Identification_Information: Citation: Citation_Information: Originator: Derek B. Booth Originator: Kathy Goetz Troost Originator: Scott A. Shimel Originator: Philip Dinterman (database) Originator: John Spritzer(database) Originator: Matt Anders (database) Publication_Date: 2008 Title: GEOLOGIC MAP OF NORTHEASTERN SEATTLE (PART OF THE SEATTLE NORTH 7.5 X 15-MINUTE QUADRANGLE), KING COUNTY, WASHINGTON Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: Part of the Seattle North, WA 7.5 x 15-minute quadrangle (informally, the Seattle Northeast quadrangle) Online_Linkage: \\typhoon.wr.usgs.gov\esp2\wells12\data\wa\seattle\seattle_NE\SeattleNEforRelease\Seattle_NE.mdb Description: Abstract: This map database, compiled from new mapping, represents the general distribution of surficial deposits in the west part of the Seattle North, WA 7.5 x 15-minute quadrangle (informally, the Seattle Northeast quadrangle). The map delineates units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source map limits the spatial resolution (scale) of the database to 1:12,000 or smaller. Purpose: General-purpose geologic map at 1:12,000 scale. Provides geologic information for the regional study of materials properties, earth history, water resources, earthquake shaking hazards, landslide hazards, and mineral resources. Supplemental_Information: GEOLOGIC SUMMARY INTRODUCTION The east part of the Seattle North quadrangle (informally, the Seattle NE quadrangle) covers nearly half of the City of Seattle and reaches from Lake Washington across to the Puget Sound shoreline. Land uses are mainly residential, but extensive commercial districts are located in the Northgate neighborhood, adjacent to the University of Washington, and along the corridors of Aurora Avenue and Lake City Way. Industrial activity is concentrated along the Ship Canal and around Lake Union. Two small pieces of land outside of the quadrangle boundaries, one in the northwest corner of the Seattle North quadrangle and the other on the east edge of the Bellevue North quadrangle, are included on the present map for geographic coherence. Similarly, a small area in the northeast corner of this quadrangle, but lying on the east side of Lake Washington, is excluded from the present mapped area. Within the boundaries of this quadrangle are located two large urban lakes, including the most heavily visited park in the state of Washington (Green Lake); a stream that still hosts anadromous salmon despite its headwaters in a golf course and a shopping center (Thornton Creek); parts of three cities, with a combined residential population of about 300,000 people; and the region's premier research institution, the University of Washington. The northern boundary of the quadrangle is at about NE 168th Street in the cities of Shoreline and Lake Forest Park, the southern boundary corresponds to Mercer Street in Seattle; the western boundary is 15th Avenue W (and NW), and the eastern boundary is formed by Lake Washington. Elevations range from sea level to a maximum of 165 m, on a broad till-covered knob in the city of Shoreline in the northwest corner of the map area. Previous geologic maps of this area include those of Waldron et al. (1962), Galster and Laprade (1991), and Yount et al. (1993). Seattle lies within the Puget Lowland, an elongate structural and topographic basin between the Cascade Range and Olympic Mountains. The Seattle area has been glaciated repeatedly during the past two million years by coalescing glaciers that advanced southward from British Columbia. The landscape we see today was molded by cyclic glacial scouring and deposition and later modified by landsliding and stream erosion. The last glacier reached the central Puget Sound region about 14,500 years ago, as measured by 14C dating, and had retreated from this area by 13,650 14C years B.P. (Porter and Swanson, 1998). Seattle now sits atop a complex and incomplete succession of interleaved glacial and nonglacial deposits that overlie an irregular bedrock surface. These glacial and nonglacial deposits vary laterally in both texture and thickness, and they contain many local unconformities. In addition, they have been deformed by faults and folds, at least as recently as 1,100 years ago, further complicating the geologic record. The landforms and near-surface deposits that cover much of the Seattle NE quadrangle record a relatively brief, recent interval of the region's geologic history. The topography is dominated in the north by a broad, fluted, and south-sloping upland plateau, which gives way to a more complex set of elongated hills in the quadrangle's southern half. The valleys of Pipers Creek, Green Lake, and Thornton Creek mark the transition between these two topographic regions. Most of the uplands are mantled by a rolling surface of sand (unit Qva) and till (unit Qvt) that was deposited during the last occupation of the Puget Lowland by a continental ice sheet. Beneath these ice-sheet deposits is a complex succession of older sediments that extends far below sea level across most of the quadrangle. These older sediments are now exposed where modern erosion and landslides have sliced through the edge of the upland, and where subglacial processes apparently left these older sediments largely free of overlying sediments. This latter condition is particularly evident on the hillslopes above Thornton Creek, adjacent to Lake Washington, and on the flanks of Capitol Hill. STRATIGRAPHY AND HISTORY Bedrock Eocene to Miocene volcanic and sedimentary rocks deposited as forearc basin fill underlie the entire east-central Puget Lowland (Yount and Gower, 1991; Tabor et al., 2000). Across much of the Seattle NE quadrangle, bedrock lies beneath 400 to 500 m of unconsolidated sediments, but it drops to over 1000 m below the modern ground surface in the southern part of the map area (Jones, 1996). The closest outcropping bedrock lies about 8 km to the southwest on Alki Point in the Seattle SW quadrangle. Quaternary Stratigraphic Framework At least 7 invasions of glacial ice and alternating nonglacial intervals have left a discontinuous geologic record in the Puget Lowland (Blunt et al., 1987; Booth et al., 2004). Originating in the mountains of British Columbia, the ice was part of the Cordilleran ice sheet of northwestern North America. During each successive glaciation, it advanced into the lowland as a broad tongue named the Puget lobe by Bretz (1913). In an area where each glacial and interglacial depositional sequence looks alike, differentiating them requires laboratory analyses and age determinations (Troost, 1999). Different depositional environments yielded distinctly different deposits. The following glacial deposits are commonly recognized across the Puget Lowland: (1) proglacial lacustrine silts and clays from the damming of the Strait of Juan de Fuca; (2) advance outwash sand and gravel deposited by streams exiting the front of the advancing glacier; (3) till-a heterogeneous mixture of silt, sand, gravel, and clay-deposited under and along the margin of the glacier; (4) recessional-outwash sand and gravel deposited as the ice melted northward; (5) recessional lake deposits of silt and sand; and (6) glaciomarine drift (sandy, clayey silt with dropstones) deposited as marine water inundated the isostatically depressed land and floated distal parts of the Puget lobe. All of the foregoing deposits, except glaciomarine drift, have been recognized in the Seattle NE quadrangle. Nonglacial deposit types include peat; volcanic ash and volcanogenic mudflows; and lake, river, and beach deposits. Deposits and Landforms Predating the Vashon Stade of the Fraser Glaciation Nearly all stratigraphic units predating the Vashon stade of the Fraser glaciation are identified on the map as either Pre-Fraser (unit Qpf) or (more specifically) pre-Olympia deposits (unit Qpo). With one exception, we have not subdivided pre-Fraser deposits into named units, because absolute age control is sparse and so the risk of spurious correlation is high. The Olympia nonglacial interval was originally defined by Armstrong et al. (1965) as "the climatic episode immediately preceding the last major glaciation, and represented by nonglacial strata beneath Vashon Drift." The Olympia beds accumulated across the Puget Lowland between about 70,000 years B.P. and 15,000 years B.P. (Troost, 1999); this interval closely approximates the temporal limits for oxygen isotope stage 3 (Winograd et al., 1997) and immediately predates the Fraser glaciation (stage 2). Deposits of unequivocal Olympia age are mapped at only one location in the Seattle NE quadrangle, on the northeast face of Capitol Hill overlooking Portage Bay, on the basis of a radiocarbon date obtained from an immediately adjacent borehole drilled for a light-rail tunnel (20,500±220 yr B.P.; BETA-119399, Table 1). Elsewhere in the quadrangle, the presence of Olympia beds is suggested, but not required, by sporadic deep borings and hillside exposures. Good outcrops are few and no material has been dated at these localities; consequently, the more general unit designator Qpf is used unless pre-Vashon glacial material requires a pre-Olympia age (unit Qpo). In borings, the presence of unit Qpf beneath the silt- and clay-rich Lawton Clay Member of the Vashon Drift (unit Qvlc) is inferred from the appearance of abundant sandy or gravelly interbeds. Although the upper contact of unit Qpf is generally ill-exposed due to overlying landslide debris and/or fill, we have constrained its mapped position by determining its elevation in nearby boreholes and projecting it out to the ground surface at constant elevation. Along the Puget Sound coastline on both this and the adjacent Seattle NW quadrangle, the maximum elevation of this contact is typically below about 30 m, rising to as high as 50 m only near the north map boundary. On the east side of the quadrangle above Lake Washington, maximum altitudes are modestly higher (75 m), but south of the Ship Canal and just east of Lake Union this contact rises to as much as 105 m, reflecting a prominent hill in the pre-Vashon topography with a relatively abrupt north-facing slope. Deposits of the Vashon Stade of Fraser Glaciation The most recent glacial advance, the Vashon stade of the Fraser glaciation (Armstrong et al., 1965), was marked by the advance and retreat of the Puget lobe of the Cordilleran ice sheet in western Washington. The glacier advanced to the central Puget Lowland about 14,500 14C years B.P. and retreated back past this area by 13,650 14C years B.P.; at its maximum, Seattle was buried by at least 900 m of ice (Booth, 1987). The modern landscape is largely the result of deposition and scouring by the Vashon glacier, and it has been only slightly modified by more recent activity of streams, wave erosion, landsliding, tectonic deformation, and volcanic events. In contrast to uncertainties in age and stratigraphic assignment of older Pleistocene deposits, the deposits at or near the constructional land surface are readily assigned to the youngest regionally recognized glacial advance, the Vashon stade. These deposits vary in both grain size and topographic expression, owing to rapidly changing depositional environments caused by the advance and retreat of the ice sheet. The leading edge of the advancing ice sheet blocked northward lowland drainage out the Strait of Juan de Fuca, which now connects Puget Sound with the Pacific Ocean. In the impounded lake that subsequently formed, laminated silt and clay were deposited. This material has been mapped as Lawton Clay (unit Qvlc), of which coastal bluff exposures immediately west of the quadrangle constitute the type section (Mullineaux et al., 1965). In this quadrangle, we have assigned deposits of silt and rare clay to unit Qvlc on the basis of proximity to the type section, stratigraphic position, and the presence of dropstones. Other fine-grained deposits throughout the quadrangle are more conservatively assigned to unit Qpf, although some of these are probably correlative as well. Coarser outwash (unit Qva) marks direct, active ice-sheet deposition by streams flowing from the advancing glacier. The broad uplands of the central part of the quadrangle are underlain by at least a few tens of meters of sandy advance outwash, exposed wherever overlying deposits are absent or incised by subsequent erosion. The maximum thickness of Qva is determined by both modern and pre-Vashon topography: in the northwest corner of the map area, it us about 60 m think; in the southwest corner on Queen Anne Hill is over 90 m think; and on Capitol Hill, it is locally absent altogether. The outwash inundated the pre-Vashon topography of the lowland and resulted in a south-sloping surface that is now about 150 m elevation at this latitude across the Puget Lowland (Booth, 1994), an elevation approached by surface exposures of Qva in several localities near the northwest and southeast corners of the quadrangle and on Queen Anne Hill. Elsewhere it displays lower maximum elevations owing to synglacial and postglacial erosion. As ice covered the region, till (unit Qvt) was deposited by the melt-out of debris at the base of the glacier. The ground surface underlain by both advance outwash and till is pervasively fluted with elongated hills throughout the quadrangle, uniformly oriented north-south (azimuth ~179o) extending almost the full north-south extent of the map area. They are interrupted but not diverted by the cross-cutting valleys of Thornton Creek and Ravenna Creek, and by the broad depression of Green Lake. Glacial fluting is not limited to till-covered areas, suggesting that many of the surfaces underlain by advance outwash (unit Qva) or older units represent regions where till was never deposited, or deposited and removed while still ice-covered. Till is very common, however, blanketing almost 60 percent of the land surface of the quadrangle and providing a low-permeability cover to underlying aquifers that reduces infiltration and groundwater recharge but also offers protection from surface contaminants. Till thicknesses average about 3 m across the map area. The matrix of the till differs from place to place in relative proportions of silt, sand, and sparse clay. The till mostly is gravelly silty sand to gravelly sandy silt, and in many places it is crudely stratified and contains lenses of sand, gravel, and silt. Cobbles and boulders are scattered throughout the till; boulders more than 3 m in diameter are rare. Unoxidized till is light gray and compact; where oxidized, till is light yellowish gray and is generally medium dense. Although a weak brown soil is developed on the till, oxidation rarely extends more than about a meter into the deposit. Vashon till is typically very dense with a fine-grained matrix, but common structural or straigraphic discontinuities locally increase its permeability by several orders of magnitude, allowing faster transmission of water and contaminants. Depending on subglacial conditions at the time the till was formed and post-depositional strain, the discontinuities locally consist of intercalated sand and silt layers, bedding planes, and/or joints. Shortly after 14,500 (radiocarbon) years ago the ice margin, which extended more than 50 km south of the map area, began to melt back. Meltwater from the ice sheet and runoff from the Cascade Range drained southward and westward, spilling over divides that were later abandoned as ice pullback exposed lower divides farther north. By the time that the Seattle NE quadrangle was uncovered by the retreating ice, proglacial drainage was well established across most of the eastern and southern lowland. Water inundated much of the central and southern Puget Lowland, including the quadrangle, because more than one thousand meters of glacial ice still filled the Strait of Juan de Fuca. The first of the two main recessional lakes occupying the lowland (Glacial Lake Russell) drained out through the Black Hills into the Chehalis River, many tens of kilometers to the south of the quadrangle (Thorson, 1980). Although the elevation of the Black Hills spillway was only about 41 m in elevation, the shoreline of Glacial Lake Russell is now higher because the land surface of the Puget Lowland has rebounded following the removal of the weight of the ice sheet. More rebound occurred in the north than in the south, because the ice sheet was thicker to the north. The Seattle NE quadrangle became ice-free during the existence of Glacial Lake Russell. In the center of the Seattle NE quadrangle rebound has been about 45 m, and so the shoreline of Glacial Lake Russell should be found today at nearly 90 m elevation. Most of the quadrangle, particularly north and northeast of the trough formed by the valleys of Pipers Creek, Green Lake, and Ravenna Creek, lies above this elevation. Outwash channels are prominent at about this altitude, notably the valley occupied by Aurora Avenue N near Northgate and the valley of the northwest branch of Thornton Creek just east of Interstate 5. Lake-bottom topography dating from this interval is suggested by extensive peat deposits at elevation 78 m, forming the headwaters of the west branch of Thornton Creek and the foundation of the Northgate Shopping Center. Ice-contact deposits, likely marking an active or stagnant ice front during this recessional interval, lie at the head of these channels at altitudes of 105-120 m. A third large ice-contact deposit heads a northwest-draining channel that now feeds Boeing Creek, in the northwest corner of the map. The second regional water body, Glacial Lake Bretz, was formed when ice retreated far enough north to uncover a lower spillway on the northeast corner of the Olympic Peninsula (Thorson, 1989). As with Glacial Lake Russell, the shoreline of Lake Bretz now slopes southward because of differential rebound. In the Seattle NE quadrangle, the calculated elevation of the lake surface ranges from about 37 m (south) to 47 m (north). Glacial Lake Bretz likely did not persist for more than a few decades because of rapid rates of glacier retreat (Porter and Swanson, 1998). Several prominent channels were exposed by the lake lowering, including a broad trough between Pipers Creek and Green Lake, occupied by extensive peat deposits underlying part of the Greenwood neighborhood, and an extensive ice-contact deposit south of NE 95th Street along the valley followed by 25th Avenue NE, possibly reflecting the collapse of a floating ice shelf upon drainage of Glacial Lake Russell. A spectacular 8-m boulder erratic marks the eastern edge of this deposit at elevation 89 m, at the intersection of NE 72nd Street and 28th Avenue NE. Although thick lake deposits associated with this regional lake are not generally observed, a lacustrine deposit at the southern edge of the quadrangle, at the head of a later outwash channel (see below) in the Washington Park Arboretum, almost certainly dates from this time. Further retreat of the ice sheet reconnected Puget Sound to the open ocean, allowing regional water levels to fall by an additional 40 m (Thorson, 1989). Thus the late-glacial marine limit falls near the southern edge of the Seattle NE quadrangle-farther south, any deposits associated with this recessional stage are now submerged below modern sea level, because isostatic rebound was exceeded by postglacial eustatic sea-level rise. Recessional deposits in the quadrangle dating from this interval are probably those mapped at low elevations along the Ship Canal and forming the valley of the Washington Park Arboretum near the southeast corner of the map. Postglacial Processes and Deposits Geologic activity since glaciation includes soil formation, widespread mass failure and cliff retreat, stream-channel erosion, and tectonic deformation. As a result of the lowered base level occasioned by drainage of Glacial Lake Bretz, several streams in the quadrangle began to incise through the sequence of glacial and nonglacial deposits that underlies the upland surface. In the quadrangle, Thornton Creek, Pipers Creek, Boeing Creek, and Ravenna Creek have all incised to their modern base level (i.e. lake level or sea level). On the upland surface, soil formation since deglaciation has proceeded slowly but with locally profound hydrologic consequences. The first meter or so beneath the ground surface usually consists of topsoil underlain by silty weathered parent material, colluvium, or fill. Where Vashon till is present, the unweathered deposit absorbs water only very slowly; in contrast, the meter or so of till-derived "Alderwood" soil (Snyder et al., 1973) that has developed since deglaciation has high infiltration capacities and a large capacity to store and slowly release subsurface runoff. The compaction or removal of that soil during typical urban development, however, has resulted in correspondingly dramatic hydrologic effects. Several recent projects by the City of Seattle, in the Broadview neighborhood on the till-mantled uplands just east of the valley of Pipers Creek, are seeking to reduce stormwater runoff from this surface by amending the remnant soil with compost to increase its water-retention capacity. On areas underlain by Vashon advance outwash (unit Qva), however, infiltration through both the soil and the parent material is relatively fast. Water permeates rapidly into the sand and then moves downward to the top of an underlying fine-grained unit, either the Lawton Clay (unit Qvlc) or older deposits of pre-Fraser age (unit Qpf). Groundwater then moves laterally to the steep hillsides along the coast and in deep ravines, where it emerges as springs (Tubbs, 1974). In general, steep slopes with fine-grained deposits overlain by coarse-grained deposits are particularly susceptible to landslide failure. This mass-wasting condition is found in most of the steeply sloping parts of the map area. Colluvium and other mass-wasting deposits are widespread; they are shown with a stippled overlay patterns on the map only where more than a few meters thick, sufficient to alter ground-surface topography or obscure the underlying deposits. Several zones of landsliding in the Seattle NE quadrangle, however, are quite extensive. The largest of these slide zones follow the Puget Sound coastline north to the edge of the quadrangle and beyond, ring most of Queen Anne Hill, flank the north end of Capitol Hill, and overlook nearly 3 km of Lake Washington shoreline. Because the slide faces are relatively steep they have not generally been the site of extensive development, but structures at the base of these areas, particularly along Lake Washington and the east slope of Queen Anne Hill, have suffered from falling debris during wet winters throughout the last century. Mapped slide localities along the Puget Sound coastline from the winter of 1996-1997 (Baum et al., 2000) and point localities of all slides on file with the city through 1999 (Shannon and Wilson, 2000) are included on this map for reference. Human Modification of the Landscape To varying degrees, nearly the entire quadrangle has been modified by human activity-either by the addition of fill, by extensive grading, or by the reconstruction of the Lake Washington drainage outlet. Although minor regrading of the land surface is common in almost any urban area, changes to the gross topography of Seattle during the early 20th century were dramatic in scope. Denny Hill, occupying the land between Lake Union and Elliott Bay (mainly on the adjoining Seattle SE quadrangle), separated the downtown shorelands from the rest of the city to the northeast. Over 4 million m3 of sediment were sluiced by hydraulic jets and by electric shovels between 1903 and 1928, opening a broad corridor of gently sloping land along the south boundary of the quadrangle, and simultaneously providing much of the fill used to expand the area of land immediately west and south of the downtown core (Morse, 1989; Galster and Laprade, 1991). Other areas of extensive modified and/or filled land include the burial of much of length of Ravenna Creek, both its past headwater connection with Green Lake and its outlet connection to Lake Washington; filling and grading associated with Interstate 5; filling of the alluvial valley bottom of Salmon Creek (now the Ship Canal west of Lake Union); and the grading for State Highway 99 (Aurora Avenue) through the landslide complex of east Queen Anne Hill. Delineation of mapped fills is not entirely consistent across the quadrangle, however, because not all such deposits have been identified by exploration sites, and because relatively isolated occurrences associated with individual building sites have not generally been noted. The distribution of the overprint units m, gr, and af, therefore, should be taken only as descriptive of the extent of human modification and neither definitive nor complete. Between 1911 and 1916, Lake Washington was lowered by 3 m following the dredging of the now-submerged valley of "Salmon Creek," west of Lake Union, and excavation of the Montlake Cut across a once-continuous rib of till extending from the University District south to Capitol Hill (Chrzastowski, 1983). This grading exposed extensive peat and lake-bottom deposits that have since been largely filled and covered with shoreline development. The largest of the in-city garbage landfills, that at Montlake, filled about 200 acres of exposed marshland between 1926 and 1966 (Seattle-King County, 1984); it is now host to a naturalize wetland area and athletic fields. Other landfills in the quadrangle include four areas around Green Lake, a site just west of Haller Lake, and a partly filled ravine at the south end of the Washington Park Arboretum. Regional Structure and Recent Seismicity The entire map area of the Seattle NE quadrangle lies within the "Seattle basin," the deepest of the structural blocks formed in western Washington in Tertiary time as a result of N-S shortening in Oregon and Washington (Pratt et al., 1997; Wells et al., 1998). The east-west Seattle fault zone forms the border between the Seattle basin (north) and the Seattle uplift (south), passing through Seattle 8-10 kilometers south of the southern boundary of the Seattle NE quadrangle (Troost et al., in press). During a great earthquake 1100 years ago, land of the adjacent Seattle NW quadrangle dropped by as much as 1 m as displayed by sub-sea-level deposits exposed by construction excavations at a regional wastewater treatment plant (Atwater and Moore, 1992). Map Summary and Acknowledgements This map is the fourth and final geologic map prepared for the City of Seattle using a larger scale and enhanced level of detail than previously available. Geologic relations shown on this map are based on several sources, including new field mapping of outcrops and excavations, subsurface data compiled in an accompanying database, topographic and geomorphic analyses, and the pre-existing geologic map of the Seattle area (Waldron et al., 1962). Across most of the area, geologic contacts and lithologic descriptions have changed from the previous map as a result of the dramatic increase in construction-related data and a revised understanding of the regional stratigraphic framework of the Puget Lowland. Particular acknowledgments are due our colleagues who have shared geologic data, insights, and interpretations throughout the current period of mapping: the Seattle Geologic Mapping Project Technical Advisory Group; William T. Laprade (Shannon & Wilson, Inc.); Brian Atwater, Thomas Brocher, Ralph Haugerud, Samuel Johnson, Brian Sherrod, Craig Weaver, and Ray Wells (USGS); and Timothy Walsh (Washington State Department of Natural Resources). Numerous personnel from the City of Seattle, including Kaveh Aminian, Bob Chandler, Ken Conradi, John Ege, Rich Folsom, Dean Griswold, Craig Ladiser, Rob McIntosh, Tom Nolan, Art Richardson, and Brian Smith provided financial support, guidance, and data for the subsurface data compilation. Michael O'Neal (University of Washington) provided ArcView and cross section tools. UW students were invaluable in collecting and entering data: Alyssa Beck, Chris Converse, Sharon Davis, Karen Dubose, Jake Fryer, Lori Greene, Douglas Hathaway, Karin Knudsen, Crystal Mann, Elizabeth Meeks, Suzanne Osborne, and Constance Rehfuss. The mapping and associated database were completed by the Center for Pacific Northwest Geologic Mapping Studies at the University of Washington, a collaborative effort of the University, the City of Seattle, and the U.S. Geological Survey. REFERENCES CITED Armstrong, J.E., Crandell D.R., Easterbrook, D.J., and Noble J.B., 1965, Late Pleistocene stratigraphy and chronology in southwestern British Columbia and northwestern Washington: Geological Society of America Bulletin, v. 76, p. 321-330. Atwater, B.F, and Moore, A.L., 1992, A tsunami about 1000 years ago in Puget Sound, Washington: Science, v. 258, p. 1614-1617. Baum, R.L., Harp, E.L., Hultman, W.A., 2000, Map showing recent and historic landslide activity on coastal bluffs of Puget Sound between Shilshole Bay and Everett, Washington: U.S. Geological Survey Miscellaneous Field Studies Map MF-2346, 1 sheet, scale 1:24,000. Blunt D.J., Easterbrook, D.J., and Rutter, N.W., 1987, Chronology of Pleistocene sediments in the Puget Lowland, Washington: Washington Division of Geology and Earth Resources Bulletin 77, p. 321-353. Booth, D.B., 1987, Timing and processes of deglaciation along the southern margin of the Cordilleran ice sheet: In W.F. Ruddimann and H.E. Wright, Jr., eds., "North America and adjacent oceans during the last deglaciation" Boulder, Colorado, Geological Society of America, Geology of North America, v. K-3, p. 71-90. Booth, D.B., 1994, Glaciofluvial infilling and scour of the Puget Lowland, Washington, during ice-sheet glaciation: Geology, v. 22, p. 695-698. Booth, D. B., Troost, K. G., Clague, J. J., and Waitt, R. B., 2004, The Cordilleran ice sheet: Chapter 2 in Gillespie, A., Porter, S. C., and Atwater, B., eds., The Quaternary Period in the United States: International Union for Quaternary Research, Elsevier Press, p. 17-43. Bretz, J H., 1913, Glaciation of the Puget Sound region: Washington Geological Survey Bulletin No. 8, 244 p. Chrzastowski, M.J., 1983, Historical changes to Lake Washington and route of the Lake Washington Ship Canal, King County, Washington: U.S. Geological Survey Water-Resources Investigations Report 81-1182, 9 p., 1 sheet, scale 1:24,000. Galster, R.W., and Laprade, W.T., 1991, Geology of Seattle, Washington, United States of America: Bulletin of the Association of Engineering Geologists, vol., 28, no. 3 (supplement), p. 239-302. Jones, M. A., 1996, Thickness of unconsolidated deposits in the Puget Sound Lowland, Washington and British Columbia: U. S. Geological Survey Water-Resources Investigations Report 94-4133, scale 1:455,000. in Galster, R.W. (chair), Engineering Geology in Washington: Washington Division of Geology and Earth Resources, Bulletin 78, p, 691-701. Mullineaux, D.R., Waldron, H.H., and Rubin, M., 1965, Stratigraphy and chronology of late interglacial and early Vashon time in the Seattle area, Washington: U.S. Geological Survey Bulletin 1194-O, 10 p. Porter, S.C., and Swanson, T.W., 1998, Radiocarbon age constraints on rates of advance and retreat of the Puget lobe of the Cordilleran ice sheet during the last glaciation: Quaternary Research, v. 50, p. 205-213. Pratt, T.L., Johnson, S.Y., Potter, C.J., Stephenson, W.J., Finn, C.A., 1997, Seismic reflection images beneath Puget Sound, western Washington State; the Puget Lowland thrust sheet hypothesis: Journal of Geophysical Research, B, Solid Earth and Planets, v. 102, p. 27,469-27,489. Seattle-King County, 1984, Abandoned landfill study in the City of Seattle: Seattle-King County Department of Public Health, July 30, 1984, 121 p. Shannon & Wilson, Inc., 2000, Seattle Landslide Study, for Seattle Public Utilities: 164 p., with map folio and Seattle landslide database. Snyder, D.E., Gale, P.S., and Pringle, R.F., 1973, Soil survey of King County area, Washington: U.S. Department of Agriculture, Soil Conservation Service, 100 p. Tabor, R.W., Frizzell, V.A., Jr., Booth, D.B., Waitt, R.B., 2000, Geologic map of the Snoqualmie Pass 30 x 60 minute quadrangle, Washington: U.S. Geological Survey Geologic Investigations Series I-2538, 1 sheet, scale 1:100,000, 57 p. Thorson, R.M., 1980, Ice sheet glaciation of the Puget Lowland, Washington, during the Vashon stade (late Pleistocene): Quaternary Research, v. 13, p. 303 321. Thorson, R.M., 1989, Glacio-isostatic response of the Puget Sound area, Washington: Geological Society of America Bulletin, v. 101, p. 1163 1174. Troost, K.G., 1999, The Olympia nonglacial interval in the southcentral Puget Lowland, Washington: M.S. thesis, University of Washington, 123 p. Tubbs, D.W., 1974, Landslides in Seattle: Olympia, WA, Washington Division of Geology and Earth Resources Information Circular 52, 15 p. Waldron, H.H., Liesch, B.A., Mullineaux, D.R., and Crandell, D.R., 1962, Preliminary geologic map of Seattle and vicinity, Washington: U.S. Geological Survey Miscellaneous Investigations Map I-354, scale 1:31,680. Wells, R.E., Weaver, C.S., and Blakely, R.J., 1998, Fore-arc migration in Cascadia and its neotectonic significance: Geology, v. 26, no. 8, p. 759-762. Winograd, I.J., Landwehr, J.M., Ludwig, K.R., Coplen, T.B., and Riggs, A.C., 1997, Duration and structure of the past four interglaciations: Quaternary Research, v. 48, p. 141-154. Yount, J.C., and Gower, H.D., 1991, Bedrock geologic map of the Seattle 30' by 60' quadrangle, Washington: U.S. Geological Survey Open-File Report 91-147, scale 1:100,000. Yount, J.C., Minard, J.P., and Dembroff, G.R., 1993, Geologic map of surficial deposits in the Seattle 30' by 60' quadrangle, Washington: U.S. Geological Survey Open-File Report 93-233, scale 1:100,000. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2008 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -122.383522 East_Bounding_Coordinate: -122.241584 North_Bounding_Coordinate: 47.751633 South_Bounding_Coordinate: 47.622526 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: geology Theme_Keyword: surficial geology Theme_Keyword: geologic history Place: Place_Keyword: Seattle Northeast Place_Keyword: King County Place_Keyword: Washington Place_Keyword: Pacific Northwest Place_Keyword: Puget Lowland Temporal: Temporal_Keyword: Quaternary Access_Constraints: None Use_Constraints: DIGITAL COMPILATION Several different feature classes were generated within a geodatabase during the construction of the Northeastern Seattle (Part of the Seattle North 7.5 x 15-minute quadrangle) map area. The LiDAR base map remains as a digital grid and is overlain on the geology feature class in ArcMap at a 70% transparency level. Some custom menus were used to project, transform, edit, tag, and build points in the map. A digital layout or map collar was made with Adobe Illustrator. The map was exported from the layout view in ArcMap as an Adobe Illustrator file, rotated clockwise 1.1 degrees and added to a single Adobe Illustrator file that also contained the description of map units, correlation of map units, cross sections, stratigraphic section, two data tables and a geologic summary. Differences between the maps as they appear in the final map sheet and as they appear in the either the .mxd or .pmf files represent changes made in the Adobe Illustrator file to the symbology only and do not reflect any changes in the actual source data. The map is in State Plane, Washington projection, NAD 83, North, FIPS 4601, feet, and 1:12,000 scale. BASE MAP The base map for the digital compilation is a shaded relief map from Digital Elevation Model (DEM) created with the Light Detection and Ranging (LiDAR) data at 4x vertical exaggeration, a sun azimuth at 45 degrees, and sun vertical angle at 45 degrees. The LiDAR data was acquired from the Puget Sound LiDAR Consortium and King County Endangered Species Act/Sensitive Areas Ordinance, LiDAR Digital Ground Model (DGM), 2001-2003. Horizontal accuracy is ~1.8 meters; vertical accuracy is ~0.3 meters. Street data was extracted from City of Seattle, WA, 1:1200-scale proprietary street data, 2001. Horizontal accuracy is ~1.5 meters. SPATIAL RESOLUTION Uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was edited at a scale of 1:12,000 means that higher resolution information is not present in the dataset. Plotting at scales larger than 1:12,000 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. Data_Set_Credit: Geology by Derek B. Booth, Kathy Goetz Troost and Scott Shimel. Digital database by Scott A. Shimel, Philip Dinterman, Matt Anders, John M. Spritzer Native_Data_Set_Environment: Microsoft Windows XP Professional, Service Pack 2; ESRI ArcInfo 9.2; ESRI ArcCatalog 9.2 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The accuracy with which earth materials are classified by this map is unquantified. We believe it to be very good relative to previously published surficial geologic maps of the region; significantly better than (for example) that of Waldron et al.,(1962, Preliminary Geologic map of Seattle and vicinity, Washington: U.S. Geological Survey Map I-35, scale 1:31,250). Sophisticated readers will note that map units are chosen to minimize potential misclassification of the age of materials. In the upland regions of the quadrangle, limited outcrop and sparse subsurface data limits our ability to separate recessional outwash (Qvr, Qvrl) from advance outwash (Qva). We suspect that confusion between these units is more common than other misclassifications. Logical_Consistency_Report: No unlabelled polygons No unlabelled arcs No topology errors Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Rarely is the locational accuracy of features on geologic maps precisely defined and this map is no exception. The circa 10 meters spatial precision of the digitization process provides a lower bound on the error with which features are located by this map. Many geologists understand that well-located (continuous line) contacts and faults should be within a millimeter or so on the map from their correct location. At 1:12,000 scale, the nominal scale of these data, one millimeter of locational error on the map corresponds to 12 meters on the ground. This may approximate the accuracy with which many features are located. We note that on the steep bluffs of this quadrangle, map features have commonly been located by elevation. They are thus shown here with a positional accuracy that corresponds to the circa +/- 10 meter (vertical) reproducibility of routine elevation determinations with a pocket barometer, locally supplemented with elevations determined from the road grid or reported in subsurface exploration logs. In the upland regions of the quadrangle, contacts between till (Qvt) and recessional and advance outwash (Qvr, Qvrl, Qva) are commonly quite difficult to observe, due to limited outcrop and extensive regrading and paving. They are also locally gradational. These contacts are in many places located with a horizontal precision no better than 100-200 meters. Lineage: Process_Step: Process_Description: Derek Booth plotted geologic contacts directly on the computer screen, using as a backdrop (1) 2-foot topographic contours provided by the City of Seattle, (2) spot locations of all field stations and of subsurface explorations archived in a separate database, (3) road edges and building outlines from the City of Seattle, (4) vertical orthophotos, and (5) a shaded digital elevation model of the Seattle topographic data. Proof plots were inspected and revised on paper by Booth and other coauthors. The intrinsic locational error (digitized lines relative to map base) of this process is potentially as small as 1 meter, though in practice it is commonly as large as 3 meters. Process_Step: Process_Description: Metadata imported. Source_Used_Citation_Abbreviation: C:\DOCUME~1\JSPRIT~1\LOCALS~1\Temp\xml656.tmp Process_Step: Process_Description: Dataset copied. Source_Used_Citation_Abbreviation: Q:\wa\seattle\seattle_NE\SeattleNEforRelease\Seattle_NE.mdb Process_Step: Process_Description: Dataset copied. Source_Used_Citation_Abbreviation: Q:\wa\seattle\seattle_NE\Seattle_NE.mdb Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: String Point_and_Vector_Object_Count: 196 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Label point Point_and_Vector_Object_Count: 120 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains Point_and_Vector_Object_Count: 120 SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 4 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Lambert Conformal Conic Lambert_Conformal_Conic: Standard_Parallel: 47.500000 Standard_Parallel: 48.733333 Longitude_of_Central_Meridian: -120.833333 Latitude_of_Projection_Origin: 47.000000 False_Easting: 1640416.666667 False_Northing: 0.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 0.000313 Ordinate_Resolution: 0.000313 Planar_Distance_Units: survey feet Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Resolution: 0.25000 Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEContacts Entity_Type_Definition: Geologic Contacts Entity_Type_Definition_Source: Author Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: LTYPE Attribute_Definition: Geologic Contacts Attribute_Definition_Source: Author Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: contact, certain Enumerated_Domain_Value_Definition: Boundary between geologic units, positional accuracy generally within 1 mm at 1:12,000 (24 m on the ground) Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: map boundary Enumerated_Domain_Value_Definition: map boundary of this 1:12,000 study Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: water boundary, certain Enumerated_Domain_Value_Definition: Outline of a body of open water; positional accuracy within 1:12,000 National Map Accuracy Standards Enumerated_Domain_Value_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEGeoPoly Entity_Type_Definition: Geologic Unit Polygons Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: Shape_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: Shape_Area Attribute_Definition: Area of feature in internal units squared. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: PTYPE Attribute_Definition: geologic unit Attribute_Definition_Source: Author Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: m Enumerated_Domain_Value_Definition: Modified land (Holocene)-Fill or extensively graded natural deposits that obscure or substantially alter original deposit. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: gr Enumerated_Domain_Value_Definition: Graded-Land that has been substantially altered by excavation or grading. Includes Seattle regrades of 1876-1928 as described by Morse (1989). Also includes substantial thicknesses of fill that are too subtle or where boring data are insufficient to delineate extent. Loose to over consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: af Enumerated_Domain_Value_Definition: Artificial fill-Gravel, sand, silt, concrete, garbage, and other materials, placed as a direct result of human activity, of substantial aerial extent or thickness. Mapped where boring data provide sufficient information to delineate extent where greater than about 2 m in thickness, or where topography and overlying development suggests likelihood of fill. Thin deposits of fill are commonly present elsewhere throughout map area but are not mapped due to lack of information. Loose to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: afl Enumerated_Domain_Value_Definition: Landfill debris - Refuse, and other types of debris materials, locally inter-mixed with concrete, bricks, coal, and wood, placed over the exposed lake bottom of Lake Washington at the Montlake landfill and in several other smaller locations across map area, mainly during first half of 20th century. Maximum depths of refuse exceed 20 m (70 ft). Labeled as afl only on Correlation of Map Units. Deposits are shown by overprint pattern; underlying unit is shown beneath pattern. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qb Enumerated_Domain_Value_Definition: Beach deposits (Holocene)-Loose sand and gravel deposited or reworked by modern wave action. Shown on map area only along Puget Sound shoreline, where it is overlain by fill. Loose to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qmw Enumerated_Domain_Value_Definition: Mass-wastage deposits (Holocene)-Colluvium, soil, and landslide debris with indistinct morphology. Mapped on steep slopes. Numerous unmapped areas of mass-wastage deposits occur elsewhere in quadrangle along ravines and sidewalls of Lake Washington trough. Deposits, both mapped and unmapped, include abundant discrete landslides up to 300 m in lateral extent. Thicknesses typically about 3 m but locally may exceed 10 m. Loose and soft to normally consolidated. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qls Enumerated_Domain_Value_Definition: Landslide deposits (Holocene)-Diamict of broken to internally coherent surficial deposits transported downslope en masse by gravity, particularly where coarse deposits (especially unit Qva) overlies fine deposits (units Qvlc and Qpff). Also common within units Qpf and Qpo where coarse and fine deposits interstratify. Loose to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qf Enumerated_Domain_Value_Definition: Alluvial fan deposits (Holocene)-Sand, silt, gravel, and cobbles, deposited in lobate form in valley of Pipers Creek where streams emerge from confining valleys and reduced gradients cause sediment loads to be deposited. Normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qal Enumerated_Domain_Value_Definition: Alluvium (Holocene)-Sand, silt, gravel, and cobbles, deposited along Thornton Creek by running water. Normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qw Enumerated_Domain_Value_Definition: Wetland deposits (Holocene)-Peat and alluvium, poorly drained and intermittently wet. Identified from borings and topography, but areas shown here are not complete inventory of such deposits. Loose and soft to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qp Enumerated_Domain_Value_Definition: Peat deposits (Holocene)-Peat, accumulated in bodies greater than about 1 m in thickness and of mappable extent. Accumulations are greatest in floors of recessional-outwash channels and where lowering of Lake Washington has exposed extensive lake-floor deposits. Gradational with units Qw, and Ql. Loose and soft Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Ql Enumerated_Domain_Value_Definition: Lake deposits (Holocene)-Silt and clay with local peat and other organic sediments, deposited in slow-flowing water. Most mapped areas are lake-bottom sediments exposed by lowering of Lake Washington in 1916. Loose to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qtf Enumerated_Domain_Value_Definition: Tide-flat deposits (Holocene)-Silt, sand, and organic sediment and detritus, historically exposed in along Interbay in southwest map corner and now fill-covered. Loose to normally consolidated Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qvr Enumerated_Domain_Value_Definition: Recessional outwash deposits-Stratified sand and gravel, moderately sorted to well sorted, and less common silty sand and silt. Locally includes high plasticity clay with swell potential. Deposited in broad outwash channels that carried south-draining glacial meltwater during ice retreat away from the ice margin. Also includes deposits that accumulated in or adjacent to recessional lakes. Discontinuous deposits less than about 1 m thick not shown on map; locally more than 6 m thick. Normally consolidated. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qvrl Enumerated_Domain_Value_Definition: Lacustrine deposits-laminated silt and minor clay along southeast shore of Lake Union Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qvi Enumerated_Domain_Value_Definition: Ice-contact deposits-Deposits similar in texture to unit Qvr but commonly less well sorted and with silt-rich matrix. Contains lenses and pods of till Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qvt Enumerated_Domain_Value_Definition: Till-Compact diamict of silt, sand and subrounded to well-rounded gravel, glacially transported and deposited under ice. Commonly is fractured and has intercalated sand lenses. Generally forms undulating, elongated surface. Unit is typically 1 m to 10 m thick and generally very dense. Upper few feet of unit generally weathered and only medium dense Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qva Enumerated_Domain_Value_Definition: Advance outwash deposits-Well-sorted sand and gravel deposited by streams issuing from advancing ice sheet. May grade upward into till. Silt lenses locally present in upper part and are common in lower part. Generally unoxidized to only slightly oxidized. May be overlain by Vashon till in areas too small to show at map scale. Locally over 60 m thick and is dense to very dense. Includes Esperance Sand Member of the Vashon Drift of Mullineaux et al., (1965). Grades downward into unit Qvlc with increasing silt content Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qvlc Enumerated_Domain_Value_Definition: awton Clay Member of the Vashon Drift-Stiff to hard, laminated to massive silt, clayey silt, and silty clay deposited in lowland or proglacial lakes. Marks transition from nonglacial to earliest glacial time, although unequivocal evidence for glacial or nonglacial origin may be absent. Deposits of correlative age and texture may be included in unit Qpff where evidence of age and/or depositional environment is absent. Locally may include fine-grained sediment of unit Qob where indistinguishable from Qvlc. Absent to over 30 m thick in map area Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpf Enumerated_Domain_Value_Definition: Pre-Fraser deposits (Pleistocene)- Interbedded silt, sand, gravel, and diamicts of indeterminate age and mostly indeterminate origin; lightly to heavily oxidized. Discriminated from texturally similar younger deposites, particularly unit Qva, on the basis of stratigraphic position, oxidation, and commonly heterogeneous grain size. Above coastline of Puget Sound, Mainly thinly laminated gray silt with neither organics nor drop-stones overlying and interbedded with oxidized sand and sandy gravel; granular layers more common below 60' altitude. Above shoreline of Lake Washington north of Thornton Creek, oxidized sand and gravel common 50' altitude; laminated silt present throughout but particularly in lower part of unit, with scattered plant debris and local peat beds (all of infinite radiocarbon age). On Capital Hill, primarily laminated silt overlying finite-dated organic material of unit Qob. Some parts of unit as mapped are probably equivalent to dated deposits of unit Qob or to overlying Qvlc but are mapped as Qpf where neither age control nor lithology allow definitive discrimination. Maximum elevation of pre-Fraser deposits as high as 65 m(215 ft) on Capital Hill but more commonly associated with groundwater emergence within and immediately above unit. Dense to Very dense. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpff Enumerated_Domain_Value_Definition: Fine-grained deposits-predominantly silt and clay Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpfn Enumerated_Domain_Value_Definition: Nonglacial sedimentary deposits-Sediment of inferred nonglacial origin, based on presence of peat or other organic material Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qob Enumerated_Domain_Value_Definition: Olympia beds (Pleistocene)-Sand, silt (locally organic-rich), gravel, and peat, discontinuously and thinly interbedded; absent to 15 m thick in map area. Assigned to Olympia interglaciation of Mullineaux and others (1965) on the basis of stratigraphic position, correlation, and two radiocarbon dates from north part of Capitol Hill. Distinguished from Qvlc on the basis of coarser grain size and presence of organics. Generally very dense and hard Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpo Enumerated_Domain_Value_Definition: Pre-Olympia deposits (Pleistocene)-Interbedded sand, gravel, silt, and diamicts of indeterminate age and origin. Very dense and hard. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpog Enumerated_Domain_Value_Definition: Glacial deposits-Weakly to strongly oxidized silt, sand, gravel, and local till of glacial origin. Underlies Vashon-age deposits and thus must also be of pre-Olympia age. Sediment is of inferred glacial (northern) origin, based on presence of till and clasts or mineral grains requiring southward ice-sheet transport. Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpogt Enumerated_Domain_Value_Definition: Glacial till-Predominantly till or other diamict where thick enough to show at map scale. Most extensive on west slopes of Queen Anne Hill, where visible in landslide scars from adjacent roadways Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qpon Enumerated_Domain_Value_Definition: Nonglacial deposits-Sand, silt (locally organic-rich), gravel, and peat, discontinuously and thinly interbedded. Mapped only along Lake Washington shoreline. Generally very dense and hard Enumerated_Domain_Value_Definition_Source: Author Attribute: Attribute_Label: SUB Attribute: Attribute_Label: OVERPRINT Attribute_Definition: Identifier for units with patterns that overprint the unit color. Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: afl_prnt Enumerated_Domain_Value_Definition: Overprint of unit afl over another geologic unit,Landfill debris?Gravel, sand, and silt, intermixed with concrete, bricks, coal, wood, refuse, and other types of debris materials; placed over tide flats of Interbay during first half of 20th century. Maximum depths of refuse exceed 20 m Enumerated_Domain_Value_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEFill Entity_Type_Definition: modified land areas Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: SHAPE_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: SHAPE_Area Attribute_Definition: Area of feature in internal units squared. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: PTYPE Attribute_Definition: Geologic map unit Attribute_Definition_Source: Author Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: af_seattle, afl_seattle, gr_seattle, m_seattle Enumerated_Domain_Value_Definition: Artificial fill-Veneer of gravel, sand, and silt, intermixed with concrete and other materials; placed as direct result of human activity. Thickest fill overlies tideflats of Interbay, where as much as 6 m (20 ft) of fill overlie 15 m (50 ft) of refuse. Thin deposits of fill are present elsewhere throughout map area but are not mapped owing to lack of information. Loose to dense Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: gr Enumerated_Domain_Value_Definition: Graded areas-Extensively graded areas. Some fill likely present. Excludes roadways, parking lots, and landscaped areas. Underlying units are shown beneath overprint Enumerated_Domain_Value_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEMassWastage Entity_Type_Definition: Mass Wastage Units Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: SHAPE_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: SHAPE_Area Attribute_Definition: Area of feature in internal units squared. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: PTYPE Attribute_Definition: Mass Wastage Unit Descriptions Attribute_Definition_Source: Author Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Qls_seattle Enumerated_Domain_Value_Definition: Landslide deposits-Diamict of broken to internally coherent surficial deposits that have been transported downslope en masse by gravity. Discriminated from other mass-wastage deposits by thickness of identifiable slide deposits, by lateral continuity, and by presence of coherent blocks of geologic materials. Located primarily along coastal bluffs of Puget Sound, particularly where coarse-grained deposits (most commonly unit Qva) overlie fine-grained deposits (either unit Qvlc and Qpf). Slumped blocks hundreds to thousands of meters in lateral extent are prominent above Golden Gardens Park and along south shoreline of Magnolia; a large slide is inferred from topography and likely offset contacts immediately east of West Point. Areas covered by landslide deposits-Mapped as dot pattern over older units. Underlying units, which are shown beneath overprint, are mapped on the basis of subsurface data. Unit label (Qls) shown only where encountered in cross section Enumerated_Domain_Value_Definition_Source: Author Enumerated_Domain: Enumerated_Domain_Value: Qmw_seattle Enumerated_Domain_Value_Definition: Mass-wastage deposits-Colluvium, soil, and landslide debris having indistinct morphology. Thickness typically about 3 m but locally may exceed 10 m. Loose to medium dense and soft to stiff. Areas covered by mass-wastage deposits-Mapped as dot pattern over older units on steep slopes, particularly along ravines and coastal bluffs of Puget Sound. Underlying units, which are shown beneath overprint, are mapped on the basis of subsurface data. Unit label (Qmw) shown only where encountered in cross section Enumerated_Domain_Value_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEContour Entity_Type_Definition: 40 foot contour base Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: CONTOUR Attribute_Definition: Elevation Attribute: Attribute_Label: Shape_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEScarps Entity_Type_Definition: Fault Scarps Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: SHAPE_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: LTYPE Attribute_Definition: Linetype scarp Attribute_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNE14CDating Entity_Type_Definition: Carbon 14 Dates Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: SAMPLE_NO Attribute_Definition: Field sample number Attribute: Attribute_Label: SAMPLE_TYPE Attribute_Definition: Type of sample (C14) Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEExposure Entity_Type_Definition: Location of Exposures Entity_Type_Definition_Source: Author Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: EXPOS_ID Attribute_Definition: Exposure ID number Attribute_Definition_Source: Author Attribute: Attribute_Label: EXPOS_TYPE Attribute_Definition: Exposure Type Attribute_Definition_Source: Author Attribute: Attribute_Label: EXPOS_NAME Attribute_Definition: Field number of exposure Attribute_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEExploration Entity_Type_Definition: Test pits and borings Entity_Type_Definition_Source: Author Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Attribute: Attribute_Label: EXPLOR_ID Attribute_Definition: Exploration ID number Attribute: Attribute_Label: EXPLOR_NAME Attribute_Definition: Name of exploration site Attribute: Attribute_Label: EXPLOR_TYPE Attribute_Definition: Type of exploration site: Boring, CPT, probe, test pit, and Well Attribute: Attribute_Label: EXPLOR_DEP Attribute_Definition: Depth of exploration in feet (ft) Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEContour_anno Entity_Type_Definition: Contour annotation Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: FeatureID Attribute: Attribute_Label: ZOrder Attribute: Attribute_Label: AnnotationClassID Attribute: Attribute_Label: Element Attribute: Attribute_Label: SymbolID Attribute: Attribute_Label: Status Attribute: Attribute_Label: TextString Attribute: Attribute_Label: FontName Attribute: Attribute_Label: FontSize Attribute: Attribute_Label: Bold Attribute: Attribute_Label: Italic Attribute: Attribute_Label: Underline Attribute: Attribute_Label: VerticalAlignment Attribute: Attribute_Label: HorizontalAlignment Attribute: Attribute_Label: XOffset Attribute: Attribute_Label: YOffset Attribute: Attribute_Label: Angle Attribute: Attribute_Label: FontLeading Attribute: Attribute_Label: WordSpacing Attribute: Attribute_Label: CharacterWidth Attribute: Attribute_Label: CharacterSpacing Attribute: Attribute_Label: FlipAngle Attribute: Attribute_Label: Override Attribute: Attribute_Label: SHAPE_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: SHAPE_Area Attribute_Definition: Area of feature in internal units squared. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNE14CDating_Anno Entity_Type_Definition: Carbon 14 annotation Attribute: Attribute_Label: OBJECTID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: SHAPE Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: FeatureID Attribute: Attribute_Label: ZOrder Attribute: Attribute_Label: AnnotationClassID Attribute: Attribute_Label: Element Attribute: Attribute_Label: SymbolID Attribute: Attribute_Label: Status Attribute: Attribute_Label: TextString Attribute: Attribute_Label: FontName Attribute: Attribute_Label: FontSize Attribute: Attribute_Label: Bold Attribute: Attribute_Label: Italic Attribute: Attribute_Label: Underline Attribute: Attribute_Label: VerticalAlignment Attribute: Attribute_Label: HorizontalAlignment Attribute: Attribute_Label: XOffset Attribute: Attribute_Label: YOffset Attribute: Attribute_Label: Angle Attribute: Attribute_Label: FontLeading Attribute: Attribute_Label: WordSpacing Attribute: Attribute_Label: CharacterWidth Attribute: Attribute_Label: CharacterSpacing Attribute: Attribute_Label: FlipAngle Attribute: Attribute_Label: Override Attribute: Attribute_Label: SHAPE_Length Attribute_Definition: Length of feature in internal units. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Attribute: Attribute_Label: SHAPE_Area Attribute_Definition: Area of feature in internal units squared. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Positive real numbers that are automatically generated. Entity_Type:Anno_29_35 Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNEBedTraces Entity_Type_Definition: Till and peat bed traces Entity_Type_Definition_Source: Author Detailed_Description: Entity_Type: Entity_Type_Label: SeattleNECrossSection Entity_Type_Definition: Map cross section line Entity_Type_Definition_Source: Author Entity_Type: Entity_Type_Label: Landslides Entity_Type_Definition: Landslide locations Entity_Type_Definition_Source: Author Detailed_Description: Landslide debris with indistinct morphology. Mapped on steep slopes. Numerous unmapped areas of mass-wastage deposits occur elsewhere in quadrangle along ravines and sidewalls of Lake Washington trough. Deposits, both mapped and unmapped, include abundant discrete landslides up to 300 m in lateral extent. Thicknesses typically about 3 m but locally may exceed 10 m. Loose and soft to normally Entity_Type: Entity_Type_Label: LiDAR base Entity_Type_Definition: LiDAR basemap Entity_Type_Definition_Source: Author Detailed_Description: La The base map for the digital compilation is a shaded relief map from Digital Elevation Model (DEM) created with the Light Detection and Ranging (LiDAR) data at 4x vertical exaggeration, a sun azimuth at 45 degrees, and sun vertical angle at 45 degrees. The LiDAR data was acquired from the Puget Sound LiDAR Consortium and King County Endangered Species Act/Sensitive Areas Ordinance, LiDAR Digital Ground Model (DGM), 2001-2003. Horizontal accuracy is ~1.8 meters; vertical accuracy is ~0.3 meters.Street data was extracted from City of Seattle, WA, 1:1200-scale proprietary street data, 2001. Horizontal accuracy is ~1.5 meters. Source: Puget Sound Lidar Consortium Entity_Type: Entity_Type_Label: Seattle DMU Entity_Type_Definition: Discri Entity_Type_Definition_Source: Author Detailed_Description: Landslide debris with indistinct morphology. Mapped on steep slopes. Numerous unmapped areas of mass-wastage deposits occur elsewhere in quadrangle along ravines and sidewalls of Lake Washington trough. Deposits, both mapped and unmapped, include abundant discrete landslides up to 300 m in lateral extent. Thicknesses typically about 3 m but locally may exceed 10 m. Loose and soft to normally Entity_Type: Distribution_Information: Distribution_Liability: Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this publication has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://geopubs.wr.usgs.gov Fees: free Metadata_Reference_Information: Metadata_Date: 20081120 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Karen L. Wheeler Contact_Organization: United States Geological Survey Contact_Address: Address_Type: mailing address Address: 345 Middlefield Rd. MS 975 City: Menlo Park State_or_Province: California Postal_Code: 94025 Contact_Voice_Telephone: 650-329-4935 Contact_Facsimile_Telephone: 650-329-4936 Contact_Electronic_Mail_Address: kwheeler@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile