U.S. DEPARTMENT OF THE INTERIOR Prepared in cooperation with PROFESSIONAL PAPER 1620 U.S. GEOLOGICAL SURVEY OREGON WATER RESOURCES DEPARTMENT Quaternary geologic units in Willamette Valley, Oregon—PLATE 1 O'Connor and others, 2001, Origin, Extent, and Thickness of Quaternary Geologic Units in the Willamette Valley, Oregon.

123°45' R. 7 W. R. 6 W. R. 5 W. 123º30' R. 4 W. R. 3 W. 123º15' R. 2 W. R. 1 W. 123°00' R. 1 E. R. 2 E. 122°45' R. 3 E. T. WASHINGTON MULTNOMAH T. 1 Gaston 205 1 S. COUNTY COUNTY S. Tigard Lake Turner Oswego Tua 99W 5 latin Clackamas ego Osw DESCRIPTION OF MAPPING UNIT CORRELATION OF MAP UNITS ake T. Creek L T. 2 Clackamas 2 S. Tualatin River Clear S. Alluvium of smaller streams (Holocene and upper Pleistocene)—Unconsolidated clay, silt, sand, and minor gravel VK Gladstone Qalf Age (Ma) 25 QTg River deposited in floodplains and active channels of smaller streams and rivers. Variable surface morphology. Thickness not Qalf defined, but probably less than 10 meters. Differentiated from units Qbf and Qau where clearly younger than Missoula Tvc Tcr Qff2 Tcr Qff2 QTb QTb 0 hill Qff2 West Linn Qalc Flood deposits. Mostly younger than 12 ka. Yam Tm Qff2 Qalf C Rock Creek North Qau Sherwood Willamette QTt Qalf Qalc h Gap Falls Creek e QTt Holocene River k h e a Tm e Qau Floodplain deposits of the Willamette River and major tributaries (Holocene and upper Pleistocene)— l r Qfc QTb W e C Tcr Oregon Qalc m Tm Tcr Qfc Unconsolidated silt, sand, and gravel of the Willamette River and major Cascade Range tributaries. Includes active il 0.01 la ar City m d channel and modern floodplain surfaces. Meander-scroll topography with surfaces as high as 15 meters above summer Disconformity Tm e QTg e Haskins C Qalf water stage. Drillers' logs and exposures indicate that unit thickness ranges up to 15 meters. Isotopic dating, tt e Qalf Cre Tcr b ek Qff RM tephrochronology, and stratigraphic relations within the Willamette Valley indicate that these deposits are mostly younger a Qalf 2 Qff2 s Creek 30 than 12 ka. i T. n Qff Qff2 Qg T. b 2 Tcr Newberg Wilsonville 3 1 3 o A u Qff b S. n Panther Qfc 2 e Sand and Gravel that postdates Missoula Floods (upper Pleistocene)—Alluvial sand and gravel deposited in broad S. d r a Tm Qff Qff n Qg r Carlton Tcr 1 Qff 2 e 1 braidplains within Willamette Valley and traced upstream as alluvial fills in major Cascade Range tributary valleys. Forms y Tcr 2 t Disconformity h RM Qfc QTt y surfaces of large fans where major Cascade Range tributaries enter the Willamette Valley. Deposits now preserved as

Molalla QTb RM Qfc

VK 40 C planar to slightly undulating terraces 0 to 15 meters above the modern floodplain. Drillers' logs and stratigraphic exposures Creek 50

50 r e indicate that unit is up to 30 meters thick. Stratigraphic relations and isotopic dating indicate that deposits primarily date Qau Qbf Qls QTt e k from about 12 ka, although some areas mapped as Qg in the Eugene-Springfield area and within the Cascade Range Qff1 Qff Canby 1 Qalc 1 Qalc foothills may be substantially older. 45°15' Qff Tcr 45°15' Qls 1 River reek QTb Disconformity C Qalf 5 n Aurora Missoula Flood deposits (upper Pleistocene)—Unconsolidated clay, silt, sand, and gravel deposited by floods o COUNTY i Pleistocene QUATERNARY Yamh s Creek il s originating in glacial Lake Missoula that flowed down the Columbia River and backflooded into the Willamette Valley l i TILLAMOOK Baker Qff Creek M 2 (Glenn, 1965; Allison, 1978). Largest flows reached stages of about 120 meters above sea level in the map area. T. Gribble Qalf Qff Qfc Dayton St Paul Qff2 T. 2 4 McMinnville QTb 4 Maximum thickness of deposits about 35 meters in northern Willamette Valley, thins to less than 1 meter at elevations S. Qalf Creek S. above about 100 meters. Radiocarbon dating, tephrochronology, and stratigraphic relations from within and outside the Qff River Weston 2 Rock map area indicate that most units date from about 15 to 12.7 ka. Divided into: Disconformity Landing RM Qg1 Bear QTt 60 99E Younger and lower fine-grained Missoula Flood deposits—Clay, silt, sand, and minor gravel forming benches along Qff Champoeg Creek Muddy 2 VK Qg2 Qff Qg River 1 Labish channel and Pudding River, and locally flanking Willamette River in northern Willamette valley. Planar to 2 iver Creek 75 R Qalf Mill Creek Qau undulating surface almost everywhere 40-50 meters above sea level. Set into main-body fine facies (Qff ). Probably Qalf Qalf Creek 2 Tvw Qalf mostly deposited by latest Pleistocene Missoula Floods between 13.5 and 12.7 ka, but possibly includes late Pleistocene River and early Holocene deposits of units Qalf and Qalc. Unconformity Bend QTt Molalla Tm Woodburn QTt Creek Main body of fine-grained Missoula Flood deposits—Stratified silt and clay with minor sand. Underlies much of T. Deer Qff T. Qff Creek l 2 2 Willamette Valley lowland floor. Many sections show rhythmic bedding, with up to 40 individual beds between 0.1 and 5 l Tvw 5 i Qau QTg S. h Palmer S. 1.0 meter thick. Encloses sparse pebbles to boulders of types exotic to Willamette Basin. Forms undulating to planar QTb 1.6 m Tm Rock QTt a Y topography in lowlands; mantles foothills below altitudes of 120 meters. Mapped where thickness is sufficient to Amity Tcr Qg1 Pudding Butte Creek Pliocene RM Gervais QTg obscure previous topography. Commonly capped by up to two meters of late Pleistocene and Holocene alluvium, Creek 70 QTg Qau Sheridan Tm Qff2 Qalf colluvium, and loess. Creek Conformity to Disconformity 5.0 Tcr Qg1 E ER Wheatland IV O R Qau Coarse Missoula Flood deposits—Bouldery, cobbly, sandy gravel fans deposited by Missoula Floods as they spilled Ferry Tcr h Tm L Qalf Sout Mount Qfc into northern Willamette Valley through the Oregon City and Rock Creek gaps. Crudely stratified, commonly with YAMHILL COUNTY A A Tcr Angel Tvw south-dipping foresets. Commonly capped by several meters of sandy silt, especially south of Willamette River. Drillers' Miocene QTg

POLK COUNTY H Tm A' logs indicate that thickness locally exceeds 30 meters. I Unconformity

L ek Swale Tcr Tcr Qau Tvw re L Qalc Qalf C Sand and gravel that predates Missoula Floods (Pleistocene)—Unconsolidated to semiconsolidated sand and gravel Qalf S QTg Qff2 Tcr 1 Qau Tm 24 k Qff T. Qg TERTIARY T. Tm e 2 deposited in broad braidplains and meandering floodplain environments within Willamette Valley and upstream as alluvial e r el Qau 6 6 E n Abiqua Tm Tm C n fills along major Cascade Range tributaries. Locally contains lahar deposits. Forms planar to slightly undulating terrace Tm T a Scotts Mills Tcr Tcr S. h Oligocene S. T y C r h e surfaces 0 to 20 meters above the modern floodplain and generally at slightly higher elevations than adjacent surfaces of E Tcr e s Qff Qau l i 1 v l b i M a a R unit Qg . Thickness not systematically determined but locally exceeds 100 meters in broad fans formed where major L A QTg 1 V t Qau

L g 38 l g n Cascade Range tributaries enter the Willamette lowlands. Isotopic dating and tephrochronology indicate these deposits a Sprin L i Coal Tvw QTg I Qff River S Tm 1 d

22 d range from greater than 0.41 Ma to about 22 ka. E W u Tm Creek Tm O P QTg 45°00' Tm Qau 45°00' Eocene Tvc

L e Tm l Silverton Alluvium, undifferentiated (Holocene and Pleistocene)—Sand, silt, clay, and minor gravel deposited by smaller streams r Keizer t Butte Qau A t C i Qau t Tm and rivers that enter the Willamette Valley, and by larger streams and rivers outside the area of detailed mapping. Age and l Tm Hayesville L a RM Creek S H Silver thickness not determined. k Qau 80 Tcr I F Tcr QTg L Tm W Tm Creek Tvc L QTg Fine-grained alluvium (Holocene and Pleistocene)—Clay, silt, sand, and minor gravel deposited in small basins Drift S Tcr Qbf Tm Pudding Qau T. flanking the Willamette Valley. Planar surfaces. Age and thickness not determined. Distinction with unit Qau locally Qff T. 2 Qff2 7 7 Qls arbitrary. Bask VK SALEM S S. S. Tm ett 100 5 L I L Landslide deposits and colluvium (Holocene and Pleistocene)—Unconsolidated and heterogeneous mixtures of rock QTg Qau Slough H Eola Tm Creek Qls fragments and soil. Some landslide deposits have hummocky surfaces. Colluvium mapped on steep debris-mantled slopes O QTg D Tvw where underlying bedrock is not known. Only larger deposits mapped, mostly after Walker and McLeod (1991). Age and Qau Qg L CLACK Tvc Creek Qalf 1 A Tm A RM Tvw M thickness not defined. QTg QTg Qg W A Dallas R eall 1 90 Tm MA S ickr 1 R Qg Creek IO COUNTY N Fk Qff2 Qls N Weathered terrace gravel (Pleistocene and Pliocene?)—Alluvial sand and gravel preserved as terraces flanking Qau 99W Qg1 River Tvw Bend Tcr CO QTg Willamette Valley and tributary valleys. Terrace surfaces planar to undulating, with thick, strongly-developed soils, and Tvc UNTY Qff2 S&G Tm severely weathered clasts. Terrace surfaces up to 100 meters above modern floodplains. Drillers' logs and stratigraphic Tm 99E Tvw Ash Tvw exposures indicate sand and gravel 0 to 60 meters thick. May be in part equivalent to Troutdale Formation (QTt) as Qalc Tm Tcr North L L S Qls mapped near Molalla. Probably mostly deposited between 2.5 and 0.5 Ma. H I T. Falls D O T. A L 8 8 City Creek W Tvw Qau Tm S. S. S Fk SA C Walling Tvw UPLAND UNITS (Primarily compiled from previous workers) LE ttle ree Creek Tvw Monmouth M Ba k S&G Turner Qff Qau Fork Independence 2 Beaver H Tm IL Tcr QTg Ash LS Boring Lava (Pleistocene and Pliocene)—Gray to light-gray, open-textured olivine basalt lava flows. Only mapped in Litt Turner Mill le L QTb u Cooper Creek Gap C' Sublimity the northern part of map area after Hampton (1973). Up to 60 meters thick. Ten radiometric ages on separate flows near c M k i c Creek Creek Oregon City span 0.427 ± 0.026 Ma to 3.15 ± 0.062 Ma (Madin, 1994). a Tm K m RM Tcr i u n Qau Qls n Qg t 100 1 Tvw Tcr e Cr e Troutdale Formation (Pleistocene? and Pliocene)—Sand, gravel, sandstone, conglomerate, siltstone, and mudstone. y Stout Tcr Sidney QTg QTt Qau C River Only mapped in northern part of map area after Trimble (1963) and Hampton (1972) where it is up to 150 meters thick. Qg r Stayton Qg 1 e 2 QTg EXPLANATION River e May be locally equivalent to the weathered terrace gravel (QTg) near Molalla. Overlain by Boring Lava near Oregon City. Tm k Qau Qff2 Qau Qalf Little North T. Tm Qg1 QTg 9 T. Sidney Qau Qalc River Lyons 9 Santiam Qalc S. Volcanic and volcaniclastic rocks of the western Cascade Range, undivided (upper Eocene to Pliocene)—Lava flows, QTg Qg1 Tvw S. Qff Tcr tuff, breccia, and volcaniclastic sediment of variable composition. Locally interfingers with marine sedimentary rocks (Tm) Water Luckiamute 2 Qg2 MARION COUNTY Qau VK in the southern portion of map area. Includes the Fisher Formation, "volcanic rocks of the western Cascade Range", and Tm Branch 125 Bear Creek 22 Sardine Formation as compiled by Gannett and Caldwell (1998). Youngest rocks are ridge-capping basalt flows in Santiam ehulpum Tvw Qau Creek River h QTg Santiam River 44°45' C QTg Cr Qau Mill 44°45' River drainage with reported ages as young as 2.80 ± 0.3 Ma (Verplanck, 1985, cited in Walker and Duncan, 1989). Contact Tm North QTg C North Qff Sa Qg Tcr City LINN COUNTY 2 ntiam 2 Riv Slough Jordan QTg er Qau QTg Qau Tvw Qau Thomas Creek Qalc Columbia River Basalt Group (Miocene)—Lava flows of dark gray to black, locally porphyritic basalt. Locally deeply A A' Trace of generalized geologic sections shown on figure 2 of the report Tm RM QTg Tcr POLK COUNTY Jont Berry weathered. Mostly between 16 and 15 Ma in northern Willamette Valley (M.H. Beeson, Portland State University, written Creek 110 Creek QTg BENTON COUNTY Tm Jefferson QTg communication, 1998). Also includes small areas of alluvium, colluvium, loess, and landslide debris. Distribution after Scio Creek Study area boundary Qff Sucker Mill Gannett and Caldwell (1998). Qg1 2 N Fk Qls T. Tvc Qg1 Qau T. 10 10 Tm Thomas Creek S Fk Marine sedimentary rocks (lower Miocene to Eocene)—Marine sandstone, siltstone, shale, and claystone, with lesser RM Qff2 S. S. Tvc Qau Tcr Neal Tm River mile location—From US Geological Survey 1:24,000-scale QTg Qalf QTg conglomerate; locally tuffaceous. Also includes numerous small mafic intrusions, and small areas of alluvium, colluvium, 110 r topographic quadrangles Qau Qls Tvw Tcr C loess, and landslide debris. Distribution after Gannett and Caldwell (1998). QTg e Tm Crabtree i VK Neal Cr r QTg i Tcr a 125 Valley kilometer—Measured from Columbia River confluence along axis of Qbf r Volcanic rocks of the Coast Range (Eocene)—Basaltic pillow lava, tuff breccia, subaerial basalt lava flows, and sills, with North Qg P Soap 1 Qff Tvc Holocene floodplain of the Willamette River Tvc QTg 2 Creek n Cr interbeds of basaltic sandstone, siltstone, and conglomerate. Includes small areas of alluvium, colluvium, loess, and Tm Albany Qff a Tm 2 i Sidney QTg Tvw d landslide debris. Distribution after Gannett and Caldwell (1998). n Ella Site location—Stratigraphic section or sample site described in accompanying text. River I Qalc Creek Note: "S&G" = Sand and Gravel. Albany Cox Roaring RM Qg Note: "Ma" refers to millions of years before present, and in this report is used to indicate radiometric and fission track ages Qff 1 QTg 2 120 on volcanic rocks. "ka" refers to kiloannum, indicating thousands of radiocarbon years before present. Tm Beaver South Tvw T. T. 11 Qau Creek D Oak Creek 11 S. i Tm x S. o QTg Qau n Qalf QTg IVER Qff2 R Tm Cr VK 99E G Crabtree 150 r RM Qff e 2 QTg Creek e Corvallis 130 Creek n

20 M Tm o u SOURCES OF GEOLOGIC MAPPING n

Lake t Qalc a

i Philomath Tm Tangent Qau n Qau Muddy Lebanon C

r

Qau QTg Calapooia e

e k Source map number and authors—Full reference citation T. ek Marys River Creek S Fk at back of text 12 re T. 18 S. C Qalf Qau 12 QTg Tm Qg2 Hamilton Scott 1 Qg Creek S. Allison (1953) Qff2 1 Creek 44°30' QTg 44°30' Qau 2 Allison and Felts (1956) y 8 s Tm Qau Tvw Green Peter ea r Qff Lake 3 Balster and Parsons (1968) G 2 Bear River 3 M Creek Qau Santiam 16 QTg ud Island Butte Creek d y RM Qg Qau 4 Bela (1979) Tm 140 Tm 2 ell 17 ow 7 C cD reek re M r C e Tvw 5 Bela (1981) e k Tvw er 14 v iv a m R Be Qalf Tm MARKS RIDGE ntia T. QTg B B' Sa 6 Beaulieu and others (1974) Tm Calapooia Tm le T. 13 13 Qau d id 13 S. Qau M S Tvw S. 7 Brownfield and Schlicker (1981a) C p re o e o Tvw ake 5 k n River Foster L Qg Qg 8 Brownfield and Schlicker (1981b) Tm 1 1 19 20 Qalf Qg2 Sweet 9 Frank (1973) Reese QTg Courtney River Home Halsey Brownsville Qau Qau Qff2 RM 10 Frank (1974) 150 Qbf 1 A W m C Qbf i 5 e le r 11 Frank (1976) Tm E Irish Creek s y VK Lake e T C e C r

175 T Bend k e Creek r e 2 E e k e Qg M 12 Gannett and Caldwell (1998) T. 1 Tm k T. QTg Qff A 14 2 L Qff2 14 L S. I S. Tm 10 6 13 Glenn (1965) W Qalf reek Tm Cartney Little C Qbf 4 14 Hampton (1972)

River Park r 12 e Monroe Tvw m 15 Piper (1942) Muddy m Creek Tm a Muddy H Pierce 11 16 Price (1967a) Tm 99W 99E BENTON COUNTY Creek Tvw 17 Price (1967b) LANE COUNTY Qalc RM T. 160 Harrisburg Qls T. 15 18 Trimble (1963) 15 Creek S. S. Tm QTg 44°15' Flat 44°15' 19 Yeats and others (1996) Ferguson Creek Dry 9 Qau Tvw Cash Not shown are the Geologic Map of Oregon Tom Junction Qbf (Walker and MacLeod, 1991), and the Soil Owens Tm LINN COUNTY City Creek Conservation Service (now Natural Resources Tm Muddy Creek Tm Qau LANE COUNTY Conservation Service) soil surveys for each of the Qg counties within the map area (Williams, 1972; Creek Creek 1 Parsons 15 Otte and others, 1974; Knezevich, 1975, 1982; Creek Mill Creek Gerig, 1985; Langridge, 1987; Patching, 1987). RM Creek 170 T. Creek Qg 2 T. 16 McGowan S. Tm 16 S.

Bear Long QTg Creek River Qbf Coburg Qg Tm 2 VK Qau 200 126 Inman Amazon 99 Qau Delta Mohawk 1 Creek Santa Qg S&G Creek Fern QTg Clara Qau Qls Wildish Tvw Qau Ridge S&G Long QTg T. Lake T. Camp 17 Qg1 17 S. Qg1 S. RM Tvw Creek enzie 180 McK QTg Qg1 Tvw Qalc Qbf Tm LOCATION MAP Qbf Tm River Tom 126 QTg 123º Eugene Springfield QTg Veneta Qbf Qbf Qg2 River Tm Tm 30 Tm Tvw QTg Tm Tvw QTg St Helens Tvw Tm Tvw RM Middle C O L U M B I A C Qau 190 O Tvw Tm L Tm Scappoose U Tvw VK Qau Creek M 44°00' Qau Qau 225 Creek 44°00' 26 Tvw B ek F Qg I T. re Qalc 1 T. A te C o 5 205 122º o QTg rk 18 W A S H I N G T O N Tualatin Mountains 18 oy Tvw Qg Hills Fall S. C 1 S. Qg1 R I V E R Tvw Little PORTLAND Tm W Tm Qg2 i PORTLAND 84 R ll Henry Forest Papenfus a a RM t m Fall 45º30' E Hagg Grove Hillsboro M U L T N O M A H River 45º30' tl 200 QTg QTg e e Run t Lake Tualatin BASIN Gresham s t G C Beaverton n e h Bull Run a Creek eh River Bull k Qau Fall Creek N a Milwaukie e River le Tualatin Lake Mt Qbf m Creek Lake Y Hood Qg QTg A North a M Sherwood Sandy 1 Creek m ou West Linn Bear h n Sandy River Creek Qau Tvw R il ta Qls l i Oregon Swale QTg Qau n Camas Lost Newburg s City Estacada 26 R Clackamas Creswell Qalc i Lowell v T. T. e E r Molalla 19 QTg W 19 McMinnville NORTHERN in G be Tvw rry St Paul River Study area S. Creek Dexter Cre S. QTg ek ver boundary i N Qau Lake R Hubbard River Y A M H I L L Timothy Creek South Woodburn Qg Lake A 1 ill C L A C K A M A S Qls mh Amity R WILLAMETTE Tvw a E R Tvw Y Mount 22 Sheridan River V

I g Angel River

n R Lookout i

d d

d

45º Keizer d 45º u

Point u

Silverton

P P Qau Lake VALLEY P O L K SALEM Dallas

Independence

Monmouth Silk STAYTON M A R I O N Qg Tvw 1 Buena e

Stayton t L 5 t T. u Vista T. e c SUBBASIN Creek Santiam Detroit Qg2 ki River Gettings a m 20 20 m River Lake Detroit a Creek u l S. t Mt S. l e North

i Jefferson

W

Row Albany South Cottage L I N N B E N T O N 20

Qau Grove

Corvallis Qg SOUTHERN 1 Marys Green E

River E

E Lebanon S Peter

River a T

Dorena T nt D T

44º30' T i 44º30'

am Lake le Santiam E Mosby Lake E dd

i

Qau R 22 A

M M M Foster i

v

A A

T

e e L

L C

r Lake r 20 QTg L Brownsville

Qau I Halsey River S S W Sweet 126

99 WILLAMETTE QTg A Home 43°45' A

43°45' Creek Ca O la po C T. R o

T. 5 Harrisburg ia Creek C Tvw 21 er River 21 iv S. R S. Tom Blue River North Fork Junction Lake Sister Martin Qg1 City INDEX MAP VALLEY River Long Middle Cottage Fern Sister Grove Cougar Ridge South Lake Lake Springfield Reservoir McKenzie Sister 126 Eugene L A N E W 44º 44º i r Portland l e Middle s v o i Fall Creek R Willamette n

Lake e Willamette t W t M Fk illamette e Lookout R m Creek basin boundary i v Willamette a Fork Point

l e

l r T. i Lake r Coast basin T. 22 W Dorena

Qau N Fk

k k r 22 S. r Cottage Lake Waldo 5 o W

F Grove i S. ll Lake a

m t e s Cottage Study tt OREGON a e Hills Tvw o Grove Creek area C Lake Lake Crater

Cr R Lake i v e 0 5 10 15 MILES r 43º30' D O U G L A S 43º30' Drue 0 5 10 15 KILOMETERS Big T. 123º D O U G L A S 122º T. River 23 23 S. S. SCALE 1:250,000 Base composited from USGS digital line graphs 0 10 20 MILES and other digital information. Universal Transverse Mercator projection, Zone 10, North American 0 10 20 KILOMETERS Datum 1927 R. 7 W. 123°45' R. 6 W. R. 5 W. 123°30' R. 4 W. R. 3 W. 123°15' R. 2 W. R. 1 W. 123°00' R. 1 E. R. 2 E. 122°45' R. 3 E.

Base compiled from U.S. Geological Survey digital base, includes: Geologic unit linework was compiled and digitized at a scale of 1:24,000, but U.S. Geological Survey Digital Line Graphs published at 1:100,000, 1987; the accuracy of the contacts varies depending on location and geologic unit. U.S. Bureau of the Census TIGER/Line® files, published at 1:100,000, 1990; U.S. Geological Survey Digital Line Graphs published at 1:100,000, 1988 GEOLOGIC MAP OF QUATERNARY UNITS IN THE WILLAMETTE VALLEY, OREGON and modified by the State of Oregon, 1994; U.S. Geological Survey quadrangle topographic maps published at 1:24,000 By as digitized by Oregon Department of Transportation Projection: Universal Transverse Mercator projection, Zone 10, 1927 North American Datum Jim E. O'Connor, Andrei Sarna-Wojcicki, Karl C. Wozniak, Danial J. Polette, and Robert J. Fleck 2001