WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES GEOLOGIC MAP GM-64 Geologic Map of the Freeland and Northern Part of the Freeland and Northern Part of the Hansville 7.5-minute Quadrangles Hansville 7.5-minute Quadrangles, Island County, Washington 122°37¢30² R 1 E R 2 E 35¢00² 32¢30² 122°30¢00² 48°07¢30² 48°07¢30² Qls Qgof Qf T 31 N Qgdme by Michael Polenz, Henry W. Schasse, and Bradley B. Petersen T 30 N S O U T H E R N W H I D B E Y I S L A N D F A U L T Z O N E Qgasv Qgtv Qgome Qgtv June 2006 Qgof Qgomee Qmw Qgtv Qb A Qgdme GEOLOGIC SETTING AND DEVELOPMENT of sliding or hazard. All shoreline bluffs in the map area are subject to UNDIVIDED PRE-FRASER NONGLACIAL DEPOSITS (PLEISTOCENE) Berger, G. W.; Easterbrook, D. J., 1993, Thermoluminescence dating tests for lacustrine, Johnson, R.; Introne, D. S.; Mattes, J.; Stipp, J. J., 1980, University of Miami radiocarbon Qm Qb Qgo T episodic landsliding and bluff retreat, but many slides are too small to glaciomarine, and floodplain sediments from western Washington and British Columbia: dates XVII: Radiocarbon, v. 22, no. 1, p. 103-104. f Qlse The map area is covered by 800 to 2500 ft (Jones, 1999; Mosher and others, 2000; show, and most slide deposits are quickly removed by beach wave action. Qc Pre-Fraser nonglacial deposits, undivided—Sand, silt, clay, peat, and Canadian Journal of Earth Sciences, v. 30, no. 9, p. 1815-1828. Johnson, S. Y.; Potter, C. J.; Armentrout, J. M.; Miller, J. J.; Finn, C. A.; Weaver, C. S., 1996, Johnson and others, 2001) of glacial and nonglacial sediment above Miocene(?) Qc some fine and rare medium gravel; compact; well stratified to massive; Blunt, D. J.; Easterbrook, D. J.; Rutter, N. W., 1987, Chronology of Pleistocene sediments in The southern Whidbey Island fault—An active structure in the Puget Lowland, Qb (Johnson and others, 1996) bedrock. Double Bluff Drift is the oldest sediment Qm Qgome Qgomee Pleistocene Glacial and Nonglacial Deposits resembles units Qco and Qcw; reflects floodplain and channel settings; the Puget Lowland, Washington. In Schuster, J. E., editor, Selected papers on the geology Washington: Geological Society of America Bulletin, v. 108, no. 3, p. 334-354, 1 plate. Hancock Qgdme exposed in the map area. Booth and others (2004, fig. 2) correlate the drift to marine Lake may include unrecognized glacial material; stratigraphically below Fraser of Washington: Washington Division of Geology and Earth Resources Bulletin 77, A We used stratigraphic position, organic content, radiocarbon and optical dating, Johnson, S. Y.; Mosher, D. C.; Dadisman, S. V.; Childs, J. R.; Rhea, S. B., 2000, Tertiary and Qm Qgtv oxygen-isotope stage (hereinafter ‘stage’) 6, about 185 to 125 ka. (Marine glacial deposits, but age and association are otherwise unresolved; likely p. 321-353. aminostratigraphic analyses, fossil content, and provenance data to separate glacial Quaternary structures of the eastern Juan de Fuca Strait—Interpreted map. In Mosher, oxygen-isotope stage numbers and corresponding ages used in this report are as includes deposits of stages 3 and 5 but may also contain older deposits. Booth, D. B., 1991, Glacier physics of the Puget lobe, southwest Cordilleran ice sheet: D. C.; Johnson, S. Y., editors; and others, Neotectonics of the eastern Juan de Fuca Qb Qgom defined in Morrison, 1991.) Berger and Easterbrook (1993), Blunt and others (1987), from nonglacial deposits. Provenance was inferred from stratigraphic relations, age ee Qgdm Qb Two new optically stimulated luminescence (OSL) dates and three Geographie physique et quaternaire, v. 45, no. 3, p. 301-315. Strait—A digital geological and geophysical atlas: Geological Survey of Canada Open Qm e data, and sand and gravel clast composition as observed petrographically and in the Qb and Easterbrook (1994a,b) report older ages for some exposures. We mapped Double new radiocarbon dates suggest that some exposures of unit Qc along File Report 3931, 1 CD-ROM. 5 field. Glacial deposits are dominated by northern provenance and therefore contain Booth, D. B., 1994, Glaciofluvial infilling and scour of the Puget Lowland, Washington, Qf 110 Bluff Drift at the type section only (bluff section A; columnar section 6). The oldest Admiralty Inlet may pre-date the Whidbey Formation. Clay from the base during ice-sheet glaciation: Geology, v. 22, no. 8, p. 695-698. Johnson, S. Y.; Dadisman, S. V.; Mosher, D. C.; Blakely, R. J.; Childs, J. R., 2001, Active Qm named nonglacial unit in the map area is the Whidbey Formation, which we show little or no Glacier Peak detritus (0–5%) and include “significant” granitic and gray horizontally 100 of more than 55 ft of gently north-dipping, apparent floodplain deposits tectonics of the Devils Mountain fault and related structures, northern Puget Lowland and bedded pebbly sand Qgasv metamorphic lithic clasts (Dragovich and others, 2005). Nonglacial deposits are Booth, D. B.; Troost, K. G.; Clague, J. J.; Waitt, R. B., 2004, The Cordilleran ice sheet. In only at and near the type section (bluff section A; columnar section 6). The Whidbey was OSL dated at >150 ka (Table 1, loc. 1b), and a peat 0.3 ft below the eastern Strait of Juan de Fuca region, Pacific Northwest: U.S. Geological Survey buff colored silt distinguished by eastern provenance. We found some petrographic and geochemical Gillespie, A. R.; Porter, S. C.; Atwater, B. F., 2004, The Quaternary period in the United (West Beach silt ?) Formation correlates to the interglacial stage 5, about 125 to 80 ka (Blunt and others, 14 Professional Paper 1643, 45 p., 2 plates. Qgdme OSL sample was dated at >43,870 C yr B.P. (Table 1, loc. 1a). Variably States: Elsevier Publishers, p. 17-43. Qgof Qb Qb 1987; Easterbrook, 1994a; Dragovich and others, 2005; Polenz and others, 2005). indications of possible ancestral Skagit and Stillaguamish River provenance Qgdme cross-bedded iron oxide– 75 dipping deposits of unit Qc about 1 mi north of Bush Point are tentatively Brocher, T. M.; Blakely, R. J.; Wells, R. E.; Sherrod, B. L.; Ramachandran, Kumar, 2005, The Jones, M. A., 1999, Geologic framework for the Puget Sound aquifer system, Washington and stained pebble gravel New luminescence dates of greater than 150 ka were acquired on nonglacial (northeast of the map area) (hypersthene, hornblende, and possible Glacier Peak mapped as unit Qmw because they may be part of a landslide, but the dips transition between N-S and NE-SW directed crustal shortening in the central and northern British Columbia: U.S. Geological Survey Professional Paper 1424-C, 31 p., 18 plates. Qgav 4 dacite) (Dragovich and others, 2005; Polenz and others, 2005; Joe D. Dragovich, 1 cross-bedded Qc sediments during this study (Table 1, locs. 1b, 2b; unit Qc). If accurate, these dates instead may be tectonic; these deposits compose a nonglacial floodplain 75 Qgdm iron oxide–stained Puget Lowland—New thoughts on the southern Whidbey Island fault [abstract]: Eos Kelsey, H. M.; Sherrod, Brian; Johnson, S. Y.; Dadisman, S. V., 2004, Land-level changes Qls e imply that sediments older than stage 5 may be more widespread than previously Wash. Div. of Geology and Earth Resources, oral commun., 2006; unpub. data from Qgdf coarse pebbly sand 50 section more than 80 ft thick, and a clay sample from near the base of the (American Geophysical Union Transactions), v. 86, no. 52, p. F1459. from a late Holocene earthquake in the northern Puget Lowland, Washington: Geology, Elevation (feet) recognized. We did not identify Possession Glaciation deposits (stage 4, 80–60 ka; this study), but agree with Terry Swanson (Univ. of Wash., oral commun., 2005) in Qgome Qls debris (mostly till) exposure was OSL dated at >200 ka (Table 1, loc. 2b). A directly adjacent Carlstad, C. A., 1992, Late Pleistocene deglaciation history at Point Partridge, central v. 32, no. 6, p. 469-472. Qgof Qgt suspecting that much of the sediment is from an ancestral Snohomish River (east of Qgome v Qgt Booth and others, 2004). We show deposits of the Olympia nonglacial interval 14 50 Qls? inferred sandy layer, likely unit Qgasv v covered radiocarbon date was reported as finite at 43,440 ±1660 C yr B.P., Whidbey Island, Washington: Western Washington University Master of Science thesis, Kovanen, D. J.; Slaymaker, Olav, 2004, Relict shorelines and ice flow patterns of the northern Qgof ? ? ? the map area). Speculations of Snohomish River source are based mostly on S O U T H E R N Qgo Qls laminated silt; slightly translated(?) 25 (representing stage 3, 60–20 ka) east of the Whidbey Formation type section, based 1 v. Puget Lowland from LIDAR data and digital terrain modelling: Geografiska Annaler. f ? however, and a nearby second one as radiocarbon infinite (Table 1, locs. Qgt ? ?? Qgof v Qgav block of unit Qc on age dates (bluff section A; Table 1) and previous identification of nonglacial stratigraphic position and proximity to that basin; we lacked petrographic reference Qb Qgtv Qgas ? road level 2a, 3). Surrounding strata suggest that a peat 1 in. beneath the couplet of Dethier, D. P.; Pessl, Fred, Jr.; Keuler, R. F.; Balzarini, M. A.; Pevear, D. R., 1995, Late Series A: Physical Geography, v. 86, no. 4, p. 385-400. Qgof v ? organic-rich silt (gyttja?) (East Point Dr.) data from Snohomish basin sediments but noted elevated levels of serpentinite, 14 15 deposits there (Easterbrook and others, 1967; Stoffel, 1980; Yount and others, 1993). 25 >38,700 C yr B.P. (Table 1, loc. 4) Qb OSL and radiocarbon samples (Table 1, locs. 2a, 2b) is the same as that Wisconsinan glaciomarine deposition and isostatic rebound, northern Puget Lowland, Lian, O. B.; Hu, Jinsheng; Huntley, D. J.; Hicock, S. R., 1995, Optical dating studies of ? Qb granitic rocks, and weathered volcanic rocks in some samples. That mix appears Elevation (feet) Some or all of the deposits mapped as Olympia in this location may instead be alpine Qgas Qc yielding the radiocarbon-infinite date (Table 1, loc. 3), although exposure Washington: Geological Society of America Bulletin, v. 107, no. 11, p. 1288-1303. Quaternary organic-rich sediments from southwestern British Columbia and northwestern v ? Qls (mostly till) SOUTHERN Qguc Qf consistent with major bedrock units in the Snohomish River basin (Joe D. Qgav Qgas outwash from the Evans Creek Stade (stage 2), based on current indicators, v Qgt beachtop Qguc Qgdme is discontinuous between the two locations. Also, the deposits in the area Domack, E. W., 1982, Facies of late Pleistocene glacial marine sediments on Whidbey Island, Washington State: Canadian Journal of Earth Sciences, v. 32, no. 8, p. 1194-1207. v proximity to the Snohomish River basin (east of the map area), age dates, and Dragovich, Wash. Div. of Geology and Earth Resources, oral commun., 2006). Qf Qguc Qguc appear more oxidized than most on Whidbey Island. These observations Washington: Rice University Doctor of Philosophy thesis, 312 p., 11 plates. Morrison, R. B., 1991, Introduction. In Morrison, R. B., editor, Quaternary nonglacial Qgtv Qls 0 Qgas Qgtv (SOUTHERN v stratigraphic relationships. DEPOSITS OF THE FRASER GLACIATION (PLEISTOCENE) and the very old OSL date lead us to suspect that the radiocarbon finite Domack, E. W., 1983, Facies of late Pleistocene glacial-marine sediments on Whidbey Island, geology—Conterminous U.S.: Geological Society of America DNAG Geology of North Qc Qgasv Qb We mapped mostly Fraser Glaciation deposits (Armstrong and others, 1965) on Qdgme Qguc Qgasv date at this site was compromised and the sediments may indeed pre-date America, v. K-2, 672 p., 8 plates in accompanying case. Qgome 4 WHIDBEY Washington—An isostatic glacial-marine sequence. In Molnia, B. F., editor, 1a,b Qga 6 Qgt upland surfaces and along some bluffs, and mass-wasting features along the v 90 Qls v Qgome Undivided Fraser Glaciation stage 5. Glacial-marine sedimentation: Plenum Press, p. 535-570. Mosher, D. C.; Johnson, S. Y., editors; Rathwell, G. J.; Kung, R. B.; Rhea, S. B., compilers, remaining bluffs. The Fraser Glaciation correlates to stage 2 (Booth and others, Qgas We also obtained new radiocarbon infinite dates for unit Qc southeast 2000, Neotectonics of the eastern Juan de Fuca Strait—A digital geological and W H I D B E Y v Qgtv Domack, E. W., 1984, Rhythmically bedded glaciomarine sediments on Whidbey Island, Qgasv 75 WHIDBEY 2004) (about 28–10 ka). Advance outwash of the Vashon Stade began to bury the Qgd(f) Fraser drift, undivided—Composite of units deposited during the Fraser of Honeymoon Bay and at a landslide southeast of Greenbank Farm geophysical atlas: Geological Survey of Canada Open File Report 3931, 1 CD-ROM. Qgdf Washington: Journal of Sedimentary Petrology, v. 54, no. 2, p. 589-602. Qb ISLAND Puget Lowland (Booth, 1994) no sooner than about 20 ka (Polenz and others, 2005; Glaciation; shown where map scale or exposure do not support (columnar sections 2 and 1; Table 1, locs. 4 and 5). Polenz, Michael; Slaughter, S. L.; Thorsen, G. W., 2005, Geologic map of the Coupeville and Qgav cross-bedded Domack, E. W.; Lawson, D. E., 1985, Pebble fabric in an ice-rafted diamicton: Journal of Qls Qgof Qgav? Qguc Qgt Johnson and others, 2001) if radiocarbon dates from northwest of the map area are stratigraphic division. sand v East of Rocky Point, a silt that, due to map scale, we mapped as unit Geology, v. 93, no. 5, p. 577-591. part of the Port Townsend North 7.5-minute quadrangles, Island County, Washington: Qgome 50 Qgtv ISLAND accurate. Radiocarbon dates on detrital samples and new luminescence dates east of Qguc is shown as unit Qc in columnar section 5. The silt resembles “West Washington Division of Geology and Earth Resources Geologic Map GM-58, 1 sheet, Qgo(f), Qgof(f) Recessional outwash—Mostly sand, but includes lenses and beds of Dragovich, J. D.; Petro, G. T.; Thorsen, G. W.; Larson, S. L.; Foster, G. R.; Norman, D. K., Qgome FAU Double Bluff (bluff section A; Table 1) suggest that Fraser outwash of the Vashon Qgo scale 1:24,000. [accessed Jan. 12, 2006 at http://www.dnr.wa.gov/geology/pdf/gm58.pdf] gray to tan sand f pebble gravel and silt, sparse clasts of diamicton, and minor clay and peat; Beach silt”, a loess facies of Olympia nonglacial deposits (Thorsen, 2005, Geologic map of the Oak Harbor, Crescent Harbor, and part of the Smith Island Qb Qgo Qgav Qc and silty sand LT Qf f Elevation (feet) (and the preceding Evans Creek?) stade(s) may have arrived earlier. The Puget lobe 1983a,b, 2001) with an estimated age between about 37,000 and 27,000 Porter, S. C.; Swanson, T. W., 1998, Radiocarbon age constraints on rates of advance and I S L A N D FAULT mapped as unit Qgoff where mostly clay; gravelly facies tend to occur 7.5-minute quadrangles, Island County, Washington: Washington Division of Geology Qgtv 25 of the Cordilleran ice sheet apparently arrived about 18 ka (Booth, 1991; Porter and 14 sand and silty sand Qgof C yr B.P. (Polenz and others, 2005). While age control is lacking at our retreat of the Puget lobe of the Cordilleran ice sheet during the last glaciation: Quaternary Qls Qgtv ZONEQb 14 f lower in the unit; loose; variably rounded; poorly to well sorted in most and Earth Resources Geologic Map GM-59, 2 sheets, scale 1:24,000. [accessed Jan. 9, Qgasv blue silty clay Qguc Swanson 1998; Booth and others, 2004; Polenz and others, 2005) (~15,000 C yr exposure, a nearby upsection(?) radiocarbon date (Table 1, loc. 15, Research, v. 50, no. 3, p. 205-213. L 10 ZONE) exposures; structureless to moderately stratified with medium to thick 2006 at http://www.dnr.wa.gov/geology/pubs/pubs_ol.htm] 5¢00² U P Qgome beach 5¢00² B.P.) and covered the map area with about 4000 ft of ice (Thorson, 1980, 1981, Qgasv Qmw OSL age estimate beds; mostly forms either valley fill in relict, late-glacial meltwater hitherto unpublished) and two unpublished dates from lower(?) in the Easterbrook, D. J., 1966a, Glaciomarine environments and the Fraser glaciation in northwest Robinson, S. W., 1977, U.S. Geological Survey, Menlo Park, California, radiocarbon A 39.3 ±2.82 ka 1989). measurements I: Radiocarbon, v. 19, no. 3, p. 462. Qgo valleys or terraces above Everson Interstade marine shorelines; section east of the map area (Hank Schasse, Wash. Div. of Geology and Washington—Guidebook for first Annual Field Conference, Pacific Coast Section, Qml f Qgomee (Table 1, loc. 6) The end of the glaciation is defined in the area by a succession of events that Qgo Qgtv Qgasv Earth Resources, written commun., 2006) are radiocarbon infinite. In Friends of the Pleistocene, September 24–25, 1966: [Privately published by the author], Sherrod, B. L., 2005, Prehistoric earthquakes in the Puget Lowland, Washington [abstract]: f Qp Qgtv Qc Qgof 3 interfingers with adjoining Everson marine deltaic deposits (unit Qgome). began with grounded ice retreat alongside calving basins that defined the northern contrast, a beach-level exposure of nonglacial silt and clay south of Rocky 52 p. Eos (American Geophysical Union Transactions), v. 86, no. 52, p. F1458-1459. G E Qgt F A U L T 175 Qgof This unit is assigned to the broader Fraser glacial period because some v Qb margins of large proglacial lakes. (Thorson, 1980; Porter and Swanson, 1998; Booth Qgas Qgtv deposits appear to (1) post-date the elevated Everson sea level, (2) fill Point yielded an OSL date of 39,310 ±2.820 ka (columnar section 4; Easterbrook, D. J., 1966b, Radiocarbon chronology of late Pleistocene deposits in northwest Sherrod, Brian; Blakely, R. J.; Weaver, Craig; Kelsey, H. M.; Barnett, Elizabeth; Wells, Ray, v Qmw and others, 2004). Meltwater-driven incision of new valleys that dissect the uplands Qgasv closed depressions above the Everson glaciomarine limit, (3) form small Table 1, loc. 6), suggesting an Olympia nonglacial age. We conclude that Washington: Science, v. 152, no. 3723, p. 764-767. 2005a, Holocene fault scarps and shallow magnetic anomalies along the southern Qml Qgtv Qmw Qls Qgtv 150 of southern Whidbey Island indicates that as ice retreated at the end of the Vashon the data are weakly suggestive of an Olympia age for part or all of the Whidbey Island fault zone near Woodinville, Washington [abstract]: Eos (American Qgasv Qf kame(?) terraces, or (4) be graded to pre-Everson(?) glaciolacustrine base Easterbrook, D. J., 1968, Pleistocene stratigraphy of Island County: Washington Department Qb Stade, part of the island was largely ice free, no longer submerged beneath exposures south and east of Rocky Point, but we cannot dismiss an older Geophysical Union Transactions), v. 86, no. 52, p. F1438. Qgtv levels. of Water Resources Water-Supply Bulletin 25, part 1, 34 p., 1 plate (in 4 parts). Qmw Qgtv Qgof ice-dammed lakes, and not yet inundated by the Everson Interstade incursion of Qguc origin for at least part of the section. We also cannot establish Easterbrook, D. J., 1969, Pleistocene chronology of the Puget Lowland and San Juan Islands, Sherrod, B. L.; Blakely, R. J.; Weaver, Craig; Kelsey, Harvey; Barnett, Elizabeth; Wells, Ray, Qgdm Qm Qgas Qgas e 125 v marine water. This seawater incursion raised base level for the meltwater streams to Qgics(f) Stratified subglacial ice-contact deposits—Interbedded gravel, 2005b, Holocene fault scarps and shallow magnetic anomalies along the southern v Qgav Qgics stratigraphic continuity along the section and therefore assigned all Washington: Geological Society of America Bulletin, v. 80, no. 11, p. 2273-2286. Qml Qgof Qgtv Qgta Qgasv f f the glaciomarine limit (maximum relative seawater elevation), causing the lower lodgment till, flow till, and sand; minor silt and clay beds; loose to Qc Whidbey Island fault zone near Woodinville, Washington: U.S. Geological Survey nonglacial exposures in columnar sections 4 and 5 to unit . Easterbrook, D. J., 1994a, Chronology of pre-late Wisconsin Pleistocene sediments in the T Qgtv Qm Qgt Qgo portions of their valleys to be filled with fluvial and deltaic outwash before isostatic compact; variably sorted; moderately to well stratified; medium to very Open-File Report 2005-1136, 35 p. [accessed Mar. 21, 2006 at v Qgasv f Qgicsf till and sand Puget Lowland, Washington. In Lasmanis, Raymond; Cheney, E. S., convenors, Regional Qgasv Qgtaf interbeds rebound began. Our interpretations of the local geomorphology place the thickly bedded; commonly contains cross-beds, contorted beds, UNDIVIDED GLACIAL AND NONGLACIAL DEPOSITS OLDER THAN http://pubs.usgs.gov/of/2005/1136/] Qgdme 100 Qgtv Qgicsf? Qb geology of Washington State: Washington Division of Geology and Earth Resources Qm Qgomee glaciomarine limit at about 125 to 130 ft (at Double Bluff) to about 180 to 190 ft oversteepened beds, and small-scale shears, all of which appear to be VASHON TILL (PLEISTOCENE) goon Qgasv Z O N E Stoffel, K. L., 1980, Stratigraphy of pre-Vashon Quaternary sediments applied to the Qgtv Bulletin 80, p. 191-206. Qgtv (north of Greenbank), which is consistent with Thorson (1980, 1981), Dethier and mostly collapse features but may include glacio- and seismo-tectonic evaluation of a proposed major tectonic structure in Island County, Washington: Qgomee Qguc Undifferentiated deposits older than Vashon till—Various mixtures of Easterbrook, D. J., 1994b, Stratigraphy and chronology of early to late Pleistocene glacial and Qgof Elevation (feet) 75 others (1995), Easterbrook (2003), and Kovanen and Slaymaker (2004). deformation and (or) reflect sub-ice flow; sub-ice deposition also appears Washington Division of Geology and Earth Resources Open File Report [80-0], 161 p. Qgdme Qguc interglacial sediments in the Puget Lowland, Washington. In Swanson, D. A.; Haugerud, Qgom Qgtv Qgt Marine shells at Lake Carpenter (south of the map area) suggest that the Everson consistent with exposures in which several till layers alternate with gravel, sand, gravel, diamicton, silt, clay, and peat; compact; well stratified to Swanson, T. W., 1994, Determination of 36Cl production rates from the deglaciation history of Qgicsf e Qgta sand v R. A., editors, Geologic field trips in the Pacific Northwest: University of Washington S O U T H E R N f Qgas 14 massive; composite of glacial and (or) nonglacial deposits; pre-dates v Interstade seawater incursion began before 14,610 C yr B.P., and freshwater gyttja sand, and fines, and where some layers gently dip south; displays shear Department of Geological Sciences, v. 1, p. 1J 1 - 1J 38. Whidbey Island, Washington: University of Washington Doctor of Philosophy thesis, Qgtv 14 Vashon till; may include Vashon advance outwash. A new radiocarbon Qgt Qgt 50 gray silt from the same site suggests that it ended before 13,600 C yr B.P. (Anundsen and fabric that commonly occurs in till and tends to parallel bedding in nearby 121 p. v Qgom Qgtv v Qgome Easterbrook, D. J., 2003, Cordilleran ice sheet glaciation of the Puget Lowland and Columbia ee Qgasv till and others, 1994), but that timeline conflicts with the apparent persistence of the Puget gravel and sand; in most exposures, unconformably overlain by unit analysis on peat from a deformed sand layer 2 ft above the beach along Thorsen, G. W., 1983a, West Beach silt—A late Pleistocene loess, central Puget Lowland, Qgics Plateau and alpine glaciation of the North Cascade Range, Washington. In Swanson, Terry Qgdm Qgtv f massive Qgo 14 14 e silty sand f ice lobe in the central Puget Lowland through at least 13,800 C yr B.P. (Booth and Qgdme or Qgtv (mostly <5 ft and thus not mapped); distinguished from the east shore of Holmes Harbor yielded a date of >42,750 C yr B.P. Washington: Washington Geologic Newsletter, v. 11, no. 2, p. 1-4. Qgomee W., editor, Western Cordillera and adjacent areas: Geological Society of America Field others, 2004; Porter and Swanson, 1998), and various workers have favored or unit Qgtv by more stratification, mostly lower density, and more distinct (Table 1, loc. 8). Qgta Qgof 25 Guide 4, p. 137-157. Thorsen, G. W., 1983b, West Beach silt—A late Pleistocene loess, central Puget Lowland, Qb Qgof f Qgasv covered Qgas Qb implied other dates for the start and (or) end of the incursion (Easterbrook, 1966a,b; bedding in sand and gravel; preferentially exposed (deposited?) along Washington: Loess Letter, no. 10, p. 15-16. v DEPOSITS OF THE OLYMPIA NONGLACIAL INTERVAL Easterbrook, D. J.; Crandell, D. R.; Leopold, E. B., 1967, Pre-Olympia Pleistocene 10 Qgdme Swanson, 1994; Dethier and others, 1995; Blunt and others, 1987; Porter and sideslopes to deep subglacial scour basins (now marine inlets). beach Qgasv stratigraphy and chronology in the central Puget Lowland, Washington: Geological Thorsen, G. W., 2001, Whidbey Island Quaternary sediments. In Northwest Geological Qgtv Qgtv (PLEISTOCENE) Qgof Swanson, 1998; Booth and others, 2004; Kovanen and Slaymaker, 2004; Polenz and Qgtv Qgta(f) Ablation till—Unsorted, unstratified, and heterogeneous melt-out deposit Society of America Bulletin, v. 78, no. 1, p. 13-20. Society field trip, June 2–3, 2001: Northwest Geological Society, p. 1-20. Qgasv others, 2005). The above age statements lack radiocarbon reservoir corrections, for Qgta Armstrong and others (1965) defined the “Olympia Interglaciation” as the “climatic f of sand, silt, clay, gravel, diamicton, and patchy stratified proximal Gower, H. D., 1980, Bedrock geologic and Quaternary tectonic map of the Port Townsend Thorson, R. M., 1980, Ice-sheet glaciation of the Puget Lowland, Washington, during the Qgasv which we refer interested readers to Hutchinson and others (2004). episode immediately preceding the last major glaciation” and associated it with outwash, ice-dammed lake sediment, and peat; loose to compact; typically area, Washington: U.S. Geological Survey Open-File Report 80-1174, 1 sheet, scale Vashon Stade (late Pleistocene): Quaternary Research, v. 13, no. 3, p. 303-321. South “nonglacial strata lying beneath Vashon Drift”. We associate those strata with stage Qgasv Drumlins formed by southward ice flow are overprinted with marine landforms 1:100,000, with 19 p. text. Qgom forms geomorphologically complex patchwork of meltout deposits, Thorson, R. M., 1981, Isostatic effects of the last glaciation in the Puget Lowland, W ee Qb (Kovanen and Slaymaker, 2004), such as terraces and spits, deltas, and shorelines. 3 (~60–20 ka) but avoid the label “Olympia Interglaciation” because stage 3 is not a Whidbey Hansen, H. P.; Mackin, J. H., 1949, A pre-Wisconsin forest succession in the Puget Lowland, Washington: U.S. Geological Survey Open-File Report 81-370, 100 p., 1 plate. H I D Qgdme Qgt outwash, closed depressions, erosional exposures of older (Fraser?) units, Qgtv Qgtaf v Above the glaciomarine limit, upland surfaces are commonly dissected by relict true interglacial period (Morrison, 1991). Qls State Qgt and incipient and larger drainages; includes kettles northeast of Freeland. Washington: American Journal of Science, v. 247, no. 12, p. 833-855. Thorson, R. M., 1989, Glacio-isostatic response of the Puget Sound area, Washington: B E v valleys (Kovanen and Slaymaker, 2004) that expose a discontinuous, diverse, and Park Qgof Qc(o) Nonglacial deposits—Sand, silt, clay, peat, and minor fine gravel; where Heusser, C. J.; Heusser, L. E., 1981, Palynology and paleotemperature analysis of the Geological Society of America Bulletin, v. 101, no. 9, p. 1163-1174. Qgdme Qgtv ≥ Y mostly thin (0–15 ft) cover of lodgment till above thick (we observed 170 ft) sheets Everson Interstade Qco shown in our map area, includes exclusively detrital peat, although Whidbey Formation, Puget Lowland, Washington: Canadian Journal of Earth Sciences, Vogel, J. C.; Waterbolk, H. T., 1972, Groningen radiocarbon dates X: Radiocarbon, v. 14, Qgasv Qgome Qgomee of advance outwash sand. Evidence that the valleys were cut by meltwater includes: Qgdme nonglacial deposits are typically distinguished by the presence of in-place v. 18, no. 1, p. 136-149. Qgasv 5 Qgdm(e) Everson Glaciomarine Drift—Clayey to silty diamicton with variable no. 1, p. 16. 2 (1) valley formation required surface runoff in excess of that in the modern Qgasv Qf Qgdme peat; compact; includes horizontally bedded, massive, and cross-bedded Hutchinson, Ian; James, T. S.; Reimer, P. J.; Bornhold, B. D.; Clague, J. J., 2004, Marine and 50 environment; (2) the valleys terminate at the glaciomarine limit, below which they amount of gravel clasts; also includes silt, clay, and sand; contains sparse Yount, J. C.; Marcus, K. L.; Mozley, P. S., 1980, Radiocarbon-dated localities from the Puget Qgdme Qc Qgt Qgof silty diamicton v facies; commonly forms vertical bluffs; like units Qcw and Qc, probably limnic radiocarbon reservoir corrections for studies of late- and postglacial environments Lowland, Washington: USGS Open-File Report 80-780, 51 p. Qgasv Qgdm Qgome Qb are infilled with recessional sand and marine delta deposits; and (3) the valleys lack shells, generally marine; dark gray where unweathered; weathers mostly e Qb Qmw deposited in a paleo-floodplain or channel setting. in Georgia Basin and Puget Lowland, British Columbia, Canada and Washington, USA: Qls Qgasv Esperance(?) Sand to buff, but ranges to olive gray, ash gray, or white; commonly forms a Yount, J. C.; Minard, J. P.; Dembroff, G. R., 1993, Geologic map of surficial deposits in the Qgasv Qgome active stream channels; some include dry, closed depressions where mass wasting Quaternary Research 61, v. 2, p. 193-203. Qgome 25 Qco? cross-laminated clay (transition beds?) from valley sidewalls has locally elevated the valley floor. dry, vertical face with failure-prone, vertical desiccation cracks with Seattle 30′ x 60′ quadrangle, Washington: U.S. Geological Survey Open-File Report 14 INTERGLACIAL DEPOSITS OF THE WHIDBEY FORMATION Qgasv peat >45,370 C yr B.P. (Table 1, loc. 5) Ives, P. C.; Levin, Betsy; Oman, C. L.; Rubin, Meyer, 1967, U.S. Geological Survey 93-233, 2 sheets, scale 1:100,000. Qgtv Qgasv dark-brown staining; massive to rhythmically bedded, commonly with Qgof Qc (PLEISTOCENE) radiocarbon dates IX: Radiocarbon, v. 9, p. 519. Qmw Qgtaf Elevation (feet) sharp upper and lower, unit-bounding unconformities (Domack, 1984); Qgta compact laminated clay STRUCTURE 3 f Qgtaf 5 Qml Qmw beach mostly loose and soft but locally hard and compact; may resemble till Qc(w) Whidbey Formation—Sand, silt, clay, peat, and minor fine gravel; 2a,b Qgom Most of the fault strands and the offshore fold shown are from Johnson and others Qc Qgasv Qgtv ee (Domack, 1982, 1984; Domack and Lawson, 1985), but in general, till w Qgof Qgdf compact; mostly weathered to subtly variegated light-yellowish in f (2000). We added one fault strand about 500 ft north of the Lagoon Point public lacks fossils and glaciomarine drift has a finer-grained, smoother-feeling Qp Qgtv exposed faces; includes floodplain and channel-sand facies. The Qp beach access, based on a bluff exposure noted in 1988 by Tim Walsh and Josh Logan Table 1. Age control data from the map area. Lab uncertainty values include random errors and are one standard deviation (68% confidence interval), except where shown in quotes, Qgasv I S L matrix, is less compact, and is more likely to be stratified; composed of floodplain facies typically is well stratified (subhorizontally) and slightly Qf Qb Qgdme (Wash. Div. of Geology and Earth Resources, oral commun., 2006). Walsh and indicating that we do not know how many standard deviations are included. OSL, optically stimulated luminescence; IRSL, OSL using infrared light as stimulant (IRSL-OSL) to date D sea-floor sediment and mostly consists of glacial flour, its textural Qgasv A Qgasv oxidized, forms prominent vertical bluffs, and contains discontinuous peat 14 N D Logan could not determine whether the strand offsets Fraser deposits or is restricted diversity reflecting proximity of the ice front (Domack, 1983; Dethier and feldspars; blue light OSL, OSL using blue light as stimulant to date quartz; TL, thermoluminescence to date polyminerals; AA, amino acid content analysis; C, radiocarbon analysis RBO beds. The channel-sand facies typically is clean, gray, and cross-bedded to 14 Qgasv by liquid scintillation counting; C AMS, radiocarbon analysis by atomic mass spectrometry. New radiocarbon analyses from this study were performed by Beta Analytic, Inc. (Miami, 10¢00² Qp Qgdme 2¢30² to underlying, older (Whidbey?) strata. Qgof others, 1995). Locally divided into: massive, and tends to form angle-of-repose slopes. Pollen indicates that 13 12 13 12 Qp Fla.). Radiocarbon ages are ‘conventional’ (that is, adjusted for measured C/ C ratio) if a C/ C ratio is shown; other entries may be ‘measured’ or ‘conventional’. Radiocarbon age Qgt Qgtv The “Southern Whidbey Island Fault”, with possible Quaternary movement, was v climate at the time of Whidbey deposition was initially cool but then estimates are in radiocarbon years before 1950 (14C yr B.P.); ka, thousands of calendar years before 1950. Where two geologic units are shown for a sample, map scale or field Qguc first inferred by Gower (1980). Johnson and others (1996) characterized the Qgom(ee) Glaciomarine drift, emergence (beach) facies—Sand and gravel, Qls Qgtv Qgomee warmed (Hansen and Mackin, 1949; Easterbrook and others, 1967; relations caused us to show the first unit on the map, while the second (in parentheses) identifies the geologic material sampled. Elevations are in feet above mean sea level, as Qb “southern Whidbey Island fault” as a long-lived transpressional zone that separates locally silty; loose; mostly structureless but may be stratified, Heusser and Heusser, 1981). The formation’s type section (Easterbrook estimated in this study using lidar data (supplemented by visual elevation estimates on bluffs) and referring to NADCON for vertical datum shifts between lidar data and map elevations. major crustal blocks. Brocher and others (2005) recently postulated that “the laminated, or ripple cross-bedded with rare boulder lag deposits; Qp T 30 N and others, 1967) is located east of Double Bluff at the south end of the Elevations in quotation marks are as reported by referenced sources (some converted from metric). Qgas Qgtv southern Whidbey Island fault … is a NW-SE oriented fold and thrust belt … [that typically only a few feet thick; occurs below the glaciomarine limit; v T 29 N map area (bluff section A). Based on a new radiocarbon date (27,980 R underlain by unit Qgdm or Qgom or older sediments; represents T 30 N Qgom accommodates] NE-directed crustal shortening”. Sherrod and others (2005a,b) e e 14 Loc. Age estimate 13C/12C Analytical Material Geologic Elev. F A Qb e ±530 C yr B.P.) from about 2000 ft northwest of that type section showed the fault zone along about 95 mi from Vancouver Island to east of Seattle, emergence deposits that cap glaciomarine drift and may include no. (14C yr B.P. or ka) (o/oo) method dated unit Lab no. (ft) Reference Notes T 29 N U L (columnar section 6; Table 1, loc. 16), we queried inclusion with the with three to four main strands crossing Whidbey Island. Johnson and others (1996) terrestrial deposits (Domack, 1983; Dethier and others, 1995); 14 14 Qgasv T 1a >43,870 C yr B.P. -26.4 C wood Qc Beta 211254 8 This report Sample from peat 4 in. beneath loc. 1b. Qgome Qp displays characteristic but subtle benches at various elevations Whidbey Formation of some deposits previously so mapped (Easterbrook noted that the Southern Whidbey Island fault zone has caused several historic 1 Qgtv Qguc 1b >150 ±12 ka n.a. OSL silty clay Qc UIC1723 8 This report Sampled from silty clay 4 in. above loc. 1a; OSL ages from quartz and feldspar. Qgasv (Carlstad, 1992; Easterbrook, 2003; Kovanen and Slaymaker, 2004) and others, 1967). We also follow Stoffel’s (1980) lead in reassigning Qgt Qmw shallow-crustal earthquakes and appears capable of generating earthquakes of 14 14 Qf v representing paleo–beach berms. Similar deposits that locally occur sediment east of the Whidbey Formation type section from Whidbey 2a 43,440 ±1660 C yr B.P. -27.5 C AMS plant material Qmw Beta 211261 14 This report Matrix around sample is loc. 2b. Sample is 2 in. above a peat. Surrounding strata surface-wave magnitude 7 or greater. Kelsey and others (2004) used Whidbey Island (Qc) suggest that the peats at locs. 2 and 3 are the same. Qb Qml above the glaciomarine limit along shorelines near Freeland are Formation (Easterbrook and others, 1967) to units Qco and Qgasv (bluff ighthhouse Qgom data to infer a moment-magnitude 6.5 to 7 earthquake on the fault zone about 3 ka. 1 e Qgdf section A). We could not locate some exposures previously mapped as 2b >200 ±20 ka n.a. OSL silty clay Qmw UIC1724 14 This report Sample is matrix around loc. 2a; see loc. 2a for relation to sample 3; OSL ages from Sherrod and others (2005a,b) and Sherrod (2005) concluded that the Southern mapped as unit Qgtaf, Qgdf, Qgtv, Qgtav, or Qgasv and were Qgof Qls Whidbey Formation (Table 1, locs. 19–22) and may have locally included (Qc) quartz and feldspar. Qgome Qgtv Whidbey Island fault zone “produced at least four events since about 16,400 years deposited by pre-Everson proglacial lakes or lakes that may have Qgasv Qgasv 3 >47,300 14C yr B.P. -26.2 14C AMS wood Qmw Beta 211256 28 This report Sampled from peaty clay ~200 ft north of loc. 2. Surrounding strata suggest that the been locally ice-dammed above Everson sea level. Whidbey deposits with unit Qco, Qc, Qguc, or Qmw. We believe the unit Qb ago, the most recent after 2,700 years ago.” (Qc) peats at locs. 2 and 3 are the same. Qgtv Qgas Qgtv age to be about 125 to 80 ka, or stage 5. v Z O N Our fieldwork revealed many possible tectonic fault strands along bluffs, but Qgdm 8 Qgom(e) Glaciomarine deltaic outwash—Mostly sand, with some sand-gravel 4 >38,700 14C yr B.P. -29.9 14C organic Qls Beta 211258 28 This report Analysis initially reported as 40,030 ±1280 BP, then adjusted to infinite (Ron Qml e Qgom Qgdme (with the possible exception of liquefaction features along bluff section A) we felt e DEPOSITS OF THE DOUBLE BLUFF GLACIATION (PLEISTOCENE) (Qc) E Qgome mixtures and minor interlayered silt and silty sand; generally loose; sediment Hatfield, Beta Analytic, Inc., oral commun., 1-30-06). Qp that we could also interpret each as a product of landsliding or glaciotectonics. We Qgome maximum clast size limited to pebbles and small cobbles; mostly at least a 5 >45,370 14C yr B.P. -28.0 14C peat Qc Beta 211259 ~19 This report Qgt Qp note, however, that the most elevated uplands of southern Whidbey Island are Qgd(d) Double Bluff Drift—Glaciomarine drift (silt, clay, and diamicton) at top, Qguc Qgome v Qgas few tens of feet thick; about 65 ft maximum thickness suggested by well 1 v Qgas Qgdd 6 39.3 ±2.82 ka OSL silty clay Qguc UIC1722 ~13 This report Analysis on quartz from blue silty clay ~3 ft above beach (columnar section 4). v Qgt bracketed by the mapped strands of the Southern Whidbey Island fault zone, and that underlain by till, glaciolacustrine silt, basal advance outwash sand, gravel, Qgtv v records; forms a marine delta–turbidite complex with a horizontally (Qc) Qgtv Qguc new age data suggest the presence of some very old (>150 ka) nonglacial sediments and some silt and clay; compact; resembles equivalent Fraser and bedded, sandy sea floor facies, an overlying delta-front foreset-bedded 7 12,670 ±90 14C yr B.P. 14C or marine shells “till” USGS-64 “10” Robinson (1977) Robinson (1977) identified unit as “Till deposited against older Double Bluff drift within the fault zone (Table 1 and description for unit Qc). Both observations are Possession drift units and may thus commonly occur unrecognized where 14 14 Qb facies, and a capping deltaic top-set, channelized facies. C AMS ca 300 m to E.” Collected by J. Yount. Date lacks C reservoir correction; see Qp Qgdme Qgtaf consistent with uplift in the fault zone and with the interpretations of Johnson and exposed sections are incomplete; typically recognized at or near sea level Hutchinson and others (2004) for suggested correction. Qguc Qmw Qls(e)? Landslide deposits—Mix of till and outwash sand and gravel; identified Qgdme others (1996) and Brocher and others (2005). The lack of recognized fault scarps (Blunt and others, 1987); shown in this map only at its type section, based 14 14 Qgtaf Qp Qlse? 8 >42,750 C yr B.P. -28 C fragmented Qguc Beta 212315 ~6 This report Sampled from limited exposure of distorted sandy layer with deformed peat ~2 ft Qgas need not reflect a lack of surface-deforming fault events, but could result from as landslide based on surface morphology; queried because assigned to on prior mapping there (Easterbrook and others, 1967). We believe, peat above east shore of Holmes Harbor; overlain by Vashon(?) till. Qgdme Qguc v Qgasv the Everson Interstade based only on field relations, low slope angle Qmw Qgtaf diffusion of fault deformation in extensive, thick, sandy deposits. however, that the exposures we saw at Double Bluff alternatively could be 2 4 3 9a 26.2 ±0.80 ka IRSL sand Qco? WA-49 “70” S. Mahan and K. Troost Minimum age estimate; weighted average of three age estimates (from weighted Qf Qgt Qmw (~12% average), and subdued morphology. Qgomee Qgtv v Qgtv interpreted as a combination of Fraser with Possession or Double Bluff average of equivalent doses); IRSL may be incompletely bleached. Qf Qb Qgdme drift because a landslide and vegetation prevented us from tracing the unit Qgasv DESCRIPTION OF MAP UNITS Vashon Stade 9b 27.9 ±0.85 ka2 IRSL4 sand Qc ? WA-49 “70” S. Mahan and K. Troost3 Minimum age estimate; weighted average of three age estimates (from weighted Qgtaf Qgof Qguc continuously from the southern end to the northern end of the type o Qgoff Qf Qm average of equivalent doses); IRSL may be incompletely bleached. Qgdm Qp Qm e Qgt(v) Till—Typically unweathered, unsorted mix of clay- through boulder-size section, and the three age analyses at the section are tentative (Table 1, 2 4 3 Qgtv Postglacial Deposits 9c 30.6 ±1.12 ka TL sand Qco? WA-49 “70” S. Mahan and K. Troost Qgtv locs. 26–28; Blunt and others, 1987; Berger and Easterbrook, 1993; Glenn material (diamicton) deposited directly by ice; includes extensive areas of 9d 18.7 ±1.52 ka2 blue light sand Qc ? WA-49 “70” S. Mahan and K. Troost3 Age estimate is a mean calculated from 21 successful, replicated equivalent dose (De) Qgicsf Qgdme Qgt o v Qp Qgdf HOLOCENE compact (advance outwash?) sand; compact, well-developed facies Berger, Desert Research Institute, Reno, Nev., oral commun., 2006). We OSL estimates; 66 De estimates were attempted; fit to linear regression. could not locate some exposures previously mapped as Double Bluff Drift resemble concrete; locally loose in ablation till (also separately mapped as 10a 21.8 ±0.63 ka2 IRSL4 silt Qgas WA-50 “160” S. Mahan and K. Troost3 Minimum age estimate. Sample may be Lawton Clay. Qm Qgtv v Qgtv Qf Fill—Clay, silt, sand, gravel, organic matter, rip-rap, and debris placed to (Table 1, locs. 17–18; Berger and Easterbrook, 1993); we likely included unit Qgtaf) and well-sorted in some sand-dominated areas; commonly has 2 4 3 Qgtv Qgtv Qf 10b 24.4 ±0.70 ka IRSL silt Qgas WA-50 “160” S. Mahan and K. Troost Minimum age estimate. Sample may be Lawton Clay. Qp elevate and reshape the land; includes engineered and nonengineered fills; these with unit Qls or Qmw. Where Double Bluff Drift has been mapped v Qgdme Qgom Qf erratic boulders on the surface; gray where fresh; oxidizes to yellowish ee Qgof 10c 24.2 ±1.40 ka2 TL4 silt Qgas WA-50 “160” S. Mahan and K. Troost3 Sample may be Lawton Clay. shown where fill is readily verifiable, is relatively extensive, and appears elsewhere on Whidbey Island, the assigned age of 185 to 125 ka (stage 6) v Qgdme brown; very low permeability in compact diamicton but locally highly Qf Qgdme 2 4 Qgas 3 sufficiently thick to be geotechnically significant; excludes roads. permeable in sandy or loose facies; most commonly matrix supported; or older relies primarily on stratigraphic position (for instance, Dragovich 11a <36.6 ±0.96 ka IRSL sand v WA-51 “200” S. Mahan and K. Troost Minimum age estimate, although IRSL ages may reflect incomplete bleaching, when and others, 2005; Polenz and others, 2005). compared to blue-light OSL ages. Qml Modified land—Local sediment, ranging from clay to gravel and cobbles and boulders commonly faceted and (or) striated; surface mostly Qgdme Qgas 11b 37.2 ±0.98 ka2 IRSL4 sand Qgas WA-51 “200” S. Mahan and K. Troost3 Second of two IRSL maximum age estimates (generally considered more reliable than v Qml fluted by overriding ice; generally forms a patchy and seemingly v diamicton, mixed and reworked by excavation and (or) redistribution that 2 Qp randomly distributed cover up to at least 70 ft thick, with 2 to 30 ft most ACKNOWLEDGMENTS first estimate, which was <56.4 ±1.9 ka ). Qgome notably modifies topography; shown where relatively extensive, masking Qm 11c 35.7 ±1.39 ka2 TL sand Qgas WA-51 “200” S. Mahan and K. Troost3 Maximum age estimate (due to TL technique). Qgt Qgt common; in the center of some well-formed drumlins, exposed as v v Qgo v underlying geology, and apparently of geotechnical significance; excludes This report was produced in cooperation with the U.S. Geological Survey National f 2 3 well-developed lodgment till more than 30 ft thick that pinches out in less 11d 23.2 ±0.81 ka blue light sand Qgasv WA-51 “200” S. Mahan and K. Troost Age estimate is a mean calculated from 10 successful, replicated equivalent dose (De) Qb roads; excludes abandoned pits where underlying units can be identified; Cooperative Geologic Mapping Program, Agreement No. 05HQAG0085, which Qgas than 300 ft, giving way to well-bedded, compact (advance outwash?) OSL estimates; 13 De estimates were attempted; fit to linear regression. AY Qf v includes aggregate pits active at time of mapping. partially supported our mapping. We thank Doug Kelly (Island Co. Health Dept.) Qgdme sand; may include flow banding; typically forms vertical faces in coastal 12 >39,000 14C yr B.P. -28.9 14C peat Qc ? Beta 212314 41 This Report Detrital peat from ~37 ft above beach from thick, gray fine sand (~20 ft below flame and other Island County staff for geologic, hydrogeologic, geotechnical, and other o Qf Qgdm structures); ~300 ft west of center of big gully. e Qb Beach deposits—Sand and cobbles; may include boulders, silt, pebbles, bluffs; locally resembles unit Qgdme; lies stratigraphically between Qb Qgtv 48°00¢00² Qb assistance and records; Terry Swanson (Univ. of Wash.), Liz Nesbitt (Univ. of 48°00¢00² Qgd and clay; pebbles and larger clasts typically well rounded and oblate; 13 34.9 ±2.56 ka OSL1 laminated silt Qc ? UIC1721 13 This Report OSL from quartz in 12 in. thick, laminated, silty clay in sand-dominated unit. f Qgasv Qgtv Qgomee overlying unit Qgdme and underlying units Qgav and Qgasv; may include o Qgdme Wash. Burke Museum), Gerald Thorsen, Katherine Reed, Deborah Mitchell, and mostly well sorted; loose; derived from shore bluffs and underlying unrecognized exposures of older till. Regional age data appear to 14a 23,600 ±275 14C yr B.P. -26.97 14C or wood Qgas UM1752 ~200 Johnson and others (1980) Sampled “from Whidbey/Esperance contact” (Johnson and others, 1980); Stoffel Yvonne Dettlaff for assistance with field work and interpretation of cliff exposures; v 14 Qf Qm deposits and (or) carried in by longshore drift. constrain the age of the unit to between about 18 ka and the onset of the C AMS fragments (1980) shows sample as DBE#1 from Esperance Sand at contact with underlying Liz Nesbitt (Univ. of Wash. Burke Museum) for identification of fossils and their Lawton Clay (bluff section A). May be same sample as loc. 14b. Qb Qm Marsh deposits—Organic and organic-rich mineral sediment deposited in Everson Interstade. paleoenvironmental implications; Kathy Troost (Univ. of Wash.), Shannon Mahan Qm Qgasv 14 14 Qm 14b 22,210 ±530 C yr B.P. C or wood Qgasv I-10, 801 ~200 Stoffel (1980) Sampled by Keith Stoffel from same (?) horizon as loc. 14a. Date may be same a saltwater or brackish marsh (estuarine or lagoonal) environment; not (U.S. Geological Survey) and Gerald Thorsen for technical and interpretive 14 Qgdf Qga(v) Advance outwash—Locally bouldery pebble to cobble gravel, sand, and C AMS fragments sample as loc. 14a. Qgav Qgdme shown in wetland settings where field data indicate a thickness of less some layers and lenses of silt and clay; may contain till fragments; gray to assistance and permission to include their unpublished age control data; Glenn A Qf 15 >40,000 14C yr B.P. 14C or wood Qguc I-? ~46 Gerald W. Thorsen ~1,600 ft east of Rocky Point from peaty layer at base of ~12 ft of massive, silty sand Qguc than 2 ft of marsh sediment. grayish brown and grayish orange; clasts typically well rounded, well Berger (Desert Research Institute, Reno, Nev.) for technical and interpretive 14C AMS (consulting geologist, and atop possible West Beach silt (shown in columnar section 5). Lab no. unknown; D Qm sorted, and clean, except in ice-proximal deposits which are less sorted assistance with some age estimates; Sam Johnson and Brian Sherrod (both U.S. written commun., 2005) analysis by Teledyne Isotopes (Westwood, N.J.) Qgdme Qgdm HOLOCENE TO LATE PLEISTOCENE Qm e and more angular; compact; mostly well stratified; very thinly to very Geological Survey) for consultations and technical reviews on the tectonic setting; 14 14 Qf 16 27,980 ±530 C yr B.P. -26.8 C dispersed Qcw? Beta 212316 ~76- This report Sample from center of silty clay that Easterbrook (1968) and Easterbrook and others Qgtv Joe Dragovich (Wash. Div. of Geology and Earth Resources) for assistance with thin M Qp Peat—Organic and organic-rich sediment, typically in closed depressions; thickly bedded; contains planar and graded beds, cut-and-fill structures, carbon in silty 86 (1967) included with Whidbey Fm. Because the new date, if correct, contradicts that Qguc Qgas v Qmw Qp trough and ripple cross-beds, and foresets; maximum observed thickness section petrography and geochemical analyses; and Joe Dragovich, Tim Walsh, and clay (gyttja?) unit assignment, we queried assignment to Whidbey Fm. (columnar section 6). Qb Qf Qguc Qm includes peat, muck, silt, and clay in and adjacent to wetlands; may Josh Logan (all Wash. Div. of Geology and Earth Resources) for technical reviews locally grade down to and composes the freshwater equivalent of unit Qm; estimated at about 85 ft; deposited as proglacial fluvial (and deltaic) Location not plotted (location not understood well enough to show on map) Qgof Qf sediment; tends to coarsen upward in complete sections; may include and interpretive assistance. Thanks also to the Washington State Department of 17 320 “±100” ka TL silty clay from Qgd LAGPT-1 Berger and Easterbrook Partial-bleach TL analysis, which assumed glacial sediment was fully zeroed before not shown where field data indicate a thickness of less than 2 ft. d Qgtv Ecology for permission to use proprietary shoreline aerial photos for our fieldwork. rhythmites (1993) burial (Glenn Berger, Desert Research Institute, Reno, Nev., oral commun., 1-3-06). N Qmw Evans Creek alpine outwash; commonly overlain by unit Qgtv along a Qb Qf Qmw Mass wasting deposits—Boulders, gravel, sand, silt, clay, and diamicton; Qc Qc Last, but not least, thanks to the many people who permitted us to study and sample Outcrop at Lagoon Point not located in this study; unit identified by referenced A sharp contact, and lies stratigraphically above units and o. The Qf Qmw source. Qgasv Qf generally unsorted, but locally stratified; typically loose; shown along estimated age is about 18 to 20 ka or older. Locally divided into: geologic exposures on their land and provided site-specific records and local L Qgt Qgasv v Qb 18 380 “±50” ka TL silty clay from Qgd LAGPT-1 Berger and Easterbrook Additive-dose TL analysis assumed glacial sediment was fully zeroed before burial L Qgdme mostly colluvium-covered or densely vegetated slopes that are potentially expertise. d Qgas(v) Advance outwash sand—Mostly lacustrine sand with layers of silt; rhythmites (1993) (Glenn Berger, Desert Research Institute, Reno, Nev., oral commun., 1-3-06). Outcrop E Qb or demonstrably unstable; includes two small, recent alluvial fans west of Qgas Qguc v locally grades upward into gravel; thick and extensive, with at Lagoon Point not located in this study; unit identified by referenced source. T Useless Bay; locally contains landslides and underlying units that either REFERENCES CITED Qp maximum observed thickness of greater than 170 ft; commonly 19 102 “±38” ka TL silty clay from Qc LAGPT-6c Berger and Easterbrook Partial-bleach TL analysis. Outcrop at Lagoon Point not located in this study; unit Qguc we could not map confidently or are too small to show. w Y Qf rhythmites (1993) identified by referenced source. Qf Qgtv forms angle-of-repose slopes along drainages and coastal bluffs; Anundsen, Karl; Abella, S. E. B.; Leopold, E. B.; Stuiver, Minze; Turner, Sheila, 1994, Qgdme Qf Qp Qls Landslide deposits—Gravel, sand, silt, clay, and boulders in slide body includes Lawton Clay and Esperance Sand (bluff section A). Late-glacial and early Holocene sea-level fluctuations in the central Puget Lowland, 20 138 “±42” ka TL silty clay from Qc LAGPT-6c Berger and Easterbrook Additive-dose TL analysis. Outcrop at Lagoon Point not located in this study; unit Qls w Qgtv and toe, and exposure of underlying units in scarp areas; angular to Washington, inferred from lake sediments: Quaternary Research, v. 42, no. 2, p. 149-161. rhythmites (1993) identified by referenced source. Qb Qgasv Qb Widespread, relict valleys in southern Whidbey Island are deeply Qgas rounded clasts; unsorted; generally loose, unstratified, broken, and Armstrong, J. E.; Crandell, D. R.; Easterbrook, D. J.; Noble, J. B., 1965, Late Pleistocene 14 14 Qc v Qls incised into unit Qgasv and typically lack modern streams, due to 21 >39,900 C yr B.P. C or wood in peat w I-2283 Easterbrook (1969) Location identified by referenced source as 48°05¢N, 122°37¢W. Coordinates point to chaotic, but may locally retain primary bedding; commonly includes high permeability in the unit. stratigraphy and chronology in southwestern British Columbia and northwestern 14C AMS ~1,500 ft west of Lagoon Point public beach access. See also location reliability in liquefaction features. Absence of a mapped slide does not imply absence Washington: Geological Society of America Bulletin, v. 76, no. 3, p. 321-330. Yount and others (1980). Unit identified by referenced source. Qm Qp Qp Qgo Qgtv Qf f 22 97 “±35” ka AA Macoma sp. Qcw 80-22A, Blunt and others (1987) Sampled blue clay outcrop at South Whidbey State Park not located in this study; unit Qgtv shells 80-22B, identified by referenced source. 6 Qgasv 14a,b 100 80-22C Qgdm 9a,b,c,d e 23 >40,000 14C yr B.P. 14C or peat Qc W-1523 “55” Easterbrook and others Easterbrook (1969) citing D. R. Crandell, written commun., reports location as Qb Qguc 10a,b,c 13 w dark gray to black, thin-bedded, silty clay Qc ? GEOLOGIC SYMBOLS 14 w 11a,b,c,d Qc ? C AMS (Ives (1967); Easterbrook (1969); 47°58¢N, 122°32¢W; coordinates plot ~600 ft north of cliff exposures. Yount and Qp o A¢ 14 orange oxidized clay Qcw? Qgdme A (14a) 23,600 ±275 C yr B.P. A¢ and Ives and others (1967); others (1980) report on location reliability and material (“wood in peat”). Easterbrook 75 16 Qgasv 14 Contact—Long dashed where pebbly sand Qgdd (14b) 22,210 ±530 C yr B.P. others) Yount and others (1980) and others (1967) locate date in “peat bed C” of the Whidbey Fm. type section. WEST Qgt EAST sand Qgomee 12 C v approximately located, short 27,980 ±530 14C yr B.P. Qco? A 14 14 gravel Qls Qb 350 350 24 >40,000 C yr B.P. C or peat bed Qcw ? ~100 Stoffel (1980) Stoffel showed sample as DBW#1 and noted that Beta Analytic, Inc. estimated the (Table 1, loc. 16) dashed where inferred 14C AMS sample age as 43,250 +200 /-2280 14C yr B.P. (see also Johnson and others, 1980, lab mostly 50 Qgd Qc (11a) <36.6 ±0.96 ka (10a) 21.8 ±0.63 ka B d w 300 Qgtv Qgas 300 no. UM-1753). Stoffel dismissed Beta’s date in favor of the age reported here because diamicton (11b) 37.2 ±0.98 ka (10b) 24.4 ±0.70 ka v D Qb Fault, unknown offset—Dotted Beta could not replicate its own age estimates on other analyses. Sampled at Whidbey Qgdd Elevation (feet) (11c) 35.7 ±1.39 ka (10c) 24.2 ±1.40 ka Esperance Sand 7 250 250 Fm. type section; location shown on bluff section A identifies source peat but not (11d) 23.2 ±0.81 ka ? E where concealed, dashed where lateral position. silt, clay, and sand 25 200 200 inferred Lawton Clay 14 14 (proglacial sediments) interbedded sand Qgt Esperance Sand 25 >49,400 C yr B.P. -18 C or wood from Qc GrN-4971 Vogel and Waterbolk Peat “bed C” (2nd peat from top), below till and interbedded in floodplain sand and A v Qgasv F w and silt 14 10 150 Qgasv 150 Syncline—Dotted where concealed C AMS peat (1972) silt. Collected from Whidbey Fm. type section and submittted by D. J. Easterbrook, beach Qco? G 1965. 14 H (24) >40,000 C yr B.P. I 100 ? 100 5 Elevation (feet) Geologic unit too narrow to show 26 177 “±38” ka TL drift Qgd DUBLF-1 Berger and Easterbrook Sample from middle of silt unit without drop pebbles within glaciomarine drift at flame Qc ? Qgt d Qgomee ? structures o J v as a polygon at map scale (1993) Double Bluff Drift type section. 122°37¢30² R 1 E R 2 E 35¢00² 32¢30² 122°30¢00² 50 peat 50 Qgdme sand ? Qc ? K 5 Qgd Qcw Qc ? o 27 “111-178” ka AA Nuculana sp. d 80-27 Blunt and others (1987) Age estimate based on leucine content of a single shell from Double Bluff Drift type Qgdd o Age-date sample location Y 0 0 shell section. Y R R AD A CENT 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 Lambert conformal conic projection OAK BO BO 5 14 28 289 “±74” ka TL silty clay Qgdd WDBLF-1 Berger and Easterbrook Sample from Double Bluff Drift type section, ~6.5 ft above sea level, below massive UTSAL CONW (12) >39,000 C yr B.P. Geochemical sample location North American Datum of 1927; to place on North American Datum HAR CRESHAR 5 (13) 34.9 ±2.60 ka (9a) 26.2 ±0.80 ka 20 south end of Whidbey Formation paleocolluvium along (1993) till. of 1983, move the projection lines 20 meters north and 532 Double Bluff Drift type section erosional unconformity (9b) 27.9 ±0.85 ka E horizontal scale 1:12,000 D type section (9c) 30.6 ±1.12 ka 29 107 “±8” ka OSL silt Qc WFP1 ~“10” Lian and others (1995) Sample from Whidbey Fm. type section. 95 meters east as shown by crosshair corner ticks 18° w SCALE 1:24,000 PER H vertical exaggeration 5x WOO (9d) 18.7 ±1.52 ka PEVILL 1 JUNI Base map from scanned and rectified U.S. Geological Survey CAMANO BEAC University of Illinois at Chicago Luminescence Dating Research Laboratory; analysis on 4-11 micron quartz grain fraction, by green light excitation using a multiple aliquot regenerative dose method. Blue emissions 1 0.5 0 1 MILE H 7.5-minute Freeland and Hansville quadrangles, 1998 and 1997 COU STAN Schematic bluff section, modified from Stoffel (1980). Subunit descriptions A–K condensed from Stoffel (1980): A, Vashon till and measured with 3 mm thick Schott BG-39 and Corning 7-59 glass filters that block >90% of luminescence below 390 and above 490 nm. Lab reports precision of analysis as “good to very good”. Samples 1b and 2b were NORT Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, but D Y also tested for feldspar and are at saturation for both feldspar and quartz. respectively 10000 1000 2000 3000 4000 5000 6000 7000 FEET P gravel; B, Vashon advance outwash silt and sand (beds dip 30-40° into bluff); C, Vashon advance outwash sand and gravel; D, Esperance AN LE not limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Department ETIC 2 Shaded relief generated from lidar bare-earth digital elevation model TRUE NORTH Sand—cross bedded, fine; E, Esperance Sand—very fine sand and silt, with (ice-rafted?) large sandstone blocks; F, Lawton of Natural Resources and the authors of this product will not be liable to the user of this product for any activity Stated errors computed by halving the two-standard-deviation error statement reported by lab, which noted that errors were calculated before rounding. 100.5 1 KILOMETER LANG TULALI MAGN NORDLAND FREEL Freeland (available from the Puget Sound Lidar Consortium, 525 Clay—glaciolacustrine silt and clay; G, nonglacial, horizontally laminated sand with reworked silt fragments; H, nonglacial, horizontally involving the product with respect to the following: (a) lost profits, lost savings, or any other consequential damages; 3 APPROXIMATE MEAN Shannon Mahan (U.S. Geological Survey) and Kathy Goetz Troost (Univ. of Wash.), written and oral commun., March through June 2006. N laminated fine sand and massive clay and silt, deformed into diapiric structures; I, nonglacial, horizontally laminated sand with scattered (b) the fitness of the product for a particular purpose; or (c) use of the product or results obtained from use of the http://pugetsoundlidar.ess.washington.edu/); sun azimuth 315 DECLINATION, 2006 O contour interval 20 feet W 4 Analysis performed on fine silt fraction (4-11 micron) by multiple aliquot additive dose technique, bleach obtained with a CS-3-67 orange filter (minimum age, 10 min. bleach; maximum age, 60 min. bleach). VILLE ELTO LTE trains and clusters of sand and silt pebbles; J, nonglacial silty sand with large flame structures of silt and sand (a prominent cliff former); product. This product is considered to be exempt from the Geologist Licensing Act [RCW 18.220.190 (4)] because it is degrees; sun angle 45 degrees; vertical exaggeration 6x PORT supplementary contour interval 10 feet 525 geological research conducted by the State of Washington, Department of Natural Resources, Division of Geology and LUDLO MUKI 5 Cartography by Anne C. Heinitz and Charles G. Caruthers HANS MAXW 99 K, nonglacial planar-bedded sand with scattered pebbles and rounded detrital peat fragments, rare cobbles, and abundant cut and fill TL data may be compromised by incomplete zeroing (Glenn Berger, Desert Research Institute, Reno, Nev., oral commun. 1-3-06). The amino acid–based age estimate from the same exposure (loc. no. 27, this table) is 5 Earth Resources. Editing and production by Karen D. Meyers columnar sections: vertical scale 1 inch = 50 feet structures. Alphanumeric symbols locate dates shown in Table 1. likewise tentative (Blunt and others, 1987).