash. Ablation till 

generally presents only minor excavation problems, 

but it does contain widely distributed large boulders. 

It is not nearly as stable in opencuts as lodgment till, 

however, and it is more permeable.

Differences between lodgment and ablation members 

in the pre-Vashon tills are of less importance, because

all have been overridden by thick ice. Orting(?) and 

Salmon Springs tills are generally stony and are similar to Vashon lodgment till. Till in the intermediate 

drift typically contains more silt and clay and is softer 

than any of the other tills, and it contains numerous 

joints along which the unit breaks (fig. 15).

LANDSLIDES

Existing and potential landslides in this area r.re 

worthy of considerable attention. They are a problem 

now and will affect an ever increasing number of 

people as urban development spreads across the area. 

Many hazardous landslide areas are shown on geologic 

maps (Mullineaux, 1965a, b, c), on which they f.re 

mapped as part of the colluvium. But it is to be emphasized that not nearly all landslides are mapped, 

and areas of potential landslides are not differentiated 

as a map unit. Urban development may well proceed, 

faster than zoning that would provide warning of 

potential landslide areas. Thus, companies and individuals concerned with development probably shovld 

recognize for themselves the problem that landslides 

embody.

Simply recognizing the areas of potential sliding is 

an important step. Once a possible landslide danger is 

recognized, each area of interest can be treated a? a 

site problem, and whatever examinations are necessary 

can be made. This recognition of areas where slides 

either exist or might occur can be gained to some extent by examination of available topographic and geologic maps. Examination on the ground, however, is 

more desirable.

Available maps can be used to a certain extent to 

locate areas of existing or potential slides, but tl ^y 

probably are more useful toward distinguishing areas 

where site evaluation is needed. The topographic mr.ps 

show factors such as location, height, and steepness of
82 GEOLOGY OP RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

slopes. As has been described, landslides are concentrated and should be expected along any steep slope, 

and especially along the walls of postglacial stream 

valleys. The topographic maps also show positions of 

rivers and creeks in some places it is possible to estimate the points at which a stream will undercut adjacent valley walls. Geologic maps not only show the 

location of many areas in which landslides are the 

dominant surficial material, but also show the types of 

materials that make up the various slopes. Map explanations, to a certain extent, and table 6 indicate 

relative susceptibility to sliding; landslides are much 

more abundant and probable on slopes in the Hammer 

Bluff Formation, for example, than on comparable 

slopes in Vashon Drift.

Field examination is desirable because sites of existing and potential slides in many places are more clearly 

evident by such examination than on maps, and because 

local conditions not evident from maps can strongly 

influence susceptibility to sliding. Landslides probably 

are most readily recognized by surface expressions, 

though recognition can be furthered through examination of internal features and stratigraphic relations. 

Descriptions of features characteristic of landslide 

types that are common in the mapped area (p. 53) are 

contained in many studies, such as those of Sharpe 

(1938) and Eckel (1958) and in the references contained in those studies. Surface features that particularly help to identify landslides locally are hummocky 

surfaces, tilted blocks, subparallel ridges that run 

across rather than down the slope, ponds and other disruptions of drainage, tilted trees, lobate surfaces that 

are convex downslope, cracks in the ground surface, 

and steep and often curved scarps that are bare or 

nearly bare of vegetation. Internal features that are 

helpful are randomly oriented blocks and small chips 

of stratified sediments in a nonstratified matrix, crude 

layering or slickensided surfaces that parallel the 

slope, and a matrix which is largely nonsorted and nonstratified like till but which is soft and sticky. Downslope displacement of identifiable stratigraphic units 

is an excellent criterion of past landsliding, but the 

recognition of this displacement usually requires detailed study.

Not only the natural conditions conducive to landsliding, but also the effects of artificial changes should 

be considered. Undercutting, loading, and addition of 

water probably are the most important artificial 

changes that cause sliding in the mapped area. Undercutting of slopes by excavation and loading (usually 

by artificial fill) are typical of urban or suburban developments. Artificial concentrations of natural rainfall and increases in the amount of water applied to 

the ground, which commonly result from paring and 

lawn watering that accompany residential development, can cause sliding on slopes that have been stable 

for many years.

CONSTRUCTION MATERIALS

SAND AND GRAVEL

Sand and gravel suitable for construction material 

is abundant in the area. For some purposes it can be 

used as taken from natural deposits, but probably most 

of it is processed. It is used locally for a wide variety of 

purposes, especially railroad ballast, common and select 

fill, roadbase and surface courses, and concrete and 

mortar aggregate.

Some physical properties that make a s^.tid and 

gravel deposit desirable for construction material are 

abundance of gravel, uniformity in grain size ?,nd quality, and ease of excavation. The component materials 

should also be durable, clean, and not chemically reactive in concrete. These requirements locally are best 

fulfilled by Vashon recessional gravels, especially the 

outwash deposits of the large ice-marginal river in the 

Black Diamond and Auburn quadrangles. T ?,se outwash deposits generally contain abundant gravel but 

few boulders too large for crushers, they are friable, 

and they occur in large accessible bodies. TH gravel 

consists largely of hard volcanic rocks that are not 

chemically reactive in concrete, and it contains only 

small amounts of clay, iron oxide, and other deleterious materials. Smaller Vashon recessional outwash 

deposits elsewhere in the quadrangles and channel deposits of the Cedar and Green Rivers are generally 

similar to the ice-marginal river gravels, except that 

they are usually finer grained and less voluminous. 

Alluvium of the White River, however, contains abundant glassy porous volcanic rocks that might be chemically reactive. Although sand and gravel is also abundant in Vashon advance outwash and in pre-Vashon 

formations, these sediments usually are accessible only 

where exposed in valley walls or on other steep slopes. 

Pre-Vashon gravels, moreover, typically arc at least 

partly coated with clay and iron oxide, and some stones 

are partly weathered. The only pre-Vashon sand and 

gravel deposits that typically are not iron stained contain abundant glassy volcanic rock fragment? like the 

material in modern alluvium along the White River.

The outwash of the large ice-marginal stream has 

been most widely exploited, and probably the most 

utilized part of the outwash deposits has been the delta 

at Auburn. The Auburn delta, because it formed as a 

fill in the Duwamish trough at the end of the long
ECONOMIC GEOLOGY 83

valley train, is thick, coarse grained, and well sorted. 

It consists of loose uniform pebble-and-cobble gravel 

and sand; it is more than 150 feet thick above the level 

of the modern flood plain; and it crops out for more 

than a mile and a half along the readily accessible Duwamish Valley between the Green and White Rivers. 

In the past, this deposit has been mined by a railroad 

company, by at least two commercial sand and gravel 

companies, by public agencies, and by numerous individuals. A large kame-terrace deposit laid down by the 

same ice-marginal river lies south of the White River 

across from the Auburn delta, but the terrace deposits 

are much less uniform overall and, in places, much 

more sandy than the delta. The kame terrace appears 

to have been exploited only intermittently and on a 

small scale.

East and northeast of the Auburn delta, valley-train, 

outwash-plain, and kame-field gravels cover 15-20 

square miles in the Black Diamond quadrangle and 

generally are from 10 feet to several tens of feet thick. 

Although these gravels are similar to those in the 

delta, they are less uniform in grain size and are thinner. Generally they have been excavated in pits, and 

this type of excavation is more complicated than that 

in the face of the Auburn delta. Many pits, however, 

have been established in the outwash, the largest of 

which is a county-owned pit in sec. 26, T. 22 N., R. 5 E. 

Most of this gravel is used locally, largely for road 

construction.

Smaller outwash deposits are widely distributed 

over the Renton quadrangle, but their small size, internal variation, and abundance of sand make them less 

desirable than the ice-marginal outwash gravels. Fairly 

extensive terrace and delta deposits in Renton on the 

north side of the Cedar River in sees. 16 and 17 are the 

most extensively worked of these deposits. The sediments in that locality are reasonably uniform but contain much more sand than the Auburn delta.

Of the modern river gravels, only the Cedar River 

deposits were being used as a major source of sand 

and gravel in 1961. Cedar River channel deposits at 

Renton have been mined for sand and gravel for many 

years by a commercial firm, and the alluvium has also 

been used as a source of sand for special purposes by 

other producers. Mining from the river channel is aided 

by the continual replenishment of the deposits by the 

river. Some older Cedar River bars also are being 

mined upstream, near the edge of the Renton quadrangle. Green River channel deposits east of Auburn 

appear to be a comparably good source of gravel but 

probably are not now economically competitive with 

gravel of the Auburn delta. The wide gravel flood 

plain of the White River could also be a source of

abundant gravel for uses in which the porous glarsy 

volcanic rocks would not be detrimental.

STONE

The Seattle metropolitan area generates a large demand for many types of stone, but only a limited 

source of broken stone is known in the mapped area, 

and 110 economic source of dimension stone or otl Q.r 

building stone (Moen, 1967) has been discovered. 

Broken stone is used in large quantities as riprap f.or 

bank protection along rivers, for bulkhead protection 

along the Puget Sound, for utilitarian retaining walls, 

and for protective blankets for slopes. It is also ured 

widely for decorative landscaping where slope protection is not a problem. Smaller pieces of the stone are 

crushed and used for ballast, fill, and concrete aggregate, and poor-quality stone and quarry strippings are 

used as fill.

Broken stone should be hard, tough, and durable; 

the rock body should be accessible, large enough to develop economically, and capable of being easily broken 

into blocks of a desirable size. Its value is considerably 

greater if it is also decorative. Very little rock in the 

area meets these standards. In general, only the int^usive rocks are suitable; sedimentary rocks of the Tukwila, Renton, and Lincoln Creek (1) Formations generally are not used because they are too poorly or too 

irregularly indurated. In 1961, only the large intrusive 

body west of Renton was being quarried. Earlier, one 

small quarry was operated in Tukwila volcanic brec°ia 

and flow rocks in northwest Renton and another vas 

operated in a sill at Tukwila, but in 1961 both were inactive and nearly surrounded by residences. An intrusive rock body south of Renton along Duwamish Valley is small but otherwise appears to be suitable for 

quarrying. No other suitable rock bodies are known in 

the Aiiburn and Black Diamond quadrangles, althorgh 

good sources exist east of the Black Diamond quadrangle.

The active quarry is in a body of hard, dense greenish-gray andesite about 2 miles west of Renton. Because 

of cross jointing, the rock breaks readily into blocks, 

many of which are large enough for riprap and also for 

decorative landscaping stone. The quality of the rock is 

generally regarded as good, but it varies considerably 

within the body, depending on amount of alteration 

and distribution of veins.

SILICA SAND

Silica sand is mined from the Hammer Bluff Formation and the Puget Group. At Hammer Bluff, in 

sec. 28, T. 21 K, R. 6 E., sand was being mined in 1961 

from the quartzose lower member of the Hammer Bluff
84 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

and from the underlying weathered Puget arkose. It 

was trucked to Seattle and was used chiefly in the 

manufacture of colored bottles. Both the Hammer 

Bluff Formation and the Puget arkosic rocks have been 

reported as being used for molding sand (Valentine, 

1949), but no sand was being produced in the mapped 

area in 1961.

Hammer Bluff quartzose sands have proved suitable 

as a source for glass sand, chiefly because of the alteration of feldspar to clay. Some of the feldspar was 

weathered to clay while the sand grains were still part 

of the Puget Group arkoses. Weathering after the 

grains were redeposited in beds of the Hammer Bluff 

Formation further reduced the feldspar content, so 

that now an adequate concentration of quartz can be 

obtained by washing out the clay. In some parts of the 

lower member, however, sand-size aggregates of siderite and clay, or other concentrations of iron oxide, exceed the limit of iron currently permissible for use of 

the sand for glass. No sand in the upper member of 

the formation is likely to prove satisfactory as a source, 

because it contains very little quartz and much iron.

Parts of the Puget arkose at Hammer Bluff are also 

suitable for glass sand, because alteration and leaching 

have reduced the amount of feldspar, iron, and cement, 

thus producing a workable sand from which the clay 

can be washed satisfactorily. The topmost part of the 

weathered Puget Group at Hammer Bluff is so low in 

iron that it has been used to "sweeten" other lessweathered arkose that contains too much iron for glass 

sand, thus increasing the usable tonnage. Distribution 

of iron oxide from leaching and redeposition strongly 

affects the amount of usable material, because the ironbearing detrital minerals nearly equals currently allowable limits. Siderite and most other iron-bearing grains 

are susceptible to laboratory removal by chemical, 

mechanical, and magnetic methods, but apparently it 

is not now economic to remove them on a large scale.

OIL AND GAS

Gas was discovered in the Lawson test hole drilled in 

1911 in Puget Group rocks near Black Diamond in the 

SMjE^ sec. 27, T. 21 N., R. 6 E., during a search for 

coal (Livingston, 1958). Oil shows were reported in 

holes drilled nearby in the late 1920's and early 1930's, 

but the first confirmed report of an oil show was in 

1936 in the Bobb 1 well drilled in the NE^ sec. 34 

(Livington, 1958). Since that time, the Puget Group 

has been investigated fairly extensively by several oil 

companies, but only a few holes have been drilled. 

Since the drilling of the Lawson test hole, 13 holes 

have been drilled on the Black Diamond anticline

south of the Green Eiver, 11 of which are within the 

mapped area (Livingston, 1958).

Exploration has been spurred by both the evidence 

of oil and gas and by conditions regarded as favorable 

for their occurrence. In virtually all parts of the stratigraphic section of the Puget Group near Bk.ck Diamond, for example, oil shows have been reported. 

Porosity and permeability of the rocks, though variable, locally are high. Marine rocks of the same age as 

part of the sequence at Black Diamond are known both 

north (Warren and others, 1945; Vine, 1969) and 

southwest of the area (Weaver, 193T; Snavely and 

others, 1958). Within the Black Diamond arer., brackish-water fossils have long been known, and s$ It water 

has been reported from test holes. The Puget Group is 

also folded into well-known anticlines and rynclines 

and is cut by numerous though mostly small faults 

that could have formed structural traps.

The Black Diamond anticline has attracted most of 

the attention so far, chiefly because previous drilling 

in it has shown some gas and oil. To and including 

1961, no drilling had been done in similar, well-known 

anticlines in the Puget Group to the northeast. The 

deepest hole on the Black Diamond anticline penetrated about 6,000 feet of the Puget Group, with oil 

shows virtually all the way to the bottom. No closure 

of this north-plunging anticline is known, although an 

interpretation of it by Anderson (1959) show? several 

faults, the importance of which he notes as possible oil 

traps. A sketch map by Anderson (1959) also shows 

other north-trending anticlines west of the Black Diamond anticline, where the bedrock is covered by Quaternary deposits; he, however, did not present evidence 

for the existence of the anticlines. A lack of surface 

evidence of structure features restricts efforts to systematically explore for oil in that part of the area.

At Renton, Puget Group arkose is also locally porous and permeable, but the section of arkosic rocks is 

much thinner, and a thick section of andesitic sedimentary rocks appears to occupy the stratigraphic interval in which oil shows have been found ne^.r Black 

Diamond. However, possible source rocks of marine 

origin crop out nearby below the Puget Group (Waldron, 1962).

CLAY

Clay suitable for a wide range of products is available in the mapped area, both in Tertiary and Quaternary formations. Some clay has been produced from 

the Renton Formation near Renton, but most has come 

from the Puget Group and Hammer Bluff Formation 

near Black Diamond. Quaternary glacial c^ays are 

abundant but little used, principally because they are
ECONOMIC GEOLOGY 85

neither as abundant nor as accessible as are similar 

clays in the city of Seattle. The Tertiary clay has been 

used for refractory ware (for this ware it is generally 

mixed with other clay), semirefractory and nonrefractory pottery, terra cotta, sewer pipe, paving brick, hollow brick, common brick, face brick, and common 

draintile. Between 1950 and 1960, however, Tertiary 

clays were mined only intermittently, and as far as is 

known, no glacial clay was taken out. Earlier in the 

century, a commercial plant at Renton used Hammer 

Bluff clay and Puget shale from the Renton and Black 

Diamond districts; the Hammer Bluff clay was also 

shipped to Seattle and Auburn for processing (Glover, 

1941).

Only one deposit in the mapped area, the flint claystone in the Puget Group at Kummer south of Black 

Diamond, meets the specifications for a refractory clay 

(Glover, 1941). Its refractory properties are suitable 

because it consists largely of the high-alumina clay 

kaolinite and of aluminum oxides or hydroxides; according to Nichols (1946), the Kummer claystone is 

composed chiefly of kaolinite and gibbsite and probably alumina gel. Cone fusion (or pyrometric cone 

equivalent) values of the claystone reported by Glover 

(1941) are as high as 32. The claystone has been mined 

on both sides of the Green River in the east limb of the 

Black Diamond anticline. The claystone has been reported to also be on the west limb of the Black Diamond anticline, but this area is largely covered by 

Quaternary deposits. As late as 1959, the claystone was 

being mined underground in the east limb of the Black 

Diamond anticline on the south side of the river.

Semirefractory and nonrefractory clays occur in 

arkosic strata of the Puget Group and in the Hammer 

Bluff Formation. A large amount of Puget shale has 

been taken from the south side of the Cedar River 

valley in Renton, but little was being mined in 1961. 

Similarly, in several places near Black Diamond, 

Puget shale and Hammer Bluff clay have been repeatedly mined for shipment to Renton, Auburn, and 

Seattle, but little was being mined in 1961. Clay minerals in the shale from the Puget are mostly kaolinite, 

but they also include mica or illite, and chlorite; the 

shale also contains much feldspar. Cone fusion values 

for various samples of Puget shales from the mapped 

area reported by Glover (1941) ranged from about 6 

to 13. Shale of comparable quality probably is widespread in the Puget Group.

Cone fusion values for Hammer Bluff sediments reported by Glover ranged from about 15 to 26. One 

light-gray clay collected from the lower member of the 

Hammer Bluff during this investigation, identified by 

X-ray methods as composed almost entirely of kaolinite, fused at cone fusion value 28. A sample of brown 

clay from the upper member, composed of about equal 

amounts of kaolinite and montmorillonite, fused at 

about cone fusion value 15.

Glacial clay that should be suitable for common and 

face brick occurs in the intermediate drift and in the 

undifferentiated drift along the Cedar River valley. 

These clays consist chiefly of mixtures of chlorite, mica 

or illite, and montmorillonite, plus quartz and feldspar ; they are similar to the glacial clay in Seattle that 

ha&been used for common brick for many years. Glover 

(1941) reported cone fusion values of 2-5 for most 

glacial clays from Seattle, and cone fusion values for 

five Pleistocene clays sampled during this investigation 

ranged from about 1 to 8.

COAL

Coal is abundant in the bedrock, both in the Renton 

Formation and in the undifferentiated Puget Group 

near Black Diamond; it was mined intermittently for 

about 100 years at Renton and for about 75 years at 

Black Diamond. Most coal of the Black Diamond district is bituminous, and most in the Renton district, is 

subbituminous (Beikman and others, 1961). The Puget 

Group in both districts is folded and cut by faults that 

make tracing and mining of the coal beds difficult. P~oduction has declined irregularly in this area since about 

the end of World-War I; in 1961 no coal was produced 

from the mapped area.

In the Renton district, the best coal occurs near the 

middle of the formation in the Renton No. 1, Renton 

No. 2, and Renton No. 3 beds, biit other coal beds n^ar 

the base of the formation have also been mined. Carbonaceous shale occurs higher than the Renton No 1 

bed, but no coal is known. At Black Diamond, in the 

western part of the Green River district, coal occnrs 

throughout most of the stratigraphic sequence. The 

principal coal bed is the McKay (Beikman and others, 

1961), near the base of the sequence exposed within the 

quadrangle. Stratigraphically higher coal is reported 

to be of lower rank. These coal fields were studied extensively during mining operations and were described 

by Willis (1886, 1898a), Evans (1912), and Warren, 

Norbisrath, Grivetti, and Brown (1945); the reserves 

of coal that remain have been described by Beikman, 

Gower, and Dana (1961). No new coal beds were discovered during the present investigation.

PEAT AND TOPS01L

Peat and topsoil are mined locally for soil beneficiation, chiefly for commercial and private landscaping. 

At various places, moss peat, shallow bog deposits of
86 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

fibrous and sedimentary peat mixed with inorganic 

silt and clay, and overbank silt and fine sand are being 

exploited and either used locally or trucked to the 

Seattle metropolitan area. According to Thorsen 

(1961), one operator was mining peat within the 

mapped area in 1960, at the south end of Lake Meridian. Overbank deposits have been mined sporadically 

from the upper 20 feet of the Duwamish Valley flood 

plain west of Kent for many years.

Peat and mixtures of silt, clay, and peat are widespread in bogs on the upland. These bogs could become 

important local sources of soil conditioners, and some 

probably will become nursery sites as suburban development spreads southeast from Eenton. Because 

these deposits contain little pure moss peat, they probably will be used only locally. Peat also occurs in a few 

deposits on the floor of Duwamish Valley; they are 

concentrated along the margins of the White Eiver fan 

near Auburn and the Cedar Eiver fan near Eenton. 

Peaty overbank silt and fine sand, similar to that being 

mined west of Kent, is abundant at and near the surface on most of the Duwamish Valley floor between 

Kent and the north boundary of the Eenton quadrangle.

REFERENCES CITED

Anderson, J. Q., 1959, Puget Sound area [Washington] has several prospective oil and gas basins: World Oil, v. 149, no. 

1, p. 111-113.

Armstrong, J. E., and Brown, W. L., 1954, Late Wisconsin 

marine drift and associated sediments of the Lower Fraser 

Valley, British Columbia, Canada: Geol. Soc. America 

Bull., v. 65, no. 4, p. 349-363.

Armstrong, J. E., Crandell, D. R., Easterbrook, D. J., and Noble, 

J. B., 1965, Late Pleistocene stratigraphy and chronology 

in southwestern British Columbia and northwestern Washington: Geol. Soc. America Bull., v. 76, no. 3, p. 321-330.

Beikman, H. M., Gower, H. D., and Dana, T. A. M., 1961, Coal 

reserves of Washington: Washington Div. Mines and Geology Bull. 47, 115 p.

Beikman, H. M., Rau, W. W., and Wagner, H. C., 1967, The 

Lincoln Creek Formation, Grays Harbor basin, southwestern Washington: U.S. Geol. Survey Bull. 1244-1, 14 p.

Bond, J. G., 1959, Sedimentary analysis of [Eocene] Kummer 

formation within the Green River Canyon, King County, 

Washington: Washington Univ., unpub. M.S. thesis.

Bressler, C. T., 1957, The petrology of the Roslyn arkose a 

study in tectonic control of sedimentation in the Cascade 

Range, central Washington, in v. 2 of Relaciones entre 

la tectonica y la sedimentacion: Internat. Geol. Cong., 

20th, Mexico 1956, sec. 5, p. 439-453.

Bretz, J H., 1913, Glaciation of the Puget Sound region: Washington Geol. Survey Bull. 8, 244 p.

Broecker, W. S., and Kulp, J. L., 1957, Lament natural radiocarbon measurements [Pt.] 4: Science, v. 126, no. 3287, 

p. 1324-1334.

Brown, R. D., Jr., Gower, H. D., and Snavely, P.D., Jr., 1960, 

Geology of the Port Angeles-Lake Crescent area, Clallam 

County, Washington: U.S. Geol. Survey Oil and Gas Inv. 

MapOM-203 [1961].

Campbell, M. R., and others, 1915, Guidebook of the western 

United States, Pt. A, The Northern Pacific Route, with a 

side trip to Yellowstone Park: U.S. Geol. Survey Bull. 611, 

212 p.

Chaney, R. W., 1938, Ancient forests of Oregon, A study of 

earth history in western America: Carnegie Inst. Washington Pub. 501, p. 631-648.

Coombs, H. A., 1936, The geology of Mount Rainier National 

Park: Washington Univ. [Seattle] Pub. Geology, v. 3, no. 

2, p. 131-212.

_____1941, Hornblende and magnetite heavies in the Ellensburg of central Washington: Jour. Sed. Petrolo-^y, v. 11, 

no. 3, p. 142-144.

Cooper, H. M., and Abernethy, R. F., 1941, Analysis of mine 

samples, in Analyses of Washington coals: U.S. Eiir. Mines 

Tech. Paper 618, p. 33-47.

Crandell, D. R., 1957, Some features of mudfiow deposits 

[Washington] [abs.] : Geol. Soc. America Bull., v. 68, no. 

12, pt. 2, p. 1821.

_____1963, Surficial geology and geomorphology of the Lake 

Tapps quadrangle, Washington: U.S. Geol. Survey Prof. 

Paper 388-A, 84 p.

_____1965, The glacial history of western Washington and

Oregon, in Wright, H. E., Jr., and Frey, D. G., eds., The 

Quaternary of the United States: Princeton Urfv. Press, 

p. 341-353.

Crandell, D. R., and Gard, L. M., Jr., 1959, Geolory of the 

Buckley quadrangle, Washington: U.S. Geol. Survey Geol. 

Quad. Map GQ-125.

Crandell, D. R., Mullineaux, D. R., and Waldron, H. H., 1958, 

Pleistocene sequence in southeastern part of the Puget 

Sound lowland, Washington: Am. Jour. Sci., v. 256, no. 6, 

p. 384-397.

_____1965, Age and origin of the Puget Sound trough in 

western Washington, in Geological Survey research 1965: 

U.S. Geol. Survey Prof. Paper 525-B, p. B132-B136.

Crandell, D. R; , and Waldron, H. H., 1954, Recent irudfiow of 

exceptional dimensions from Mt. Rainier, Washington, 

[abs.]: Geol. Soc. America Bull., v. 65, no. 12, pt. 2, p. 

1337.

 1956, A recent volcanic mudflow of exceptional dimensions from Mount Rainier,-Washington: Am. Jonr. Sci., v. 

254, no. 6, p. 349-362.

Dart, J. O., 1952, The changing hydrologic pattern of the Renton-Sumner lowland, Washington: Assoc. Pacific Coast Geographers Yearbook, v. 14, p. 19-23.

Durham, J. W., 1944, Megafaunal zones of the Oligocene of 

northwestern Washington: California Univ. Prbs. Geol. 

Sci., v. 27, no. 5, p. 101-211.

Easterbrook, D. J., 1963, Late Pleistocene glacial events and 

relative sea-level changes in the northern Puget Lowland, 

Washington: Geol. Soc. America Bull., v. 74, no. 12, p. 

1465-1483.

Easterbrook, D. J., Crandell, D. R., and Leopold, E. B., 1967, 

Pre-Olympia Pleistocene stratigraphy and chronology in 

the central Puget Lowland, Washington: Geol. Foe. America Bull., v. 78, no. 1, p. 13-20.
REFERENCES CITED

Eckel, E. B., ed., 1958, Landslides and engineering practice: 

Natl. Acad. Sci. Natl. Research Council Highway Research Board Spec. Rept. 29, 232 p.

Evans, G. W., 1912, The coal fields of King County: Washington Geol. Survey Bull. 3, 247 p.

Fenneman, N. M., 1906, Floodplains produced without floods: 

Am. Geog. Soc. Bull., v. 38, p. 89-91.

Fisher, R. V., 1961, Stratigraphy of the Ashford area, southern 

Cascades, Washington: Geol. Soc. America Bull., v. 72, no. 

9, p. 1395-1407.

Fiske, R. S., Hopson, C. A., and Waters, A. C., 1963, Geology 

of Mount Rainier National Park, Washington: U.S. Geol. 

Survey Prof. Paper 444, 93 p. [1964].

Flint, R. F., 1957, Glacial and Pleistocene geology: New York, 

John Wiley & Sons, Inc., 553 p.

Folk, R. L., and Ward, W. C., 1957, Brazos River bar [Texas] 

 a study in the significance of grain size parameters: 

Jour. Sed. Petrology, v. 27, no. 1, p. 3-26.

Frye, J. C., and Willman, H. B., 1960, Classification of the 

Wisconsinan Stage in the Lake Michigan glacial lobe: 

Illinois Geol. Survey Circ. 285,16 p.

Gard, L. M., Jr., 1960, Suggested source of Miocene volcanic 

detritus flanking the central Cascade Range, Washington, 

in Short papers in the Geological sciences: U.S. Geol. Survey Prof. Paper 400-B, p. B306-B307.

_____1968, Bedrock geology of the Lake Tapps quadrangle, 

Pierce County, Washington: U.S. Geol. Survey Prof. Paper 

388-B, 33 p.

Geer, M. R., 1941, Description of mine samples, in Analyses of 

Washington coals: U.S. Bur. Mines Tech. Paper 618, p. 

48-78.

Glover, S. L., 1936, Hammer Bluff formation of western Washington [abs.] : Pam-Am. Geologist, v. 65, no. 1, p. 77-78.

_____1941, Clays and shales of Washington: Washington 

Div. Mines and Geology Bull. 24, 368 p.

Gould, H. R., and Budinger, T. F., 1958, Control of sedimentation and bottom configuration by convection currents, Lake 

Washington, Washington: Jour. Marine Research, v. 17, p. 

183-198.

Gower, H. D., and Wanek, A. A., 1963, Preliminary geologic 

map of the Cumberland quadrangle, King County, Washington : Washington Div. Mines and Geology Geol. Map 

GM-2.

Hansen, H. P., 1941, Further pollen studies of post Pleistocene 

bogs in the Puget lowland of Washington: Torrey Bot. 

Club Bull., v. 68, no. 3, p. 133-147.

_____ 1947, Postglacial forest succession, climate, and 

chronology in the Pacific Northwest: Am. Philos. Soc. 

Trans., v. 37, pt. 1, 130 p.

Hansen, H. P., and Mackin, J. H., 1949, A pre-Wisconsin forest 

succession in the Puget Lowland, Washington: Am. Jour. 

Sci., v. 247, no. 12, p. 833-855.

Happ, S. C., Rittenhouse, Gordon, and Dobson, G. C., 1940, 

Some principles of accelerated stream and valley sedimentation : U.S. Dept. Agriculture Tech. Bull. 695, 134 p.

Jahns, R. H., 1947, Geologic features of the Connecticut Valley, Massachusetts, as related to recent floods: U.S. Geol. 

Survey Water-Supply Paper 996, 158 p.

Kimball, J. P., 1897, Physiographic geology of the Puget Sound 

basin: Am. Geologist, v. 19, p. 225-237, 304-322.

Kleinpell, R. M., 1938, Miocene stratigraphy of California: Am. 

Assoc. Petroleum Geologists, 450 p.

Landes, Henry, 1902, The coal deposits of Washington: Washington State Geologist's Ann. Rept. 1, pt. 4, p. 257-281.

Laval, W. N., 1956, Stratigraphy and structural geology of 

portions of south-central Washington: Washington Univ., 

unpub. Ph. D. thesis.

LeConte, J. L., 1874, On the great lava flood of the Northwest; 

and on the structure and age of the Cascade Mountains: 

Am. Jour. Sci., ser. 3, v. 7, p. 167-180, 259-267.

Liesch, B. A., Price, C. E., and Walters, K. C., 1963, Geology 

and ground water resources of northwestern King County, 

Washington: Washington Div. Water Resources Water 

Supply Bull. 20, 241 p.

Livingston, V. E., Jr., 1958, Oil and gas exploration in Wa^hington, 1900-1957: Washington Div. Mines and Geology 

Inf. Cir. 29, 61 p.

Luzier, J. E., 1969, Geology and ground-water resources of southwestern King County, Washington: Washington Dent. 

Water Resources Water-Supply Bull. 28, 260 p.

Mackin, J. H., 1937, Erosional history of the Big Horn Bar*n, 

Wyoming: Geol. Soc. America Bull., v. 48, no. 6, p. 813- 

893.

_____ 1938, Eastern margin of the Puget glacial lobe [ab£-.] : 

Geol. Soc. America Proc. 1937, p. 248.

_____ 1941, Glacial geology of the Snoqualmie-Cedar area, 

Washington: Jour. Geology, v. 49, no. 5, p. 449-481.

 1948, Concept of the graded river: Geol. Soc. Airerica Bull., v. 59, no. 5, p. 463-511.

1956, Cause of braiding by a graded river [Idaho]

[abs.] : Geol. Soc. America Bull., v. 67, no. 12, pt. 2, p. 

1717-1718.

Mackin, J. H., and Cary, A. S., 1965, Origin of Cascade landscapes: Washington Div. Mines and Geology Inf. Circ. 41, 

35 p.

McLellan, R. D., 1927, The geology of the San Juan Islands: 

Washington Univ. [Seattle] Pub. Geology, v. 2, 185 p.

McLerran, J. H., and Krashevski, S. H., 1954, State of Washington Engineering Soils Manual, Pt. 3, Soils of King 

County: Washington State Council Highway Research, 

107 p.

Mallory, V. S., 1959, Lower Tertiary biostratigraphy of the 

California Coast Ranges: Am. Assoc. Petroleum Geologists, 

416 p.

Moen, W. S., 1967, Building stone of Washington: Washington 

Div. Mines and Geology Bull. 55, 85 p.

Mullineaux, D. R., 1961, Geology of the Renton, Auburn, and 

Black Diamond quadrangles, Washington: U.S. Geol. £''irvey open-file report, 202 p.

_____ 1965a, Geologic map of the Renton quadrangle, King 

County, Washington: U.S. Geol. Survey Geol. Quad. Map 

GQ-405.

_____ 1965b, Geologic map of the Auburn quadrangle, King

and Pierce Counties, Washington: U.S. Geol. Survey Geol. 

Quad. Map GQ-406. 

___1965c, Geologic map of the Black Diamond quadrangle, King County, Washington: U.S. Geol. Survey Geol. 

Quad. Map GQ-407. 

___ 1967, Gross composition of Pleistocene clays in Seattle, Washington, in Geological Survey research 1967: U.S. 

Geol. Survey Prof. Paper 575-B, p. B69-B76.
88 GEOLOGY OF RENTON, AUBURN, AND BLACK DIAMOND QUADRANGLES, WASHINGTON

Mullineaux, D. R., Crandell, D. R., and Waldron, H. H., 1957, 

Multiple glaciation in the Puget Sound basin, Washington 

[abs.] : Geol. Soc. America Bull., v. 68, no. 12, pt. 2, p. 

1772.

Mullineaux, D. R., Gard, L. M., Jr., and Crandell, D. R., 1959, 

Continental sediments of Miocene age in Puget Sound 

lowland, Washington: Am. Assoc. Petroleum Geologists 

Bull., v. 43, no. 3, p. 688-696.

Mullineaux, D. R., Nichols, T. C., and Speirer, R. A., 1964, 

A zone of montmorillonitic weathered clay in Pleistocene 

deposits at Seattle, Washington, in Geological Survey research 1964: U.S. Geol. Survey Prof. Paper 501-D, p. 

D99-D103 [1965].

Mullineaux, D. R., Waldron, H. H., and Rubin, Meyer, 1965, 

Stratigraphy and chronology of late interglacial and early 

Vashon glacial time in the Seattle area, Washington: U.S. 

Geol. Survey Bull. 1194-O, 10 p.

Newconib, R. C., 1952, Ground-water resources of Snohomish 

County, Washington: U.S. Geol. Survey Water-Supply 

Paper 1135, 133 p. [1953].

Nichols, R. L., 1946, Preliminary report on King County, Washington, high-alumina clay deposits: U.S. Geol. Survey openfile report, 41 p.

Pettijohn, F. J., 1957, Sedimentary rocks [2d ed.] : New York, 

Harper & Brothers, 718 p.

Poulson, E. N., Miller, J. T., Fowler, R. H., and Flannery, R- D-, 

1952, Soil survey of King County, Washington: U.S. Soil 

Conserv. Service Soil Survey Rept, ser. 1938, no. 31, 106 p.

Powers, H. A., and Wilcox, R. E., 1964, Volcanic ash from 

Mount Mazama (Crater Lake) and from Glacier Peak: 

Science, v. 144, no. 3624, p. 1334-1336.

Rau, W. W., 1958, Stratigraphy and foraminiferal zonation in 

some of the Tertiary rocks of southwestern Washington: 

U.S. Geol. Survey Oil and Gas Inv. Chart OC-57.

_____ 1966, Stratigraphy and Foraminifera of the Satsop 

River area, southern Olympic Peninsula, Washington: 

Washington Div. Mines and Geology Bull. 53, 66 p.

Rigg, G. B., 1958, Peat resources of Washington: Washington 

Div. Mines and Geology Bull. 44, 272 p.

Rigg, G. B., and Gould, H. R., 1957, Age of Glacier Peak eruption and chronology of post-glacial peat deposits in Washington and surrounding areas: Am. Jour. Sci., v. 255, no. 

5, p. 341-363.

Rittmann, Alfred, 1952, Nomenclature of volcanic rocks proposed for the use in the catalogue of volcanoes, and keytables for the determination of volcanic rocks: Bull. Volcanol., -ser. 2. v. 12, p. 75-102.

Roberts, A. E., 1958, Geology and coal resources of the ToledoCastle Rock district, Cowlitz and Lewis Counties, Washington: U.S. Geol. Survey Bull. 1062, 71 p.

Rubin, Meyer, and Alexander, Corrinne, 1958, U.S. Geological 

Survey radiocarbon dates, [Pt.] 4: Science, v. 127, no. 

3313, p. 1476-1487.

 1960, U.S. Geological Survey radiocarbon dates, [Pt.] 

5: Am. Jour. Sci. Radiocarbon Supp., v. 2, p. 129-185.

Russell, I. C., 1898, Glaciers of Mount Rainier, with a paper on 

the rocks of Mount Rainier, by G. O. Smith: U.S. Geol. 

Survey 18th Ann. Rept., pt. 2, p. 349-423.

Sceva, J. E., 1957, Geology and ground-water resources of 

Kitsap County, Washington: U.S. Geol. Survey WaterSupply Paper 1413, 178 p.

Schenck, H. G., and Kleinpell, R. M., 1936, Refugian stage of 

Pacific coast Tertiary: Am. Assoc. Petroleum Geologists 

Bull., v. 20, no. 2, p. 215-225.

Sharpe, C. F. S., 1938, Landslides and related pheromena; a 

study of mass-movements of soil and rock: F>w York, 

Columbia Univ. Press, 136 p.

Smith, G. O., 1902, The coal fields of the Pacific C^ast: U.S. 

Geol. Survey 22d Ann. Rept., pt. 3, p. 479-513.

_____ 1903, Description of the Ellensburg quadrangle 

[Washington] : U.S. Geol. Survey Geol. Atlas, Folio 86, 

7 p.

Snavely, P. D., Jr., Brown, R. D., Jr., Roberts, A. E., and Rau, 

W. W., 1958, Geology and coal resources of the CentraliaChehalis district, Washington, with a section on Microscopical character of the Centralia-Chehalis coal, by J. M. 

Schopf: U.S. Geol. Survey Bull. 1053, 159 p.

Snavely, P. D., Jr., and Wagner, H. C., 1963, Tertiary geologic 

history of western Oregon and Washington: Washington 

Div. Mines and Geology Rept. Inv. 22, 25 p.

Stokes, W. L., and Varnes, D. J., 1955, Glossary of selected 

geologic terms with special reference to their use in engineering: Colorado Sci. Soc. Proc., v. 16, 165 p.

Straub, L. G., 1942, Mechanics of rivers, in Meinzer, O. E., ed., 

Physics of the earth, Pt. 9. Hydrology: New York, McGraw-Hill Book Co., p. 614-636.

Theobald, P. K., Jr., 1957, The gold pan as a quantitative geologic tool: U.S. Geol. Survey Bull. 1071-A, p. 1-54.

Thorsen, G. W., 1961, Directory of Washington miring operations 1960: Washington Div. Mines and Geology Inf. Circ. 

35, 84 p.

Trask, P. D., 1932, Origin and environment of source sediments 

of petroleum: Am. Petroleum Inst, 323 p.

U.S. Army Corps of Engineers, 1953, The Unified Soil Classification System: U.S. Army Corps of Engineers Tech. 

Memo. 3-357, v. 1-3.

U.S. Weather Bureau, 1961, Climatic guide for Seattle, Washington and adjacent Puget Sound area: 48 p.

Valentine, G. M., 1949, Inventory of Washington minerals, Pt. 

1, Nonmetallic minerals: Washington Div. Mines and Geology Bull. 37, 113 p.

Varnes, D. J., 1958, Landslide types and processes, Chap. 3 of 

Eckel, E. B., ed., Landslides and engineering practice: 

Natl. Acad. Sci. Natl. Research Council Highway Research Board Spec. Rept. 29, p. 20-47.

Vine, J. D., 1962a, Stratigraphy of Eocene rocks ir a part of 

King County, Washington: Washington Div. Mines and 

Geology Rept. Inv. 21, 20 p.

_____ 1962b, Preliminary geologic map of the ITobart and 

Maple Valley quadrangles, King County, Washington: 

Washington Div. Mines and Geology Geol. Map GM-1.

Vine, J. D., 1969, Geology and coal resources of tl ? Cumberland, Hobart, and Maple Valley quadrangles, King County, 

Washington: U.S. Geol. Survey Prof. Paper 624, 67 p. 

[1970].

Waldron, H. H., 1961, Geology of the Poverty Bay quadrangle, 

Washington: U.S. Geol. Survey Geol. Quad. Map GQ-158.

_____1962, Geology of the Des Moines quadrarsle, Washington: U.S. Geol. Survey Geol. Quad. Map GQ-159.

.1967, Geologic map of the Duwamish Head quadrangle, King and Kitsap Counties, Washington: U.S. Geol. 

Survey Geol. Quad. Map GQ-706.
REFERENCES CITED

Waldron, H. H., Liesch, B. A., Mullineaux, D. R., and Crandell, D. B., 1962, Preliminary geologic map of Seattle an-d 

vicinity, Washington: U.S. Geol. Survey Misc. Geol. Inv. 

Map 1-354.

Waldron, H. H., Mullineaux, D. B., and Crandell, D. B., 1957, 

Age of the Vashon glaciation in the southern and central 

parts of the Puget Sound basin, Washington [abs.] : Geol. 

Soc. America Bull., v. 68, no. 12, pt. 2, p. 1849-1850.

Walters, K. L., 1965, Mashel Formation of southwestern Pierce 

County, Washington, in Cohee, G. V., and West, W. S., 

Changes in stratigraphic nomenclature by the U.S. Geological Survey 1964: U.S. Geol. Survey Bull. 1224-A, p. 

A55-A59.

Warren, W. C., Norbisrath, Hans, Grivetti, R. M., and Brown, 

S. P., 1945, Preliminary geologic map and brief description 

of the coal fields of King County, Washington: U.S. Geol. 

Survey Coal Inv. Map.

Weaver, C. E., 1912, A preliminary report on the Tertiary 

paleontology of western Washington: Washington Geol. 

Survey Bull. 15, 80 p.

_____ 1916, The Tertiary formations of western Washington : Washington Geol. Survey Bull. 13, 327 p.

_____ 1937, Tertiary stratigraphy of western Washington

and northwestern Oregon: Washington Univ. [Seattle] 

Pub. Geology, v. 4, 266 p. 

___ 1942, Paleontology of the marine Tertiary formations

of Oregon and Washington: Washington Univ. [Seattle] 

Pub. Geology, v. 5, pts. 1-3, 789 p. 

___1945, Geology of Oregon and Washington and its relation to occurrence of oil and gas: Am. Assoc. Petroleum 

Geologists Bull., v. 29, no. 10, p. 1377-1415. 

Weaver, C. E., and others, 1944, Correlation of marine Cenozoic formations of western North America [chart 11]: 

Geol. Soc. America BulL, v. 55, no. 5, p. 569-598.

White, C. A., 1888, On the Puget group of Washington Territory: Am. Jour. Set, v. 36, p. 443-450.

_____1889, On invertebrate fossils from the Pacific coast: 

U.S. Geol. Survey Bull. 51, 102 p.

Williams, Howel, Turner, F. J., and Gilbert, C. M., 1954, Petrography an introduction to the study of rocks in tl in 

sections: San Francisco, W. H. Freeman and Co., 406 p.

Willis, Bailey, 1886, Beport on the coal fields of Washington 

Territory: U.S. 10th Census, v. 15, p. 759-771.

_____1898a, Some coal fields of Puget Sound: U.S. Geol. 

Survey 18th Ann. Bept., pt. 3, p. 393-436.

._____ 1898b, Stratigraphy and structure of the Puget groTTp,

Washington: Geol. Soc. America BulL, v. 9, p. 2-6. 

___1898c, Drift phenomena of Puget Sound: Geol.

America Bull., v. 9, p. 111-162.

Willis, Bailey, and Smith, G. O., 1899, Description of the ^acoma quadrangle [Washington] : U.S. Geoh Survey Gool. 

Altas, Folio 54, 10 p.

Wilson, S. D., and Johnson, K. A., 1964, Slides in over-consolidated clays along the Seattle Freeway, in 2d Ann. E^TGeology and Soils Eng. Symposium Proc., Pocatello, Idaho, 

1964: p. 29-43.

Wolfe, J. A., 1968, Paleogene biostratigraphy of nonmarine 

rocks in King County, Washington: U.S. Geol. Surrey 

Prof. Paper 571, 33 p.

Wolfe, J. A., Gower, H. D., and Vine, J. D., 1961, Age and 

correlation of the Puget group, King County, Washington, 

in Short papers in the geologic and hydrologic sciences: 

U.S. Geol. Survey Prof. Paper 424C, p. C230-C232.

Wolman, M. G., and Leopold, L. B., 1957, River flood plains; 

Some observations on their formation: U.S. Geol. Surrey 

Prof. Paper 282-C, p. 87-109.

INDEX

A Page 

Acknowledgments _______..--. ---. --- 4

AldertonInterglaciation_................... 27,31

Altitudes, range...._.............__.--.-. 7

Analyses, chemical............._........... 24

heavy-mineral.................__------- 28,29

X-ray.................................... 36

Andesite, intrusive.._...........__... 10,#0,83

Andesitic sedimentary rocks, correlation...... 22

Lincoln Creek Formation..-.---._-.----. 19

Puget Group..-.--...-..-......-.....---. 10,13

Tukwila Formation...................... 15

Arkose, correlation...........__..._..... 22

Puget Group.....-..-_----.---....-...... 10,13

Renton Formation....................... 18

silica sand.__........................... 84

Tukwila Formation...---..__-.--.-_... 16

B

Bayne Series, Puget Group. __ .......... _ 10, 11

Bedrock, previous studies..-------------.---- 6

Big Soos Creek............................... 8,57

Black Diamond anticline. -------------------- 11, 71

Black River _ ............................... 8

Blackmon, P. D., analyst--.... ... ...----.. 36

Brown, R. W., fossil identification. .... ... 26

C 

Carbonado Formation.............. _ ..

Carroll, Dorothy, analyst--..-. .........

Cedar River, diversions. -.-_._. ...-.-..-

Cedar River fan... ....... _ ... _ __ ..

Cedar River valley, alluvium, lithology.

alluvium, thickness.-.------.------.

drainage __ .........................

topography. .........................

Cedar Spillway. ....... __ ............

22 

36 

63 

59 

57 

57 

64 

7

65 

Cedar Spillway of Mackin... ................. 47

Central Cascade detrital material _ ---------- 27

C hannel deposits. ............................ 68

Chemical analysis, andesite. ................. 24

Chloe, Gillison, analyst.... .................. 36

Chlorite.. ...... ...... -.-.......-..---..-..-.. 20

Clay, refractory.................. __ ........ 85

Clay-mineral content, Hammer Bluff Formation... -.-______________.___..____ 25

intermediate drift... ........ ............. 38

Lincoln Creek Formation. ............... 20

Orting Drift -- ..... ............... 32

Puget Group----.... ..................... 12

Renton Formation--....-... ............. 18

Tukwila Formation. ..................... 16

Vashon Drift till..... ..................... 45

Climate, Pleistocene..... ..................... 30,72

present................................... 8

Coal.......................................... 85

Construction materials..-..-. _ ... _ ....... 82

C ovington bog. .............................. 52

C ovington channel. ..................... 7, 47, 48, 65

D 

Delta, at Auburn _ .......................... 49

Drainage................................. 6,9,63,78

effects of postglacial changes .............. 65

historic changes. . _ ..................... 8

[Italic page numbers indicate major references]

Page

Drift plain, relief............................. 7,45

D uwamish Valley, alluvium, dating.......... 61

alluvium, lithology of fans.. _. 59

thickness.... -..._....__ _ _ 59

definition... .- 7

drainage. 62

origin.................................... 62

topography__...... .-...-... ...-- 7

E 

Economic geology.-----.------------.

clay......._........_...........

coal.-........_......._.-..---..._

oil and gas__.___-_.. _.. 

peat and topsoil----..............

silica sand-...-----------.--------

Engineering geology.-------.--------.

construction materials..-..----.--

engineering properties of depositsground water.....................

landslides. -----------------------

overconsolidation problems. ------

77

84

85

84

85

83

77

82

78

80

81 

77 

till, heterogeneity_.-.-.. .-...--...... 80

Excavation properties........--....-..--.---. 79

Faults.... -.-.....-........--_-.......-...-.-. 69

Folds................................-... . 69

Fossils, diatoms..... ------- - 30,40

Forminifera---.- - _ . - 18,21 

plants.... ........._._._._...._.-... 14,17,21,26

pollen.. ...._. ... ...... 26,30,40,43

stages. _____...__.-_- --._-. 14

Foundation stability. ......... ...........- . 79

Franklin fault... .......... ...... .. ... 71

Franklin Series, Puget Group..- 10,11

Fraser Glaciation. .........---.......--..-. 27, 44, 50

G

modern alluvium. ........................

P leistocene deposits ............ ..........

Puget Group. -.....-....--.......-.--....

Renton Formation. ______ ... .____ .- 

VashonDrift till . ......................

Geologic history. _..______ ______ _ _. .

Geologic quadrangle maps _ ............----.

Geomorphology... .................. .- -

flood -plain development ..-.-......-. ...

river characteristics. .....................

Glacierice, thickness.. _..__._ ..............

Grain size, arkose.. _ _ _ .....................

channel gravel... ._.-._.__-_-...__._-- 58, 

Green River, diversions. ... ................

streamflow .......................... ...

Green River valley, alluvium, channel material-... ..--..-... ....-----

alluvium, flood -plain material ________- 

thickness. _ ................. . .-...

drainage _ ............-.--...-...- ...-.

topography. _ __. - - - -- 

Ground moraine. ................. ...---..--.

Ground water. ...............................

30

28

29

12

18

45

72

3

61

68

66

44

12

59,66

63

58

58

57

64

7

45

78

H Page

Hammer Bluff Formation ... ... 84 

Hathaway, J. C., analyst..-.--.---.-.- 28,29,36 

Heavy-mineral content, Cedar River valley

alluvium..___... .. ... 57 

Green River valley alluvium.. __. __. 58 

Hammer Bluff Formation----..-..... 25

modern alluvium............. ......... 28

Pleistocene deposits...................... 29

Puget Group.----..------ ------- 12

White River valley alluvium............ 59

Hornblende, as characteristic mineral..... 25,26,28

Hypersthene, as characteristic mineral.... 28,56,59

Intermediate drift............ ._ . SB

Intrusive rocks, location and analysis. ..... 22 

Israelsky, M. C., fossil Foraminiferaidentification...---.-..----......-.----- 21

Kaolinite, as characteristic mineral. _ _ 16

Kummer flint clay. __________ __.- . --. 13

Kummer Series, Puget Group..-....---...... 10,11

Kummer syiicline...._____ .- - - 11

Land use, geologic influence on............... 77

vegetation_............................. 9

Landslides, causes_ 54,82

recognition criteria__ .- - _ 53,82 

types.----...----.......------------------ 53

See also Engineering geology, landslides. 

Leopold, E. B., fossil identification..... 26,30,40,43

Lincoln C reek Formation.....-.....---...... 19

Location of area..--- .-- --- -------- 3

Lohman, K. E., fossil diatom identification.. 30,40 

Lower Tertiary rocks............-..-...-----. 10

correlation..____._._ ._._- _. -. 22

structure.. - . -- ....... 69

M

McNeil, F. S., fossil identifications........... 14

MarinetQl 39

Melt-water rivers . . 46,47,48,65 

Montniorillonite, as characteristic mineral.. 24,32,56 

Moore, E.J., fossil identification.--------- 21,61

Mount Rainier detrital material-_... 27

N 

Newaukum Creek........ 8,57

Newcastle Hills promontory..... - - 6

Nonglacialsediments..___. -- -. 27,30

Northcraft Formation.. 22

Northern Cascade detrital material........... 27

O

Ohanapecosh Formation...-_-- ............ 22

Olympia Interglaciation- .... 27,31,62

Orting Drift SI

Osceola Mudfiow....___. _ - - -- 54

91
92 INDEX

P Page

Peat deposits .... ... ..... 51

Petroleum_. -- --.. .......__.... 84

Physiography..--..--------------..-..... 6

Pleistocene deposits-.. .----.-.---........ 27

age and correlation............__....... 49

climate-----------------------....... 30,72

heavy-mineral content --- . _. . 29

mineralogy of silt and clay....__....... 36

previous studies. _ - . ___. _______ 6

provenance.... -----_-------.---....---. 29

sources of material_ . ...______ 27

stratigraphic sequence.................... 27,31

structure _ 72

weathering-. . . . ......... 30

Pleistocene geologic history..... _ ........... 76

Postglacial deposits. __. -...-......___ SO

colluvium, composition............-----.. 53

landslides........ .................. 54

location and thickness........... ... 53

flood-plain alluvium...-- ..... ... ... 56

heavy-mineral content.. _. _. ._.._. 28

lacustrine deposits, composition.......... 51

dating ...- . ..-.. ........ 52

location ----- - - ._ 51

Osceola Mudflow, age. ................... 56

composition. ---------_ -. .. .-. 56

distribution__...............__ £4

effect on drainage. ______ 7,65

terrace alluvium_-.__ __ ___ _ 52

Postglacial geologic history................... 76

Previous work.--_-. .._.__-. ._.....-. 3,5

Puget glacial lobe_-- -- _ 27

Puget Group, depth of weathering............ 13

environment of deposition __ __ 19

fossils and age............................ 13

gross composition................ .-_ - 10

lithology..--.....-..........-.-.-..--.-- 12

named__ .--.--............... ----_. 6,10

near Black Diamond....._ _........ 11

previous work.............._ __.__._.. 10

Renton Formation..........__..__....... 17

source._._ . ........-._..-.. ,.. 14

stratigraphic relations.----.-..-.......... 13

subdivision.---....--.. .....-.._........ 10

thickness-.-.--------..---....-........... 11

Tukwila Formation. 15

Puget Sound trough, origin__............... 62

Page

Pumice.----.._.....__.__..._------- 25,26

Purpose and scope..----...---.-..-.--------- 3

Puyallup Formation.......----_.---.-. ... 39

Rau, W. W., fossil Foraminifera identification..--......-.........--.-----.. 18,21

References cited.................--..--.---.-. 86

Renton anticline..-..............-.....--..-- 69

Renton Formation....----_--.....--.-- ... 17

River channel migration_............... 66,67,68

River gradients_........................... 66

River overbank deposits........--.--.--.-...- 68

Roslyn Formation___...---.--_.----..-- 15

Rubin, Meyer, radiocarbon analyses.......... 4

S 

Salmon Springs Drift__.................... 41

Sand and gravel.............................. 82

Schlocker, Julius, analyst..-.-..--......-.... 24

Siderite.....-....--............ .... ... 32

Slope stability__................ ... ... 79

South Prairie Creek.......-----.---------- 65

Springbrooksyncline.---..-----.------------- 71

Starkey, H. C., analyst. ..... . ..... 28,29,36

Steele Crossing locality....-. . . .... 17

Stone.... . .... . - ... 83

Streamflowmeasurements____..__. - 66

Structure-.-..--.-.-.. -------------- 69

Stuck Qlaciation.......................... 27,31,35

Sunbeamfanlt. .....- --- - 71

T 

Talbotsyncline....-.............---._.-.-..- 69

Taylor, D. W.,molluskidentification......... 52

Tertiary geologic history._..... ..... .... 75

Tertiary rocks....-.. .. --.- ..- 9

Tiger Mountain area__..-.-... .. --- 17,19,22 

Tiger Mountain Formation....-.......--- 10,16,22

Till deposits, ablation----.-----.------------- 45

engineering properties.._.-..-...-.---- 80

lodgment..-................__.. . . 45

mineralogv of silt and clay fractions...... 36

particle-size distribution.._ _- 35

texture-..-.-...._..........-...--..--.- 34

Todd, Ruth, fossil Foraminifera identification. 21 

Troughs, geomorphic, origin.................. 62

Tuff. 

Tukwila anticline 

Tukwila Formation..

Page 

16 

69

IS

u

Unconformity, Hammer Bluff Formation __ 25

intermediate drift....-.-.----------._..-- 38

Lincoln Creek Formation... ____..... 20

Renton Formation.._. . _ . 18

Salmon Springs Drift....__..._...__ 42

Uiidifferentiated drift._..___......__ Ifl

Upper Tertiary rocks, structure..._ ------- 72

See also Hammer Bluff Formation.

Vashon Drift..... . 43,80

Vashon glacier, effects on drainage............ 64

Vegetation, relation to geologic deposits. -. 9 

Volcanicash 25,39

Mazama layer__... . .. .. 51,61 

Volcanic mudflows...--------------- 16,26,39,54,68

Volcanic rocks, history._ ------------ 75

See also Tukwila Formation.

W

Weathering, Hammer Bluff Formation ------- 25,84

intermediate drift. . 38

Orting Drift 32

Pleistocene deposits- - 30

Puget Group-------...--- ... ------- 13

Puyallup Formation.........-....----..- 40

Tukwila Formation..---.--.----.- -..- 16

White River, diversions. _ .- 63

streamflow..----------------------------- 66

White River fan.... . - 60

White River vaUey, aUuvium, litholopiy and

source.------------------ ------- 59

alluvium, thickness._-----.-----.--.---- 58

drainage_..__---------- ... ... 64

topography . - - ---- - 7

Willis, BaUey, quoted......-.------..------ 43,44

Wolfe, J. A., fossil plant identification..___-.. 17,18

Y, Z 

Yucca Formation. _. ._ --- ------ 36

Zircon, as characteristic mineral-------------- 12

U. S. GOVERNMENT PRINTING OFFICE : 1970 O - 380-731