GEOLOGICAL SURVEY MAP SERIES 2017-01 Geologic Map of the Littlerock 7.5-minute Quadrangle GEOLOGIC MAP OF THE LITTLEROCK 7.5-MINUTE QUADRANGLE, Geologic Map of the Littlerock 7.5-minute Quadrangle, Pamphlet accompanies map

123°07ƍ30Ǝ R4W R3W 05ƍ00Ǝ 02ƍ30Ǝ 123°00ƍ00Ǝ 47°00ƍ00Ǝ 47°00ƍ00Ǝ Thurston County, Washington Evc Qgt Evc Qgt Qaf Qls Qgo Qgog Qgo THURSTON COUNTY, WASHINGTON G2 Evc Evc Qgt Michael Polenz, Jessica L. Vermeer, Gabriel Legorreta Paulín, Evc ? ? Qls T18N Download the G40-41,48 Qa Qoa Evc ? Evc Qgaf Jeffrey H. Tepper, Shannon A. Mahan, and Recep Cakir T18N Qa T17N Qgo T17N Qgo? Evc Qaf Qgic Qgog Qgt ? G10 Qa June 2017 Evc Qgo ? publication ? Qaf C19-20 G14 Qgic Michael Polenz—Washington Geological Survey, Department of Natural Resources Evc Qgo ? Qgog? Qls Qa Qa G3 ? Qoa Qgic C26 Qgic Jessica L. Vermeer—Washington Geological Survey, Department of Natural Resources Qgoaf Evc Qaf Qgag C4 Qoa Evc QEcf QEcf Qgo Qgic Gabriel Legorreta Paulín—Universidad Nacional Autónoma de México, Ciudad Universitaria Del Coyoacán Qls Qa ? S1 Qaf MAJOR FINDINGS GEOLOGIC SYMBOLS G34 ? Qgoaf Qgog Jeffrey H. Tepper—University of G58-59 Qgo • A new ~47.4 Ma laser-ablation U-Pb date on zircon from a slightly reworked airfall tuff provides a close maximum Mass-wasting landforms (overlay pattern)—Landforms that suggest mass movement on unstable Magnetic 47°02' Evc ? Qaf Qgt limiting age for the McIntosh Formation. anomalies 122 Qge Qgo? slopes, but evidence for landslide deposits is inconclusive. Evc Qaf Qp (nanoteslas) Evc Qgo 40 39 ° Shannon A. Mahan—U.S. Geological Survey, Denver Federal Center Qaf Qgo • A new 46 Ma Ar/ Ar date suggests that basalt east of the Black Hills is younger than the Crescent Formation in 45

? Mima mounds (overlay pattern)—Dark brown to black, organic-rich sand to pebbly sand loam soil in 15.1 ' Qgo the Black Hills and older than gabbroic intrusive rocks east of the Littlerock quadrangle. Chemical similarities 35 Qaf Evc Qgic 8.6 regularly spaced round to oval mounds about 2 to 6 ft high and 10 to 30 ft across, with little or no " Qa suggest that all of these volcanic rocks shared the same mantle source(s). 5.2 ? Qge Qp Recep Cakir—Washington Geological Survey, Department of Natural Resources G56-57 G13 Qgic comparable soil between mounds. The black color is mostly due to ash from burned organic matter. 3.1 Evc Qaf Qge G12 • Ice covered the east half of the Littlerock quadrangle during the Vashon glaciation. It was preceded by at least one NTRMounds rest on Vashon proglacial outwash terraces with a highly permeable substrate of mostly 1.7 0.8 Qge Qoa Qaf ice incursion that reached higher elevations farther west in the Black Hills. Each ice incursion appears to have northern-sourced pebbles and cobbles. Mapped where landforms and (or) field-observed deposits indicate 0.1 Evc Qp Qgag ? Qp Qgo impounded a south-draining lake in the Waddell Creek valley, with an earlier lake reaching at least 800 ft elevation the presence of such mounds. Their enigmatic origin is discussed below (Mima Mounds in -0.7 Qa -1.3 Qaf Qpd and the Vashon lake reaching close to 465 ft. Qgo Paleoenvironmental Interpretation section). -2.0 Qp -2.8 ? G16 Qgt ? Qaf Qgim • Geochemical traits separate Olympic Mountains–style Crescent basalt in the southern third of Littlerock quadrangle -3.9 C31 Qgic Qgt Qa Qge -5.5 ? from –style basalt farther north, likely due to separate eruptive centers. Field relations suggest that the Contact—solid where location accurate; long-dashed where approximate; short-dashed ? -8.2 Evc Qge southern basalts are stratigraphically above those farther north. where inferred -18! ? Evc -14.3 Evc -68,-31 ? Qgag • Although Possession ice (MIS 4) never came close to the Littlerock quadrangle, new luminescence dates on fluvial U -269 ! Qoa Qa ? ? High-angle dip-slip fault—inferred; identity or existence questionable, location ! ! ! A deposits imply that Possession meltwater, like Vashon meltwater, drained through the Black River valley, D Aero- -4,-67 ? QEcf Qgic concealed; relative motion shown by U and D -14 ! Evc Qls ? suggesting that the pre-Vashon landscape was similar to the modern southern Puget Lowland. magnetic 17,66 ! Qgt Abstract—No. 387-2 (297674): LITTLEROCK QUADRANGLE -130 A new 47.4 Ma U/Pb zircon date from tuff in McIntosh Fm. marine sedimenta- Qge max spots 58,64 Qge Qa ? Geologic unit too thin to show as a polygon—solid where location accurate; Qp strong QEcf G54-55 long-dashed where approximate; short-dashed where inferred; queried where identity Qp ? ry rocks that overlie Crescent Fm. basalt in the southern Black Hills constrains Qge or existence questionable ? DESCRIPTION OF MAP UNITS We present a new 1:24,000 scale geologic map of the Littlerock 7.5-minute Qoa ? Qge Qgog Qgic weak 78 C21 Evc Qgic (see pamphlet for detailed map unit descriptions) ? ? Continental ice limit, late Wisconsinan—solid where location accurate; long-dashed Evc C30 Qge the transition from Siletzia volcanism and accretion to marine sedimentation. Qpd ? Quaternary Unconsolidated Deposits where approximate; short-dashed where inferred; dotted where concealed; queried quadrangle, which straddles the eastern Black Hills and southern Puget G52-53 Bedrock Qge ? Ev where identity or existence questionable elevation (ft) Qoa 8 Qpd c Qaf Qgic? POSTGLACIAL DEPOSITS -18 Qp Qge Qge !-18 seismic C Qgic ? Continental ice limit, pre–late Wisconsinan—long-dashed where approximate; o Lowland southwest of Olympia and was previously mapped at smaller Qp Holocene Nonglacial Deposits survey a Evc Qge l short-dashed where inferred; queried where identity or existence questionable C Qaf Qp Qp Qa ? C28 Modified land—Boulders, cobbles, pebbles, sand, silt and clay in varied amounts; locally derived, but -14 water re We mapped glacial deposits from the Vashon stade and at least one prior gla- e C22 Qa Qa Qaf ml AAƍ Cross section line well k scales. More detailed geologic mapping is needed for informed land man- Qpd C29 ? redistributed to modify topography. Qoa Qp Qp F Evc C5 Qge a G38-39, W1 Qpo1 ? Fluvial terrace—solid where location accurate; short-dashed where inferred; queried where uult 47 W3 Qp Evc K lt ciation that was slightly more extensive; these glaciations created ice Evc Evc Peat—Organic and organic-rich sediment; includes peat, gyttja, muck, silt, and clay; typically in closed 57ƍ30Ǝ S2 Qp 57ƍ30Ǝ identity or existence questionable; hachures point down slope Mima Prairie o agement; forestry, agriculture, recreation, ecologically sensitive areas, and ? G15 Qp p C52 Qoa depressions. basin ia Ev G11 Qaf h Evc c Geophysical data collection line F N Qa ? Qpd a QEcf W2 QEcf S u e dammed lakes in the Waddell Creek valley. New OSL and IRSL dates on fluvial ? Qp c w W4 Qp Evc Landslide deposits—Cobbles, pebbles, sand, silt, clay, boulders, and diamicton of basalt, siltstone, and a lltt development increasingly compete for natural resources. We support the Qoa Qa Qls ? Former shoreline or marine limit—identity or existence questionable, location accurate m a C34 ? Qge sandstone in varied amounts; clasts angular to rounded; unsorted; mostly loose, jumbled, and unstratified; m u ? Evc Qp o k 42 Inclined bedding—showing strike and dip n u ? locally retains primary bedding and compaction. Fault C m sediments suggest that Possession (MIS4) meltwater drained south via the Qge ? ? r ? Qp e F new map with field work, lidar, subsurface exploration data, aeromagnetic Small, minor inclined joint—showing strike and dip " ek Qp 79 F a 20 u Pleistocene to Holocene Nonglacial Deposits ' a l Qgo Qoa Qgag uultl t 40 39 Qa Qgim Small, minor vertical or near-vertical joint—showing strike 10 t Black River Valley, although Possession ice never came close to the map area. Qp ° data, geophysical explorations, geochemistry, and new Ar/ Ar, detrital Qpd Alluvium—Pebbles, cobbles, sand, silt, clay, peat, and boulders in varied amounts; along streams and on ? Qp Qgo Qoa Qge Qa Qoa Inclined asymmetric (Z-shaped, clockwise sense of shear) minor fold hinge—showing bearing and plunge 123 Qgic flood plains; gray, or dark brown due to organic matter, locally iron-stained red or yellowish brown; loose; 8 C45 ? thinly bedded to massive; unit Qoa where relict. Inclined flow bands, lamination, layering, or foliation in igneous rock—showing strike and dip 46°40' zircon U/Pb, luminescence and radiocarbon dates. Qp W5 15 Qp Qgt 0 4 8 mi Alluvial fan deposits—Pebbles, sand, silt, cobbles, and boulders in varied amounts; gray to brown; loose; 90 Shear—showing strike and dip Geochemistry and clay mineral identification by XRD of thick, deeply weath- ? Qp Qgic Qaf Qp Qgo ? W6 subangular to rounded; moderately to poorly sorted; stratified to poorly stratified; form concentric lobes. Qa 55 Shear—showing strike Qgo Qp Figure M2. Aeromagnetic image of the Littlerock quadrangle and vicinity. Faults are from Walsh and others (1987). Max spots mark New bedrock geochemistry confirms that the Black Hills are cored by Cres- Qp ? W10 Qgic GD9 W14 inflections in the aeromagnetic anomalies and tend to form linear clusters (that commonly coincide with topographic lineaments). Mima QEcf ? W15 Age site, fossil ered, clay-rich soils in the Black Hills suggest that most of the Black Hills are Qp W7 Evc Prairie basin (informally named here) is delineated based on an aeromagnetic trough. No measurements were made where the Ev W9 PLEISTOCENE GLACIAL DEPOSITS c Qp GD4 magnetic trough is strongest, and basin depth likely exceeds the lowest estimated levels from our seismic depth stations (82 m [270 ft] Qp W13 Qgo Age site, U-Pb, uranium-lead cent Formation basalt. North of Mima Creek the geochemical signature is ? W8 below sea level). The northwest-trending magnetic anomaly that bounds the northeast side of the basin is aligned with several mapped Qa Qaf Qge W16 Vashon Drift of the Fraser Glaciation GD1 Qp Age site, 14C, carbon-14 faults to the southeast and parallels faults observed in the Littlerock quadrangle (see Structures in the Map Area and shear symbols on unglaciated and have been subaerially weathered since before the Quaterna- ? (All Vashon units are northern-sourced.) Qa Qp W12 W11 Qp map). Fault names are from Snavely and others (1958). similar to Willapa Hills Crescent Fm. South of the creek it is more similar to GD2 Age site, luminescence (OSL and (or) IRSL) Qgo Qp Recessional Vashon outwash, undivided—Pebbles, cobbles, sand, and silt in varied amounts; light gray, G17 ry. Onlapping of Eocene to Miocene marine sediments indicates that the hills G29 ? Qpd Qp Qgo Geochemistry sample location 40 39 G6 Qge weathers to pale brown or tan, light orange where iron stained; loose; well sorted; clasts well rounded; ? G22 ? Olympic Mtns. Crescent Fm. Geochemistry and a new 46.0 Ma Ar/ Ar date locally lightly cemented; massive to bedded. Divided into: W20 Evc Qoa W17 Water well C25 have been a topographic high since the Eocene and may never have been Qp Qp Qp Qgag GD1 S2 Vashon recessional alluvial fan deposits—Pebbles, sand, silt, clay, cobbles, and boulders in Significant site ? C41 Qgoaf Em1 suggest that basalt east of the Black River is chemically distinct and younger ? Qgim Qp c Qgoaf varied amounts; gray, weathers brown; lightly to heavily weathered; loose; clasts subangular to Qpo Qp Geologic unit too small to show as a polygon at map scale buried. Isolated shear exposures and geophysical data suggest a northwest 1 Qgt Table M1. Summary of ages and biostratigraphic analyses from the Littlerock quadrangle and select nearby locations. See Data Qgic W18 rounded; moderately to poorly sorted; stratified to poorly stratified; forms concentric lobes. ? ? Qgo Qgo D1 Supplement for more detailed analytical results for biostratigraphy samples from sites GD5 and GD6. Samples from sites GD7 to GD18 C11 Qgo Location of schematic section than Crescent Formation but older than nearby intrusive rocks, though all Qaf QEcf did not yield age-diagnostic constraints and are therefore not further characterized, although foraminifera at site GD14 could be Qp Qgt W19 Vashon recessional outwash gravel—Pebble to cobble gravel with a coarse sand matrix; pale GP1 striking, southwest down fault beneath Mima Prairie. This fault may extend ml Qgag Qgog Geophysical data collection location identified to genus or family level. Biostratigraphy data from site GD19 is compiled from Pease and Hoover (1957) and is omitted from G7 Ev ? Qgo gray, weathering to tan, red-orange where iron stained; lightly weathered; may be lightly 14 Ev c ml Qp Appendix A because all pertinent information provided by Pease and Hoover is reproduced here. The radiocarbon date ( C) is given c Qgo Evc Qgt C42 are likely from the same mantle source. Qp Qgim cemented; loose; clasts subrounded to well rounded; well sorted; massive to bedded. Clast count sample DVDFDOLEUDWHGıUDQJH FDOHQGDU\HDUV WRIDFLOLWDWHHTXLYDOHQFHWROXPLQHVFHQFHGDWDDQGDJHVWDWHPHQWVUHSRUWHGHOVHZKHUH ? Qgt OXPLQHVFHQFHDJHV 26/RSWLFDOO\VWLPXODWHGOXPLQHVFHQFH,56/LQIUDUHGVWLPXODWHGOXPLQHVFHQFH DUHVKRZQZLWKıXQFHUWDLQW\ structures previously mapped farther southeast, but it has not offset the 40 39 Qge and argon ( Ar/ $U DQGXUDQLXPOHDG 83E DJHVZLWKı/$,&306ODVHUDEODWLRQLQGXFWLYHO\FRXSOHGSODVPDPDVVVSHFWURPHWU\ Qp Qgic Vashon recessional outwash, Yelm lobe—Sandy pebble gravel; pale gray, locally stained pale ? Qgoy3 ? Qgog yellow to orange-tan; lightly weathered; loose; contains less basalt and more intermediate to Age site Unit symbol Location Method Result Ev Vashon outwash terraces. c Evc Qa felsic volcanic rocks than other Vashon deposits. Age control data samples Evc Qgo sec. 29, 14 81 Qa Vashon ice-contact deposits—Patchy lodgment till, ablation till, flow till, and ice proximal outwash of all GD1 Qoa C 17.075–16.850 ka W20 Qgic T17N R3W S6 Qgo sizes in varied amounts; pale gray or stained tan to reddish brown; lightly to moderately weathered; clasts ? Qgo Qp sec. 34, OSL 58.910 ±3.960 ka mostly well rounded, sand and fines angular to well rounded; poorly sorted to well sorted; massive to GD2 Qpo Qgag Evb T17N R3W IRSL 65.820 ±4.590 ka Qgo 123°0'0"W 47°04'15" C48 bedded. Divided into: O 122 GD5-6 L G28 C47 Qga Em1c? ? Y 40 39 8 M sec. 36, Ar/ Ar age plateau on Evc Evc Qa $ƍ ° GD3 45.97 ±0.23 Ma 45 Evb Qp Qaf W21 —Deposits resemble unit Qgic but tend to be looser and less fluted; 101 P 5 T17N R3W plagioclase GD9 Qls Vashon terminal moraine IA Olympia Qp Qge Qgim ! ' ? ? Qp Qgo chaotic topography, kettles, eskers, varied compaction, and varied texture indicate deposition in ? 66 Qa S C53 S sec. 8, U-Pb by LA-ICP-MS on 86 T GD4 Em 47.35 ±0.21 Ma1 contact with stagnant ice; appears to be an ice-marginal moraine. L R 2m Evc Qp U T16N R3W zircon C23 Qp L CTUR 79 ? 47°0'0"N G33 GD8 Qgog I GD20 Biostratigraphy samples Qoa Vashon esker—Pebbles and sand; medium gray; lightly to moderately weathered; loose; clasts H E 12 G21,24 C32-33 Qge Qge Por Black 47°0'0"N SUMMIT LAKE QUADRANGLE FeO* QEcf South Fork ter Creek sec. 33, G2 TUMWATER QUADRANGLE Qpo Qp Qgt well rounded; well sorted; bedded; forms distinctive long, sinuous hills. Capitol Lake GD5 Em ? Fossil content analysis indicates Eocene age. G40–41 2 C27,46 55ƍ00Ǝ 1c Littlerock Evc 55ƍ00Ǝ 42 Qa Peak T17N R3W ? Em1 G59–60 Qpd c W Olympic Peninsula affinity 10 Qp G18 G48 Qgag Vashon lodgment till—Compact diamicton; matrix supported with clasts ranging from pebbles to a sec. 33, S5 d GD6 Em1c? Fossil content analysis indicates Eocene age. Qgt E–W LINEAMENT d T17N R3W Littlerock Evc MORB Qp Qgag S4 e D ? boulders; light gray, light brown where weathered or basalt rich; lightly to moderately weathered; very l e G14 C24 C18 l s 8 c G3 Willapa Hills affinity h C K

? u

U Evc sec. 8,

Qp ? compact with little porosity; clasts angular to well rounded; massive or stratified. h t

e GD7 Em Fossil content analysis yielded no biostratigraphic constraint.

D ? e s 2m GP1 Eig and Evb, this study ? h C T16N R3W ? k G19 G10 6 Qgog a e C R l e iv Ev G17 i A r r e c Qp Qgt s C e r sec. 33, Olympic Peninsula Qgim Vashon advance outwash, undivided—Cobble gravel, pebble gravel, and sand in varied amounts; pale e Ev Y/Nb Qp R GD8 Fossil content analysis yielded no biostratigraphic constraint. tholeiitic Qga L n k c G34 i a T17N R3W Crescent Fm. v r GD3 38.76 ±2.5 Ma G58–59 C14 gray, pale brown where basalt rich or weathered, red to yellow where iron stained; lightly to moderately e calc-alkaline 4 D1 Qp e m C37 r B v Qa r i Ev GD2 e c ? R sec. 32, Willapa Hills T17N Qaf ? weathered; compact; well sorted; well rounded; thin to massively bedded. Locally divided into: h G8 GD9 Ev Fossil content analysis yielded no biostratigraphic constraint. T17N S c Crescent Fm. C42,44, T17N R3W G13 2 k e 49,50-52 c i T16N Qa C35 r Qa a i G56–57 T16N l R a Qpd Qpd Qgo Vashon(?) advance outwash lake deposits—Clay with sparsely scattered pebbles; blue-gray Cedar o c k P r sec. 8,

G12 B y

OIB Qgaf GD12 Em

Na O OIB ? 12 GD10 Fossil content analysis yielded no biostratigraphic constraint.

2 Creek 2m 0 ? to brown; clast weathering moderate to heavy; compact; massive. T16N R3W +K O MgO G35 2 0.0 5.0 10.0 15.0 20.0 25.0 30.0 LITTLEROCK QUADRANGLE Qp ? G49 sec. 8, Black Lake ? GD11 Em2m Fossil content analysis yielded no biostratigraphic constraint. G16 Zr/Nb Qp Vashon advance outwash gravel—Sandy pebble gravel; pale gray, pale brown where basalt G45 T16N R3W S Qgt Qgo Qgag GD19 ? y3 Qa rich or weathered, red to yellow where iron stained; lightly to moderately weathered; compact; 5 GD13– Biostratigraphy samples from sedimentary rocks outside the Littlerock quadrangle Eig (Moothart, 1993) Olympic Peninsula Northcraft Fm. Eig and Evb, this study ? well rounded; moderately to well sorted; poorly bedded to unbedded. eek C36 tter Cr 14 ? Qp ca Eig (Logan and Crescent Fm. Littlerock Evc Littlerock Evc ? S E sec. 14, 84 N MAYTOWN QUADRANGLE Willapa Hills affinity Olympic Peninsula affinity I Em L others, 2009) Willapa Hills ? Qgic L GD12 2m T16N R1W Fossil content analysis yielded no biostratigraphic constraint. G54–55 LITTLE ROCK QUADRANGLE Qpd Pre-Vashon Glacial Deposits Ev lis Ri IC Crescent Fm. c ha ve T (Bucoda quadrangle) Che r N C 87 ? Qgo A O Qgt C 12 O A sec. 23, Possession-age distal outwash—Northern-sourced sand and pebble gravel; tan to orange; moderately to E N L Qpo N I Em ? Qa ? 2 N C GD13 2m T16N R1W Fossil content analysis yielded no biostratigraphic constraint. L G52–53 U S T E G25 G9 ? GP2 heavily weathered; compact; clasts subrounded to well rounded; sorting varied; bedded or crossbedded. R T R 80 ? D A (Bucoda quadrangle) C15 ? L L E IA E

L S K sec. 23, Black River Qa Y G15 75 Ev ? Pre-Possession outwash—Northern-sourced pebble gravel, sand, and silt; dark brown or reddish brown; FA c GP4 I N GD14 Em T16N R1W Fossil content analysis yielded no biostratigraphic constraint. I Qgim Qp Qgo Qpo1 C G43–44 2m Major and trace element geochemistry results G1 moderately to heavily weathered; loose; clasts subrounded to well rounded; moderately to well sorted; no LI ULT 89 H N 43 Evc ? GP6 LINCOLN E GD15–16 (Bucoda quadrangle) G47 ? G11 G38 55 ? bedding. SCA sec. 34, G39 G30-31 CREEK Lincoln Creek Qls M K for Littlerock samples. Y M GD15 T15N R3W Fossil content analysis yielded no biostratigraphic constraint. O O Formation QEcf? —Gray clay and silt with occasional pebbles; UPLIFT N P N H Em2m C17 Pre-Vashon glaciolacustrine deposits (cross section only) T I E (Adna quadrangle) ? Qpf C A Qpd Qgoy3 R H W Qa O GD17 interpreted from well records; age of deposit unclear, but it is beneath pre-Vashon unit Qoa. E F A sec. 34, ? E ! U Qgic G50 K A F Lincoln Creek ? D K Centralia U A GD16 T15N R3W Fossil content analysis yielded no biostratigraphic constraint. F LT U Formation Evc A U (Adna quadrangle) ? G5 QEcf Qls S3 W22 Pre-Vashon drift—Diamicton with small boulders, pebbles, sand, and clay; light brown to deep red; SALZER C ULT L M Qpd REE T C1 heavily weathered, matrix mostly clay; compaction undetermined; clasts angular to well rounded; K FAU sec. 18, C8 ? LT Skookumchuck Qa Qls ? ? Qgt GD17 T14N R3W Fossil content analysis yielded no biostratigraphic constraint. ? Evc 33 C9 Qp unsorted; massive. DOTY FAULT G42 Formation 90 15 ml Qp (Adna quadrangle) K G29 C6 GP5 Qa Chehalis G20 ! G6 Qpd C40 GD18 sec. 24, G22 W C2 Eocene to Quaternary Continental Deposit Qa " G37,46 ? ? C3 ? Skookumchuck a Qa ? GD10 C43 Qp 6 GD18 T14N R4W Fossil content analysis yielded no biostratigraphic constraint. 25 Cross-sectional view of a Mima mound (clast count sites C2 and C3). ' Chehal Formation d Qa Qpd Terrestrial weathering clay (Eocene to Quaternary)—Clay soil and saprolite (halloysite and goethite) is River (Adna quadrangle) d G26 U Qp 19 6 GP3 QEcf ° C e G19 Qp D l Qls Em concealing underlying bedrock or sediment; locally contains basalt core-stones; red to reddish yellow and 5 l soil G4 Evc 2m GD11 C16 Biostratigraphy samples from sedimentary rocks outside the Littlerock quadrangle, compiled from prior studies G27 ? 123 C reddish brown, locally variegated; loose to dense; structureless, pedogenic, or saprolitic textures; as much 123°0'0"W G7 r ? Qp 46°36'25" e C10 ? e G41 as 30 ft thick. Middle Eocene. Compiled from Pease and Hoover (1957): “Two k Qls Qp Pre-Quaternary Pre-Quaternary Geologic structures Sample sites foraminiferal assemblages collected from [sed. rock] strata A QEcf G32 QEcf igneous rocks sedimentary rocks Fault Qgog ? Biostratigraphy site interbedded with [basalt] flows ... are thought to be middle Eocene ? Qp Tertiary Volcanic and Sedimentary Bedrock sec. 27, ? Grande Ronde Basalt Sedimentary rocks Fold axis Ev  in age.” Location approximate: sec. 27, T16N R4W; location G23, Qgog Qp (Miocene) (Miocene) 40 39 GD19 c T16N R4W ? C12-13 Ar/ Ar site plotted on Fig. M1 to coincide with more precise location 36,51 McIntosh Formation (middle Eocene)—Claystone with tuffaceous interbeds of siltstone and sandstone; Other igneous (Eocene) Lincoln Creek Formation Ice limits (Oakville quadrangle) Qp (Eocene–Oligocene) description for same? record no. 119 of Rau (2004), who described L G28 Qp Em2m Northcraft Formation, Vashon ice limit Significant site Qa tan to dark olive brown; lightly to heavily weathered; moderately lithified; silt- and sand-sized particles Skookumchuck Formation his sample as “sandstone” from “lower McIntosh Formation, now C38 Qpd bimodal (Eocene) G40 Qgim ? (Eocene) Pre-Vashon G8 Qgic Geochemistry site considered Crescent Formation”. GD7 ? angular to rounded; poorly sorted; faintly bedded. Eocene basalt ice limit Map unit Bedrock geochemistry Clay mineralogy and geochemistry Thin section analysis Placer geochemistry Evc Qp McIntosh Formation G33 G21,24 Evc GD4 (Eocene) (Eocene) QEcf ? Qp Qpd Clast count site 0 5 Inferred northern provenance Possible Cascades-source Cascades-sourced outwash Qgoy3 C39 Qgt Crescent Formation Crescent Formation mi Middle Eocene Ulatisian Stage. Lithology “limey”. Compiled from B Qa—Alluvium Basalt (early middle Eocene)—Aphanitic basalt; dark gray, weathers to medium gray; mildly weathered; Qoa Qa ml Evb basalt (Eocene) sedimentary rocks (Eocene) Qaf Qa ? Qgog ? NW cor. sec. 31, Rau (2004) record no. 3327, file no. 8743. Location approximate: G17 inferred from lithology basalt U moderately dense; not vesicular; fine grained, porphyritic, trachytic. Ev  Qpd—Pre-Vashon drift G48 Qoa D GD20 c T18N R3W “NW cor. sec. 31, T18N R3W”. Collector: Valintine. Analysis by G18 46°52ƍ30Ǝ ? Qaf 46°52ƍ30Ǝ Figure M1. Regional geologic map for the Littlerock quadrangle (red outline). Geologic units and ice limit lines within the quadrangle are from this study. Geologic units, faults, and folds outside the mapping area are adapted from published 1:24,000- and (Summit Lake quadrangle) Weldon Rau (WA Dept. of Nat. Res., 2004). Water depth 50 m or 2% 3% 2% 1% core stones 123°07ƍ30Ǝ R4W R3W 05ƍ00Ǝ 02ƍ30Ǝ 123°00ƍ00Ǝ Crescent Formation marine sedimentary rocks (early to middle Eocene)—Claystone; contains less. Water temperature 25–30° C. G35 Willapa Hills affinity saprolite Em1c? 1:100,000-scale geologic maps. The ice limit outside the Littlerock quadrangle is approximate and modified from Logan and Walsh 4% foraminifera and a few silt-size lithic fragments; blue-gray to olive brown; moderately to well lithified; (2004), Logan and others (2009), and Thorson (1980). Samples shown outside the Littlerock quadrangle provide new reference data Ev —Crescent Formation basalt c 10% 5% 6% SCALE 1:24,000 1–4 cm thick beds. (see pamphlet). All samples are from this study, except for site GD19 (Pease and Hoover, 1957 Rau, 2004), GD20 (Rau, 2004), and a 1 Lab notes that due to the large number of analyses, the intercept age error is unrealistically low for this technique, and a more Lambert conformal conic projection 38.76 Ma 40Ar/39Ar date from Walsh and Logan (2005). realistic estimate of the total uncertainty for the intercept age is ~2% (1 Ma), thus yielding an age range of ~48.4 to 46.4 Ma. 6% 1 0.5 0 1 MILE 108 101 QEcf—Terrestrial weathering clay 2% 7% 11% North American Datum of 1927; to place on North American Datum of Crescent Formation (early to middle Eocene)—Basalt flows; dark gray or black; lightly to heavily 1983, move the projection lines approximately 23 meters north and 1000 0 1000 2000 3000 4000 5000 6000 7000 FEET Evc weathered; massive; commonly vesicular; aphanitic to porphyritic; fine- to coarse-grained phenocrysts. SUMMITLAKE G9 46% KAMILCHE 8 Olympic Peninsula affinity 9% 6% 95 meters east as shown by crosshair corner tics VALLEY TUMWATER G25 9% 1 0.5 0 1 KILOMETER Olympia 52% Base map from scanned and rectified U.S. Geological Survey Evc—Crescent Formation basalt G1 61% Littlerock 7.5-minute quadrangle, 1986 16° Tumwater G30–31 contour interval 40 feet 10% Shaded relief generated from a lidar bare-earth digital elevation model QEcf—Terrestrial weathering clay 20% (available from the Washington Geological Survey, CAPITOLPEAK 28% 121 G5 LITTLEROCK MAYTOWN Em2m—McIntosh Formation covered Littlerock G37 G20 S3 This geologic map was funded in part by the 5 GIS by Michael Polenz and Jessica L. Vermeer TRUE NORT H Oakville G46 U.S. Geological Survey National Cooperative Geologic Mapping Program MAGNETIC NORTH Evb—Eocene volcanic basalt n=30 n=7 n=2 Digital cartography by Daniel E. Coe 12 G4 under USGS award number G16AC00286. APPROXIMATE MEAN Grand G26 DECLINATION, 2017 G27 Editing and production by Jessica L. Czajkowski, Jaretta M. Roloff, and Mound VIOLET PRAIRIE Eig—Eocene intrusive gabbro OAKVILLE Daniel E. Coe ROCHESTER basalt intermediate igneous basalt intermediate igneous basalt intermediate igneous 507 G51 Research supported by the U.S. Geological Survey, National Cooperative G32 0 1 Miles2 granitoid metamorphic granitoid metamorphic granitoid metamorphic Geologic Mapping Program, under USGS award number G16AC00286. G23 Evc affinity boundary Roadcut with clay at geochemistry sampling sites. quartz/chert unknown quartz/chert unknown quartz/chert unknown The views and conclusions contained in this document are those of the CORRELATION OF MAP UNITS G36 authors and should not be interpreted as necessarily representing the PERIODS AND EPOCHS BASED ON USGS FACT SHEET 2010-3059 sedimentary sedimentary sedimentary official policies, either expressed or implied, of the U.S. Government. Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Department of Natural Resources and the authors of this product will not be liable to the user of NONGLACIAL UNITS GLACIAL UNITS this product for any activity involving the product with respect to the following: (a) lost profits, lost savings, or any other consequential damages; (b) fitness of the product for a particular purpose; or (c) use of the product or results obtained from use of the product. This product is considered to be exempt from the SCHEMATIC DIAGRAM 1 Simplified geologic map showing geochemistry sample locations, Geologist Licensing Act [RCW 18.220.190 (4)] because it is draft geological research conducted by or for A $ƍ ml Waddell Creek Road Bridge [wt%] the State of Washington, Department of Natural Resources, Washington Geological Survey. E (sec. 34, T17N R3W) W Pie charts showing clast lithologies from unlithified deposits. No Data where blank 2500 CROSS SECTION EXPLANATION 2500 geologic units, and analysis type. Qp Qls Qa Qaf ? QEcf

Geologic units too thin to show HOLOCENE terrace surface Qoa Qoa elev. 241 ft Qa as polygons at the scale of the 11.700 ±0.099 ka tuffaceous tuffaceous Sampled material siltstone soil basalt soil basalt soil basalt saprolite basalt soil basalt saprolite basalt saprolite basalt and (basalt drift rich) andesite drift drift drift claystone claystone cross section; tics mark separate Vashon ice retreat Qgo Qgoaf Qgog Qgoy3 covered Geologic unit Em(2m) QEcf* QEcf QEcf QEcf QEcf QEcf QEcf Qpd Qpd Qpd Qpd Em(2m) Em(2m) 2000 2000 from map area is Vashon ice arrival in Qgim Qge Qgic Qgt C50 and C49: units. map area is likely MIS 2—FRASER Site ID G30 G31 G34 G29 G32 G41 G42 G39 G38 G51 G33 G35 G36 G37 likely between 15.8 GLACIATION northern source, elev. 233 ft after 16.5 ka and 15.3 ka ~18 ka Vashon ice dammed the Qga Qgaf Qgag lightly weathered Qgog Quartz 43 38 5 18 Trace Trace Trace 10 40 29 32 6 1 (Polenz and others,

W146 Water well or boring (Polenz and ? Strait of Juan de Fuca, diverting elev. 228 ft 2015) Plagioclase feldspar (albite) 21 9 Trace Trace 3 7 11 9 10 others, 2015) meltwater south into the map area Qgt QUATERNARY Waddell K-feldspar (orthoclase) Trace (Polenz and others, 2015) MIS 3 GD2: 58,910 ±3,960 yr (OSL) elev. 224 ft 3 5 2 1 4 2 4 7 20 1500 1500 Creek Road 65,820 ±4,590 yr (IRSL) Clast weathering (all lithologies) Clast weathering by age and lithology K-feldspar (sanidine) 2 ~76 ka Possession ice dammed the 65,820 ±4,590 yr MIS 4—POSSESSION C42 PLEISTOCENE Qpo2 covered Range of 80 90 Clast Amphibole 4 1 2 1 Strait of Juan de Fuca (Troost, 2016), 58,910 ±3,960 yr GLACIATION < 0.5 mm rind (this study) elev. 222 ft Chlorite diverting meltwater south, leading to

C-line Road

15 24 3 4 8 creek 0.5 – 2 mm rind QEcf deposition of unit Qpo . MIS 5 AND EARLIER elev. 216 ft clast 80 weathering map) on shown (not 2 70 Muscovite/illite 6 9 2 7 Qpo1 QpoQpd Qpf INTERVALS bedded sand with Qpo2 > 2 mm rind 1000 1000 sparse pebbles 70 Rotten Halloysite 71 44 80 69 57 73 63 36 37 36

Sherman Road UNCONFORMITY weathering 60 in units Kaolinite Creek Waddell elev. 212 ft

3 6 Elevation (ft) Elevation (ft) C51: northern source, Waddell Creek Road Creek Waddell

Black River Black Qpo 60 Smectite (nontronite) 65 75 ? C42: northern source, 2 moderately weathered 50 45.97 ±0.23 ? moderately weathered for unit Qa Qpo (site (this study) Evb

W2 bedded sandy 110th Avenue SW Avenue 110th

Smectite (montmorillonite) W7 1 C51 2 6 SW Avenue 105th 500 Qoa 500 ? Em2m QEcf 50 W1 Qoa Qa W8 pebble gravel W3 W4 Qa Gibbsite 4 10 6 Trace 1 Qpd 47.35 ±0.21 40 < 0.5 mm rind Qgim W5 W6 W11 W9 W10 W16 W15 Qgim W14 W12 (this study) and Vashon C11) and Qpf Qgo Qpd W13 Qgo 40 0.5 – 2 mm rind Goethite 5 22 20 15 19 26 20 12 2 12 13 1 Qgo Qgo Qgic Em2m in the map area covered W17 W18

Qgic W21 Ev W19 Qp elev. 197 ft c W20 > 2 mm rind Hematite 2 2 1 4 1 1 1 Qgt G17: medium-grained basalt 30 Qpd Qgim Qgag EOCENE and 30 Qpo (sites Rotten Qgo TERTIARY 2 Magnetite Trace 2 2 7 7 2 3 Qp Evb C44: Waddell Creek 0 0 Evc Em1c? active alluvium elev. 188 ft 20 20 Ilmenite 2 2 4 4 4 1 1 Trace Ev pre-Vashon C42 and c Evc % mildly weathered clasts Zeolite (heulandite) % mildly weathered clasts C11 3 10 10 55.8 ±0.2 Ma elev. 184 ft Apatite 1 3x vertical exaggeration Waddell Creek glacial C51). < 0.5 mm rind Anatase 4 0 0 0.5 – 2 mm rind Waddell Creek channel is lined with bedrock and a discontinuous thin bedload deposits. Qa Vashon pre-Vashon Vashon basalt Vashon all pre-Vashon basalt pre-Vashon all > 2 mm rind Rotten n=3 n=16 n=18 n=16 n=16 n=17 n=17 XRD results (clay mineral percent). © 2017 Washington Geological Survey