WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES OPEN FILE REPORT 2009-7 Belfair 7.5-minute Quadrangle July 2009

122°52¢30² R 2 W R 1 W 50¢ 47¢30² 122°45¢ Fulmer, C. V., 1975, Stratigraphy and paleontology of the type Blakeley and Blakely Harbor 47°30¢ Qgt Qgt ml ml 47°30¢ GEOLOGIC SETTING terrace of an undated, lower Union River valley archeological site that Solimano and way but form relict fans that are tied to an elevated, former base level (see Pre-Vashon Glacial Deposits Qgt Qpu Qga Qa Qp Qgo Qgof Qgof others (1995) suggested was once near the marine shore suggests that at least some of discussion of elevated terraces and fans under Structure). Such older fans Formations. IN Weaver, D. W.; Hornaday, G. R.; Tipton, Ann, editors, Paleogene Qa Qp Qgt Qgt The map area is located in the central Puget Lowland and lacks bedrock exposures, Qge Qgo Qgof Qgt symposium and selected technical papers—Conference on future energy horizons of the Qgt Qgic the terraces are marine coastal features. If so, then their elevation requires typically are dissected by a distinctly incised modern stream channel. The Qpt Pre-Vashon till—Unsorted, unstratified mix of clay, silt, sand, and gravel; Qgic Qgo Qgt except perhaps near the northwest map corner, where a few highly weathered sandy Qpt Pacific coast: American Association of Petroleum Geologists Pacific Section, 50th Annual Qga ml Qgof considerable late Holocene uplift at Lynch Cove and suggests significant differences unit post-dates Vashon ice and is predominantly Holocene but locally orange-tan to gray-green; mostly angular; cobbles range from angular to Qgt Qgof and gravelly exposures (included with units Qpu and Qpg) could be saprolitized among land-level changes across the map area because no equivalent of the elevated probably includes some late Pleistocene deposits. Meeting, p. 210-271. Creek” Qa rounded; compact; deposited directly by glacial ice; resembles unit Qgt Qgic Qga Qgof Qa bedrock but are probably sediment derived from bedrock at Green and Gold Lynch Cove terrace set has been recognized to the south, east, or west. Also, a marine but typically contains a higher percentage of weathered particles. It is Garrison-Laney, C. E., 2003, Subsidence within the past 600 years at Puget Sound, Qpt Qgt Qgt Mountains two to six miles north of the map area. With that possible exception, the Washington [abstract]: Geological Society of America Abstracts with Programs, v. 35, no. Qgt terrace origin suggests a terrace age less than about 6,000 years because prior to that, PLEISTOCENE GLACIAL AND NONGLACIAL DEPOSITS unclear if the weathering resulted from a depositional age that pre-dates Qgt Qp Qga Qgic Qaf Qgic map area is covered by allochthonous glacial sediment. Buchanan-Banks and Collins 6, p. 582. Qgo Qmw relative sea level in the region was significantly below modern sea level (Beale, Deposits of the Fraser Glaciation, Vashon Stade the Double Bluff Glaciation (Easterbrook and others, 1967), as one might Qp (1994) estimated sedimentary thickness above Tertiary bedrock in the map area at Qgt Qp 1990), and their emergence would therefore have required even more uplift. Other Gower, H. D.; Yount, J. C.; Crosson, R. S., 1985, Seismotectonic map of the Puget Sound Qgt Qp conclude from the fact that many Puget Lowland exposures of Double Qga “Courtney Qa under 330 ft in the north and over 650 ft in the south. However, Haeussler and Clark region, Washington: U.S. Geological Survey Miscellaneous Investigations Series Map Qgic Qa Qgof Qgof elevated relict beach terraces and mud flats have been recognized east of the map Qa Qgt (2000) estimated depth to bedrock in the Union River valley near the northern map Qgo Vashon recessional outwash—Gravel and sand; locally includes silt or Bluff till (including at the Double Bluff Drift type section) appear as Qgo Qmw Qa Qgt area (Bucknam and others, 1992; Bucknam, 1998; Martin and others, 2007; Polenz Qgo I-1613, 1 sheet, scale 1:250,000, with 15 p. text. Qgo 2 Qga clay; tan to gray; rounding and sorting diverse, but most commonly unweathered as Vashon till. Unit Qpt is clearly recognized only along the Qmw Qgic edge at close to 950 ft. Near Carney Lake in the southeast of the map area, the Hofert Haeussler, P. J.; Clark, K. P., 2000, Preliminary geologic map of the Wildcat Lake 7.5' Qgic Qp and others, 2009). In all cases, the elevation of emergent coastal terraces appears to informally named Courtney Creek, a western tributary to Union River, Qgo Qls Qaf # 1 well record (well location per Washington Division of Geology and Earth subrounded and moderately sorted; stratified and loose; ranges from a few Qpt Qga ml Qgic quadrangle, Kitsap and Mason Counties, Washington: U.S. Geological Survey Open-File Qpg Qmw be at grade with relict fluvial terraces (included with unit Qoa) and alluvial fans (unit feet to a few tens of feet thick but may locally exceed 100 ft along Mission where the unit is exposed along much of the stream channel. Unit Qpt may Qpu Qpu Qp Resources website, http://erpl.dnr.wa.gov/) noted basalt bedrock from 620 ft below Report 00-356, 1 sheet, scale 1:24,000 [accessed Apr. 15, 2008 at Qls Qgof Qoaf) in the lower portions of nearby drainages, thus providing another indirect (and Qgo Qgt Qgt Creek; deposited by Vashon meltwater in outwash channels or isolated be more common in the map area but was not recognized elsewhere, Qgo the surface to the base of the well at 6,688 ft below the surface (Union Oil Company http://pubs.er.usgs.gov/usgspubs/ofr/ofr00356] Qgt Qaf largely unexplored) record of the tectonic activity in the area. That record can be perhaps only because absent age control and (or) recognition of Qgic Qgt Qgof of California and Standard Oil Company of California, 1950; see also McFarland, basins; generally less compact than advance outwash (unit Qga), but in Qa Haugerud, R. A., 2009, Deglaciation of the southern Salish lowland [abstract]. In Northwest Qga difficult to separate from glaciolacustrine terracing and the potentially complex some exposures difficult to distinguish from unit Qga where not separated stratigraphic field relations, surficial exposures of till were mapped as Qpu Qgt 1983, p. 38-39). Surficial exposures of Tertiary volcanic and igneous intrusive rocks Scientific Association, The Pacific Northwest in a changing environment—Northwest Qgic Qga Qaf Qgic incision history of the post-glacial streams. Vashon even in deep troughs like Mission Creek valley. Qa at Green and Gold Mountains were mapped by Reeve (1979), Clark (1989), and by till; stratigraphically overlies till. Most deposits of this unit are Scientific Association 81st annual meeting; Program with abstracts: Northwest Scientific Qgo Qga Qgof Qp Qmw Qga Qa Qgt Yount and Gower (1991) as mostly basalt and diabase. Clark (1989) and Haeussler ice-proximal and difficult to separate from unit Qgic, locally resulting in Association, p. 27-28. Qge Qgos Qa Qmw Qgt Qa Qpf Pre-Vashon glaciolacustrine silt and clay—Mostly silt with some clay Qp and Clark (2000) noted ophiolitic tendencies among the rocks, and Haeussler and DESCRIPTION OF MAP UNITS gradational boundaries and poor distinction between units Qgic and Qgo Qpf Haugerud, R. A.; Harding, D. J.; Johnson, S. Y.; Harless, J. L.; Weaver, C. S.; Sherrod, B. L., Qa Qpg Qpt and some sandy interbeds; contains little or no organic matter; brown to Qga Clark (2000) included basalt from this area with the Crescent Formation. The (and subunits). This difficulty is illustrated, for instance, by a “leaping” 2003, High-resolution lidar topography of the Puget Lowland, Washington—A bonanza Qga Surficial deposits in the map area generally consist of a diverse mix of glacially blue-gray; lightly to moderately weathered; angular to subrounded; Qgo Qgof Qgof presence of 6,068 ft of volcanic (basalt) rock at Hofert # 1 well is consistent with outwash channel (Fig. 2). Locally divided into: for earth science: GSA Today, v. 13, no. 6, p. 4-10. Qpt Qgof Qp derived, plutonic, volcanic, and metamorphic lithic fragments, indicative of sediment Qls Qaf Qp compact; thinly bedded to massive. Assignment to pre-Vashon time is Qaf Qp Crescent Formation, and analysis of magnetic and gravity records by Danes and Heiskanen, W. A., 1951, On Seattle earthquakes and gravity anomalies: Seismological Society Qgos Qls Qga contribution from a northern source (including the North Cascades of Washington inconclusive because direct age estimates are absent and clear field Qga Qa Qgos Vashon recessional outwash sand—Mostly sand, but locally Qa Qaf Qgt others (1965) suggests volcanic rock is widespread beneath the map area. East of Qgos of America Bulletin, v. 41, no. 4, p. 303-305. Qa Qp and/or Coast Ranges of British Columbia). Most deposits are relatively unweathered, includes lenses and beds of pebble gravel and silt; mostly relations have not been established. Qgt Qgof Green and Gold Mountains, Fulmer (1975) described Tertiary volcaniclastic bedrock Hemphill-Haley, Eileen, 1996, Diatoms as an aid in identifying late-Holocene tsunami Qmw Qgos Qls but deep weathering of some exposures, ranging in color from red to brown and matrix-free; gray to tan; loose; moderately to well sorted; Qgic Qga Qaf Qp of the marine Blakeley and the overlying terrestrial Blakely Harbor Formations, and Undifferentiated Deposits Older than Vashon Till deposits: Holocene, v. 6, no. 4, p. 439-448. Qaf Qp yellowish brown, is confirmed by their petrography and suggests that these are quite moderately to well rounded; generally less compact than but in Qgof Qgic McLean (1977) characterized typical Blakeley Formation rocks as Johnson, S. Y.; Blakely, R. J.; Stephenson, W. J.; Dadisman, S. V.; Fisher, M. A., 2004, Active Qaf old. Other exposures include unweathered particles alongside significant quantities of some exposures difficult to distinguish from advance outwash Qgt Qgic Qgt Qgt feldspathic-volcanolithic wacke, but it is unclear if these clastic rocks extend into the Qgd Qgic weathered ones. This weathering contrast within individual exposures suggests a mix Qpu Undifferentiated sediment older than Vashon till—Gravel, sand, fines, shortening of the Cascadia forearc and implications for seismic hazards of the Puget Qgic Qgo map area. sand (unit Qgas). Qpu Qaf Qp of allochthonous, unweathered and proximally sourced, previously weathered and diamicton older than Vashon till; compact; may include any Lowland: Tectonics, v. 23, TC1011, doi:10.1029/2003TC001507, 27 p. Qgt Qp Qgt Qgt Repeated Pleistocene incursions into the map area of northern-source ice sheets Qls Qgof Qgof Qgic particles and causes some apparent advance outwash to look less “fresh” than Qgof Vashon recessional outwash fines—Mostly silt, commonly pre-Vashon unit and units Qga and Qgas where those could not be Jovanelly, Tamie J., 2006, Tsunami origin for an ~1,100 year old enigmatic sand sheet in Qgic Qgo and nonglacial periods of erosion contributed to sediment older than the Vashon Qgof Qaf Qa Qgo Qgd Qgo deposits of comparable age elsewhere in the Puget Lowland. We attribute the mixing ranges to fine sand or locally clay; may contain dropstones, but differentiated from pre-Vashon outwash. A map boundary mismatch with Lynch Cove, Puget Sound, Washington: Kent State University Doctor of Philosophy Qp Qgos Qa Qgof Qp Stade of the Fraser Glaciation of Armstrong and others (1965); we were unable to to entrainment of deeply weathered sediment and bedrock from between the Seattle the Vaughn quadrangle to the south resulted where Logan and Walsh thesis, 98 p. Qmw Qgof Qp very few were observed during mapping; gray to brown; Qoaf subdivide this sediment by age. The pre-Vashon deposits in the map area are likely Qpu fault and the map area. The bedrock consists of ophiolitic tertiary bedrock that is generally angular to subangular, well-sorted, and loose; may be (2007) included narrow exposures of pre-Vashon deposits along steep Jovanelly, Tamie J.; Moore, Andrew L., 2005, Tsunami origin for an 1,100 year old enigmatic Qp Qa Qmw Qp Qgo Qgt older than most others in exposures beneath Vashon till throughout the Puget sand sheet in Lynch Cove, Puget Sound, Washington, U.S.A. [abstract]: Geological Qa exposed at Green and Gold Mountains and dominated by subaerial and submarine locally stiff, but not usually compact (Fig. 4); laminated to valley walls with Vashon till (unit Qgt). Qoa Lowland, based on generally significant and locally intense weathering and the Society of America Abstracts with Programs, v. 37, no. 7, p. 65. Qgic Qgd Qgd porphyritic, aphanitic, and amygdaloidal basalt with lesser amounts of leucogabbro, structureless; deposited in ice-dammed lakes near the end of the Qls Qgic Qgo Qp Qgd Qaf Qgt absence of unambiguously finite radiocarbon age estimates among these deposits Qpg Pre-Vashon gravel—Sand and gravel; typically matrix-rich (>5% fines); Kelsey, H. M.; Sherrod, Brian, 2005, Earthquakes generated from bedding-plane reverse faults Qmw Qgt diabase, amygdaloidal quartz latite, quartz monzonite, quartz diorite, andesite, and Fraser Glaciation; according to one well driller, may locally be Qpg Qa Qaf Qgt (see Table 1). Furthermore, the Seattle uplift (see Structure) created a topographic Qgt dacite (Clark, 1989). We speculate that the deeply weathered sediment in the map more than 500 ft thick in the lower Union River valley (Mike may contain minor silt layers; moderately to heavily oxidized; poorly to of the Seattle fault zone—The roof thrust is not passive [abstract]: Eos (American Qoa Qgof Qgt barrier in the path of northern-sourced glaciers and thereby may have caused younger Qoaf area resulted from reworking of this bedrock. Davis, oral commun., 2008). Map boundary mismatches with well bedded; commonly includes localized cementation by iron oxide or Geophysical Union Transactions), v. 86, no. 52, p. F1438. Qgic Qp Qgo Qgt Qa Qgt Qgo Qgt Qgo Qgo pre-Vashon sediment to be preferentially removed by erosion during successive We sought to show as geologic units those deposits that form a sufficiently thick manganese; locally found as inclusion of weathered clasts or clumps up to Kelsey, H. M.; Sherrod, B. L.; Nelson, A. R.; Brocher, T. M., 2008, Earthquakes generated Qmw the Vaughn quadrangle to the south (Logan and Walsh, 2007) Qpu Qa Qgt glacial incursions. boulder size within units Qgt and Qga; assumed to be glacial based on from bedding plane-parallel reverse faults above an active wedge thrust, Seattle fault zone: Qgic Qoa surficial cover to be of geotechnical significance, generally requiring a thickness of 5 resulted where Logan and Walsh mapped terrace segments as Qgic Qmw Qgo Surficial geologic deposits in the map area are dominated by till, ice-contact coarse grain size coupled with location near center of Puget Lowland Geological Society of America Bulletin, v. 120, no. 11-12, p. 1581-1597. Qpu Qgt ft, although where stiff, impermeable, or geotechnically challenging units (for till (unit Qgt) because they lacked the landform images or field Qmw Qgt deposits, lake sediments, and outwash of the upper Wisconsinan Fraser Drift. Qa example, till or peat) were encountered or we sought to illustrate a geologic process, data that might have permitted them to recognize a broader (where nonglacial conditions would not generally support streams large Karel, Patrick; Liberty, L. M., 2008, The western extension of the Seattle fault—New insights Qgt Qgt Landforms include both deposition and scour features from ice and meltwater. Booth Qa Qgo Qgt we locally mapped thinner deposits. In most areas, exposure or access was too terrace cover of unit Qgof. enough to deposit appreciable gravel packages) but could locally include from seismic reflection data: American Geophysical Union Fall Meeting 2008, poster Qgt Qgo Qgof Qgic Qgo Qgic and others (2004) associated the Fraser Glaciation with marine oxygen isotope stage Qgo Qgic Qp limited to determine unit thickness, and we relied considerably on geomorphology, nonglacial deposits; locally exposed in deeply incised valleys such as T21B-1951. Qoa 2, and Morrison (1991) assigned the glaciation to the period between 28 and 10 ka. Qaf Qa Qp Qgo Qp field relations, or, where available and helpful, subsurface records. A U.S. Geologic Qgol Vashon recessional lake-marginal outwash—Gravel, sand, Mission Creek. Kimball, J. P., 1897, Physiographic geology of the Puget Sound basin [in 2 parts]: American Qgt Qgt Qgol Fraser Drift in the map area is herein associated exclusively with the Vashon Stade Survey 7.5-minute topographic map was used as the base map, but contact locations and locally fines; gray to brown; formed by proximal reworking Geologist, v. 19, no. 4, p. 225-237 [part 1]; v. 19, no. 5, p. 304-322 [part 2]. Qgt Qa Qp Qaf Qgt Qgo Qge Qaf 27¢30² because no evidence encountered during this project would indicate deposits from Qps Pre-Vashon sand—Compact sand, locally with layers and lenses of silt, 27¢30² Qgo Qp Qgo Qa were generally refined by reference to lidar, aerial photos, and field observations. of upslope units (usually ablation till) into a systematic Qps Laprade, W. T., 2003, Subglacially reworked till in the Puget Lowland [abstract]: Geological Qaf Qaf Qmw Qp Qgic Qp Qp Qgo Qgo other parts of the glaciation. lake-marginal deltaic assemblage of fluvial beds near the top, clay, peat, and minor gravel; moderately to heavily oxidized; poorly to Society of America Abstracts with Programs, v. 35, no. 6, p. 216 Qp Qa Qaf Qoa Qgo Surficial glacial deposits are mapped as Fraser Drift, except where stratigraphic well bedded; locally iron-oxide cemented; locally found as inclusion of Qgt Qga Qgo Quaternary Unconsolidated Deposits foreset beds in the center, and quiet-water lake-bottom beds at Liberty, L. M., 2005, Land seismic profiling of the Tacoma fault, Washington—Final technical Qgt Qp Qoaf Qp Qp field relations and weathering (see unit Qpt) point to an older origin. The outwash weathered clumps up to boulder size within units Qgt and Qga; assumed to Qgo Qoa Qoa Qgo the base; fines typically limited to the bottomset beds, where report: U.S. Geological Survey Earthquakes Hazards Program, External Research Support, Qaf Qgo HOLOCENE NONGLACIAL DEPOSITS Qgof unit Qgol was recognized as draping of proximal, generally subtle, relict, the unit grades laterally into unit Qgof. See Geologic Setting be nonglacial based on the grain size, common presence of organic-rich Funded Research Final Technical Reports. [accessed Mar. 30, 2009 at Qgic Qls Qgt Qa fluvio-deltaic terraces that mark a paleo-lake surface near the top of the unit. This layers, and sedimentary characteristics (suggestive of slower Qgt Qaf Qgt Qp Qa for notes on unit thickness and distribution. http://earthquake.usgs.gov/research/external/reports/05hQGR0024.pdf] Qgo Qaf Qp af Artificial fill—Clay, silt, sand, gravel, organic matter, and rip-rap; placed unit is very likely more widespread than shown by our mapping, but most exposures af sedimentation rates and relative paucity of lacustrine settings when Liberty, L. M.; Pratt, T. L., 2008, Structure of the eastern Seattle fault zone, Washington Qoa Qpg Qgic Qgt Qpf Qga form only a thin (less than 10 ft) draping of loose deposits. The presence of to elevate and reshape the land; may be engineered or non-engineered; Qgic Vashon glacial ice-contact deposits—Sand, gravel, lodgment till, and compared to sandy glacial deposits), but could locally include glacial Qgic Qmw Qp Qgic Qgic State—New insights from seismic reflection data: Bulletin of the Seismological Society of Qoa Qls fluvio-deltaic terraces associated with unit Qgol at various elevations (such as along shown where fill is readily verifiable and relatively extensive and appears flow till; minor silt and clay beds; tan to gray; variably sorted; loose to deposits; shown on map only as a single polygon along Mission Creek but America, v. 98, no. 4, p. 1681-1695. Qgt Qp the east shore of North Bay, where we locally recognized at least two benches) sufficiently thick to be geotechnically significant (greater than 5 ft); also locally exposed in deeply incised valleys such as Rocky Creek and Qgic Qm Qa Qgt Qgo Qgol compact; massive to well stratified; locally includes over-steepened beds Logan, R. L.; Walsh, T. J., 2007, Geologic map of the Vaughn 7.5-minute quadrangle, Pierce Qgt Qa excludes roads, except across water basins. Qaf Qgo documents the transient existence during deglaciation of several regional lake levels that typically reflect sub-ice flow, but their dip may, along with the westernmost tributary to Union River shown on the base map, and Mason Counties, Washington: Washington Division of Geology and Earth Resources Qge Qa Qp? Qgo Qp Qgd Qp Qaf (Haugerud, 2009, recognized five) and several more local ones. small-scale shears, also have developed as collapse features or due to informally known as “Courtney Creek”. At Rocky Creek, we radiocarbon Geologic Map GM-65, 1 sheet, scale 1:24,000. [accessed Mar. 28, 2008 at Qa Qoa Qp Qmw Qa Haugerud (2009) noted that deglaciation in the southern Puget Lowland probably ml Modified land—Local sediment ranging from clay to gravel and dated peat that was interbedded with silt and clay at the base of the Qmw Qa ml glaciotectonic and tectonic deformation; formed in the presence of http://www.dnr.wa.gov/Publications/ger_gm65_geol_map_vaughn_24k.pdf] Qgic Qm Qp Qmw diamicton; mixed and reworked by excavation and (or) redistribution that Qgt began with stagnation of the ice sheet, which resulted in preservation of subglacial meltwater alongside ice, generally toward the end of the glaciation, and is exposure (see Table 1). Based on the degree of weathering of the overlying Ma, Li; Crosson, R. S.; Ludwin, R. S., 1996, Western Washington earthquake focal Qoa Qgic Qa notably modifies topography; shown where relatively extensive, masking sand and the fact that the residual carbon available for a 14C signal at over Qgic Qgt drainage features. Within the map area, these features include eskers (unit Qge; Fig. thus commonly accompanied by stagnant-ice features, such as kettles and mechanisms and their relationship to regional tectonic stress. In Rogers, A. M.; Walsh, T. Qgic Qga Qoa Qp Qgt Qgic underlying geology, and geotechnically significant (greater than 5 ft); Qls? Qm Qp Qp 1), subglacial channels eroded into the till plain (locally marked on our map by less-orderly hummocky topography, eskers (also separately mapped as 40,000 years of age is less than 1% of the original 14C content, we J.; Kockelman, W. J.; Priest, G. R., editors, Assessing earthquake hazards and reducing Qaf Qa Qgo Qgol excludes roads and abandoned pits where underlying units can be Qaf Qp Qpu Qp Qgt elongate polygons of units Qgic and Qgo; Fig. 2), and locally voluminous stagnant subunit Qge), and subglacial or subaerial outwash channels. Deposits and question the validity of the radiocarbon “finite” age estimate. risk in the Pacific Northwest: U.S. Geological Survey Professional Paper 1560, v. 1, p. Qaf Qga Qa Qgol ice deposits (unit Qgic). In some areas that generally slope south toward larger identified; includes aggregate pits active at time of mapping. morphologies that support conceptual association with both ice and 257-283. Qm Qgo Qgt Qp Qps af Qgt basins, locally permeable and relatively loose till that is typically 2 to 10 ft thick and meltwater are common in the map area and suggest that where unit Qgic is Martin, M. E.; Maxcia, Claudia; Gerardi, Flavia; Bourgeois, Joanne, 2007, Anomalous sand Qmw Qgo Qgo Qa Qb, Qob Beach deposits—Sand, pebbles, pebbly sand, cobbles, silt, clay, and GEOLOGIC SYMBOLS Qoa Qb Qa Qgt Qa commonly overlies angular sand was found below 350 ft in elevation. These deposits Qb mapped in the presence of fluted topography, it is commonly only a few deposit associated with evidence of late Holocene uplift near Bremerton, Washington Qgic Qgic Qp shells; clasts typically moderately to well rounded and oblate; locally well Qa appear to be the “subglacially reworked till” noted by Laprade (2003) and were Contact—long dashed where approximately located, short [abstract]: Eos (American Geophysical Union Transactions), v. 88, no. 52, pt. 2, Qm Qm Qgic Qgo feet thick and locally could have been mapped as undifferentiated drift Qaf Qga Qa included with unit Qgic. These sediments likely formed in response to the presence to sorted; loose; derived from shore bluffs, streams, and underlying deposits. dashed where inferred. Supplement, p. F1433. Qgic (unit Qgd). Elsewhere, the unit may be over 100 ft thick. Unit Qgic also Qgd Qgol Qob Uplifted (relict) beach terraces are apparent in parts of the map area and, Qb Qgol Qgo Qp the south of proglacial or subglacial lakes that caused the overlying ice to float. includes poorly consolidated till commonly accompanied by underlying, McFarland, C. R., 1983, Oil and gas exploration in Washington, 1900-1982: Washington Qgt Qa where map scale permits, are separately shown as subunit Qob. A map ? Fault—unknown offset, queried where existence Qmw Qgo Qmw Subglacial drainage features in the map area are commonly laterally continuous angular sand and noted as “sub-glacially reworked till” by Laprade (2003) Division of Geology and Earth Resources Information Circular 75, 119 p. [accessed Apr. Qm boundary mismatch with the Vaughn quadrangle to the south resulted questionable Qpg Qga Qpu Qaf with and appear to grade into clearly subaerial outwash terraces (unit Qgo) that in (see Geologic Setting), especially in fluted areas that lack dead-ice 28, 2009 at http://www.dnr.wa.gov/Publications/ger_ic75_oil_gas_exploration.pdf] Qpf Qgic Qob Qmw Qga Qa where Logan and Walsh (2007) used notes to alert readers to uplifted Qmw Qaf Qgol turn appear to be graded to a glaciolacustrine base level. While various different base features. See unit Qgo and Fig. 4 for discussion of similarities between R ? Fault—reverse offset, R on upthrown side, queried where McLean, Hugh, 1977, Lithofacies of the Blakeley Formation, Kitsap County, Washington—A Qpg Qgt beach but included the beach with unit Qgt or unit Qaf, whereas this map submarine fan complex?: Journal of Sedimentary Petrology, v. 47, no. 1, p. 78-88. Qb Qga Qoaf Qmw levels are locally apparent, the most prominent one points to a lake surface at roughly units Qgic and Qgo (and its subunits Qgos, Qgof, and Qgol). A existence questionable Qa af af Qgo shows unit Qob. Qm Qgo Qgo 300 ft, apparently associated with glacial Lake Russell (Bretz, 1910; Thorson, 1981). discrepancy between this map and the Vaughn quadrangle to the south McMurphy, C. J., 1980, Soil survey of Kitsap County area, Washington: U.S. Soil T 23 N Qb Qm T 23 N Some lower-elevation outwash terraces that post-date glacial Lake Russell proved resulted where Logan and Walsh (2007) mapped undifferentiated Scarp—hachures point downslope Conservation Service, 127 p., 31 plates. Qm af Qls Qm Marsh deposits—Organic sediment and (or) loose clay, silt, and sand in Qgol Qoa Qm T 22 N Qga T 22 N difficult to separate from and may locally be included with more recent alluvium Quaternary deposits (unit Qu) because they lacked field exposures and Mitchell, Michael; Liberty, L. M.; Pratt, T. L., 2008, Segmentation of the Tacoma af Qgd tidal flats and coastal wetlands; saltwater to brackish equivalent of unit Qls Qga Qmw Qa Qmw (units Qa, Qoa). The combination of abundant stagnant ice deposits, till plain surface geomorphic signs of the dead-ice deposits that are apparent north of the Lineament fault—Evidence from seismic and magnetic data [poster]: American Geophysical Union Qb Qgol Qgt Qp; includes layers of freshwater peat in some areas, due to relative Qm Qoaf irregularities (subglacial channels, “ripples on flutes”; Fig. 3), and subglacially Fall Meeting 2008, poster T21B-1952. Qb Qgt Qgic sea-level changes. boundary. Dead-ice topography north of the boundary also reveals a sandy 6 14 Qmw Qa Qgo Age-date sample site, C Qgt Qoa Qpu Qgo reworked and/or otherwise poorly developed till in the map area suggests that the ice deposit mapped as unit Qgos by Logan and Walsh (2007) to be a facies Morrison, R. B., editor, 1991, Quaternary nonglacial geology—Conterminous U.S.: Geological Qaf Qm mass stagnated against the shores of the large proglacial lakes that filled Case and HOLOCENE AND LATE PLEISTOCENE NONGLACIAL DEPOSITS within unit Qgic. Locally divided into: Hydrocarbon exploration well Hofert #1 Society of America DNAG Geology of North America, v. K-2, 672 p., 8 plates in Qgol Qoa Carr Inlets south of the map area late in the Vashon Stade, perhaps because, in the accompanying case. Qp Qga Qgic Qa words of Haugerud (2009), the ice mass was “decapitated by collapse of the Juan de Qge Vashon glacial eskers—Sand and gravel; tan to brown; loose; Qgd Qgt Qp Peat—Organic and organic-rich sediment; includes peat, muck, silt, and Qge Shear-wave velocity test location Nelson, A. R.; Personius, S. F.; Sherrod, B. L.; Buck, Jason; Bradley, Lee-Ann; Henley, Gary, Fuca lobe”. Qp moderately to well sorted; moderately to well rounded with Qmw Qgic clay; typically in closed depressions; includes all recognized upland II; Liberty, L. M.; Kelsey, H. M.; Witter, R. C.; Koehler, R. D.; Schermer, Elizabeth; Qga good porosity and permeability; deposited subglacially by Qgic Qgd Qge wetland areas and flat surfaces in closed depressions, unless a different Nemser, E. S.; Cladouhos, T. T., 2009, Field and laboratory data from an earthquake Qgol Qgas Vashon melt-water in areas occupied by stagnant ice; forms history study of scarps in the hanging wall of the Tacoma fault, Mason and Pierce Qgic Qgo STRUCTURE unit or standing water was specifically identified (identification of some ACKNOWLEDGMENTS Qga Qa Qgt low, elongate, sinuous hills that seem to rest like slugs on fluted Counties, Washington: U.S. Geological Survey Scientific Investigations Map 3060, 3 Qga polygons is therefore tentative); freshwater equivalent of unit Qm; where Qgol Qgt Qgo Tectonic Setting uplands or subglacial outwash channels and locally can be seen This report was produced in cooperation with the U.S. Geological Survey National sheets. [accessed Apr. 28, 2009 at http://pubs.usgs.gov/sim/3060/] field data were unavailable, mapped on the basis of topography, aerial Qa Qpu Qaf Cooperative Geologic Mapping Program, Agreement No. 08HQAG0104, which ? Qa Qgt to merge into channel incisions (Fig. 1). One such transition Polenz, Michael; Alldritt, Katelin; Hehemann, N. J.; Logan, R. L., 2009, Geologic map of the Qls Qgt Qgd Broadly situated in the forearc of the Cascadia subduction zone, the map area is photos, or prior mapping—for example, peat beneath the runway at Qgas partially supported our mapping. We thank Jerry Deeter (Kitsap County) for geologic Burley 7.5-minute quadrangle, Kitsap and Pierce Counties, Washington: Washington 3a,3b Qpu Qgol Qaf located in the south half of the tectonically active Seattle uplift, a west-trending causes a map boundary mismatch between unit Qgic on this Qpu Qgo Qgt Qgo Bremerton National airport was noted on a 1934 soil map (U.S. Bureau of Qga Qgic map and unit Qgoe (esker) on the Vaughn quad to the south insights; Kitsap, Mason and Pierce Counties for sharing geographic information Division of Geology and Earth Resources Open File Report 2009-8, 1 sheet, scale Qp Qa Qgo structural high between the Seattle fault to the north and the Tacoma fault zone to the Chemistry and Soils, 1934 ) and in geotechnical borings drilled in 2008 ? Qgt Qmw Qp (Logan and Walsh, 2007). Some polygons of this unit abut systems (GIS) addressing and other records; Stephanie Neil for providing 1:24,000. Qmw Qgd south. Post-glacial uplift along what is now known as the Seattle fault was first noted (Fred Salisbury, Port of Bremerton, oral commun., 2008) that suggested Qpu Qgo Qa Qoa Qgic geo-archeological expertise; the Department of Archaeology and Historic Pratt, Thomas; Troost, Kathy, 2009, Is the Seattle fault beneath downtown Seattle? [abstract]. ? Qaf Qgt Qpu against unit Qgic in the Lake Wooten quadrangle to the west Qls Qmw Qgol Qa Qgd by Kimball (1897). Raisz (1945) suggested a major fault along a topographically some peat outside the area shown on the 1934 soils map. This discrepancy 25¢ ? Qgt Qgt 25¢ (Derkey and Hehemann, 2009), where eskers are noted by Preservation for archeological records; Mike Davis for a well-driller’s insight into In Northwest Scientific Association, The Pacific Northwest in a changing Qgol Qaf Qgt prominent, regional lineament that he termed the Olympic–Wallowa lineament, and the absence of peat in the area according to a more recent soils map Qgt Qp Qga Qp Qgol Qmw linear symbols over unit Qgic. The underlying interpretation is local subsurface conditions; Tim Walsh and Josh Logan (Wash. Div. of Geology and environment—Northwest Scientific Association 81st annual meeting; Program with Qgic Qa Qgt which coincides with what is now considered the Seattle fault in and near Seattle. (McMurphy, 1980) caused us to show the peat boundaries as inferred. The Qga Qoa Qls Qgic Qgic Earth Resources) for technical reviews and interpretive assistance; Josh Logan for abstracts: Northwest Scientific Association, p. 53-54 ? Qa identical. Qp Heiskanen (1951) used Puget Lowland seismicity and a gravitational low at Seattle to unit post-dates Vashon ice and is predominantly Holocene but locally assistance with thin section petrography and interpretation; and Recep Cakir and Qgol Qa Qpu Qgo Raisz, E. J., 1945, The Olympic–Wallowa lineament: American Journal of Science, v. 243A Qmw Qgic Qgt call for detailed gravitational analysis of the region. Geophysical evidence for the includes some late Pleistocene deposits. Qgt Qaf Qgt Vashon till—Unsorted, unstratified (but locally banded) mix of clay, silt, Trevor Contreras (Wash. Div. of Geology and Earth Resources) for collection, [Daly volume], p. 479-485. Qp Qp Qpu Qgo Seattle uplift and the faults that bound it has since been summarized by Danes and Qgt Qp Qgt sand, and gravel; typically supported by a sandy matrix; mostly gray but processing, and assistance with interpretation of shear wave velocity data. Last, but ? Qp Qp Qgol Qgd Qgo others (1965), Rogers (1970), Gower and others (1985), and Brocher and others Qls Landslide deposits—Gravel, sand, silt, clay, and boulders in slide body Reeve, William, 1979, Bedrock geology of the Blue Hills, Kitsap County, Washington: Qgo Qp Qls locally ranging to tan, light brown, or orange; typically unweathered; not least, thanks to the many people who permitted us to study and sample geologic Colorado School of Mines Master of Science thesis, 58 p., 1 plate. Qgo (2001). Interpretations of the exact character and activity level of the Seattle uplift and toe; due to map scale, includes exposure of underlying units in scarp Qgol Qaf Qpu Qp Qp lodgment till compact, with well-developed facies resembling concrete, exposures on their land and provided site-specific records and local expertise. Rogers, W. P., 1970, A geological and geophysical study of the central Puget Sound lowland: Qls Qga Qgt Qgt and the faults that bound it continue to develop (for example, Bucknam and others, areas; angular to rounded clasts and grains; unsorted; generally loose, Qgic Qgic Qgic Qge but near the surface commonly hackly and (or) looser and covered by 1 to University of Washington Doctor of Philosophy thesis, 123 p., 9 plates. Qgo 1992; Bucknam and Biasi, 1994; Blakely and others, 2002; Sherrod and others, jumbled, and unstratified, but may locally retain primary bedding; ? Qgic 6 ft of loose ablation till; deposited directly by glacial ice and commonly Hoffert #1 2003a,b; Sherrod and others, 2004; Johnson and others, 2004; Kelsey and Sherrod, commonly includes liquefaction features. Absence of a mapped slide does REFERENCES CITED Sarikhan, I. Y.; Walsh, T. J.; Cakir, Recep, 2007, Morphology of the Alderwood landslide—A Qga Qgol includes clasts or clumps plucked from underlying units. Clasts are Qpu Qgt Qga 2005; Liberty, 2005; Martin and others, 2007; Logan and Walsh, 2007; Karel and not imply absence of sliding or hazard as some slides are too small to probable origin for tsunami in Lynch Cove, Puget Sound, Washington [abstract]: Qgt Qb Qgt commonly striated and faceted, with angular or rounded edges. Boulders Armstrong, J. E.; Crandell, D. R.; Easterbrook, D. J.; Noble, J. B., 1965, Late Pleistocene Qa Qgol Liberty, 2008; Mitchell and others, 2008; Liberty and Pratt, 2008; Kelsey and others, show at map scale. Although the large Alderwood landslide southwest of Geological Society of America Abstracts with Programs, v. 39, no. 4, p. 31. Qmw Qgt Qgic stratigraphy and chronology in southwestern British Columbia and northwestern Qgo Qgt Qgo are generally sparse within the till but large (erratic) boulders of plutonic Sherrod, B. L.; Brocher, T. M.; Weaver, C. S.; Bucknam, R. C.; Blakely, R. J.; Kelsey, H. M.; 2008; Pratt and Troost, 2009). These and many other studies from recent years Belfair may have been triggered by seismicity about 1.1 ka (see Structure), Washington: Geological Society of America Bulletin, v. 76, no. 3, p. 321-330. Qm Qa Qgo or metamorphic rock are common on till surfaces. Some exposures include Nelson, A. R.; Haugerud, R. A., 2003a, Evidence for a late Holocene earthquake on the Qaf Qp together indicate that the faults are active, with kilometers of post-Eocene reverse review of aerial photographs also suggests historic movement for this Qaf Qga Qga interbands and lenses of sand and gravel, locally with shears and joints. Beale, Harriet, 1990, Relative rise in sea-level during the late Holocene at six salt marshes in Tacoma fault, Puget Sound, Washington [abstract]: Geological Society of America Qpu Qga Qgic offset that has led to exposure of bedrock north of the map area and elevated the map slide. The unit post-dates Vashon ice and is predominantly Holocene but Qb Qgol Till forms a locally patchy and seemingly randomly distributed cover up to the Puget basin, Washington: Western Washington University Master of Science thesis, Abstracts with Programs, v. 35, no. 6, p. 98. Qpu Qgt locally may include some late Pleistocene deposits. Qp area against the Tacoma basin to the south. Earthquake focal mechanisms 157 p. Qls Qm a several tens of feet thick, with a thickness of 5 to 20 ft most common. It Sherrod, B. L.; Brocher, T. M.; Weaver, C. S.; Bucknam, R. C.; Blakely, R. J.; Kelsey, H. M.; Qga Qaf summarized by Ma and others (1996) suggest north-south compressive stress and a Qga Qgic Qgol Qmw Mass wasting deposits—Boulders, gravel, sand, silt, clay, and diamicton; typically dominates, but is also locally discontinuous on, fluted surfaces, Blakely, R. J.; Wells, R. E.; Weaver, C. S.; Johnson, S. Y., 2002, Location, structure, and Nelson, A. R.; Haugerud, Ralph, 2004, Holocene fault scarps near Tacoma, Washington, Qgt Qp possible strike-slip component to offset in the area. Evidence of coseismic land level Qmw seismicity of the Seattle fault zone, Washington—Evidence from aeromagnetic anomalies, Qga Qgol Qp generally unsorted, but locally stratified; typically loose; shown along with individual drumlins measuring 0.1 to 0.3 mi wide by 0.8 to 1.3 mi USA: Geology, v. 32, no. 1, p. 9-12. Qgic Qpu Qp changes and some fault strands are located within the map area (see map and geologic mapping, and seismic-reflection data: Geological Society of America Bulletin, v. Qb Qa long and the long axis aligned with the direction of ice flow. Till typically Sherrod, B. L.; Nelson, A. R.; Kelsey, H. M.; Brocher, T. M.; Blakely, R. J.; Weaver, C. S.; Qaf af Qbo Qgo Evidence for Post-glacial Tectonic Effects). These are attributable to either the mostly colluvium-covered or densely vegetated slopes that are potentially Qa Qaf 114, no. 2, p. 169-177. Qgt Qgt Qgt or demonstrably unstable; may locally include exposures of underlying is in sharp, unconformable contact with underlying units, most commonly Rountree, N. K.; Rhea, B. S.; Jackson, B. S., 2003b, The Catfish Lake scarp, Allyn, Qm Tacoma fault zone or other faulting within the Seattle uplift. Sherrod and others Booth, D. B.; Troost, K. G.; Clague, J. J.; Waitt, R. B., 2004, The Cordilleran ice sheet. In Qaf Qgt advance outwash (unit Qga and subunit). Unit Qgt lies stratigraphically Washington—Preliminary field data and implications for earthquake hazards posed by the Qpu Qpg Qgo Qb Qgic (2003a) have suggested that earthquake effects in and near the map area may units that either we could not map confidently or are too small to show, as Qpg below unit Qgo. It may include unrecognized exposures of older till. A Gillespie, A. R.; Porter, S. C.; Atwater, B. F., editors, The Quaternary period in the United Tacoma fault: Version 1.0: U.S. Geological Survey Open-File Report 03-0455, 1 sheet, Qa represent a Tacoma fault earthquake up to magnitude 7 between A.D. 770 and 1160, well as debris fans, alluvial fans, and landslides. Absence of a mapped Qaf Qpu Qga Qgol Qb Qob States: Elsevier, p. 17-43. with 12 p. text. [accessed March 23, 2009 at http://pubs.usgs.gov/of/2003/of03-455/] Qgic Qp Qgas mass-wasting deposit does not imply absence of slope instability or map boundary mismatch between unit Qgt on this map and unit Qgos on Qp but separating such an event from an A.D. 900-930 earthquake on the Seattle fault or Qgic the Vaughn quadrangle to the south (Logan and Walsh, 2007) may have Bourgeois, Joanne, 2008, Hazards inferred from tsunami deposits in Washington and Oregon: Solimano, P. S.; Forsman, L. A.; Larson, L. L., 1995, Cultural resource assessment, Sand Hill Qpu Qgt late Holocene activity on other nearby structures (for example, Witter and others, hazard. The unit post-dates Vashon ice and is predominantly Holocene but Qpg Qaf Qa resulted from a map-production error in the northwest corner of the U.S. Geological Survey, Earthquake Hazards Program, External research support—Final Mobile Home Park, Mason County, Washington: prepared for Sand Hill Mobile Home Qaf Qa 2008; Walsh and Logan, 2007) has proven elusive (Sherrod and others, 2004; Nelson locally may include some late Pleistocene deposits. Qgo Qa Vaughn map (Josh Logan, Wash. Divn. of Geology and Earth Resources, technical reports—Funded research, Pacific Northwest, [34 p.]. [accessed Jun. 18, 2009 at Park by Larson Anthropological/Archaeological Services [Seattle, Wash.], 1 v. Qa Qgt and others, 2009). Confident assignment of specific earthquake effects to specific http://earthquake.usgs.gov/research/external/reports/07HQGR0009.pdf] Qaf Qaf R Qpg Qgt Qgol Qgic Qa, Qoa Alluvium—Silt, sand, and gravel; clasts typically well rounded; typically oral commun., 2009). Thorson, R. M., 1981, Isostatic effects of the last glaciation in the Puget Lowland, Washington: Qp Qgo Qgt events on particular faults in the area will require further study. Qa Bretz, J Harlen, 1910, Glacial lakes of Puget Sound—Preliminary paper: Journal of Geology, Qa ? well sorted and loose; stratified to massively bedded; deposited in streams U.S. Geological Survey Open-File Report 81-370, 100 p., 1 plate. Qob Qoa Qgt Qga Vashon advance outwash—Pebble to cobble gravel, sand, and layers and v. 18, no. 5, p. 448-458. and adjacent banks. The sediment source is most commonly reworked Qga Union Oil Company of California; Standard Oil Company of California, 1950, Hofert #1: Qb Evidence for Post-glacial Tectonic Effects lenses of silt and clay; gray to tan; typically stratified, well rounded, well Brocher, T. M.; Parsons, T. E.; Blakely, R. J.; Christensen, N. I.; Fisher, M. A.; Wells, R. E.; Qp Qgic Qoa recessional outwash, ablation till, advance outwash, and (or) Washington Division of Geology and Earth Resources unpublished mineral exploration Qgt Qgo Qgo Qoa Qgic Two scarps cross each other 4,600 ft north of the southeast corner of the map area sorted, and clean (<5% silt or clay in matrix), except in less-sorted and SHIPS Working Group, 2001, Upper crustal structure in Puget Lowland, file 035-0009 (Kp-8). Qp Qb R Qgic glaciolacustrine deposits, but may include lodgment till, nonglacial Qgol th Washington—Results from the 1998 Seismic Hazards Investigations in Puget Sound: (144 Street and Wright Bliss Road scarps, after Sherrod and others, 2003b, and deposits, and bedrock. Exposures locally resemble the unit’s sediment more angular ice-proximal deposits; compact (Fig. 4) and resistant to U.S. Bureau of Chemistry and Soils, 1934, Soil map, Kitsap County, Washington: U.S. Bureau Qp Journal of Geophysical Research, v. 106, no. B7, p. 13,541-13,564. Qgt Qpu Nelson and others, 2009). Trenching failed to reveal evidence of faulting on the erosion, except where well sorted and well rounded; very thinly to very Qgt Qob Qgt source units, a particularly notable feature in the Union River valley, of Chemistry and Soils, 1 sheet. Qgt th Buchanan-Banks, J. M.; Collins, D. S., 1994, Map showing depth to bedrock of the Tacoma Wright Bliss Road scarp but suggested an earthquake on the southeast-trending 144 where the unit is mostly derived from glaciolacustrine and (or) ice-contact thickly bedded; contains planar and graded beds, cut-and-fill structures, Walsh, T. J.; Logan, R. L., 2007, Field data for a trench on the Canyon River fault, southeast Qpu Qpu Qge and part of the Centralia 30' x 60' quadrangles, Washington: U.S. Geological Survey Qpu Qgt Street scarp between 1.1 and 1.5 ka (Nelson and others, 2009). Liberty (2005) used deposits (units Qgof and Qgic). Shear-wave velocity profiles confirm, trough and ripple cross-beds, and foresets; thickness not well constrained Olympic Mountains, Washington: Washington Division of Geology and Earth Resources Qpu Miscellaneous Field Studies Map MF-2265, 2 sheets, scale 1:100, 000. Qgo Qb Qgt seismic profiles to suggest several fault strands with south-directed reverse offset however, that unit Qa forms a more diverse deposit than unit Qgof and at by this mapping but ranges from a few feet to more than (?) 100 ft; Open File Report 2007-1, 1 plate. [accessed Apr. 3, 2009 at Qgt between this area and about 4000 ft farther north, where we noted additional, faint least some deposits of unit Qgic (Fig. 4). Subunit Qoa is older alluvium deposited as proglacial fluvial and deltaic sediment during Vashon glacial Bucknam, R. C., 1991, Puget Sound paleoseismicity. In Jacobson, M. L., compiler, National http://www.dnr.wa.gov/Publications/ger_ofr2007-1_canyon_river_fault_trench.pdf] Qgt Qa Earthquake Hazards Reduction Program, summaries of technical reports Volume XXXII: Qp Qgt scarps and lineaments on lidar-based images of the map area and the adjacent Burley advance and typically overlain by unit Qgt along a sharp, unconformable Qaf Qpu Qgic that resembles unit Qa in every way but forms elevated, relict terraces. Witter, R. C.; Givler, R. W.; Carson, R. J., 2008, Two post-glacial earthquakes on the Saddle Qgic Qa U.S. Geological Survey Open-File Report 91-352, p. 526-527. Qgt Qaf quadrangle (Polenz and others, 2009). We caution that we did not systematically Most appear to be tied to an elevated base level that prevailed prior to a contact. Locally divided into: Mountain west fault, southeastern Olympia Peninsula, Washington: Bulletin of the Qgt Qgt Qb survey the map area for such lineaments and may have missed others of equal Bucknam, R. C., 1998, Puget Sound paleoseismology. In U.S. Geological Survey, Annual Seismological Society of America, v. 98, no. 6, p. 2894-2917. Qp Qp Qgol local base-level lowering event(s) (see discussion of elevated terraces Qob Qa Qgas Vashon advance outwash sand—Sand; fluvial facies may project summaries—Volume 39, Pacific Northwest, p. 8-9. [accessed Dec. 2, 1998 at Qp subtlety. under Structure). Where unit Qoa is correctly identified along the lower Qgas Yount, J. C.; Gower, H. D., 1991, Bedrock geologic map of the Seattle 30' by 60' quadrangle, Qob Qpu Qpu include minor layers and lenses of gravel; lacustrine facies may http://erp-web.er.usgs.gov/reports/vol39/pn/pn_vol39.htm] Qgt Qpu Qgic Qgic Qoa About three miles farther northwest, a prominent line of scarps was first noted as reaches of streams that are graded to sea level, the age of unit Qoa should Washington: U.S. Geological Survey Open-File Report 91-147, 37 p., 4 plates. Qgo Qgof include lenses and layers of silt; gray to tan; typically well Bucknam, R. C.; Biasi, G. P., 1994, An improved estimate of the time of a prehistoric Qgt Qpu “Sunset Beach scarp” by Haugerud and others (2003). Although some of the scarps not exceed about 6,000 years because prior to that, sea level was Qgic Qge ml Qgt Qaf Qao Qb Qgt Qgic Qm Qls Qp Qpu Qaf Qoa Qmw Qa are south-down, combined offset for the line of scarps is north-down. (Due to map rounded, well sorted, and clean (<5% silt or clay in matrix); earthquake in the southwest Puget Sound region, Washington [abstract]: Geological Qao Qb Qgt Qgt Qoa significantly lower, which likely resulted in an erosional setting that Qls Qob Qgof Qgt generally compact but due to lack of cohesion locally appears Society of America Abstracts with Programs, v. 26, no. 7, p. A-522. Qa Qa 1 Qpu Qgt Qa Qoa Qa Qoa Qgt scale, offset for individual scarps is not shown.) Nelson and others (2009) precluded deposition of alluvium. As mapped, the unit is generally 47°22¢30² 47°22¢30² loose where well sorted and well rounded; generally porous and Bucknam, R. C.; Hemphill-Haley, Eileen; Leopold, E. B., 1992, Abrupt uplift within the past R 2 W R 1 W 50¢ Qgt 47¢30² 122°45¢ documented faulted offset about 1.3 ka in two of the scarps and used a seismic profile Holocene but may locally include some unrecognized recessional outwash 122°52¢30² permeable; deposited during Vashon glacial advance; prone to 1700 years at Southern Puget Sound, Washington, Science, vol. 258, pp. 1611-1614. to suggest steeply dipping faults in Quaternary sediment beneath the scarps. A half terraces (unit Qgo) and other late Pleistocene deposits. A map boundary rapid landslides where resting on impermeable substrate. mile south of the scarps, they used the same profile to infer a steeply dipping reverse mismatch with the Vaughn quadrangle to the south resulted where Logan Clark, Kenneth P., 1989, The stratigraphy and geochemistry of the Crescent Formation basalts Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, Lambert conformal conic projection SCALE 1:24,000 This geologic map was funded in part by the fault that offsets over 6,000 ft of Quaternary deposits north of the fault against and Walsh (2007) lumped unit Qoa into unit Qa. Elsewhere, the contact and the bedrock geology of associated igneous rocks near Bremerton, Washington: including, but not limited to, the implied warranties of merchantability and fitness for a particular use. The North American Datum of 1927; to place on North American Datum of 1983, 1 0.5 0 1 MILE U.S. Geological Survey National Cooperative Geologic Mapping Program. Qgd Undifferentiated glacial drift—Heterogeneous patchwork of stratified Tertiary bedrock that they inferred south of the fault at a depth of 700 ft (see also Qgd Western Washington University Master of Science thesis, 171 p., 1 plate. Washington Department of Natural Resources and the authors of this product will not be liable to the user of move the projection lines approximately 20 meters north and 95 meters between unit Qa (this map) and units Qgt and Qaf (Vaughn quadrangle) this product for any activity involving the product with respect to the following: (a) lost profits, lost savings, 10000 1000 2000 3000 4000 5000 6000 7000 FEET and unstratified sand, silt, clay, gravel, and diamicton; may locally include Daneš, Z. F.; Bonno, M.; Brau, J. E.; Gilham, W. D.; Hoffman, T. F.; Johansen, D.; Jones, M. east as shown by crosshair corner ticks Liberty, 2005). Because no surface expression of the inferred fault has been runs so close to the map boundary that map scale did not permit separating or any other consequential damages; (b) fitness of the product for a particular purpose; or (c) use of the till, subglacial outwash, advance outwash, proximal recessional outwash, H.; Malfait, Bruce; Masten, J.; Teague, G. O., 1965, Geophysical investigation of the Base map from scanned and rectified U.S. Geological Survey Belfair 7.5-minute 1 0.5 0 1 KILOMETER recognized and the strike of the fault is unconstrained, this fault is omitted on this the geologic boundaries from the map boundary. product or results obtained from use of the product. This product is considered to be exempt from the 3 and ice-dammed-lake sediment; gray to tan; loose to compact; typically southern Puget Sound area, Washington: Journal of Geophysical Research, v. 70, no. 22, p. quadrangle, 1999 101 map. Our mapping of the Sunset Beach scarps approximates that of Nelson and Geologist Licensing Act [RCW 18.220.190 (4)] because it is geological research conducted by the State of E R AUP forms geomorphologically complex patchwork of mounds, terraces, 5573-5580. Washington, Department of Natural Resources, Division of Geology and Earth Resources. Shaded relief generated from a lidar bare-earth digital elevation model (available from contour interval 20 feet TEN FAI LEY others (2009), but we added faint and questionable scarps and lineaments that we Qaf, Qoaf Alluvial fan—Silt, sand, gravel, and boulders; typically poorly sorted and LIW LAK Qaf BEL BUR incipient to fully developed channels, closed depressions, and erosional LIL WOO Derkey, R. E.; Hehemann, N. J.; Alldritt, Katelin, 2009, Geologic map of the Lake Wooten Puget Sound Lidar Consortium, http://pugetsoundlidar.ess.washington.edu/); 302 noted on lidar-derived images up to three miles northeast of the Sunset Beach scarps stratified; forms concentric lobes where streams emerge from confining sun azimuth 315°; sun angle 45°; vertical exaggeration 6 17° and that hint at possible northeast extension of the line of scarps. We also added faint exposures of older units; predominantly Vashon Drift but may also include 7.5-minute quadrangle, Mason County, Washington: Washington Division of Geology and 106 3 Tacoma fault zone valleys and reduced gradients cause sediment load to be deposited. Digital cartography and GIS by Anne C. Heinitz and J. Eric Schuster Seattle fault zone Qoaf older drift; shown where map scale or exposure do not support Earth Open-File Report 2009-5, 1 sheet, scale 1:24,000. H ON and questionable northwest-trending, conjugate(?) scarps and lineaments of unknown Subunit Qoaf identifies relict late Holocene (or in at least one instance H T FOX AND Tacoma fault zone stratigraphic division. Editing and production by Karen D. Meyers UNI MASONLAKE Easterbrook, D. J.; Crandell, D. R.; Leopold, E. B., 1967, Pre-Olympia Pleistocene VAUGHN ISL significance. Polenz and others (2009) noted additional northeast- and probably Vashon recessional) alluvial fans that resemble unit Qaf in every NOR stratigraphy and chronology in the central Puget Lowland, Washington: Geological ETIC northwest-trending lineaments east of the map area. Shelton TRUE NORT N Society of America Bulletin, v. 78, no. 1, p. 13-20. N NCH MAGN EIL The southwest end of the Sunset Beach scarps coincides with the 101 AXI APPROXIMATE MEAN LTO AND BRA AND MCN headscarp of the large Alderwood landslide. Sarikhan and others (2007) DECLINATION, 2009 SQUISL ISL SHE ONG L suggested coseismic slide initiation and speculated on a possible link to a Table 1. Age control data from the map area. Lab uncertainty values are one standard deviation (68% confidence interval) and include random errors that can be estimated by the lab but exclude sand sheet that covers mudflat deposits in Lynch Cove. Hemphill-Haley uncertainties that cannot be detected by the laboratory’s analytical procedures. 14C, radiocarbon analysis by liquid scintillation counting. 14C AMS, radiocarbon analysis by atomic mass spectrometry. (1996), Jovanelly and Moore (2005), and Jovanelly (2006) demonstrated a Analyses were performed by Beta Analytic, Inc. (Miami, FL). ‘14C yr B.P.’ signifies radiocarbon years before A.D. 1950. Radiocarbon ages are ‘conventional’ (that is, adjusted for measured 13C/12C ratio). We consider ‘finite’ age estimates in excess of 40,000 14C yr B.P. to be speculative because they are based on less than 0.8% of the original 14C content (see also notes to Beta 253255). Elevations are in feet marine source for the sand and inferred a tsunami, which Sarikhan and others Qgt 0 .25 mi 1 Qa 0 .25 mi above mean sea level, as estimated in this study using lidar data (supplemented by visual elevation estimates on bluffs) and referring to VERTCON (http://www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html) MAJOR FINDINGS (2007) speculated may have been driven by the landslide, although Qgd 0 25. km for vertical datum shifts between lidar data and map elevations. Qp 0 25. km Qgt • Faint scarps and lineaments and elevated relict beaches, stream terraces, and Bourgeois (2008) and her collaborator M. Elizabeth Martin (Univ. of Wash.) Loc Age estimate 13C/12C Analytical Material Geologic Elev. suggested that at least some of the sand may have resulted from liquefaction. Qgd Lab no. Notes alluvial fans may be due to post-glacial tectonic activity. no. (14C yr B.P.) (‰) method dated unit (ft) The mud flat and sand were abruptly uplifted by over 6.5 ft about 0.9 to 1.3 • The Seattle uplift may be responsible for exposure of relatively old(?) sediment ka (Bucknam, 1991; Bucknam and others, 1992; Bucknam and Biasi, 1994). Sampled from stiff silt in interbedded silt and sand below pre-Vashon sand; lab cautions that 2 Qgo Beta in the map area. Garrison-Laney (2003) suggested, on the basis of cedar snags rooted in a 1 43,560 ±820 -27.4 14C peat Qps1 40 due to low 14C activity, the conservative interpretation of the age is ‘infinite’ (too old to Suggested citation: Polenz, Michael; Alldritt, Katelin; Hehemann, 253255 14 buried soil in the same area, that the 1,100 14C yr B.P. event was followed by N. J.; Sarikhan, I. Y.; Logan, R. L., 2009, Geologic map of the estimate by C). • Weathered bedrock exposures a few miles north of the map area appear to have 4 subsidence, although the timing and rate of subsidence are unresolved. In Belfair 7.5-minute quadrangle, Mason, Kitsap, and Pierce Counties, contributed significantly to the polymictic sedimentary deposits in the map Qgt Washington: Washington Division of Geology and Earth Resources Outer growth rings of degraded, bark-free log horizontally sticking out of sand in river cutbank 14 14 Beta summary, the C data and geologic observations from the Sunset Beach Open File Report 2009-7, 1 sheet, scale 1:24,000. 2 290 ±40 -25.0 C AMS wood Qa 98 8 ft below ground surface and 1 ft above channel water (8-8-08); 2-sigma calibrated date area. 5 Qgt 253254 Qgt estimate A.D. 1480 to 1660. scarps, the Alderwood landslide, and Lynch Cove each suggest a tectonic • Ubiquitous subglacial channels and fluvial sediment are evidence that the event about 1.1 to 1.3 ka, and the data permit a single earthquake on the charred Charred organic matter, sampled by push core from ~3(?) ft (depth in boring poorly Beta Vashon Stade glacier stagnated at the end of the last glaciation. Sunset Beach scarps as common cause. We speculate that the deformation is Qgd 3a 540 ±40 -24 14C AMS organic Qls 174 constrained) below surface in sag pond; 2-sigma calibrated date estimate A.D. 1310 to 1360 and Qgic 229237 an expression of transpressional faulting in this part of the Seattle uplift, but matter 1390 to 14402. • Deposits associated with late Wisconsinan ice-dammed lakes are widespread in the map area and record several late-glacial lake levels. the exact location, character, and importance of individual structures is 14 wood Beta Wood from basal clay above till in sag pond, sampled by push core from ~4–5 ft below surface; 3b 1040 ±40 -25.5 C AMS Qls 172 2 poorly constrained. The considerable north-down offset suggested by fragments 229238 2-sigma calibrated date estimate A.D. 900 to 920 and 950 to 1040 . • Stagnant-ice deposits and subglacial erosion channels likely provide pathways Liberty’s (2005) seismic profile of the Sunset Beach scarps area also Qgt Qgas 1 Sample collected from unit Qps at the base of a cliff. The map displays unit Qpu at this location because map scale and perspective prohibit display of unit Qps. for near-surface water drainage and groundwater infiltration. suggests that another north-up structure, as yet unrecognized, may exist Qgo 2 Age estimate encompasses two discrete age ranges because the intensity of cosmogenic radionuclide input into the biosphere varies over time. An age estimate in radiocarbon years measures only the residual strength of the • Radiocarbon age data suggest that the Alderwood landslide, the Sunset Beach farther north in or near the map area, perhaps partly along the north side of 3 Site No. Site Name Unit Vs(30m) Quality radionuclide signal imparted in the sample (resulting in a single age range estimate in ‘radiocarbon years’). The conversion to calendar years based on tree -ring calibration reveals that two discrete age ranges in calendric Union River valley at the north end of the map area, where a straight valley Qgo years could have resulted in the measured residual signal strength. scarps, and Lynch Cove deformation may all have occurred simultaneously. 6 1 Davis Farm (lower) Qa 225 Good side nearly parallels the Sunset Beach scarps. Qgas 3 Qgt 2 Davis Farm (upper) Qgof 246 Good Sherrod and others (2003a, 2004) suggested that uplifted shorelines that Qgas Qgd we mapped as relict beaches (unit Qob) at North Bay may have resulted from 3 Belfair Park Qa 252 Good a large Tacoma fault earthquake between A.D. 770 and 1160. West of the bay Figure 2. The outwash channel (unit Qgo) in this image from 2.7 mi north of the Qgo 4 Sand Hill Elem. Qgic 373 Good 0 .25 mi southeast corner of the map must have formed subglacially because, like many at Sherwood Creek, a terrace composed of relict beach sediment with shell outwash channels in the map area, it begins abruptly in the upper right of the Qgic Qgt 5 Romance Hill Qaf / Qga 452 Fair 0 25. km Qgic Qa Geologic Map of the Belfair 7.5-minute Quadrangle, fragments is clearly elevated about 15 to 20 ft above the modern beach. The image and ends as abruptly in the lower left. This suggests that it emanated from Qgo 6 Kimberly Road Qgic 295 Good separation between this and the modern beach terrace is progressively subtler an ice mass and drained back into ice. More strikingly, in the lower left of the Figure 1. Subglacial drainage features on a fluted surface, southwest corner of Qgt Qgd image, the channel “jumps” a trough between two drumlins. The trough therefore Qgt Figure 4. Shear-wave velocity (Vs) profiles at six sites (see map). The profiles were surveyed by Washington Division of Geology and Earth farther north in North Bay and in places lacks a clear terrace riser. map and extending into adjacent quadrangles. A meandering, subglacial channel had to be ice-filled when the channel was active. The ice had to be stagnant Resources geologists Ray Cakir and Trevor Contreras. Velocity estimates are reliable to 15 m depth, less so below (Ray Cakir, oral commun., (1) with no apparent headwaters source cuts the convex-up surface of a Figure 3. Flutes in the map area (southwest-oriented in this image from 3.5 mi On the north shore of Hood Canal, elevated terraces that we interpreted because flowing ice would have destroyed such landforms. The channel surface 2009). The tabulated numeric velocity estimates for each site are for a depth of 30 m. While Vs profiles can be interpreted in multiple ways, each Mason, Kitsap, and Pierce Counties, Washington south-southwest-trending drumlin (2). At the south end of the drumlin, both the was mapped as unit Qgo not only to document outwash deposits, which may north-northwest of the southeast corner of the map) are commonly rippled as probable relict marine terraces (mostly mapped as unit Qob) are about 25 profile is consistent with the properties we would expect for the mapped and underlying geologic units at the profile sites. The lower Davis Farm channel and the drumlin lose definition (3) and topography becomes irregular, perpendicular to the ice flow direction, as illustrated by the northwest-trending locally be too thin to demand mapping, but also to set it apart from the adjacent and Belfair Park profiles (unit Qa) are marked by relatively low wave velocities that vary erratically with depth, consistent with heterogeneities, to 35 ft above the top of the modern beach terrace surface. We cannot rule suggesting dead-ice deposits more than a well-developed till surface. The ribs and troughs across a southwest-trending drumlin and an adjacent trough, unchannelized ice contact deposits (unit Qgic) and illustrate the influence of the such as gravel layers between sand. In contrast, unit Qgof (upper Davis Farm), although commonly appearing very similar to unit Qa where channel atop the drumlin is in turn incised by a smaller, narrow channel (4). The both of which extend from the upper right to the lower left of this image from 1 mi out a glaciolacustrine base level for these terraces or demonstrate that all stagnant ice throughout the map area on modern surface and groundwater exposed in the Union River valley, is marked by a smooth, gradual increase in velocity with depth, consistent with the homogeneous section of fine end of the inset channel (5) marks the beginning of a southeast-trending esker. north-northwest of Carney Lake. We do not know how these ripples formed, but share the same origin. At least some in the Union River valley are pathways. Geotechnical records and numerous wetlands document limits on sand to fines that one would expect from a lake bottom deposit. The Kimberly Road and Sand Hill Elementary profiles are compatible with by Michael Polenz, Katelin Alldritt, Nicholas J. Hehemann, Isabelle Y. Sarikhan, and Robert L. Logan The position of the channel end half-way up the flank of the drumlin suggests that they are widespread and distinctive in the map area. At least some are till-cored infiltration in the till-dominated and fluted uplands, but the widespread dead-ice properties of unit Qgic, which vary considerably across locations, as the upper 8 m at Kimberly Road is marked by variability much like Qa, geomorphically inseparable from surfaces on which we mapped glacial lake the esker may have been deposited by an englacial stream. At its southeast end, on both sides. Possible origins include (sub-ice) drainage or formation of deposits, channel incisions (the one shown is up to 50 ft deep), and other surface consistent with stratification within that part of the unit at that site, whereas the lower profile and that from Sand Hill Elementary present a this esker joins up with a longer, southwest-trending esker (6). Shaded relief chatter-marks by moving ice. Shaded relief generated from lidar using 6x vertical deposits (unit Qgof). More targeted study may be able to identify the origin modifications suggest that the aquitard is discontinuous. Shaded relief generated systematic increase in velocity with depth, consistent with a more uniform deposit. The Romance Hill profile starts in unit Qaf near the surface but generated from lidar using 6x vertical exaggeration, a vertical sun angle, and a exaggeration, a vertical sun angle, and a smooth multi-color ramp as proxy for of the terraces and the base level changes, but the presence on one such from lidar using 6x vertical exaggeration, a vertical sun angle, and a smooth quickly gains velocity with depth, which we attribute to compaction of the underlying unit Qga. July 2009 smooth multi-color ramp as proxy for elevation (brown is highest, lilac lowest). multi-color ramp as proxy for elevation (brown is highest, lilac lowest). elevation (brown is highest, lilac lowest). http://www.dnr.wa.gov/AboutDNR/Divisions/GER/ © 2009 Washington Division of Geology and Earth Resources