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The Geological Society of America Special Paper 548 OPEN ACCESS

Deglaciation of the Puget Lowland, Washington

Ralph A. Haugerud* U.S. Geological Survey, c/o Department of Earth and Space Sciences, Box 351310, University of Washington, Seattle, Washington 98195, USA

ABSTRACT

Recently obtained radiocarbon ages from the southern Puget Lowland and reevaluation of limiting ages from the Olympic Peninsula in the light of new light detection and ranging (LiDAR) data suggest that the Juan de Fuca and Puget lobes of the Cordilleran ice sheet reached their maximum extents after 16,000 calibrated yr B.P. Source areas for both lobes fed through a common conduit, likely requiring that downstream responses to changes in either source area were similar. Dates for ice-sheet retreat are sparse and contradictory, but they suggest that retreat was rapid. Depositional and geomorphic evidence shows that retreat of the Juan de Fuca lobe predated retreat of the Puget lobe. No recessional end moraines have been identified in the Puget Lowland, in contrast to numerous recessional end moraines constructed by the Okanogan lobe east of the Cascade Range, and in contrast to later ice-sheet retreat in western Whatcom County north of the Puget Lowland. These observations lead to the hypothesis that collapse of the Juan de Fuca lobe, hastened by the instabil- ity of a marine-based ice sheet, steepened the ice-sheet surface over the eastern Strait of Juan de Fuca and diverted ice flow upstream of the Puget lobe to the west. Starved of ice, the Puget lobe retreated quickly.

INTRODUCTION stade of their Fraser glaciation. Ice of the younger Sumas stade extended only as far south as the Bellingham, Washing- During the last glaciation (marine isotope stage [MIS] ton, area. 2), the Cordilleran ice sheet advanced south from British Heusser (1973) dated the maximum extent of the Juan de Columbia into northwest Washington (Fig. 1). The ice sheet Fuca lobe as sometime prior to ca. 17,600 calibrated (cal.) yr split at the northeast margin of the Olympic Mountains, where B.P. Porter and Swanson (1998) elegantly summarized radio- one arm flowed west to form the Juan de Fuca lobe, which carbon constraints on the age of the Puget lobe. They concluded extended onto the continental shelf, and the other arm flowed that (1) the ice front crossed the 49th parallel at ca. 18,800 cal. south to form the Puget lobe, which reached its terminus near yr B.P. and advanced south at ~135 m/yr, (2) the maximum Olympia, Washington. Armstrong et al. (1965), echoing ear- extent was at ca. 16,950–16,850 cal. yr B.P., and (3) retreat was lier usage by Willis (1898), named this episode the Vashon about twice as rapid as advance.

*[email protected]

Haugerud, R.A., 2020, Deglaciation of the Puget Lowland, Washington, in Waitt, R.B., Thackray, G.D., and Gillespie, A.R., eds., Untangling the Quaternary Period—A Legacy of Stephen C. Porter: Geological Society of America Special Paper 548, p. 279–298, https://doi.org/10.1130/2020.2548(14). © 2020 The Geo- logical Society of America. All rights reserved. For permission to copy, contact [email protected].

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124°W 122°W 120°W Bretz (1913), Thorson (1980, 1981, 1989), Waitt and Thorson 50°N (1983), and Booth et al. (2004a) have provided details and fur- Coast Mountains ther references.

Va North-Derived Ice nc Vancouver ou R ve a r BRITISH COLUMBIA n Is Nineteenth-century visitors to the region recognized signs g la WASHINGTON es n FL Bellingham d e of former glaciation: Bauerman (1860) mentioned widespread g Ju Victoria SJI n drift and boulder-clay on southern Vancouver Island and nearby a a n de F R Washington Territory. Near Esquimault, British Columbia (Fig. u ca lob JFL e e 2), he noted widespread erratic boulders and glacial grooves that d 48°N a trend N-S to NNW-SSE. Gibbs (1874) described north-derived e c Olympic b s erratics in the San Juan Islands. Chamberlin (1888) mapped the o a l Seattle Mtns t C e extent of “later drift” in northwest Washington and recognized g u PL that ice originated in the mountainous regions of British Colum- P Olympia bia. Willis (1898) and Willis and Smith (1899), in the first sys- tematic treatment of the geology of the Puget Lowland, described 100 Km multiple glacial episodes and gave the name Vashon to the most recent episode of north-derived glaciation and its deposits. Later, Figure 1. Maximum extent of the Cordilleran ice sheet in northwest Bretz (1920) recognized that ice from the same northern source Washington. Ice-free inliers (nunataks) within the ice sheet are not spread west along the Strait of Juan de Fuca and onto the conti- shown. Hachured lines show approximate boundaries of physiographic nental shelf. regions named in text: FL—Fraser Lowland; SJI—San Juan Islands; JFL—Juan de Fuca Lowland; PL—Puget Lowland. Ice-sheet bound- Vashon Stade ary (thick bold line) modified from Schuster (2010) and Haugerud and Tabor (2009). Mullineaux et al. (1965) described, in the vicinity of Seat- tle, glaciogenic sediments beneath Vashon till; they consist of a lower unit of lacustrine clay, silt, and fine sand (Lawton Clay This report (1) summarizes the sequence of events dur- Member of the Vashon Drift), which recorded damming of the ing Vashon-age deglaciation of northwest Washington; Puget Lowland by the advancing Vashon-age ice sheet to form a (2) reviews new light detection and ranging (LiDAR) topog- regional lake. These sediments coarsen upward into prodeltaic, raphy1 and published radiocarbon data, updating Porter and deltaic, and fluvial sand and gravel (Esperance Sand Member, Swanson’s summary, to conclude that the maximum extents sometimes mapped as “Vashon advance outwash”), which record of the Juan de Fuca and Puget lobes were younger than previ- closer approach of the ice sheet. These deposits are overlain by ously thought, after 16,000 cal. yr B.P., and that retreat was Vashon lodgment till, which is locally succeeded by recessional rapid; (3) summarizes published and unpublished work that ice-contact deposits (ablation moraine, kettle fill, etc.) and (or) shows retreat of the Puget lobe occurred without construction fluvial and deltaic recessional outwash. of end moraines, unlike retreat of the nearby Okanogan lobe Thorson (1980) mapped Vashon stade flow lineations evi- or Sumas ice; and (4) hypothesizes that the proximal cause of dent in 1:24,000 scale contour maps, which gave a coherent pic- Puget lobe retreat was starvation by more-rapid retreat of the ture of overall southward flow of the Puget lobe. Juan de Fuca lobe. The Juan de Fuca lobe retreat was likely At the north side of the Olympic Mountains, Thorson hastened by the instability of a marine-based ice sheet with a (1980) showed the south-flowing Cordilleran ice sheet separated landward-sloping floor. into the Juan de Fuca and Puget lobes at ~123°15′W. Regional topography dictates that, despite their different source areas, ice LAST GLACIATION IN NORTHWEST WASHINGTON flow into the Puget and Juan de Fuca lobes was likely synchro- nized. Flow to both lobes passed through a common reservoir More than a century of research has produced a robust over the San Juan Islands, where Booth’s (1986) reconstruc- understanding of the late Pleistocene physical stratigraphy of tion shows the ice-sheet surface was near its equilibrium line northwest Washington and the sequence of events that produced altitude. Change in ice input into the San Juan reservoir would this stratigraphy. The following review is necessarily brief; have been relatively equally distributed to both lobes, unless the relative transmissivity of the lobes changed due to changes in surface slope or basal conditions. 1LiDAR topography is readily inspected at and downloaded from http://­ Extension of the Juan de Fuca lobe onto the continental lidarportal.dnr.wa.gov/. shelf was described by Herzer and Bornhold (1982). Their Juan

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124°W 123°W 122°W

S G t e r o D a r it g ia B DK

H SI a r o San Juan LP S Islands tr SW a it RJ E Vi DP Stra it o f Ju an Figure 2. Locations named in text. Ab- de F PP uca C breviations: B—Bellingham; BL— A d Black Lake; C—Coupeville; CL— m i Lake Carpenter; CR—Chehalis River; PT ra l D—Deming; Da—Dabob Bay; DB— ty LCr DR SB DB In Discovery Bay; DK—Deep Kettle bog; le 48°N t DP—Deception Pass; DR—Dungeness River; E—Esquimault; GH—Grays LC Harbor; LC—Leland Creek; LCr— Lake Crescent; LP—Lyman Pass; CL LW—Lake Washington; O—Olym- Da l a n pia; PP—Point Partridge; PT—Port a C Townsend; RJ—River Jordan; S—Se- d o attle; SB—Sequim Bay; SI—Saanich o LW H S SP Inlet; SP—Sammamish Plateau; SW— Kitsap Sedro Woolley; T—Tenino; TP—Te- Peninsula nalquot Prairie; Vi—Victoria.

Sound t uge P

O 47°N BL GH CR 50 TP Km T

de Fuca trough, the southeasternmost of several troughs eroded by Willis. Glacial Lake Russell drained south via Black Lake by the ice sheet west of the Strait of Juan de Fuca, extends to the near Olympia to the Chehalis River and thence west to the Pacific shelf edge, where, at its shallowest, it is presently ~240 m deep, Ocean at Grays Harbor (Fig. 2). well below the lowest late Pleistocene global sea level. Isostatic Thorson (1980, 1981, 1989) extended Bretz’s survey of late- depression by the weight of the ice sheet would have further glacial lake, river, and delta features with more modern maps deepened the trough. and new observations. He found that as the Puget lobe retreated farther north, a new spillway opened near Port Townsend, gla- Vashon Recession cial Lake Russell catastrophically drained, and a lower-elevation lake (named glacial Lake Bretz by Waitt and Thorson, 1983) was Bretz (1910, 1911, 1913) showed that large proglacial lakes established. Little is known about the retreat of the Juan de Fuca formed south of the ice sheet as Vashon-age ice retreated. He lobe, but Thorson (see also Waitt and Thorson, 1983) noted that named the largest of these glacial Lake Russell, in honor of I.C. drainage of glacial Lake Bretz required that the Juan de Fuca Russell, who first recognized multiple glaciations in this region lobe had retreated at least to Discovery Bay before the Puget lobe and whose unpublished notes provided a foundation for the work cleared Admiralty Inlet.

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124°W 123°W 122°W

S G A t e r o a r 0 20 40 it g Be ia Km

Vi Stra it o f Juan C

de F uca A d m i ra B l ty I n 48°N le t

S

B C

0.5 1 Km Km

Figure 3. (A) Region of late Vashon ice-flow reorientation. Flow directions are from stream-lined ground moraine observed on light detection and ranging (LiDAR) topography, and on southern Vancouver Island, as reported by Alley and Chatwin (1979). Solid lines mark directions of main Vashon ice flow. Double-dash lines mark directions of late Vashon flow. LabelsB (east of Admiralty Inlet) and C mark approximate locations of parts B and C. Vi—Victoria; Be—Bellingham; S—Seattle. (B) Shaded-relief image of northwest-trending (parallel to dashed line) late Vashon ice-flow lineations on southern Whidbey Island.a Main Vashon ice flow was to south-southeast (parallel to solid line). Note faint spiderwork of washboard moraine. (C) Shaded-relief image of southwest-trending late Vashon ice-flow lineations east of Oak Harbor, northern Whidbey Island.b Southwest-trending late flow has nearly obliterated evidence here for main Vashon ice flow to the south, parallel to solid line (Haugerud et al., 2003; Kovanen and Slaymaker, 2004b). Subsequent erosion at marine shorelines erased lineations from lower-elevation areas.

ahttp://lidarportal.dnr.wa.gov/#48.082:-122.59:15 bhttp://lidarportal.dnr.wa.gov/#48.31:-122.55:14

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The demise of the Juan de Fuca lobe appears to have been extended this analysis to the north, demonstrating that the rapid. A significant pulse of ice-rafted debris in core MD02-2496, marine limit (highest postglacial marine shoreline) in north- from the continental slope northwest of the lobe, was interpreted west Washington has roughly the same 1 m/km up-to-the-north by Hendy and Cosma (2008) as representing rapid retreat by calv- slope. Tilting was accompanied by remarkable local relative ing of the Juan de Fuca lobe in late Fraser time; most of the core sea-level (RSL) histories (Fig. 4) that reflect the interaction of has little such debris, implying minimal calving throughout most postglacial isostatic rebound with rising global sea level. Late- of Fraser glaciation. This interpretation is consistent with evi- glacial RSL near Vancouver, British Columbia, was as high as dence from bathymetry, sediment distribution, and seismic stra- 195 m above modern sea level at ca. 14,000 cal. yr B.P. (Low- tigraphy, which shows that the Juan de Fuca lobe was grounded don et al., 1977, sample GSC-2193), fell rapidly while isostatic for much of its history, and excellent preservation of submerged rebound outstripped eustatic sea-level rise to reach a minimum glacial troughs at the western end of the Strait of Juan de Fuca, (as low as –55 m at Seattle) in the latest Pleistocene or early which appears to reflect ice withdrawal at a rate greater than late- Holocene, rose slowly to near-modern level as eustatic rise glacial marine transgression (Herzer and Bornhold, 1982). Hendy overtook waning rebound, and stabilized in mid-Holocene time and Cosma (2008) suggested that rapid calving of the Juan de (James et al., 2009; see also Mathews et al., 1970; Clague et al., Fuca lobe may have been driven by rising global sea level. 1982; Dethier et al., 1995; Clague and James, 2002; Kovanen and Slaymaker, 2004b; Hutchinson et al., 2004a; Mosher and Demise of the Puget Lobe Hewitt, 2004; Haugerud et al., 2017). Less has been known about RSL history along the Strait of The Puget lobe then retreated farther, and Admiralty Inlet Juan de Fuca and the Pacific Coast. James et al. (2009) reported opened, glacial Lake Bretz drained, and Puget Sound became marine shells as high as 65 m in the Victoria area. marine. Opening of Admiralty Inlet was succeeded by stabili- zation of the ice-sheet margin at the Coupeville moraine (Fig. 3), known from central Whidbey Island, where a short length of end-moraine ridge2 adjoins large outwash deltas (Carlstad, 1992; Polenz et al., 2005). The kame-kettle complex at Point Partridge3 180 is part of this terminus. To the northwest. the mostly submarine 160 extent of this end moraine (including Partridge Bank, Smith C C northern Georgia Strait 140 B Island, McArthur Bank, and Cattle Point) was described by Chr- B central Georgia Strait 120 A Victoria zastowski (1980), Dethier et al. (1996), and Mosher and Hewitt 100 (2004). Stabilization at the Coupeville moraine marked the end 80 of a distinct Puget lobe. 60 Deltas associated with the Coupeville moraine on Whidbey A Island record relative sea level at ~60 m above modern sea level. 40 As the Cordilleran ice sheet retreated further, low-elevation­ areas 20 in the northern Puget Lowland, San Juan Islands, and Fraser 0 Lowland were blanketed with glaciomarine drift (Easterbrook, -20 1963; Dethier et al., 1995). Glaciomarine deposits are found in -40 Elevation (m NAVD88) the Fraser Lowland as far east as 122°21′W (Armstrong, 1981), -60 Seattle showing ice-sheet retreat at least to that longitude before the -80 readvance of the Sumas stade. Sumas ice reached beyond the -100 modern shoreline west of Bellingham at ca. 13,500 cal. yr B.P., followed by episodic retreat that ended by ca. 11,000 cal. yr B.P. 16 14 12 10 8 6 4 2 0 Sumas glaciation south of 49°N has been described in detail by Age (cal k.y. B.P.) Kovanen et al. (2020) and Clark and Clague (this volume). Figure 4. Relative sea-level (RSL) histories. Gray line—global ice- Relative Sea-Level Histories volume–equivalent sea-level history from Lambeck et al. (2014). Dashed line—RSL curve for Seattle. Constraints are shown as boxes: RSL of 15–20 m (elevation by projection from Thorson, 1989; De- Elevations of deltas built into glacial lakes Russell and thier et al., 1995) at 15.5–15.0 calibrated (cal.) k.y. B.P. (shortly after Bretz show ~1 m/km up-to-the-north tilting during post­ deglaciation; Fig. 8), and RSL of ~55 m (marine lowstand shoreline) glacial isostatic rebound (Thorson, 1989). Dethier et al. (1995) at 15–11 cal. k.y. B.P. (after deglaciation and before global sea level [gray line] rose above ~55 m). RSL for Seattle after 6 cal k.y. B.P. is from Engelhart et al. (2015). Dotted lines—modeled RSL curves for Victoria, central Georgia Strait, and northern Georgia Strait (James et 2http://lidarportal.dnr.wa.gov/#48.215:-122.69:14 al., 2009). NAVD88—North American Vertical Datum of 1988. Figure 3http://lidarportal.dnr.wa.gov/#48.22:-122.75:15 is from Haugerud et al. (2017); used with permission.

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OBSERVATIONS FROM AGES OF ICE MAXIMA AND RETREAT LiDAR-DERIVED TOPOGRAPHY Radiocarbon ages relevant to the ages of ice maxima and High-resolution topography obtained from LiDAR sur- deglaciation are summarized in Table 1. Measured ages, with veys of northwest Washington in the past 20 yr contains a rich appropriate reservoir corrections, were converted to calibrated yr record of the last glaciation (e.g., Haugerud, 2009; Kovanen et B.P. (cal. yr B.P., where “present” = 1950 CE) using the IntCal13 al., 2020). A few observations relevant to Vashon deglaciation are calibration (Reimer et al., 2013, as implemented in OxCal 4.3.2 summarized here. [Bronk Ramsey, 2009, 2017]). Flow of the ice sheet was remarkably uniform. For the most Published radiocarbon ages for late Pleistocene deposits in part, relict flow lineations are nearly parallel, with less deviation northwest Washington are internally inconsistent, as some post– than mapped by Thorson (1980) (e.g., Eyles et al., 2018). ice sheet ages are older than some pre–ice sheet ages. The most Northward extrapolation of flow lineations at the northeast probable explanation is reservoir effects in lacustrine and marine corner of the Olympic Peninsula, where the Juan de Fuca and samples. However, in some cases, the most parsimonious expla- Puget lobes separated, and in the San Juan Islands suggests that nation may be incorrect interpretation of stratigraphic context. the Juan de Fuca lobe was fed by ice accumulation west and north of Vancouver, British Columbia (Vancouver Island Ranges, Strait Juan de Fuca Lobe Maximum of Georgia, and western Coast Mountains). The Puget lobe was fed by accumulation east of Vancouver (southern Coast Moun- A ca. 17,600 cal. yr B.P. age of “silt containing organic detri- tains, interior of British Columbia, and North Cascades). tus” from the bottom of Wessler bog northeast of Lake Ozette As noted above, this apportionment of source areas could (Heusser, 1973, sample Y-2452) has been widely cited as the have been fluid: Variations in ice supply or ice sinks (e.g., minimum age for the maximum extent of the Juan de Fuca lobe increased snowfall in the western Coast Mountains, increased (e.g., Waitt and Thorson, 1983; Booth et al., 2004a; Cosma and ablation at the snout of the Juan de Fuca lobe) would have been Hendy, 2008). Heusser (1973) also reported ages of ca. 16,100– compensated by a shift in flow direction over the San Juan 15,570 cal. yr B.P. from logs (8–20 cm diameter) buried within Islands. Such a shift in flow direction occurred late in the Vashon thick (6–9 m) exposures of till at four sites. Heusser (1973) inter- stade. Ice flow over most of the area between 122°W–123°W preted the samples as logs broken up and buried in an ablation and 48°N–48°30′N—the northern Puget Lowland, eastern Juan moraine when underlying stagnant ice slumped and collapsed. de Fuca lowland, and San Juan Islands—was to the south. Flow In support of this interpretation, Heusser cited Porter and Car- then shifted westward into the eastern Strait of Juan de Fuca and son (1971), who obtained younger-than-expected ages from the thence WNW along the Juan de Fuca lowland (Fig. 3; see also southern Puget Lowland and interpreted their samples to have Alley and Chatwin, 1979; Haugerud et al., 2003; Mullen et al., been buried by collapse of a superglacial forest and consequent 2003; Kovanen and Slaymaker, 2004b; Polenz et al., 2005; Rie- incorporation of wood into ablation drift. del, 2017). LiDAR data collected in the winter of 2014–2015 over Heuss- LiDAR topography shows glacial Lake Bretz to have er’s sample sites show a fluted surface shaped by the sole of the drained into Discovery Bay via the Chimacum Valley4 south ice sheet, locally incised by Holocene drainage and road building, of Port Townsend, not Leland Creek as suggested by Thorson and locally modified by landsliding into Holocene valleys (Fig. 5). (1981, 1989). Nearby relict marine shorelines5 at elevations equal Signs of the former presence of debris-covered stagnant ice, such to and higher than the Chimacum Valley outfall demonstrate that as kames, kettles, and lumpy ablation moraine, are absent. In con- glacial Lake Bretz drained into open water. trast, a lumpy ablation moraine is clearly evident in LiDAR-derived Highest postglacial shorelines at Port Townsend6 are at topography of Porter and Carson’s (1971) sample locale.8 I thus ~52 m. At Sand Point,7 on the Pacific Coast west of Lake reinterpret Heusser’s samples as relicts of a forest overridden by Ozette, subglacial landforms are preserved down to a relict the advancing Juan de Fuca lobe of the ice sheet and incorporated shoreline 2 m higher than the modern shoreline, showing that into lodgment till. The Wessler bog age is instead too old, prob- post­glacial RSL there was never higher than 2 m. These obser- ably because of incorporation of old carbon or mineral carbonate vations require at least 0.3 m/km up-to-the-east postglacial tilt (perhaps eroded from underlying Paleogene strata, or from the ice along the Strait of Juan de Fuca. sheet) within the sampled gyttja. Heusser’s log ages are corrobo- rated by a ca. 15,850 cal. yr B.P. age from wood (Beta-123219) in till at a nearby locale (H. Schasse, 2016, written commun.). Gerstel and Lingley (2000) reported an age of ca. 14,900 yr 4https://lidarportal.dnr.wa.gov/#47.883:-122.744:14, https://lidarportal.dnr.wa .gov/#47.99:-122.759:14, https://lidarportal.dnr.wa.gov/#48.043:-122.797:14 B.P. from wood (Beta-116786) in outwash overlying till ~4 km 5https://lidarportal.dnr.wa.gov/#48.029:-122.828:16, https://lidarportal.dnr.wa north of the town of Forks, Washington. Heusser (1973, p. 289) .gov/#48.13:-122.84:17 6https://lidarportal.dnr.wa.gov/#48.134:-122.813:16, https://lidarportal.dnr.wa .gov/#48.138:-122.769:16 7https://lidarportal.dnr.wa.gov/#48.122:-124.703:15 8https://lidarportal.dnr.wa.gov/#47.129:-123.343:16

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Upper Finch Creek, ~168 m el e K . Ceda r Ceda r “At Garcia , ood delta, 75 m el e Chimacum Creek, Center 7.5 ’ Deep K Deep K Whidb e 40 m el e Borehole D Borehole M W Whidb e Sunset Beach, same ho r elcome glacioma r Col w W side Capitol Hill unde r W side Capitol Hill unde r W oir correction of –940 ± 260 y r # v ance-retreat sequence (Fig . j j l l i i i r c c s k k d p d d n n n n n n n n b b b b q a a a h e e d m Source ON AND SOUTHWEST BRITISH COLUMBIA § (°W) 48.395 48.349 47.967 48.339 48.400 48.324 49.087 49.087 47.941 47.658 47.630 47.630 47.618 47.545 47.545 47.545 47.545 47.545 47.545 47.543 47.418 47.426 47.451 47.226 47.226 47.129 47.116 47.074 47.804 47.804 47.804 48.455 48.833 48.833 48.831 48.779 48.779 48.838 Latitude ASHING T y position within ad v W § ated ages assume rese r (°N) Calib r . 122.242 122.808 122.717 122.687 123.414 122.653 121.805 121.805 122.818 122.426 122.326 122.326 122.193 122.027 122.027 122.027 122.027 122.027 122.027 121.975 123.171 121.616 123.154 122.562 122.562 122.522 122.605 122.691 122.519 122.519 122.519 123.540 122.283 122.283 122.273 122.115 122.115 122.163 THWEST Longitude C ag e 14 y min OM NO R 13,851 13,946 13,843 13,990 14,146 13,745 19,035 19,197 17,905 17,694 17,289 17,655 17,905 17,358 17,446 17,526 17,558 17,541 17,537 17,563 15,861 15,981 16,977 16,161 14,972 16,013 16,160 15,861 13,394 14,427 15,223 14,091 12,912 12,906 13,075 14,047 14,095 13,555 Samples are ordered b (yr) † GES F R (95.4%) (14,817) (14,789) (14,745) (14,946) (15,124) (15,051) (19,309) (19,429) (18,089) (17,962) (18,233) (18,340) (18,103) (17,616) (17,651) (17,730) (17,760) (17,777) (17,797) (17,752) (16,135) (16,363) (17,199) (16,419) (15,507) (16,269) (16,435) (16,135) (13,659) (15,508) (15,662) (14,404) (13,770) (13,505) (13,298) (14,457) (14,463) (13,730) (median) ated age Calib r Samples are ordered b max 15,781 15,727 15,668 15,941 16,371 15,966 19,560 19,641 18,228 18,289 19,161 18,965 18,314 17,895 17,890 17,941 17,964 18,006 18,045 17,945 16,386 16,810 17,441 16,734 16,084 16,556 16,782 16,386 14,021 16,344 16,102 14,807 15,081 14,175 13,543 15,003 14,940 13,984 ed wn on Figure 6 . ial agment agments ood ood ood ood ood ood ood ood SELECTED RADIOCARBON A ood ood ood ood ood ood ood ood ood ood ood ood ood ood ood ood ood ood Shell Shell Shell Shell Shell Shell Chitin W W W W W W W W W W W W W W W W W W W W W W W W W W Gyttja** Gyttja** Gyttja** Mate r analy z and peat Plant f r Plant f r ABLE 1 . T , with locations sh o (yr) error* C age ± 13,500 ± 50 13,470 ± 90 13,690 ± 50 14,760 ± 95 14,880 ± 60 14,890 ± 70 14,450 ± 90 14,480 ± 70 14,550 ± 70 14,580 ± 70 14,600 ± 90 14,570 ± 60 13,410 ± 80 14,130 ± 60 13,620 ± 80 13,510 ± 80 13,630 ± 90 13,410 ± 80 12,360 ± 70 12,380 ± 90 11,910 ± 80 14 13,515 ± 140 13,595 ± 145 13,650 ± 350 16,000 ± 180 16,100 ± 150 15,000 ± 400 15,100 ± 300 14,620 ± 100 13,570 ± 130 12,960 ± 180 12,450 ± 140 13,600 ± 280 13,700 ± 150 11,800 ± 400 11,640 ± 275 11,455 ± 125 12,365 ± 115 agment, chitin, gyttja, and peat ages plotted in Figures 6 7 . ine shell age s -35 ood, plant f r -1227 -1305 -940 Beta-1322 CAMS-58701 AA-10077 Older ma r Sample W Beta-1716 CAMS-58696 Beta-1319 GSC-4355 GSC-4363 NSRL-11244 W Beta-365739 W Beta-112019 CAMS-23160 CAMS-23176 CAMS-23177 CAMS-23171 CAMS-23175 CAMS-23170 QL-4620 U W Beta-288370 Beta-288369 Beta-89876 IS-3343 Beta-79885 Beta-52222 Beta-173043 QL-4064 QL-4065 QL-4067 B-109128 I-1037 W Beta-1324 AA-20750 AA-22198 B-1220447

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v

anson y R.H. , ainag e y R.H. ly wrong ; ter and S w y R.H. y R.H. y R.H. y R.H. y R.H. er d r o r ash ld Geodetic Su r ) o r ued Note y (2000), g—Heusser (1973), Conti n ter (1976), n— P ed NAD83/ W o r sample HS 9-23-98-2 est of site 1, location assigned b in recessional out w th and Nelson (2014). Site 5, location assigned b Site 2, location assigned b Site 3, location assigned b Site 4, location assigned b Site 1, location assigned b essler bog, location assigned b o r lished age error (6 yr) is proba b k bog, w ely are mi x W Collected from till in Di cke y Ri v Pu b (2012), m— P Soledu c olenz et al . # (2014), s—Ash w est. . f g g o g g g g g Source C ag e 14 § olenz et al . (1965), l— P y (°W) ON AND SOUTHWEST BRITISH COLUMBIA ( 48.15 48.15 48.06 48.06 48.12 47.96 47.96 48.087 47.980 Latitude (1995), e—Easterbrook (1969), f—Gerstel and Lingl e § (2003a), r— P

ASHING T W (°N) or other locations are not documented and li k 124.58 124.54 124.50 124.49 124.48 124.46 124.48 124.510 124.397 Longitude alsh et al . Samples are ordered b THWEST Datums f y OxCal 4.3.2 . min 17,071 15,339 15,302 15,191 14,835 14,760 14,494 13,433 10,239 e displacements of ~100 m, mostly east- w witt (2004), k—Mullineaux et al . (1988), d—Dethier et al . . (yr) † OM NO R wn in Figure 5 . ee (2001), q— W σ error s (95.4%) (17,612) (16,106) (15,845) (15,698) (15,667) (15,569) (14,898) (13,924) (10,644) (median) GES F R ated age xt. 1950, as estimated b . Calib r xt. see t e ; anson and Caf f , which are 2 max 18,095 16,865 16,305 16,212 16,487 16,300 15,166 14,727 11,156 ican Datum of 1983 (NAD83) . ore A. D see t e roost (2001), c—Clague et al . T th Ame r ears be f un.), p—S w ed ial ood ood ood ood ood ood ood ical y oir correction ; ette area, with some locations sh o W W W W W W W Gyttja Gyttja v Mate r analy z xcept GSC sample s SELECTED RADIOCARBON A oir correction of –625 y r e O z , e v itten com m y rese r anen and Easterbrook (2001), j—Mosher H e v .) = calend r o ud (R.H.) are No r . P ican Datum of 1927 (NAD27), with consequent relati v ABLE 1 . y error s T (2016, w r yr B (1994), b—Borden and ato r (yr) Hauge r error* th Ame r C age ± 12,570 ± 60 9,380 ± 180 14 14,460 ± 200 13,380 ± 250 13,200 ± 170 13,100 ± 180 13,080 ± 260 13,010 ± 240 12,020 ± 210 (2009), i— K y R.A . Schass e ated age includes rese r ated age is without a n undsen et al . ated age (cal . †† ames et al . Calib r Calib r Locations b a—A n **Calib r † § # †† *Errors are 1 σ labo r -2452 -2449 -2450 uan de Fuca lobe ages from La k Sample h— J (WGS84) and No r (1998), o—H . Y J RL-140 Beta-123219 Y Y RL-139 Beta-116787 RL-138 RL-137

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125°W 124°W

Site 5, RL-140

5 WB 4 0.5 Km 3 2 Site 4, RL-139

48°N 25 Km

Sites 2 & 3, Y-2449 & Y-2450

0.5 Km

0.5 Km

Figure 5. Radiocarbon sample locations, northwest corner of Olympic Peninsula, Washington. Insets show light detection and rang- ing (LiDAR) topography at Heusser’s (1973) sample sites. All insets have same scale. Locations were reported as quarter-quarter sections, shown here as white boxes. WB—Wessler bog, source of 14,460 ± 200 14C yr B.P. age cited widely as evidence for retreat of Juan de Fuca lobe by that time. At sites 2, 3, 4, and 5, topography reflects NE to SW flow of late Pleistocene Juan de Fuca lobe and subsequent dissection by Holocene streams, landslides, and road building. Note the absence of end moraines and kames, kettles, or irregular ground moraine that would indicate significant ablation drift. Isolated hummocks along roads are burn piles. Wood samples collected from these four sites were in lodgment till; ca. 13,100 14C yr B.P. ages from these samples indicate that maximum extent of Juan de Fuca lobe occurred after that time.

reported an age of ca. 13,920 cal. yr B.P. (RL-138) for “wood Puget Lobe Maximum from clasts of till measuring ca. 2 m, 15 m below the surface in a gravel pit” in alluvium of the Soleduck River, ~5 km WSW of Several radiocarbon ages obtained since Porter and Swan- Gerstel and Lingley’s site. I infer that sample RL-138 also post- son’s (1998) analysis indicate a significantly younger age of dates local ice cover. maximum extent for the Puget lobe. Sample locations are shown From these ages, I conclude that the Juan de Fuca lobe in Figure 6. reached its maximum extent after ca. 15,670 cal. yr B.P. and Sample Beta-89876, with an age of 13,620 ± 80 14C yr B.P. before ca. 14,900 cal. yr B.P. This interpretation is supported (Borden and Troost, 2001), is flattened wood from fine-grained by those who have worked nearby: Gerstel and Lingley (2000) silty sand with abundant woody debris. It was collected from the described ice-sheet glaciation as “~14,000–12,000 B.P.” (ca. shoreline bluff at Sunset Beach ~8 km southwest of Tacoma, 17,000–13,800 cal. yr B.P.). Washington, at an elevation of 43 m. Borden and Troost reported

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123°W 122°W Beta-79885, with an age of 13,510 ± 80 14C yr B.P. (Bor- den and Troost, 2001), is flattened wood from a borehole on GSC-4355 McChord Air Force Base, 15 km south of Tacoma, collected GSC-4363 49°N from 28 m depth at an elevation of 55 m. Enclosing sediments Beta-1324 were gray, clayey silt with scattered medium to coarse sand and B-1220447 I-1037 some organic debris. These sediments underlie interbedded till W-940 AA-22198 AA-20750 and sandy outwash of the Vashon Drift. Beta-173043, with an accelerator mass spectrometry (AMS) age of 13,410 ± 80 14C yr B.P. (Walsh et al., 2003a), is detri- tal wood from an exposure ~27 km southwest of Tacoma on the B-109128 CAMS-58701 Beta-1322 east wall of the Nisqually River valley, south of Interstate 5. The Beta-1716 CAMS-58696 sample was collected from lacustrine silt and clay within Vashon Beta-1319 advance outwash at an elevation of ~40 m. Beta-288370, also with an age of 13,410 ± 80 14C yr B.P. (Polenz et al., 2012, p. 40), was collected at an elevation of Beta-365739 48°N AA-10077 ~168 m. The sample was a “cluster of detrital small sticks, QL-4064 QL-4065 peat, and soft plant debris from laminated to structureless silt QL-4067 QL-4620 and clay” within Vashon advance outwash—here overlain by W-1227 CAMS-23160 NSRL-11244 W-1305 CAMS-23170 Vashon till—exposed in the valley wall above Finch Creek, CAMS-23171 3 km west of southern Hood Canal. Beta-112019 CAMS-23175 CAMS-23176 Most of these are wood ages, with no uncertainty regarding Beta-288369 CAMS-23177 marine reservoir effects or lacustrine hard-water corrections, Beta-288370 UW-35 from sediments deposited in front of the advancing ice sheet. Beta-89876 The relative consistency of these ages reinforces their likely Beta-52222 validity. However, they are all younger than the 16,950 cal. yr Beta-79885 B.P. (ca. 13,960 14C yr B.P.) age of maximum ice extent inferred Beta-173043 47°N by Porter and Swanson (1998). These and other radiocarbon ages relevant to the Puget lobe are plotted in Figure 7. Curves A–D illustrate four advance sce- 50 narios. Curve A is the constant-rate advance curve proposed by Km

Figure 6. Locations of selected radiocarbon samples. Maximum ice extent and Coupeville moraine are shown in solid gray; dotted exten- sions are approximate. Long-dashed gray line is University of Wash- ington (UW) ice-surface contour; faint gray dashed lines are ice-flow Figure 7. Time-distance diagram of 14C age constraints for Vashon stade paths to and from UW contour. x—Marine shell sample not plotted on Puget lobe of the Cordilleran ice sheet. Samples are plotted according Figure 7. to their distance south of an ice-surface contour that passes over the University of Washington campus in Seattle, Washington. Distances were measured along flow lines drawn parallel to ice-flow lineations. Samples north of 48.1°N are plotted according to their distance south- a measured section that showed the sample to have been collected west of the Coupeville moraine, which (at Coupeville) is 62 km north ~10 m below Vashon till, at the base of the Vashon Drift. Sample of Seattle. Samples Beta-288369 and Beta-288370 are shifted south 14 by 3 and 10 km, respectively, to correct for later glacial inundation of ISGS-3343, a wood fragment with an age of 12,960 ± 180 C yr these higher-elevation sites; displacements were obtained from Thor- B.P., is a recollection from the same horizon. son’s (1980) ice-surface slope model. Sample UW-35 (Porter, 1976; Beta-5222, with an age of 13,620 ± 90 14C yr B.P. (Bor- Porter and Carson, 1971) is from sediment deposited in a lake im- den and Troost, 2001; data attributed to T.J. Walsh, Washing- pounded by the ice sheet; it is plotted at the position of the morainal ton Division of Geology and Earth Resources, 1995, written dam. Colors denote material dated: red, orange—wood; green—­gyttja; blue—marine shells; purple—chitin; gray—peat, plant fragments. commun.), is peaty silt from a borehole collected from ~18 Gray line denotes inferred position of ice margin. With the exception m depth at 54 m elevation. The sampled horizon was logged of samples from the Issaquah delta (CAMS-23160 to CAMS-23170, as ~2 m of gray silt with interlayers of brown peat, overlain 15 km south of University of Washington [UW] contour), sample la- by 18 m of coarse gravel and sand interpreted as Vashon out- bels are positioned at most-probable age. Ages were calibrated with wash. Absent actual Vashon till in the core, the discrimination OxCal 4.3.2 using INTCAL13. Line A is constant-rate advance curve proposed by Porter and Swanson (1998). B is the same line fit to recali- between advance and recessional outwash can be difficult, but brated ages. Curve C honors all post-1998 data, whereas D is drawn to the coarsening-upward stratigraphy in this borehole is indica- minimize change in the rate of ice-sheet advance at the cost of ignoring tive of advance outwash. samples IS-3343 and Beta-288370. See text for discussion.

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retreat 0 Seattle W-1227 W-1305

stagnation-zone Beta-112019 NSRL-11244 QL-4065 QL-4067 QL-4064 Figure 7. AA-10077 Beta-365739 CAMS-58696 -50 km south of University of Washington contour km south of University Washington Coupeville

B-109128 ice advance ice Beta-1716 Beta-1319 CAMS-58701 -100 C Beta-1322 Beta-1324 W-940 I-1037 B A AA-20750 AA-22198

B-1220447 ice retreat -150

GSC-4355 GSC-4363 OxCal v4.3.2 Bronk Ramsey (2017); r:5 IntCal13 atmospheric curve (Reimer et al 2013) al et (Reimer curve atmospheric IntCal13 r:5 (2017); Ramsey Bronk v4.3.2 OxCal

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Porter and Swanson (1998), drawn to pass through ages of sam- Duration of Deglaciation ples GSC-4355 and GSC-4363 at Allison Pool, British Columbia, and the average age of several samples collected from topset beds The time required for deglaciation of the Puget Lowland is of a delta built into a proglacial lake at Issaquah, Washington, not well constrained. The oldest relevant postglacial wood ages with ages calibrated using CALIB 3.0.3c (Stuiver and Reimer, are from Deep Kettle Bog east of Bellingham, where sample 1993). Curve B is drawn to fit to the same analyses calibrated AA-22198 documents ice-free conditions at ca. 14,300 cal. yr with OxCal 4.3.2 and IntCal13. In this scenario, advance was at B.P. (Kovanen and Easterbrook, 2001; see also Fig. 6, Table 1). 116 m/yr, i.e., less than the 135 m/yr calculated by Porter and The Coupeville delta, built when the margin of the ice sheet was Swanson (1998), and maximum ice extent was coincidentally at 75 km to the southwest, must be older. 16,950 cal. yr B.P. as they suggested. Curve C honors all post- The tops of the Colwood delta at Esquimault, British Colum- 1998 data. Samples Beta-365739 and NSRL-11244 require ini- bia (Fig. 2), and the Coupeville delta have similar tilt-corrected tial advance to have been somewhat slower than 116 m/yr. Note elevations, which—given the rapid fall of postglacial RSL (Fig. that samples NSRL-11244, W-1227, and W-1305 are from non- 4)—suggests they formed at about the same time. Flow of melt- glacial strata that could significantly predate arrival of the ice water south along Saanich Inlet (Fig. 2) fed the Colwood delta. sheet. The ice front accelerated to impound the proglacial lake Maintenance of this flow required ice in the Victoria area and east at Issaquah by ca. 17,700 cal. yr B.P., stabilized (or advanced to block a lower-level flow path via Haro Strait, and so I infer even more slowly) for nearly 2000 yr, and then advanced over the that the Coupeville ice margin extended west to Victoria at this southern Puget Lowland to reach maximum extent shortly after time. James et al. (2009) reported a wood date from the Colwood ca. 15,500 cal. yr B.P. Sample IS-3343 could be interpreted as delta (sample B-109128) that is younger than the Deep Kettle indicating a younger maximum, but this is not required. Curve D Bog samples, and so I suspect sample B-109128 is from a deposit is drawn to minimize variations in the rate of ice-sheet advance, younger than the bulk of the Colwood delta. at the cost of ignoring samples IS-3343 and Beta-288370, and it Porter and Swanson (1998) pinned the age of ice retreat to predicts maximum ice extent at ca. 15,800 cal. yr B.P. gyttja dates from the Lake Carpenter core described by Anundsen The age of maximum Puget lobe extent is not well con- et al. (1994). Interpretation of this core is problematic. Anundsen strained. Radiocarbon age data show that the maximum extent et al. (1994) reported a history of marine → lacustrine → marine of the Puget lobe was likely younger than 16,000 cal. yr B.P. and → lacustrine conditions that is at odds with the robust inference somewhat older than 14,500 cal. yr B.P. (AA-22198), perhaps at that Puget lobe ice at this site ceded to glacial Lake Bretz, and 15,500 cal. yr B.P. then to marine conditions as Admiralty Inlet became ice-free, Thus reinterpreted, the ages of maximum extent of the Juan and finally to lacustrine conditions as local sea level fell because de Fuca and Puget lobes are similar, as is to be expected given of isostatic rebound (Waitt and Thorson, 1983; Thorson, 1989). that both lobes were fed via a shared ice reservoir in the San Juan Perhaps ice lingered at Lake Carpenter and prevented Bretz-age Island region. lacustrine deposition, but pre-Bretz, post-ice, marine deposition Maximum-extent ages for the Juan de Fuca and Puget lobes is improbable. Repetition of marine-lacustrine strata in the core of 16,000–15,000 cal. yr B.P. are consistent with recent deter- is coincident with an age inversion, and Kelin Wang and Thomas mination, via relatively imprecise 10Be dating, that the Okano- James have suggested that perhaps the core penetrated the toe of gan and Purcell Trench lobes farther east began to retreat from a subaqueous landslide (T.S. James, 2017, personal commun.). their maximum extents at ca. 15.5 ka (Balbas et al., 2017). These In addition, dates on postglacial gyttja from the lower part of ages are also consistent with the uncertainty-weighted mean 10Be the Lake Carpenter core are similar to preglacial wood ages from exposure age, with correction for snow shielding, of 15.3 ± 1.1 ka the southern Puget Lowland and significantly older than pre- for initial deglaciation of the Marble Range in south-central Brit- glacial sample IS-3343. The dates are likely too old because of ish Columbia at 51°N (Margold et al., 2014). The Marble Range incorporation of dead carbon. If a 15,400 yr maximum ice extent was in the ice-shed that fed the Purcell Trench, Okanogan, Puget, age is accepted (curve C in Fig. 7), the 625 ± 60 yr gyttja correc- and Juan de Fuca lobes (Dyke and Prest, 1987). tion of Hutchinson et al. (2004b, averaged from observations at These young ages for maximum ice extent at the south several sites not including Lake Carpenter) is probably too small margin of the Cordilleran ice sheet reinforce the evidence for (Fig. 7). A larger gyttja correction and(or) an older maximum diachroneity noted by Darvill et al. (2018). They reported ice extent are required. Similar corrections are required for the exposure ages from coastal sites along Queen Charlotte Sound 13,650–13,430 14C yr B.P. gyttja and peat dates from Lake Wash- (~51°N) that indicated ice-sheet retreat began by 18.1 ± 0.2 ka. ington reported by Rigg and Gould (1957), Leopold et al. (1982), Farther north, in southeast Alaska, at 55°N–56°N, Lesnek et al. and Porter and Swanson (1998). (2018) demonstrated ice-sheet deglaciation by ca. 17 ka. The Radiocarbon ages from marine shells collected in the north- ice-sheet reconstruction presented by Dyke and Prest (1987) ern Puget Lowland and eastern Strait of Juan de Fuca (e.g., East- showed that these coastal sites were in an ice-shed distinct erbrook, 1969; Dethier et al., 1995, 1996; Mosher and Hewitt, from that of the Marble Range and the south margin of the 2004) are of little use for refining the timing of retreat. Ages from Cordilleran ice sheet. marine shells are commonly too old because the shells incorporate

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14C-depleted carbon from a deep-marine reservoir that is incom- Tenalquot Prairie,10 where sediment carried by the main subgla- pletely mixed with the atmosphere. Modern (pre–atomic bomb) cial meltwater channel buried stagnating marginal ice. Conver- marine shells collected from the NE Pacific coastline show a gent ice-flow lineations (interpreted by Thorson [1980] as the reservoir effect of 790 ± 35 yr (Robinson and Thompson, 1981). boundary between his eastern and western sublobes) suggest The latest Pleistocene marine reservoir correction in this region is that melting along this channel was a major ice sink. Most of controversial (cf. Swanson, 2005): Suggested values range from the inferred maximum ice margin is now occupied by outwash 680 ± 110 yr (Southon et al., 1990) to 1100 yr (Kovanen and East- flats, a consequence of the large meltwater discharge funneled erbrook, 2002) and 1200 ± 130 yr (fjord heads; Hutchinson et through the confined terminal region. Small, and in places nested, al., 2004b). In light of this uncertainty, I have assumed a marine end moraines locally mark the Puget lobe maximum position in reservoir correction of 940 ± 260 yr. Resulting uncertainties in the foothills of the Cascade Range (Fig. 8B). calibrated ages are large, on the order of ±1000 yr (95.4% confi- The next-younger end moraine is the Coupeville moraine, dence), because uncertainties in analyses and reservoir correction some 130 km to the north. End moraines built during the advance are substantially augmented by plateaus in the radiocarbon cali- phase, or during earlier ice-sheet glaciation, and subsequently bration curve (Reimer et al., 2013). Because of these large uncer- overridden by Vashon ice are evident south of Orting,11 southwest tainties, few conclusions can be drawn from the shell data. of American Lake,12 and elsewhere. In the remainder of the Puget In summary, published radiocarbon ages are consis- Lowland, end moraines appear to be absent. tent with stabilization of the ice margin at the Coupeville In contrast to the Puget lobe, numerous recessional end moraine sometime between a few decades and several cen- moraines are evident within the extent of the coeval (Balbas et al., turies after ice reached its maximum extent (Fig. 7). Retreat 2017) Okanogan lobe east of the Cascades, where Kovanen and could have taken less time than the half-millennium or more Slaymaker (2004a) documented recessional end moraines with suggested by Porter and Swanson (1998). Note that the age spacings (in the direction of ice flow) of <1–10 km (Fig. 8C). inferred here for Puget Lowland deglaciation is similar to the The absence of end moraines within the Puget Lowland ca. 15,500 cal. yr B.P. age assumed by Swanson and Caffee south of the Coupeville moraine also contrasts sharply with (2001) when they used Whidbey Island samples to determine abundant end moraines—both large hummocky moraines13 built 36Cl production rates. by significant readvances and small, perhaps annual, chevron- shaped push moraines14 (e.g., Chandler et al., 2016; Evans et Retreat without Construction of End Moraines: al., 2017)—constructed during the younger Sumas glaciation of Contrast with the Okanogan Lobe and Sumas Glaciation the Fraser Lowland north of Bellingham (Fig. 8D; Kovanen et al., 2020; Clark and Clague, this volume). Recognition of these End moraines are absent throughout most of the Puget features near Bellingham demonstrates that poor preservation Lowland. This was noted by Bretz (1913, p. 61), though he cau- and difficulty recognizing moraines in the forested terrane of tioned, “For the successful delineation of the systematic relations northwest Washington are unlikely explanations for the apparent of moraine ridges, a forested country is about the last place to absence of end moraines farther south. choose.” Only with the advent of LiDAR, which maps forested ground with decimeter (z) to meter (x-y) resolution, has it been HYPOTHESIS: COLLAPSE OF JUAN DE FUCA LOBE possible to confidently observe the absence of moraines through- STARVED THE PUGET LOBE out most of the Puget Lowland. The conclusion of no end moraines between the Puget lobe I hypothesize that, starting sometime after 16,000 cal. yr terminus near Olympia and the Coupeville moraine is based B.P., collapse of the Juan de Fuca lobe steepened the ice-sheet on detailed, LiDAR-based geologic and geomorphic map- surface over the eastern Strait of Juan de Fuca, diverted ice flow ping of about half the area of the Puget lobe published by the upstream of the Puget lobe to the west, and starved the Puget Washington Geological Survey and the U.S. Geological Survey lobe of ice. Throughout the consequent retreat of the Puget lobe, (USGS; see inventory at https://www.dnr.wa.gov/programs-and its marginal zone was stagnant (the “stagnation-zone retreat” of -services/geology/publications-and-data/publications-and Koteff and Pessl, 1981). Collapse of the Juan de Fuca lobe likely -maps#geologic-maps.1); unpublished detailed geologic map- resulted from instability of a marine-based ice sheet with a land- ping by USGS and University of Washington staff; and my exten- ward-sloping floor, triggered by rising global sea level. sive reconnaissance of LiDAR topography. Some scraps of end moraine mark the maximum extent of the ice sheet near9 Olympia (Fig. 8B). The largest of these is the ice-contact complex around 10https://lidarportal.dnr.wa.gov/#46.920:-122.71:13 11http://lidarportal.dnr.wa.gov/#47.05:-122.26:13 12http://lidarportal.dnr.wa.gov/#47.06:-122.65:13 13http://lidarportal.dnr.wa.gov/#48.87:-122.66:14, http://lidarportal.dnr.wa.gov/ 9http://lidarportal.dnr.wa.gov/#47.065:-123.18:16, http://lidarportal.dnr.wa.gov/ #48.87:-122.63:14 #46.857:-123.099:16 14http://lidarportal.dnr.wa.gov/#48.813:-122.435:16

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124°W 122°W 120°W 123°W 122°W

A B D

48°N B C 48°N

100 Km

122°30'W 119°W 49°N C D

48°N 47°N

50 Km

20 Km 20 Km

Figure 8. Distribution of end moraines at the southwest margin of the Cordilleran ice sheet. (A) Index map showing location of insets B–D. Gray line is limit of Cordilleran ice sheet. (B) End moraines (black lines) associated with the Puget lobe. Inventory of end moraines along west margin of Puget lobe may be incomplete because of lack of light detection and ranging (LiDAR) coverage. (C) End moraines (black lines) of the Okanogan lobe east of the Cascade Range. Gray line is limit of ice sheet, dashed where it crossed Grand Coulee. Figure is modified from Kovanen and Slaymaker (2004a). (D) End moraines (black lines) built by Sumas stade glacier in the southern Fraser Lowland, modified from Kovanen et al. (2020).

The inferred evolution of the retreating ice sheet is shown Stagnation of the Puget Lobe Margin diagrammatically in Figure 9. This hypothesis is informed by: (1) geologic evidence Starvation-zone retreat of the Puget lobe is consistent with showing that the Juan de Fuca lobe retreated prior to Puget lobe widespread preservation of delicate subglacial landforms, which retreat; (2) effectively shared accumulation zones for the Juan de formed beneath active or recently active ice, that were neither Fuca and Puget lobes, which would require that any differential reshaped by the rapidly moving Puget lobe nor buried beneath retreat was driven by phenomena in their distal reaches, not in debris accumulated at a retreating active-ice margin. Such pre- their accumulation zones; (3) flow reorganization at the east end served subglacial landforms include delicate esker complexes of the Strait of Juan de Fuca during deglaciation, as indicated southwest of Arlington,15 on the Sammamish Plateau east of by superposed flow lineations on Whidbey Island and elsewhere; Seattle,16 northwest of Belfair,17 north of Shelton,18 southeast (4) limited geochronologic data that suggest retreat of the Puget of Olympia between the towns of Rainier and McKenna,19 and lobe was fairly rapid; (5) the absence of recessional end moraines northeast of McKenna.20 in the Puget Lowland, which suggests a lack of minor readvances or stillstands; and (6) coincidence of Juan de Fuca lobe retreat 15http://lidarportal.dnr.wa.gov/#48.14:-122.23:15 with global ice-volume–equivalent sea-level rise at 1–3 cm/yr 16http://lidarportal.dnr.wa.gov/#47.59:-122.0:14 (Lambeck et al., 2014). The isostatic response to recent loading 17http://lidarportal.dnr.wa.gov/#47.50:-122.88:15 18http://lidarportal.dnr.wa.gov/#47.29:-123.12:14 by the advancing Juan de Fuca lobe would have further increased 19http://lidarportal.dnr.wa.gov/#46.89:-122.63:14 the local rate of sea-level rise. 20http://lidarportal.dnr.wa.gov/#46.97:-122.52:13

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124°W 122°W 124°W 122°W TISH COLUMBIA TISH COLUMBIA Bellingham Bellingham

Victoria Victoria

48°N 48°N

Seattle Seattle

Olympia Olympia

Maximum phase Russell phase

124°W 122°W 124°W 122°W ITISH COLUMBIA ITISH COLUMBIA Bellingham Bellingham

Victoria Victoria

48°N 48°N

Seattle Seattle

Olympia Olympia

Bretz phase Whulge phase 100 Km

Figure 9. Cartoon history of deglaciation in NW Washington. Thick gray lines are ice-sheet margins, thin gray lines are contours on the ice- sheet surface, arrows mark ice-flow directions, and stipple denotes stagnant ice. All phases date to a short period within the interval 15.6– 15.0 cal. ka.

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Washboard moraine (as defined by Cline et al., 2015) is wide- or sufficiently long-lived, to have created observable flow linea- spread in the Puget Lowland (e.g., Haugerud, 2009; Polenz et al., tions that recorded focused flow into the calving zones. Much 2009; see also Fig. 3B). It is characterized by subparallel ridges of the southeastern bed of the lobe was above the level of Lake less than a few meters high and 40–100 m apart. Most ridges Russell. are normal to the ice-flow direction. They probably originated as crevasse-fill ridges (Sharp, 1985) or crevasse-squeeze ridges Collapse of Juan de Fuca Lobe (Evans and Rea, 1999) in active ice. An origin as ­grounding-line (De Geer) moraines (Finlayson et al., 2007; Ojala, 2016) can be A grounded, marine-based ice sheet embodies a balance ruled out, because the Puget Lowland washboard was largely among basal friction, lateral restraints, strength of the ice, and above contemporaneous water levels. An origin as push moraines spreading forces due to surface slope. If the ice-sheet floor slopes is unlikely given the large numbers of ridges, their limited lateral landward, and rising sea level or thinning ice causes the ice continuity, and their lack of chevron geometry. Preservation of sheet tip to float, basal friction drops, the ice sheet extends and the delicate washboard was likely dependent on subsequent ice thins, and more of the ice sheet floats in a positive feedback loop stagnation (Ingólfsson et al., 2016, p. 44). (Weertman, 1974; Thomas and Bentley, 1978; Schoof, 2007). Stagnation of the marginal zone of the retreating Puget lobe At present, the floor of most of the Strait of Juan de Fuca slopes is also consistent with the widespread occurrence of kame-kettle gently seaward at ~0.5 m/km (Fig. 10). As discussed above, topography (e.g., Haugerud, 2009) and ice-contact deposits (e.g., available evidence demonstrates there was at least 0.3 m/km Troost et al., 2005; Polenz et al., 2014; Booth et al., 2004b) that of down-to-the-east tilt at the onset of deglaciation. If actual tilt are distinctly not arranged in end-moraine–like bands. were somewhat greater, the Juan de Fuca lobe would have had Calving into proglacial lakes may have facilitated ice retreat a landward-sloping floor and could have collapsed because of (Porter and Swanson, 1998). However, calving was not sufficient, this feedback.

modern sea level

50x vertical exaggeration

50 m depth contours

Figure 10. Top: Histogram of depths within yellow box projected onto black line that approximates thalweg: white—no depths; magenta—few depths; blue, yellow—more abundant depths. Lines of down-to-the-east tilt along the thalweg are shown for reference. With 1 m/km of tilt, floor of Strait of Juan de Fuca (the sole of the Juan de Fuca lobe) would have been landward-sloping. Bottom: Present-day bathymetry along the Strait of Juan de Fuca.

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DISCUSSION (4) Glacial lakes Russell and Bretz were short-lived features. Walsh et al. (2003a, 2003b) mapped recessional lake Alternative Explanations for the Lack of End Moraines deposits, including deposits from glacial Lake Russell, and counted no more than 20 apparent varves in any one Alternative explanations for the absence of recessional Puget exposure. However, they examined shoreline outcrops lobe end moraines include ice-sheet termination in lakes, melt- that were incomplete, commonly lacking the top of the water deposition at the expense of end moraines, and delivery of section. Coring of carefully selected upland depressions insufficient sediment loads to the terminus. These explanations has the potential to recover complete sections of Lake seem insufficient because moraines form where ice terminates Russell and Lake Bretz strata, and varve counts could tell subaqueously (e.g., at Coupeville); areas of meltwater deposition us how long these lakes lasted. are easily discerned in LiDAR topography and, except in parts of the terminal zone near Olympia, are not ubiquitous; and wide- ACKNOWLEDGMENTS spread kame-kettle terrain and ice-contact deposits demonstrate a significant sediment supply. I thank the local governments, tribal nations, and nonprofit Stagnation of the retreating terminal zone appears to be the organizations that funded public-domain light detection and most viable explanation for the lack of recessional end moraines. ranging (LiDAR) data acquisition for northwest Washington, my colleagues in the Puget Sound LiDAR Consortium for their Testable Predictions efforts in managing acquisitions and curating the resulting data, and the Washington Geological Survey for continuing this The collapse and starvation hypothesis could be further work. I thank Michael Polenz and Jim O’Connor for discus- tested by assessment of several resulting predictions: sion and comments on the manuscript; Richard Waitt, David (1) Ice retreat along the Strait of Juan de Fuca was very Dethier, Jon Riedel, and two anonymous reviewers for helpful rapid—perhaps too rapid to clock with 14C or 10Be. How- formal reviews; and Glenn Thackray for editorial handling. ever, progressive postglacial RSL change may allow fairly precise dating of the times when surfaces emerged REFERENCES CITED from the ice, were exposed to wave action, and developed shoreline knicks and deposits. Unfortunately, the west- Alley, N.F., and Chatwin, S.C., 1979, Late Pleistocene history and geomorphol- ern margins of the Strait of Juan de Fuca are steep and ogy, southwestern Vancouver Island, British Columbia: Canadian Journal of Earth Sciences, v. 16, p. 1645–1657, https://doi.org/10.1139/e79-154. rocky, and there is limited potential to preserve such fea- Anundsen, K., Abella, S.E.B., Leopold, E.B., Stuiver, M., and Turner, S., 1994, tures. I have not seen obvious shoreline knicks in existing Late-glacial and early Holocene sea-level fluctuations in the central LiDAR, but there have been significant gaps in LiDAR Puget Lowland, Washington, inferred from lake sediments: Quaternary Research, v. 42, p. 149–161, https://doi.org/10.1006/qres.1994.1064. coverage. Protected alcoves might preserve a deposi- Armstrong, J.E., 1981, Post-Vashon Wisconsin Glaciation, Fraser Lowland, tional record. British Columbia: Geological Survey of Canada Bulletin 322, 34 p., (2) The floor of the Strait of Juan de Fuca sloped down to the https://doi.org/10.4095/109532. Armstrong, J.E., Crandell, D.R., Easterbrook, D.J., and Noble, J.B., 1965, Late east at 15.6 ka. At present, we only have a minimum for Pleistocene stratigraphy and chronology in southwestern British Colum- the amount of glacio-isostatic tilt. It would be helpful to bia and northwestern Washington: Geological Society of America Bul- know the position of the glacial maximum (ca. 15.6 ka) letin, v. 76, p. 321–330, https://doi.org/10.1130/0016-7606(1965)76[321 :LPSACI]2.0.CO;2. shoreline along the Pacific Coast. Detailed bathymetric Ashworth, A.C., and Nelson, R.E., 2014, The paleoenvironment of the Olympia surveys, shallow seismic-reflection surveys, and perhaps beds based on fossil beetles from Discovery Park, Seattle, Washington, coring might identify this feature. U.S.A.: Quaternary International, v. 341, p. 243–254, https://doi.org/ 10.1016/j.quaint.2013.09.022. (3) The burst of offshore ice-rafted debris associated with Balbas, A.M., Barth, A.M., Clark, P.U., Clark, J., Caffee, M., O’Connor, J., collapse of the Juan de Fuca lobe started at 15.6 ka Baker, V.R., Konrad, K., and Bjornstad, B., 2017, 10Be dating of late and did not last long. Studies of core MD02-2496 Pleistocene megafloods and Cordilleran ice sheet retreat in the northwest- ern United States: Geology, v. 45, p. 583–586, https://doi.org/10.1130/ by Hendy and colleagues (Hendy and Cosma, 2008; G38956.1. Cosma and Hendy, 2008; Cosma et al., 2008) hint Bauerman, H., 1860, On the geology of the southeastern part of Vancouver at rapid emptying of ice from the Strait of Juan de Island: Quarterly Journal of the Geological Society of London, v. 16, p. 198–202, https://doi.org/10.1144/GSL.JGS.1860.016.01-02.29. Fuca, but dating of this core is subject to uncertainty Booth, D.B., 1986, Mass balance and sliding velocity of the Puget lobe of the in the (perhaps time-varying) marine radiocarbon res- Cordilleran ice sheet during the last glaciations: Quaternary Research, ervoir correction. If this uncertainty could be elimi- v. 25, p. 269–280, https://doi.org/10.1016/0033-5894(86)90001-3. Booth, D.B., Troost, K.G., Clague, J.J., and Waitt, R.B., 2004a, The Cordille- nated, perhaps by direct sedimentological ties with ran ice sheet, in Gillespie, A.R., Porter, S.C., and Atwater, B.F., eds., The onshore events, then the following questions could be Quaternary Period in the United States: Amsterdam, Elsevier, Develop- answered: Is the timing of ice-rafted debris deposition ments in Quaternary Science 1, p. 17–43, https://doi.org/10.1016/S1571 -0866(03)01002-9. consistent with the terrestrial record? How rapidly did Booth, D.B., Waldron, H.H., and Troost, K.G., 2004b, Geologic Map of the the Juan de Fuca lobe collapse? Poverty Bay 7.5′ Quadrangle, King and Pierce Counties, Washing-

Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/5324892/spe548-14.pdf by guest on 28 September 2021 296 R.A. Haugerud

ton: U.S. Geological Survey Scientific Investigations Map 2854, scale Dyke, A.S., and Prest, V.K., 1987, Paleogeography of Northern North America, 1:24,000, https://pubs.usgs.gov/sim/2004/2854/. 18,000–5,000 Years Ago: Geological Survey of Canada Map 1703A, Borden, R.K., and Troost, K.G., 2001, Late Pleistocene Stratigraphy in the scale 1:12,500,000. South-Central Puget Lowland, Pierce County, Washington: Washing- Easterbrook, D.J., 1963, Late Pleistocene glacial events and relative sea-level ton Division of Geology and Earth Resources Report of Investigations changes in the northern Puget Lowland, Washington: Geological Society 33, 34 p. of America Bulletin, v. 74, p. 1465–1484, https://doi.org/10.1130/0016 Bretz, JH., 1910, Glacial lakes of Puget Sound (preliminary paper): The Journal -7606(1963)74[1465:LPGEAR]2.0.CO;2. of Geology, v. 18, p. 448–458, https://doi.org/10.1086/621758. Easterbrook, D.J., 1969, Pleistocene chronology of the Puget Lowland and Bretz, JH., 1911, The terminal moraine of the Puget Sound glacier: The Journal San Juan Islands, Washington: Geological Society of America Bulletin, of Geology, v. 19, p. 161–174, https://doi.org/10.1086/621826. v. 80, p. 2273–2286, https://doi.org/10.1130/0016-7606(1969)80[2273 Bretz, JH., 1913, Glaciation of the Puget Sound Region: Washington Geologi- :PCOTPL]2.0.CO;2. cal Survey Bulletin 8, 244 p., 3 plates. Engelhart, S.E., Vacci, M., Horton, B.P., Nelson, A.R., and Kopp, R.E., 2015, Bretz, JH., 1920, The Juan de Fuca lobe of the Cordilleran ice sheet: The Jour- A sea-level database for the Pacific coast of central North America: nal of Geology, v. 28, p. 333–339, https://doi.org/10.1086/622717. Quaternary Science Reviews, v. 113, p. 78–92, https://doi.org/10.1016/j Bronk Ramsey, C., 2009, Bayesian analysis of radiocarbon dates: Radiocarbon, .quascirev.2014.12.001. v. 51, p. 337–360, https://doi.org/10.1017/S0033822200033865. Evans, D.J.A., and Rea, B.R., 1999, The geomorphology and sedimentology of Bronk Ramsey, C., 2017, Methods for summarizing radiocarbon datasets: Radio- surging glaciers: A land-systems approach: Annals of Glaciology, v. 28, carbon, v. 59, p. 1809–1833, https://doi.org/10.1017/RDC.2017.108. p. 75–82, https://doi.org/10.3189/172756499781821823. Carlstad, C.A., 1992, Late Pleistocene Deglaciation History at Point Partridge, Evans, D.J.A., Ewertowski, M., and Orton, C., 2017, Skaftafellsjökull, Ice- Central Whidbey Island, Washington [M.S. thesis]: Bellingham, Wash- land: Glacial geomorphology recording glacier recession since the Little ington, Western Washington University. Ice Age: Journal of Maps, v. 13, p. 358–368, https://doi.org/10.1080/ Chamberlin, T.C., 1888, The rock-scorings of the great ice invasions, in Seventh 17445647.2017.1310676. Annual Report of the United States Geological Survey, 1885–86: Wash- Eyles, N., Arbelaez Moreno, L., and Soohkan, S., 2018, Ice streams of the late ington, D.C., U.S. Geological Survey, p. 155–248. Wisconsin Cordilleran ice sheet in western North America: Quaternary Chandler, B.M.P., Evans, D.J.A., and Roberts, D.H., 2016, Characteristics of Science Reviews, v. 179, p. 87–122, https://doi.org/10.1016/j.quascirev recessional moraines at a temperate glacier in SE Iceland: Insights into .2017.10.027. patterns, rates and drivers of glacier retreat: Quaternary Science Reviews, Finlayson, A., Bradwell, T., Golledge, N., and Merritt, J., 2007, Morphology v. 135, p. 171–205, https://doi.org/10.1016/j.quascirev.2016.01.025. and significance of transverse ridges (De Geer moraines) adjacent to the Chrzastowski, M.J., 1980, Submarine Features and Bottom Configuration in Moray Firth, NE Scotland: Scottish Geographical Journal, v. 123, p. 257– the Port Townsend Quadrangle, Puget Sound Region, Washington: U.S. 270, https://doi.org/10.1080/14702540801968477. Geological Survey Open-File Report 80-14, scale 1:100,000. Gerstel, W.J., and Lingley, W.S., Jr., compilers, 2000, Geologic Map of Clague, J.J., and James, T.S., 2002, History and isostatic effects of the last ice the Forks 1:100,000 Quadrangle, Washington: Washington Division sheet in southern British Columbia: Quaternary Science Reviews, v. 21, of Geology and Earth Resources Open-File Report 2000-4, scale p. 71–87, https://doi.org/10.1016/S0277-3791(01)00070-1. 1:100,000, 36 p. Clague, J.J., Harper, J.R., Hebda, R.J., and Howes, D.E., 1982, Late Qua- Gibbs, G., 1874, Physical geography of the north-western boundary of the ternary sea levels and crustal movements, coastal British Columbia: United States (Part 2): Journal of the American Geographical Society of Canadian Journal of Earth Sciences, v. 19, p. 597–618, https://doi.org/ New York, v. 4 (for 1872), p. 298–392. 10.1139/e82-048. Haugerud, R.A., 2009, Preliminary Geomorphic Map of Kitsap County, Wash- Clague, J.J., Saunders, I.R., and Roberts, M.C., 1988, Ice-free conditions in ington: U.S. Geological Survey Open-File Report 2009-1033, 2 sheets, southwestern British Columbia at 16 000 years BP: Canadian Journal of scale 1:36,000, http://pubs.usgs.gov/of/2009/1033. Earth Sciences, v. 25, p. 938–941, https://doi.org/10.1139/e88-093. Haugerud, R.A., and Tabor, R.W., 2009, Geologic Map of the North Cascade Clark, D.H., and Clague, J.J., 2020, this volume, Glaciers, isostasy, and eustasy Range, Washington: U.S. Geological Survey Scientific Investigations in the Fraser Lowland: A new interpretation of late Pleistocene glaciation Map 2940, scale 1:200,000; 2 pamphlets, 29 p. and 23 p., https://pubs. across the international boundary, in Waitt, R.B., Thackray, G.D., and Gil- usgs.gov/sim/2940/. lespie, A.R., eds., Untangling the Quaternary Period—A Legacy of Ste- Haugerud, R.A., Harding, D.J., Johnson, S.Y., Harless, J.L., Weaver, C.S., and phen C. Porter: Geological Society of America Special Paper 548, https:// Sherrod, B.L., 2003, High-resolution LiDAR topography of the Puget doi.org/10.1130/2020.2548(13). Lowland, Washington: GSA Today, v. 13, no. 6, p. 4–10, https://doi.org/ Cline, M.D., Iverson, N.R., and Harding, C., 2015, Origin of washboard 10.1130/1052-5173(2003)13<0004:HLTOTP>2.0.CO;2. moraines of the Des Moines lobe: Spatial analyses with LiDAR data: Haugerud, R.A., Troost, K.G., and Laprade, W.T., 2017, Geology of Seat- Geomorphology, v, 246, p. 570–578, https://doi.org/10.1016/j.geomorph tle, a field trip, in Haugerud, R.A., and Kelsey, H.M., eds., From the .2015.07.021. Puget Lowland to East of the Cascade Range: Geologic Excursions in Cosma, T., and Hendy, I.L., 2008, Pleistocene glacimarine sedimentation on the the Pacific Northwest: Geological Society of America Field Guide 49, continental slope off Vancouver Island, British Columbia: Marine Geol- p. 1–24, https://doi.org/10.1130/2017.0049(01). ogy, v. 255, p. 45–54, https://doi.org/10.1016/j.margeo.2008.07.001. Hendy, I.L., and Cosma, T., 2008, Vulnerability of the Cordilleran ice sheet to Cosma, T.N., Hendy, I.L., and Chang, A.S., 2008, Chronological constraints on iceberg calving during late Quaternary rapid climate change events: Pale- Cordilleran ice sheet glaciomarine sedimentation from core MD02-2496 oceanography, v. 23, PA2101, https://doi.org/10.1029/2008PA001606. off Vancouver Island (western Canada): Quaternary Science Reviews, Herzer, R.H., and Bornhold, B.D., 1982, Glaciation and post-glacial history of v. 27, p. 941–955, https://doi.org/10.1016/j.quascirev.2008.01.013. the continental shelf off southwestern Vancouver Island, British Colum- Darvill, C.M., Menounos, B., Goehring, B.M., Lian, O.B., and Caffee, M.W., bia: Marine Geology, v. 48, p. 285–319, https://doi.org/10.1016/0025 2018, Retreat of the western Cordilleran ice sheet margin during the last -3227(82)90101-3. deglaciation: Geophysical Research Letters, v. 45, p. 9710–9720, https:// Heusser, C.J., 1973, Environmental sequence following the Fraser advance of doi.org/10.1029/2018GL079419. the Juan de Fuca lobe, Washington: Quaternary Research, v. 3, p. 284– Dethier, D.P., Pessl, F., Jr., Keuler, R.F., Balzarini, M.A., and Pevear, D.R., 306, https://doi.org/10.1016/0033-5894(73)90047-1. 1995, Late Wisconsinan glaciomarine deposition and isostatic rebound, Hutchinson, I., James, T.S., Clague, J.J., Barrie, J.V., and Conway, K.W., 2004a, northern Puget Lowland, Washington: Geological Society of America Reconstruction of late Quaternary sea-level change in southwestern Brit- Bulletin, v. 107, p. 1288–1303, https://doi.org/10.1130/0016-7606 ish Columbia from sediments in isolation basins: Boreas, v. 33, p. 183– (1995)107<1288:LWGDAI>2.3.CO;2. 194, https://doi.org/10.1080/03009480410001299. Dethier, D.P., White, D.P., and Brookfield, C.M., 1996, Maps of the Surficial Hutchinson, I., James, T.S., Reimer, P.J., Bornhold, B.D., and Clague, J.J., Geology and Depth to Bedrock of False Bay, Friday Harbor, Richardson, 2004b, Marine and limnic radiocarbon reservoir corrections for studies of and Shaw Island 7.5-Minute Quadrangles, San Juan County, Washington: late- and postglacial environments in Georgia Basin and Puget Lowland, Washington Division of Geology and Earth Resources Open-File Report British Columbia, Canada and Washington, USA: Quaternary Research, 96-7, 2 plates, scale 1:24,000, 7 p. v. 61, p. 193–203, https://doi.org/10.1016/j.yqres.2003.10.004.

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Ingólfsson, Ó., Benediktsson, Í.Ö., Schomacker, A., Kjær, K.H., Brynjólfs- Polenz, M., Alldritt, K., Hehemann, N.J., Sarikhan, I.Y., and Logan, R.L., 2009, son, S., Jónsson, S.A., Korsgaard, N.J., and Johnson, M.D., 2016, Glacial Geologic Map of the Belfair 7.5-Minute Quadrangle, Mason, Kitsap, and geological studies of surge-type glaciers in Iceland—Research status and Pierce Counties, Washington: Washington Division of Geology and Earth future challenges: Earth-Science Reviews, v. 152, p. 37–69, https://doi Resources Open-File Report 2009-7, scale 1:24,000. .org/10.1016/j.earscirev.2015.11.008. Polenz, M., Miller, B.A., Davies, N., Perry, B.B., Hughes, J.F., Clark, K.P., James, T., Gowan, E.J., Hutchinson, I., Clague, J.J., Barrie, J.V., and Conway, Walsh, T.J., Tepper, J.H., and Carson, R.J., 2012, Analytical Data from K.W., 2009, Sea-level change and paleogeographic reconstructions, the Hoodsport 7.5-Minute Quadrangle, Mason County, Washington— southern Vancouver Island, British Columbia, Canada: Quaternary Sci- Supplement to Open-File Report 2011-3: Washington Division of Geol- ence Reviews, v. 28, p. 1200–1216, https://doi.org/10.1016/j.quascirev ogy and Earth Resources Open-File Report 2011-4, 42 p. .2008.12.022. Polenz, M., Gordon, H.O., Hubet, I.J., Contreras, T.A., Patton, A.I., Paulin, Koteff, C., and Pessl, F., Jr., 1981, Systematic Ice Retreat in New England: U.S. G.L., and Cakir, R., 2014, Geologic Map of the Center 7.5-Minute Quad- Geological Survey Professional Paper 1179, 20 p. rangle, Jefferson County, Washington: Washington Division of Geology Kovanen, D.J., and Easterbrook, D.J., 2001, Late Pleistocene, post-Vashon, and Earth Resources Map Series 2014-02, scale 1:24,000, 35 p. alpine glaciation of the Nooksack drainage, North Cascades, Washington: Porter, S.C., 1976, Pleistocene glaciation in the southern part of the North Cascade Geological Society of America Bulletin, v. 113, p. 274–288, https://doi Range, Washington: Geological Society of America Bulletin, v. 87, p. 61–75, .org/10.1130/0016-7606(2001)113<0274:LPPVAG>2.0.CO;2. https://doi.org/10.1130/0016-7606(1976)87<61:PGITSP>2.0.CO;2. Kovanen, D.J., and Easterbrook, D.J., 2002, Paleodeviations of radiocarbon Porter, S.C., and Carson, R.J., III, 1971, Problems of interpreting radiocarbon marine reservoir values for the northeast Pacific: Geology, v. 30, p. 243–246, dates from dead-ice terrain, with an example from the Puget Lowland, https://doi.org/10.1130/0091-7613(2002)030<0243:PORMRV>2.0.CO;2. Washington: Quaternary Research, v. 1, p. 410–414, https://doi.org/ Kovanen, D.J., and Slaymaker, O., 2004a, Glacial imprints of the Okanogan 10.1016/0033-5894(71)90074-3. lobe, southern margin of the Cordilleran ice sheet: Journal of Quaternary Porter, S.C., and Swanson, T.W., 1998, Radiocarbon age constraints on rates of Science, v. 19, p. 547–565, https://doi.org/10.1002/jqs.855. advance and retreat of the Puget lobe of the Cordilleran ice sheet during Kovanen, D.J., and Slaymaker, O., 2004b, Relict shorelines and ice flow pat- the last glaciation: Quaternary Research, v. 50, p. 205–213, https://doi.org/ terns of the northern Puget Lowland from LiDAR data and digital terrain 10.1006/qres.1998.2004. modeling: Geografiska Annaler, v. 86A, p. 385–400. Reimer, P.J., Bard, E., Bayliss, A., Beck, J.W., Blackwell, P.G., Ramsey, C.G., Kovanen, D.J., Haugerud, R.A., and Easterbrook, D.J., 2020, Geomorphic Map Buck, C.E., Cheng, H., Edwards, R.L., Friedrick, M., Grootes, P.M., Guil- of Western Whatcom County, Washington: U.S. Geological Survey Sci- derson, T.P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T.J., Hoffman, entific Investigations Map 3406, 42 p., 1 sheet, scale 1:50,000, https:// D.L., Hogg, A.G., Hughen, K.A., Kaiser, K.F., Kromer, B., Manning, doi.org/10.3133/sim3406. S.W., Niu, M., Riemer, R.W., Richards, D.A., Scott, E.M., Southon, J.R., Lambeck, K., Rouby, H., Purcell, A., Sun, Y., and Sambridge, M., 2014, Sea Staff, R.A., Turney, C.S.M., and van der Plicht, J., 2013, INTCAL13 and level and global ice volumes from the Last Glacial Maximum to the Holo- MARINE13 radiocarbon age calibration curves, 0–50,000 years cal BP: cene: Proceedings of the National Academy of Sciences of the United Radiocarbon, v. 55, no. 4, p. 1869–1887, https://doi.org/10.2458/azu_js States of America, v. 111, p. 15,296–15,303, https://doi.org/10.1073/ _rc.55.16947. pnas.1411762111. Riedel, J.L., 2017, Deglaciation of the North Cascade Range, Washington and Leopold, E.B., Nickmann, R., Hedges, J.I., and Ertel, J.R., 1982, Pollen and British Columbia, from the Last Glacial Maximum to the Holocene: lignin records of late Quaternary vegetation, Lake Washington: Science, Cuadernos de Investigación Geográfica, v. 43, p. 467–496, https://doi.org/ v. 218, p. 1305–1307, https://doi.org/10.1126/science.218.4579.1305. 10.18172/cig.3236. Lesnek, A.J., Briner, J.P., Lindqvist, C., Baichtal, J.F., and Heaton, T.H., 2018, Rigg, G.B., and Gould, H.R., 1957, Age of Glacier Peak eruption and chronol- Deglaciation of the Pacific coastal corridor directly preceded the human ogy of post-glacial peat deposits in Washington and surrounding areas: colonization of the Americas: Science Advances, v. 4, p. eaar5040, https:// American Journal of Science, v. 255, p. 341–363. doi.org/10.1126/sciadv.aar5040. Robinson, S.W., and Thompson, G., 1981, Radiocarbon corrections for marine Lowdon, J.A., Robertson, I.M., and Blake, W., Jr., 1977, Geological Survey of shell dates with application to southern Pacific Northwest Coast prehis- Canada Radiocarbon Dates XVII: Geological Survey of Canada Paper tory: Syesis, v. 14, p. 45–57. 77–7, 25 p. Schoof, C., 2007, Ice sheet grounding line dynamics: Steady states, stability, Margold, M., Stroeven, A.P., Clague, J.J., and Heyman, J., 2014, Timing of and hysteresis: Journal of Geophysical Research, v. 112, F03S28, https:// terminal Pleistocene deglaciation at high elevations in southern and cen- doi.org/10.1029/2006JF000664. tral British Columbia constrained by 10Be exposure dating: Quaternary Schuster, J.E., 2010, ice_limit_250k: Washington Geological Survey On-Line Science Reviews, v. 99, p. 193–202, https://doi.org/10.1016/j.quascirev GIS Data, http://www.dnr.wa.gov/publications/ger_portal_surface_ .2014.06.027. geology_250k.zip (accessed 11 October 2019). Mathews, W.H., Fyles, J.G., and Nasmith, H.W., 1970, Postglacial crustal move- Sharp, M., 1985, “Crevasse-fill” ridges—A landform type characteristic of ments in southwestern British Columbia and adjacent Washington State: surging glaciers?: Geografiska Annaler, ser. A, Physical Geography, v. 67, Canadian Journal of Earth Sciences, v. 7, p. 690–702, https://doi.org/ p. 213–220. 10.1139/e70-068. Southon, J.R., Nelson, D.E., and Vogel, J.S., 1990, A record of past ocean-­ Mosher, D.C., and Hewitt, A.T., 2004, Late Quaternary deglaciation and sea- atmosphere radiocarbon differences from the northeast Pacific: Paleocean- level history of eastern Juan de Fuca Strait, Cascadia: Quaternary Inter- ography, v. 5, p. 197–206, https://doi.org/10.1029/PA005i002p00197. national, v. 121, p. 23–39, https://doi.org/10.1016/j.quaint.2004.01.021. Stuiver, M., and Reimer, P.J., 1993, Extended 14C data base and revised CALIB Mullen, M.M., Mano, R.S., Nelson, J.W., and Swanson, T.W., 2003, Till-fabric 3.0 14C age calibration program: Radiocarbon, v. 35, p. 215–230. analyses of NE-SW trending flutes on northern Whidbey Island: Evidence Swanson, T.W., 2005, Reply to comment by D.J. Easterbrook (Quaternary of readvance of the Cordilleran ice sheet during the latest Vashon stade Research 2003, 59 #1, 132–134) on “Determination of 36Cl production of the Fraser glaciation: Geological Society of America Abstracts with rates from the well-dated deglaciation surfaces of Whidbey and Fidalgo Programs, v. 35, no. 6, p. 80. Islands, Washington”: Quaternary Research, v. 63, p. 228–230, https:// Mullineaux, D.R., Waldron, H.H., and Rubin, M., 1965, Stratigraphy and Chro- doi.org/10.1016/j.yqres.2004.10.002. nology of Late Interglacial and Early Vashon Glacial Time in the Seattle Swanson, T.W., and Caffee, M.L., 2001, Determination of 36Cl production rates Area, Washington: U.S. Geological Survey Bulletin 1194-O, 10 p. derived from the well-dated deglaciation surfaces of Whidbey and Fidalgo Ojala, A.E.K., 2016, Appearance of De Geer moraines in southern and west- Islands, Washington: Quaternary Research, v. 56, p. 366–382, https://doi. ern Finland—Implications for reconstructing glacier retreat dynamics: org/10.1006/qres.2001.2278. Geomorphology, v. 255, p. 16–25, https://doi.org/10.1016/j.geomorph Thomas, R.H., and Bentley, C.R., 1978, A model for Holocene retreat of the .2015.12.005. West Antarctic Ice Sheet: Quaternary Research, v. 10, p. 150–170, https:// Polenz, M., Slaughter, S.L., and Thorsen, G.W., 2005, Geologic Map of the doi.org/10.1016/0033-5894(78)90098-4. Coupeville and Part of the Port Townsend North 7.5-Minute Quadrangles, Thorson, R.M., 1980, Ice-sheet glaciation of the Puget Lowland, Washington, Island County, Washington: Washington Division of Geology and Earth during the Vashon stade (late Pleistocene): Quaternary Research, v. 13, Resources Geologic Map GM-58, scale 1:24,000. p. 303–321, https://doi.org/10.1016/0033-5894(80)90059-9.

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Thorson, R.M., 1981, Isostatic Effects of the Last Glaciation in the Puget Low- Walsh, T.J., Logan, R.L., and Polenz, M., 2003b, Geologic Map of the McNeil land, Washington: U.S. Geological Survey Open-File Report 81-370, Island 7.5-Minute Quadrangle, Pierce and Thurston Counties, Washing- 1 plate, scale 1:250,000, 100 p. ton: Washington Division of Geology and Earth Resources Open-File Thorson, R.M., 1989, Glacio-isostatic response of the Puget Sound area, Wash- Report 2003-22, scale 1:24,000. ington: Geological Society of America Bulletin, v. 101, p. 1163–1174, Weertman, J., 1974, Stability of the junction of an ice sheet and an ice https://doi.org/10.1130/0016-7606(1989)101<1163:GIROTP>2.3.CO;2. shelf: Journal of Glaciology, v. 13, p. 3–11, https://doi.org/10.1017/ Troost, K.G., Booth, D.B., Wisher, A.P., and Shimel, S.A., 2005, The Geologic S0022143000023327. Map of Seattle—A Progress Report: U.S. Geological Survey Open-File Willis, B., 1898, Drift phenomena of Puget Sound: Geological Society of Report 2005-1252, scale 1:24,000, https://pubs.usgs.gov/of/2005/1252/. America Bulletin, v. 9, p. 111–162, https://doi.org/10.1130/GSAB-9-111. Waitt, R.B., and Thorson, R.M., 1983, The Cordilleran ice sheet in Washington, Willis, B., and Smith, G.O., 1899, Tacoma Folio, Washington: U.S. Geological Idaho, and Montana, in Wright, H.E., ed., Late Quaternary Environments Survey Folios of the Geologic Atlas 54, scale 1:125,000. of the United States, Volume 1: The Late Pleistocene: Minneapolis, Min- nesota, University of Minnesota Press, p. 53–70. Walsh, T.J., Logan, R.L., Polenz, M., and Schasse, H.W., 2003a, Geologic Map of the Nisqually 7.5-Minute Quadrangle, Thurston and Pierce Coun- ties, Washington: Washington Division of Geology and Earth Resources Manuscript Accepted by the Society 28 May 2020 Open-File Report 2003-10, scale 1:24,000. Manuscript Published Online 7 December 2020

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