Identification_Information: Citation: Citation_Information: Originator: Ray E. Wells (geologic mapping) Originator: Michael G. Sawlan (digital compilation) Publication_Date: 20140716 Title: Preliminary Geologic Map of the Eastern Willapa Hills, Cowlitz, Lewis, and Wahkiakum Counties, Washington Geospatial_Data_Presentation_Form: map database Series_Information: Series_Name: Open-File Report Issue_Identification: OFR 2014-1063 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/of/2014/1063 Online_Linkage: http://dx.doi.gov/10.3133/ofr20141063 Larger_Work_Citation: Citation_Information: Originator: Wells, Ray E. Publication_Date: 20140716 Title: Preliminary Geologic Map of the Eastern Willapa Hills, Cowlitz, Lewis, and Wahkiakum Counties, Washington Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: Open–File Report Issue_Identification: OFR 2014–1063 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/of/2014/1063 Online_Linkage: http://dx.doi.gov/10.3133/ofr20141063 Description: Abstract: This digital map database was created from the analog geologic map: Wells, R. E., 1981, Geologic Map of the Eastern Willapa Hills, Cowlitz, Lewis, and Wahkiakum Counties, Washington, U.S. Geological Survey Open File Report 81-674. This geodatabase replicates the geologic mapping of the 1981 report with minor exceptions along water boundaries and the northern and southern map boundaries. Slight adjustments were made to contacts along water boundaries due to differences in these boundaries between the topographic base used in the 1981 analog compilation (USGS 15-minute series quadrangle maps at 1:62,500 scale) and the base used for this digital compilation (USGS 7.5-minute series quadrangle maps at 1:24,000 scale). The northern and southern boundaries of the base map for this digital compilation were defined along lines of latitude as compared straight-edge drawn bounding lines used in the 1981 analog map. This boundary adjustment eliminated approximately 45m or less along the northern map boundary and approximately 107m or less along the southern map boundary as compared to the area of the 1981 map. These minor adjustments did not materially alter the geologic map. No new mapping was performed in creating this digital map database, and no attempt was made to fit geologic contacts to match the new 1:24,000 topographic base, except as noted above. We did correct typographical errors, formatting errors, and errors of attribution (e.g., name change of Goble Volcanics to Grays River Volcanics following current State of Washington usage; e.g., Walsh and others, 1987). We also updated selected references, substituting published papers for abstracts, and citing published radiometric ages for the volcanic and plutonic rocks. The reader is referred to Magill and others, (1982), Wells and Coe (1985), Walsh and others (1987), Moothart (1993), Payne (1998), Kleibacker (2001), McCutcheon (2003), Wells and others (2009), Chan and others (2012), and Wells and others, (2014) for subsequent interpretations of Willapa Hills geology. Locations of point, line and polygon features in this digital compilation were created in reference to a georeferenced image of a stable-base frosted mylar compilation (inked lines and labels on screened topography in grayscale) of the 1981 USGS Open File map. The mylar compilation map was scanned at 300dpi and georeferenced to USGS 1:24,000-scale DRGs (Digital Raster Graphics). The 1981 map was published at a scale of 1:62,500 using as a topographic base USGS 15-minute series topographic maps composited into a single sheet on mylar. This digital database was created using a topographic base USGS 7.5-minute series topographic maps published at 1:24,000 scale. Georeferencing between the 1:24,000- and 1:62,500-scale base maps was carried out mainly using lat-long tiks as link points. Where lat-long tiks were not present on the 1981 map (near the northern and southern map boundaries), corresponding survey benchmarks and intersections of prominent roads were used as link points for georeferencing. Digitization of linework shown on the analog map was performed such that digital lines (and boundaries of polygons features derived from such lines) are located within the width of the lines shown on the georeferenced analog map. Due to differences between the topographic base maps used for field mapping and the 1981 map compilation, during digitization particular attention was taken to ensure consistency of contacts in relation to water courses and topographic contours. Point locations of structural measurements (attitudes of bedding, foliation) were located from the georeferenced 1981 compilation map. Values for strike azimuth of point features were determined by interactively estimating strike for a given point feature until the digitally symbolized result overlay the strike of the feature as hand-drafted on the georeferenced 1981 analog map. Locations of point features such as bedding and foliation were taken at the mid-point of the strike line of the symbol. Values for dip or plunge of inclined planes or lineations were transcribed from values hand-written on the 1981 map. Locations of orientation measurements made by the author for the 1981 analog map correspond to the observation location 'on the ground'. Locations during field mapping were determined using either topographic maps at a scale of 1:62,500 or maps of logging roads at a scale of 1:24,000 to 1:62,500. Locations identified initially on logging road maps were transferred to 1:62,500 topographic maps in compilation mainly on the basis of PLSS (Public Land Survey System) section lines for reference. An uncertainty of 1mm in plotting point locations on the 15-minute series topographic maps corresponds to a minimum uncertainty at map scale of approximately 63m in the location of point features. Minimum uncertainty of point locations plotted first on logging road maps and transferred to 15-minute series topographic maps is estimated at 2mm, or 125m, given the compilation scale of 1:62,500 of the base used for the 1981 analog map. The topographic base map covers an area of nearly 30' x 30' between longitude 123° 00' 00.00"W and 123° 30' 00.00"W, and latitude 46° 08' 33.00"N (46.142500°N) and 46° 38' 13.00" N (46.636944°N) (NAD27). The topographic base used for this digital compilation was created by assembling into a digital mosaic DRGs of twenty USGS 7.5-minute quadrangles, and clipping this mosaic to a map boundary created from a table of lat-long coordinates at intervals of 0.0025°. Eastern and western map boundaries of this digital compilation are identical to those of the 1981 analog compilation map. The northern and southern boundaries of this digital compilation lie along lines of latitude, and differ slightly from those of the 1981 analog compilation map which were hand-drawn using a straight edge. Digital boundaries along lines of latitude accounts for a slight curvature of lines of latitude in the map projection (UTM). The base map includes the entire area of 7.5-minute quadrangles between latitude 46.250°N and 46.625°N for the following quadrangles: Abernathy Mountain, Blaney Creek, Boistfort Peak, Boistfort, Curtis, Elochman Pass, Elochoman Lake, Pe Ell, Pluvius, Skamokawa Pass, Skamokawa, and Wildwood. The southern part of the map between latitude 46.142500°N and 46.250000°N includes northern parts of the Cathlamet, Nassa Point, Oak Point and Coal Creek quadrangles. The northernmost part of the map area between latitude 46.625000°N and 46.636944°N includes the southern parts of the Dean Creek, Doty, Rainbow Falls and Adna quadrangles. The area of the geologic map includes areas within this base map area only within the State of Washington. The geology of areas within the State of Oregon in the southernmost part of the base map was not mapped in this study. Purpose: This geodatabase makes this map, previously available only in analog form (paper), available as a geospatial digital database. This map database increases the availability of the map to the public, professional and engineering geologists, and researchers in academic and government roles. The digital database format allows specific areas or components of the map to be readily extracted for specific purposes using GIS software. Supplemental_Information: DESCRIPTION OF MAP UNITS Qal Alluvial deposits (Holocene)—Silt, sand, and gravel along rivers and streams; some low-lying river-terrace deposits, thick colluvium, tidal-flat mud, and beach sand along Columbia River Qls Landslide debris (Holocene and Pleistocene)—Landslides very abundant in all rock units; only largest are shown on map Qlh Logan Hill Formation of Snavely and others (1958) (Pleistocene)—Deeply weathered gravel and sand Tsmp Saddle Mountains Basalt of the Columbia River Basalt Group; Pomona Member (middle Miocene)—One basalt flow, as much as 100 m thick west of Mill Creek; exhibits characteristic wavy, irregular columnar jointing; contains as much as 20 percent stubby plagioclase phenocrysts, some having clinopyroxene inclusions; magnetic polarity is reversed (Magill and others, 1982); chemistry2 is equivalent to that of Pomona Member (Swanson and others, 1979; Wells and others, 2009); unit locally includes underlying flow of Huntzinger of the Saddle Mountains Basalt in Abernathy and Germany Creek drainages (Beeson and Tolan, 2002; Wells and others, 2009); basalt is overlain by deeply weathered basalt conglomerate containing ferruginous bauxite deposits (Livingston, 1966) Tnm Nonmarine sedimentary rocks of Snavely and others (1958) (middle Miocene)—Poorly consolidated siltstone, sandstone, and conglomerate; contains fossil plants Tau Astoria (?) Formation, upper member (middle Miocene)—Thick- to thin-bedded, friable, very fine- to medium-grained, micaceous, arkosic sandstone and silty sandstone; plane-laminated, thin-bedded micaceous siltstone, some having large, low-angle cross bedding sets; large channels in siltstone filled with very coarse sand and transported siltstone blocks; convolute bedding and slump structures common; fossils not yet found in unit Twf Wanapum Basalt of the Columbia River Basalt Group; Frenchman Springs Member (middle Miocene)—At least two flows of fine-grained basalt and associated flow breccia, having total thickness of 100 m; flows have well-developed colonnades, that have straight-sided columns as much as 2 m in diameter; flows are very sparsely plagioclase-phyric, with phenocrysts as much as 1.5 cm long; magnetic polarity is normal, and chemistry matches the Frenchman Springs Member on the Columbia Plateau (Swanson and others, 1979; Wells and others, 2009) Timb Basaltic intrusive rocks (middle Miocene)—Dikes and sills of dark-gray, aphanitic, aphyric to sparsely plagioclase-phyric basalt intruding the Lincoln Creek and Cowlitz Formations; could be the (invasive) Grande Ronde Basalt (Tgr) or the Wanapum Basalt (Twf) from adjacent flows; see Beeson and others (1979), Snavely and others (1973), and Wells and others (2009) Tgr Grande Ronde Basalt of the Columbia River Basalt Group (middle Miocene)—One or more flows of dark-gray, aphanitic, aphyric basalt that has well-developed entablature; overlain by three or four flows of light-gray, sugary, fine-grained aphyric basalt with well-developed colonnades; flows locally pillowed at base; hyaloclastite abundant west of Skamokawa; magnetic polarity is normal, and chemistry of upper three flows is similar to high-Mg flows at the top of the Grande Ronde Basalt of the Columbia Plateau (Swanson and others, 1979; Sentinel Bluff Member, Wells and others, 2009); chemistry of lower flows is similar to low-Mg flows of the Grande Ronde Basalt on the Columbia Plateau; flows are separated by basaltic conglomerate and basaltic to arkosic, fine- to very-coarse sandstone and siltstone; separated from the overlying Frenchman Springs Member of the Wanapum Basalt (Twf) by discontinuous arkosic sandstone containing carbonized logs; maximum thickness, 75 m Tal Astoria (?) Formation, lower member (middle and early Miocene)—Thick- to thin-bedded, very fine- to medium-grained, plane-laminated, carbonaceous, micaceous, friable sandstone; basalt- and quartzite-conglomerate lenses locally common; bioturbation and slump structures in places; Molluscan fauna referred to Newportian or Pillarian Stages of Addicott (1976)3 Tlc Lincoln Creek Formation (upper Eocene and Oligocene)—Tuffaceous siltstone and very fine-grained sandstone; massive to thick bedded, concretionary, bioturbated, with interbeds of glauconitic sandstone and tuff; thin-bedded, laminated siltstone in southwesternmost exposures; Molluscan fauna referred to Blakely Stage of Weaver (1944); Foraminifera referred to Refugian and Zemorrian Stages of Kleinpell (1938)4 Tlcs Sandstone at base of Lincoln Creek Formation (late Eocene)—Massive to thick-bedded, moderately well-sorted and indurated, fossiliferous, dark-gray, fine-grained arkosic to basaltic sandstone; Molluscan fauna referred to Galvinian Stage of Armentrout (1975) and Lincoln Stage of Weaver (1944) Tsc Siltstone of Skamokawa Creek (late Eocene)—Thin-bedded, laminated, burrowed, concretionary, tuffaceous siltstone; contains thin tuff beds in places; abundant Foraminifera referred to upper part of Narizian Stage of Mallory (1959) Tiqm Quartz monzonite stock (late Eocene to Oligocene?)—Light-gray to tan, quartz monzonite to granodiorite with blocky jointing; contains inclusions of the Grays River Volcanics (Tgv); hypidiomorphic-granular, granophyric, and porphyritic textures; see Livingston (1966) for chemical analysis; U/Pb age is 39.6±0.5 Ma (J. Wooden, written commun., 2003; Wells and others, in press) Tgv Grays River Volcanics (late Eocene)—Subaerial basalt flows and interbedded siltstone and sandstone; flows show columnar and platy jointing, weathered flow tops, and oxidized, red basal-flow breccias overlying baked and altered sedimentary interbeds; basalts, which are aphyric to densely porphyritic, contain phenocrysts of plagioclase, clinopyroxene, and olivine; Foraminifera from siltstones beneath unit and immediately overlying it are referred to upper Narizian Stage of Mallory (1959); 40Ar/39Ar ages of 42 to 37 Ma reported in Chan and others (2012); called “Goble Volcanics” in Wells (1981) Tib Basaltic intrusive rocks (Eocene)—Dikes and sills of medium- to fine-grained aphyric to extremely porphyritic basalt; many related to the Grays River Volcanics (Tgv), but some may be older Tc Cowlitz Formation (late and upper middle Eocene)—Massive to thin-bedded, plane-laminated and cross bedded, friable, very fine- to coarse-grained, micaceous, arkosic sandstone; interbedded, laminated, micaceous, carbonaceous siltstone, tuffaceous siltstone, and very coarse-grained basaltic, andesitic, and tuffaceous sandstone; thin subbituminous coal as much as 30 cm thick north of Abernathy Mountain; see Livingston (1966) for additional coal localities; see Payne (1998) and Kleibacker (2001) for facies analysis of this unit and adjacent units; Foraminifera referred to upper Narizian Stage of Mallory (1959) Tcv Basalt breccia and flows (late and upper middle Eocene)—Basalt breccia, massive flows and intrusive rock interbedded in the Cowlitz Formation along Columbia River Tm Undifferentiated McIntosh Formation and sandstone (Eocene)—Includes the upper and lower members of the McIntosh Formation (Tmu and Tml, respectively) and the unnamed sandstone (Tmus); shown only in cross section at depth Tmu McIntosh Formation, upper member (late and middle Eocene)—Dark-gray, massive to laminated, thin-bedded, tuffaceous siltstone, silty sandstone, and arkosic sandstone; basalt-cobble conglomerate and slump breccias are found locally; upper part of unit is equivalent in age to the Cowlitz Formation in west half of map area (Rau, 1958); Foraminifera referred to Narizian Stage of Mallory (1959); equivalent to upper part of Henriksen’s (1956) Stillwater Creek Member of the Cowlitz Formation; coccoliths from lower part of referable to CP 14a zone (R. Wells sample W92-2a,b,c; D. Bukry written commun., 1992) Tmus Unnamed sandstone (middle Eocene)—Massive to thick-bedded, plane-laminated to crossbedded, friable, fine- to medium-grained, arkosic sandstone interbedded at base of the upper member of the McIntosh Formation (Tmu) Tig Gabbro and basaltic intrusive rocks (middle or early Eocene)— Massive to blocky and columnar-jointed, fine- to very-coarse grained gabbro sill complex; marginal facies are basalt and have well-developed columnar jointing, whereas interiors are very coarse grained to pegmatitic; gabbro and basalt are vesicular and typically flow-banded, result of planar concentrations of vesicles and (or) crystal sorting; interstitial glass generally altered to green clays, and vesicles are filled with clay, calcite, or zeolite; gabbros intrude upper part of the Crescent Formation and along contact between the Crescent Formation and the lower member of the McIntosh Formation (Tml); some gabbro and basalt that intrudes the Crescent Formation may be part of the Crescent Formation magmatism; some may be younger and related to the Grays River Volcanics (Tgv); 40Ar/39Ar age of 48.7 Ma from sills reported west of map area (Moothart, 1993) Tml McIntosh Formation, lower member (lower and middle Eocene)—Massive to thin-bedded and laminated, very fine- to coarse-grained basaltic sandstone, arkosic sandstone, and laminated, tuffaceous siltstone; sandstone commonly shows graded bedding; sandstones are less common on east flank of Willapa Hills; interbedded in lower part are pillow basalt flows of the Crescent Formation; Foraminifera referred to upper Ulatisian and lower Narizian Stages of Mallory (1959); equivalent to lower part of Henriksen's (1956) Stillwater Creek Member of the Cowlitz Formation Tcbs Basalt breccia and sandstone (middle and lower Eocene)—Massive to well-bedded basalt-lapilli tuff, tuff breccia, basaltic sandstone, siltstone, and conglomerate; lapilli tuff consists of palagonitic vesicular basaltic glass and altered glass shards commonly cemented by calcite and zeolite; graded bedding is common; forms thick sequences interbedded with the lower member of the McIntosh Formation (Tml) and upper part of the Crescent Formation Tcb Crescent Formation (lower middle lower Eocene)—Pillow flows, massive and columnar-jointed flow interiors, pillow breccia, lapilli-tuff breccia, and filled lava tubes of tholeiitic and alkalic basalt; basalt groundmass altered to green and brown clays; zeolite and calcite fracture fillings are ubiquitous; contains minor amounts of mudflow breccia, basaltic sandstone, and interbedded laminated siltstone; includes a few dikes and sills not differentiated on map; unit is interpreted as faulted, deformed, and clockwise-rotated seamount built on oceanic crust (Wells and Coe, 1985), similar to the Siletz River Volcanics of Snavely and others (1968); Foraminifera from interbedded siltstones referred to upper Penutian or Ulatisian Stages of Mallory (1959); 40Ar/39Ar ages of 53.6±2.0 and 55.7±1.0 Ma are reported from the unit in the western Willapa Hills (Moothart, 1993); locally subdivided into the following: Tcs Siltstone—Thin-bedded, laminated, tuffaceous siltstone interbedded with pillow basalt of the Crescent Formation Tcsb Subaerial basalt—Massive to very vesicular, platy, plagioclase-phyric basalt flows and flow breccias that have weathered tops and baked and oxidized bottom contacts; interbedded with basalt-boulder conglomerate; basalt groundmass is in part altered to clays, and vesicles are filled with calcite and zeolite 1 Radiometric and coccolith ages shown in Correlation of Map Units on page 2 cited in Description of Map Units 2 Chemical analyses of the Columbia River Basalt samples by P. R. Hooper 3 Identification of Molluscan fauna by Ellen James Moore 4 Identification of Foraminifera by Weldon W. Rau EXPLANATION OF MAP SYMBOLS Contact—Approximately located; dashed where location is inferred; dotted where location is concealed. Queried where uncertain (in cross section only) Fault—Approximately located; dashed where location is inferred; dotted where location is concealed; showing dip of fault plane where known; vertical fault shown by bar across fault; paired arrows and letters on opposite sides of fault show inferred sense of relative displacement in vicinity of symbol; letters U (upthrown) and D (downthrown) show vertical displacement; arrows show lateral displacement on map and vertical displacement in cross section Fault inferred from side-looking radar imagery (SLRI)—Showing sense of vertical displacement; not field-checked Thrust fault—Approximately located; sawteeth on upper plate Slickenlines—On fault plane, showing azimuth and plunge Inclined Horizontal—Combined with fault-dip symbol on vertical faults Folds—Showing fold crestline; showing direction of plunge where it can be inferred; dashed where location is inferred; dotted where location is concealed Anticline Syncline Bedding in pillow lava—Showing up direction; shown only in cross-section within the Crescent Formation Strike and dip of beds Inclined—Dips along streams in unit Qal are measured on bedrock Overturned Vertical—Top side of bedding shown by placement of 90° dip value Horizontal Strike and dip of igneous foliation—Shown only in unit Tig, gabbro and basalt intrusive rocks Water well with gas show—Showing total depth (TD) of well in feet INTRODUCTION This digital map database and the PDF derived from the database were created from the analog geologic map: Wells, R.E. (1981), “Geologic map of the eastern Willapa Hills, Cowlitz, Lewis, and Wahkiakum Counties, Washington.” The geodatabase replicates the geologic mapping of the 1981 report with minor exceptions along water boundaries and also along the north and south map boundaries. Slight adjustments to contacts along water boundaries were made to correct differences between the topographic base map used in the 1981 compilation (analog USGS 15-minute series quadrangle maps at 1:62,500 scale) and the base map used for this digital compilation (scanned USGS 7.5-minute series quadrangle maps at 1:24,000 scale). These minor adjustments, however, did not materially alter the geologic map. No new field mapping was performed to create this digital map database, and no attempt was made to fit geologic contacts to the new 1:24,000 topographic base, except as noted above. We corrected typographical errors, formatting errors, and attribution errors (for example, the name change of Goble Volcanics to Grays River Volcanics following current State of Washington usage; Walsh and others, 1987). We also updated selected references, substituted published papers for abstracts, and cited published radiometric ages for the volcanic and plutonic rocks. The reader is referred to Magill and others (1982), Wells and Coe (1985), Walsh and others (1987), Moothart (1993), Payne (1998), Kleibacker (2001), McCutcheon (2003), Wells and others (2009), Chan and others (2012), and Wells and others (in press) for subsequent interpretations of the Willapa Hills geology. OIL AND GAS POTENTIAL Commercial quantities of natural gas were discovered at Mist, Oregon, about 10 miles south of the map area, while this mapping project was in progress [1979]. As a result, the eastern Willapa Hills are a target for oil and gas exploration. The Mist gas field and the southern Willapa Hills face each other across the broad, east-west-trending Columbia River syncline that forms a low point in the Coast Range uplift. The stratigraphic section is similar on both sides of the Columbia River, but facies relations may be more complex on the Washington side. The thick Cowlitz Formation deltaic- and shallow-marine sediments of the type area (Weaver, 1937) are deposited unconformably across older strata and apparently thin rapidly to the west, where they are replaced by laminated siltstones of the same age. This rapid facies change is mapped across the gently south-plunging nose of the eastern Willapa Hills uplift, which is coincident with the axis of the Coast Ranges gravity high. The Willapa Hills structural high may have been an active tectonic feature throughout most of the Tertiary and may have controlled basin geometry and sediment-dispersal patterns. The Cowlitz Formation lies beneath subaerial rocks of the Grays River Volcanics of latest Narizian age, which are in turn overlain by more deep-water siltstones in the western part of the map area. Sandstones of the Cowlitz Formation above the Grays River Volcanics are not exposed, but they may be present in the eastern part of the map area beneath the Lincoln Creek Formation. The thick, friable arkoses of the Cowlitz Formation and the basal arkoses of the upper member of the McIntosh Formation have good reservoir potential, and they are the most likely reservoir rocks to be found at depth. Siltstones of the McIntosh and Cowlitz Formations may be suitable source rocks, but they have not been tested for source-rock potential. In general, source rocks in the Coast Ranges have marginal to adequate organic richness, but they are commonly thermally immature (Snavely and others, 1977). However, source rocks in the southern Willapa Hills may have been subjected to higher heat flow during late Eocene volcanism and plutonism associated with the Grays River Volcanics. The McIntosh and Cowlitz Formations have abundant herbaceous material that may have provided a source for natural gas. A series of en echelon northwest-trending folds are present on the south flank of the Willapa Hills uplift. Their structure is complex; the fold axes typically are offset by numerous cross faults. Some of these structures merit further investigation for their petroleum potential. The Wilson Creek uplift may have closure, and several cross faults may have created local traps across the plunging structure. "Marsh gas" has been reported from a 140 ft water well drilled near the axis of this structure (Washington State Dept. of Natural Resources well log 69-559; written communication), but the gas may be a result of decaying organic material beneath a relatively impermeable cover of landslide debris. The Arkansas Creek uplift is another complexly faulted anticline that may have a thick Eocene-age section beneath it. Other possible traps may be present in structures beneath the relatively flat-lying basalts of the Columbia River Group, as well as where sandstones of the Cowlitz Formation are faulted up-dip against impermeable strata. Stratigraphic traps also may be present where sandstones of the Cowlitz or McIntosh Formations pinch out or become channelized in the western-facies deeper water siltstones. REFERENCES CITED Addicott, W.O., 1976, Neogene molluscan stages of Oregon and Washington, in Fritsche, A.E. (chairman), Ter Best, Harry, Jr., and Wornardt, W.W., eds., The Neogene symposium, selected technical papers on paleontology, sedimentology, petrology, tectonics and geologic history of the Pacific Coast of North America—Tomorrow's oil from today's provinces: Society of Economic Paleontologists and Mineralogists, Pacific Section, Proceedings, 51st Annual Meeting, San Francisco, Calif., April 21-24, 1976, no. 51, p. 95–115. Armentrout, J.M., 1975, Molluscan biostratigraphy of the Lincoln Creek Formation, southwest Washington, in Weaver, D.W., Hornaday, G.R., and Tipton, Ann., eds., Paleogene symposium and selected technical papers—Future energy horizons of the Pacific coast: American Association of Petroleum Geologists–Society of Economic Paleontologists and Mineralogists–Society of Economic Geologists, Pacific Sections, 50th Annual Meeting, Long Beach, Calif., April, 1975, p. 14–48. Beeson, M.H., Perttu, R., and Perttu, Janice, 1979, The origin of the Miocene basalts of Coastal Oregon and Washington—An alternative hypothesis: Oregon Geology, v. 41, no. 10, p. 159–166. Beeson, M.H., and Tolan, T.L., 2002, Basalt of Huntzinger, Asotin Member of Saddle Mountains Basalt, Columbia River Basalt Group (CRBG) identified in western Washington [abs.]: Geological Society of America Abstracts with Programs, v. 34, no. 5, p. 33. Chan, C.F., Tepper, J.H., and Nelson, B.K., 2012, Petrology of the Grays River volcanics, southwest Washington—Plume-influenced slab window magmatism in the Cascadia forearc: Geological Society of America Bulletin, v. 124, p. 1324–1338. Henriksen, D.A., 1956, Eocene stratigraphy of the lower Cowlitz River eastern Willapa Hills area, southwestern Washington: Washington Division of Mines and Geology Bulletin 43, 122 p. Kleibacker, D.W., 2001, Sequence stratigraphy and lithofacies of the middle Eocene upper McIntosh and Cowlitz Formations—Geology of the Grays River Volcanics, Castle Rock–Germany Creek area, southwest Washington: Corvallis, Oregon State University, M.S. thesis, 219 p. Kleinpell, R.M., 1938, Miocene stratigraphy of California: Tulsa, Okla., American Association of Petroleum Geologists Special Volume SP9, 450 p. Livingston, V.E., Jr., 1966, Geology and mineral resources of the Kelso-Cathlamet area, Cowlitz and Wahkiakum Counties, Washington: Washington Division of Mines and Geology Bulletin 54, 110 p. Magill, J., Wells, R.E., Simpson, R.W., and Cox, A.V., 1982, Post 12 m.y. rotations of southwestern Washington: Journal of Geophysical Research, v. 87, p. 3761–3776. Mallory, V.S., 1959, Lower Tertiary biostratigraphy of the California Coast Ranges: Tulsa, Okla., American Association of Petroleum Geologists Special Volume SP20, 416 p. McCutcheon, M.S., 2003, Stratigraphy and sedimentology of the Middle Eocene Cowlitz Formation and adjacent sedimentary and volcanic units in the Longview–Kelso area, southwest Washington: Corvallis, Oregon State University, M.S. thesis, 346 p. Moothart, S.R., 1993, Geology of the middle and upper Eocene Mcintosh Formation and adjacent volcanic and sedimentary rock units, Willapa Hills, Pacific County, southwest Washington: Corvallis, Oregon State University, M.S. thesis, 265 p. Payne, C.W., 1998, Lithofacies stratigraphy and geology of the middle Eocene type Cowlitz Formation and associates volcanic and sedimentary units, eastern Willapa Hills, southwest Washington: Corvallis, Oregon State University, M.S. thesis, 253 p. Pease, M.H., and Hoover, L., 1957, Geology of the Doty–Minot Peak area, Washington: U. S. Geological Survey Oil and Gas Investigations Map OM–188, scale 1:62,500. Rau, W.W., 1958, Stratigraphy and foraminiferal zonation in some of the Tertiary rocks of southwestern Washington: U.S. Geological Survey Oil and Gas Investigations Chart OC–57. Snavely, P.D., Jr., Brown, R.D., Jr., Roberts, A.E., and Rau, W.W., 1958, Geology and coal resources of the Centralia-Chehalis district, Washington: U.S. Geological Survey Bulletin 1053, 159 p. Snavely, P.D., Jr., MacLeod, N.S., and Wagner, H.C., 1968, Tholeiitic and alkalic basalts of the Eocene Siletz River Volcanics, Oregon Coast Range: American Journal of Science, v. 266, p 454–481. Snavely, P.D., Jr., MacLeod, N.S., and Wagner, H.C., 1973, Miocene tholeiitic basalts of coastal Oregon and Washington and their relationship to coeval basalts of the Columbia Plateau: Geological Society of America Bulletin, v. 84, p. 387–424. Snavely, P.D., Jr., Pearl, J.E., and Lander, D.L., 1977, Interim report on petroleum resources potential and geologic hazards in the outer continental shelf—Oregon and Washington Tertiary province: U.S. Geological Survey Oil and Gas Investigations Open-File Report 77–282, 64 p. Swanson, D.A., Wright, T.L., Hooper, P.R., and Bentley, R.D., 1979, Revisions in stratigraphic nomenclature of the Columbia River Basalt Group: U. S. Geological Survey Bulletin 1457–G, 59 p. Walsh, T.J., Korosec, M.A., Phillips, W.M., Logan, R.L., and Schasse, H.W., 1987, Geologic map of Washington—Southwest quadrant: Washington Division of Geology and Earth Resources Geologic Map GM–34, scale 1:250,000. Weaver, C.E., 1937, Tertiary stratigraphy of western Washington and northwestern Oregon: Seattle, University of Washington Publications in Geology, v. 4, 266 p. Weaver, C.E., and others, 1944, Correlation of the marine Cenozoic formations of western North America: Geological Society of America Bulletin, v. 55, no. 5, p. 569–598. Wells, R.E., 1981, Geologic map of the eastern Willapa Hills, Cowlitz, Lewis, Pacific, and Wahkiakum Counties, Washington: U.S. Geological Survey Open-File Report 81–674, scale 1:62,500. Wells, R.E., and Coe, R.S., 1985, Paleomagnetism and geology of Eocene volcanic rocks of southwest Washington—Implications for mechanisms of tectonic rotation: Journal of Geophysical Research, v. 90, p. 1925–1947. Wells, R.E., Niem, A.R., Evarts, R.C., and Hagstrum, J.T., 2009, The Columbia River Basalt Group from the gorge to the sea, in O'Connor, J.E., Dorsey, R.J., and Madin, I.P., eds., Volcanoes to vineyards—Geologic field trips through the dynamic landscape of the Pacific Northwest: Geological Society of America Field Guide 15, p. 737–774, doi: 10.1130/2009.fl d015(32). Wells, R.E., Bukry, D., Friedman, R., Pyle, D., Duncan, R., Haeussler, P., and Wooden, J., in press, Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range—Correlation to the Geomagnetic Polarity Timescale and implications for a long-lived Yellowstone hot spot; Geosphere, 80 p. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2014 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Keywords: Theme: Theme_Keyword: geologic map Theme_Keyword: geology Place: Place_Keyword: Eastern Willapa Hills Place_Keyword: Southwestern Washington Place_Keyword: Lower Columbia River Place_Keyword: Cowlitz County, WA Place_Keyword: Lewis County, WA Place_Keyword: Wahkiakum County Stratum: Stratum_Keyword: Columbia River Basalt Stratum_Keyword: Alluvial deposits Stratum_Keyword: Landslide debris Stratum_Keyword: Logan Hill Formation Stratum_Keyword: Columbia River Basalt Stratum_Keyword: Saddle Mountains Basalt Stratum_Keyword: Pomona Member Stratum_Keyword: Pomona Basalt Stratum_Keyword: Grande Ronde Basalt Stratum_Keyword: High-Mg Grande Ronde Basalt Stratum_Keyword: Wanapum Basalt Stratum_Keyword: Astoria Formation Stratum_Keyword: Basalt intrusive rocks Stratum_Keyword: Frenchman Springs Member Stratum_Keyword: Lincoln Creek Formation Stratum_Keyword: Siltstone of Skamokawa Creek Stratum_Keyword: Quartz monzonite stock Stratum_Keyword: Grays River Volcanics Stratum_Keyword: Basalt intrusive rocks Stratum_Keyword: Cowlitz Formation Stratum_Keyword: Basalt breccia and flows Stratum_Keyword: McIntosh Formation Stratum_Keyword: Crescent Formation Access_Constraints: None Use_Constraints: Users of this geospatial database and geologic information derived from it should acknowledge the U.S. Geological Survey as the source of the data. 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 for a scale of 1:24,000 means that higher resolution information is not present in the dataset. Plotting at scales larger than 1:24,000 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. Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.2.6.1500 Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Ray E. Wells Contact_Organization: U.S Geological Survey Contact_Position: Geologist, Project Chief - Pacific Northwest Geologic Mapping and Urban hazards Contact_Voice_Telephone: 650-329-4933 Contact_Electronic_Mail_Address: rwells@usgs.gov Contact_Instructions: Additional contact: Karen Wheeler, PNW Project Data Manager, 650-329-4935, kwheeler@usgs.gov Data_Set_Credit: Original field mapping and compilations by Ray Wells. Geospatial compilation by M. Sawlan. S. Foreman contributed initial digitization of point data, R. Wells contributed new text. Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 10.1 Cross_Reference: Citation_Information: Originator: Ray E. Wells (geologic mapping) Originator: M. Sawlan (digital compilation) Publication_Date: 2014 - digital map database; 1981 - analog map Title: Geologic Map of the Eastern Willapa Hills, Cowlitz, Lewis, and Wahkiakum Counties, Washington, U.S. Geological Survey Open File Report 2014-1063 Series_Information: Series_Name: Open File Report Issue_Identification: 2014-1063 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Data_Quality_Information: Lineage: Source_Information: Source_Scale_Denominator: 62500 Type_of_Source_Media: stable-base material (mylar) Source_Citation_Abbreviation: Wells (1981), Geologic Map of the Eastern Willapa Hills, USGS Open File Report 81-674 Metadata_Reference_Information: Metadata_Date: 20140430 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Ray Wells Contact_Organization: U.S. Geological Survey Contact_Position: Geologist / Project Chief, Pacific Northwest Geologic Mapping Contact_Address: Address_Type: mailing address Address: U.S. Geological Survey Address: 345 Middlefield Rd MS-973 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Voice_Telephone: 650-329-4933 Contact_Electronic_Mail_Address: rwells@usgs.gov Contact_Instructions: Additional contact: Karen Wheeler, PNW Project Data Manager, 650-329-4935, 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