n!¾NSACLASSNLABELCNAMEC„AGEC.DESCRIPTIOCþSOURCESCþSYMBOLNOVERPRINTN 2530Kg Granodiorite and granite Early Cretaceous Consists of the Nyac pluton in Kilbuck Mountains, only a small part of which is exposed in the northernmost part of the Bethel quadrangle; the bulk of the exposure of the pluton is in the adjacent Russian Mission quadrangle (Box and others, 1993). AboutWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku6 1625TKr Rhyolite and dacite flows, tuff, dikes, and sills Early Tertiary and (or) Late Cretaceous Rhyolite and dacite flows and tuff including block-and-ash flows as well as rhyolite domes. Unit includes felsic rocks of the Swift Creek, Tulip, and Eek volcanic fields of Box and others (1993). Consists of fresh to moderately altered, densely welded Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku15 1603TKr Rhyolite and dacite flows, tuff, dikes, and sills Early Tertiary and (or) Late Cretaceous Rhyolite and dacite flows and tuff including block-and-ash flows as well as rhyolite domes. Unit includes felsic rocks of the Swift Creek, Tulip, and Eek volcanic fields of Box and others (1993). Consists of fresh to moderately altered, densely welded Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku15 1604TKr Rhyolite and dacite flows, tuff, dikes, and sills Early Tertiary and (or) Late Cretaceous Rhyolite and dacite flows and tuff including block-and-ash flows as well as rhyolite domes. Unit includes felsic rocks of the Swift Creek, Tulip, and Eek volcanic fields of Box and others (1993). Consists of fresh to moderately altered, densely welded Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku15 100 Qs Surficial deposits, undivided Quaternary Unconsolidated, poorly to well-sorted, poorly to moderately well-stratified deposits; consist predominantly of alluvial, colluvial, glacial, marine, lacustrine, eolian, and swamp deposits (Hoare and Coonrad, 1959a, 1961a, b; Box and others, 1993; CoonradWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku20 1053Tfi Felsic intrusive rocks Tertiary, Miocene? Light-colored, fine-grained, commonly porphyritic felsic intrusive rocks. Chiefly rhyolitic to dacitic dikes and sills. K/Ar age on biotite of 13.00ñ0.50 Ma (Hoare and Coonrad, 1978, sample 74AHr 26, table 1, herein) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku28 3380JTrotDismembered ophiolite of Box (1985a) - Trondhjemite Lower Jurassic to Middle Triassic Light-gray, medium-grained trondhjemite consisting of abundant quartz, plagioclase, and minor chlorite, sericite, and clinozoisite (Hoare and Coonrad, 1978; Box, 1985a). Found in small bodies mapped in a number of areas of the Hagemeister Island and GooWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku34 105 Qa Alluvial deposits Quaternary Flood-plain alluvium of sand, gravel, and boulders. Locally may include sand and small pebbles from beach deposits, clay-rich silt from estuarine deposits, fine-grained eolian sand, and small areas of undivided surficial deposits (Hoare and Coonrad, 195Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku40 140 Qgo Outwash deposits Quaternary Poorly to well-sorted sand and gravel with some silt and a few boulders, constituting terraces and outwash-fan plains (Hoare and Coonrad, 1959a, 1961a, b) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku42 1658TKqm Quartz monzonite and quartz monzodiorite Tertiary and [or] Cretaceous Medium- to coarse-grained, light-gray monzogranite or quartz monzodiorite plutons which may contain biotite, hornblende, sodic amphibole, and (or) clino- and orthopyroxene (Wilson, 1977). Locally contain phenocrysts of perthitic feldspar; biotite to horWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku48 115 Qb Beach deposits Quaternary Primarily fine sand to coarse gravel along modern and raised ancient beaches. Locally includes wind blown dune sand. In the Kuskokwim Bay, Baird Inlet, and eastern Nunivak Island quadrangles, these deposits extend 3 km inland as a series of raised beacWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku50 310 Qpd Pyroclastic rocks Quaternary Pyroclastic rocks in the Pribilof Islands, largely basaltic tuff (Barth, 1956) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku54 1120Tvep Rhyolite and dacite tuff Tertiary Chiefly rhyolite and dacite welded tuff and tuff breccia and dark rhyolite vitrophyre on the northern part of Saint Matthew Island (Patton and others, 1975) containing minor intercalated andesite and basalt flows and dikes. On southwestern part of islanWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku54 1301Tad Aplite on Saint George Island Tertiary, Eocene Aplite dike, about 400 m wide has chilled margins where it intrudes peridotite on Saint George Island (Barth, 1956). This large dike. Overlain by till and fine-grained sedimentary deposits, in turn overlain by basalt and basanite flows of map unit Qvb.Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku55 119 Qed Eolian deposits Quaternary Derived from alluvial sediments in the Pribilof Islands, mostly composed of sand. Elsewhere, primarily derived from glacial deposits or nearby tidal flats. In most places, the sand is loose and moves with the wind. Along the north shore of Saint Paul Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku61 120 Qed Eolian deposits Quaternary Derived from alluvial sediments in the Pribilof Islands, mostly composed of sand. Elsewhere, primarily derived from glacial deposits or nearby tidal flats. In most places, the sand is loose and moves with the wind. Along the north shore of Saint Paul Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku61 125 Qg Glacial deposits, undivided Quaternary Glacial drift deposited during the last three glacial advances. Consists of sand, gravel, and boulders. Includes end and lateral moraine deposits, as well as colluvium, talus, landslide debris, alluvium, and local silt (Hoare and Coonrad, 1959a, 1961a,Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku61 320 Qcs Alkalic basalt of Karon Lake Quaternary Cinder cones, flows, and tephra; normally polarized rocks of Brunhes polarity epoch (Hoare and others, 1968). K/Ar ages range from 0.03ñ.02 to 0.74ñ.09 Ma (table 1) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku64 2900TJis Slate Creek pluton of Box and others (1993) earliest Tertiary? to Late Jurassic? Small, medium-grained hypidiomorphic-granular, hornblende tonalite and granodiorite pluton, less than 2 km2. Intrudes rocks of map unit Jab without development of a prominent contact-metamorphic zone. Pluton is relatively quartz-rich, containing 20 toWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku69 1656TKgr Granite Tertiary and [or] Cretaceous Coarse- to medium-grained granite and granitoid porphyry. Biotite is dominant mafic phase, hornblende is sparsely present; feldspars are microcline and albite-oligoclase (Wilson, 1977). Unit includes the Akuluktok and Gechiak plutons of Wilson (1977) aWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku88 1655TKg Granitic rocks, undivided Tertiary and [or] Cretaceous Fine- to coarse-grained or porphyritic, light- to dark-gray, rarely pink, granitic rocks. Range in composition from granite to quartz diorite, including granodiorite, quartz monzonite, and quartz monzodiorite. Biotite and hornblende are locally common;Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku89 330 Qvb Basalt flows, undivided Quaternary, Pleistocene Widely distributed fine- and medium-grained, columnar jointed tholeiite and alkali-olivine basalt flows. Columnar-jointed subaerial alkali olivine basalt flows have ropy tops and include minor interflow tuff and breccia. Generally non-porphyritic, darkWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku12521 350 Qvbm Basalt flows, Matuyama polarity epoch Quaternary, Pleistocene Reversely and normally magnetized flows of the Matuyama polarity epoch on Nunivak Island (Hoare and others, 1968); similar rocks may occur on the mainland but can not be distinguished because no magnetic studies have been undertaken Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku125 450 QTv Volcanic rocks, undivided Quaternary, Pleistocene or Tertiary, Pliocene Widely distributed basalt flows in the western part of the map area (Coonrad, 1957). Possibly equivalent in part to flows of map unit Qvb. Additionally, includes vesicular and dense basalt and olivine basanite flows and sills in the Pribilof Islands (BWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku133 116 Qes Estuarine deposits Quaternary Generally fine silt to sand, but may include a significant proportion of mud. Primarily located in the vicinity of Nushagak Bay, these deposits extend well inland along the Nushagak and Igushik Rivers Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku140 113 Qrs Reworked silt Quaternary Chiefly reworked silt, sandy silt, and bog deposits underlying a plain that is transitional with or slightly above areas of flood-plain alluvium of Holocene age and separated from higher plains and residual 'islands' of older silt deposits by an erosionaWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku142 135 Qgm Glacial moraine Quaternary Morainal ridges of generally late Wisconsin age, but may include deposits of other ages. Largely mapped from air-photo and topographic map interpretation. Likely composed of poorly sorted silt to cobble and boulder sized material Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku143 1605TKa Eek and Swift Creek volcanic fields of Box and others (1993); andesite flows Early Tertiary and (or) Late Cretaceous Small outcrops and columnar jointed andesite flows. Subordinate altered andesite porphyry is exposed in the northern part of the Eek volcanic field. Map unit also includes minor olivine basalt, andesitic lithic tuff, dacite, and a small amount of obsidWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku143 317 Qvs Volcaniclastic sediment Quaternary Fossiliferous sediments consisting of sand and yellow tuff containing rounded basalt pebbles. On Saint Paul Island, sediments are polymictic, but composed primarily of basaltic boulders and clasts; locally cross-bedded. On Saint George Island, sedimentWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku153 2885TJih Hypabyssal felsic intrusive rocks earliest Tertiary? to Late Jurassic? Highly altered porphyritic rocks consisting of orange weathering rhyolite having as much as 10 percent phenocrysts in an altered groundmass of quartz, potassium feldspar and plagioclase, locally in graphic intergrowths, and dacite having as much as 5 perWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku157 1024Ttb Tholeiitic basalt of Binakslit Bluff Tertiary, Pliocene Tholeiitic basalt of Binakslit Bluff on Nunivak Island; massive, columnar-jointed flows; normally polarized flows of Gauss polarity epoch as well as normally and reversely polarized flows older than Gauss polarity epoch (Hoare and others, 1968). MultiplWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku162 121 Qsd Silt deposits Quaternary Chiefly light- to dark-gray silt and sandy silt containing abundant permafrost. Deposits become sandier with depth and locally contain pebbles and wood fragments. Deposits are probably of nonmarine fluvial origin but may include eolian and marine membeWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku162 1023Talb Alkalic basalt of Ahzwiryuk Bluff Tertiary, Pliocene Alkalic basalt of Ahzwiryuk Bluff on Nunivak Island; nubbly mottled flows and pyroclastic ejecta; includes both normally and reversely polarized rocks older than Gauss polarity epoch (Hoare and others, 1968). Two samples from this unit yielded K/Ar agesWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku174 117 Qmt Marine terraces Quaternary Raised terraces composed of many types of surficial deposits; primarily estuarine, tidal flat, and alluvial deposits, but may include glacial debris and outwash. Surfaces may be separated from younger active deposits by a bluff or may be gradational. RWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku183 103 Qtf Tidal flat and active estuarine deposits Quaternary, Holocene Fine-grained silt and mud in tidal flats and active estuaries as shown on topographic maps. Also includes older, topographically higher deposits on land. The abrupt ending of the tidal flat deposits at approximately 163ø 20'W longitude in the KuskokwimWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku210 466 QTab Older alkalic basalt of Karon Lake Quaternary, Pleistocene and Tertiary, PlioceneCinder cones, flows, and tephra; reversely and normally polarized rocks of Matuyama(?) epoch (Hoare and others, 1968) on Nunivak Island. A sample of basalt from this unit yielded an age of 0.67ñ.07 Ma (sample A50, table 1) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku222 2021Kys Sandstone, shale, and conglomerate deltaic deposits Upper Cretaceous? Fluvial and shallow marine deltaic deposits of sandstone, siltstone, shale, and conglomerate. Locally crossbedded and ripple marked. Unit contains abundant plant debris and fresh- and brackish-water mollusks. Unit is widely exposed in a broad belt thaWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku230 1660TKgd Granodiorite Tertiary and or Cretaceous Consists of plutons in the Saint Matthew, Goodnews Bay, and Bethel quadrangles. On Saint Matthew Island, is a fine-grained hornblende granodiorite which yielded a 62.3ñ2.0 Ma K/Ar age on hornblende (Patton and others, 1975, 71AMm 45, table 1 herein). IWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku248 2872KTrvsVolcanic and sedimentary rocks Lower Cretaceous to Upper Triassic? Thick unit consisting of low-grade metamorphic or contact metamorphosed marine volcanic and sedimentary rocks. According to Hoare and Coonrad (1978), "the volcanic rocks range in composition and type from mafic pillow basalts to more abundant andesitic Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku250 8610P_km Kanektok metamorphic complex - Marble Paleoproterozoic White, gray, and brownish garnetiferous marble generally associated with quartzose schist (Hoare and Coonrad, 1978). Mapped separately only where it forms the dominant rock unit; similar rocks also occur as thin, discontinuous bands in the lower grade mWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku263 282 QTs Semiconsolidated marine beach deposits Quaternary, Pleistocene or Tertiary, Pliocene Semiconsolidated marine beach deposits consisting of poorly bedded, soft, pebbly siltstone that caps sea cliffs of volcanic rock (map unit Kv) on Hagemeister Island. Shallow-water marine fossils of Pliocene or Pleistocene age Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku271 4880TJik Little Kasigluk River pluton of Box and others (1993) earliest Tertiary? to Late Jurassic? Medium-grained, hypidiomorphic granular hornblende diorite and gabbro in a number of small plutons (Box and others, 1993) in the central to western Bethel quadrangle. Age is uncertain Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku276 1111Tnba Nukluk Volcanic Field, basalt and andesite Tertiary, Eocene Massive, columnar-jointed, basalt and subordinate andesite flows. Minor latite and dacite. Overlies Tnr in Fog River area. Elsewhere, interbedded with rhyolite (Box and others, 1993) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku307 3892JTrotDismembered ophiolite of Box (1985a) - Trondhjemite Lower Jurassic to Middle Triassic Light-gray, medium-grained trondhjemite consisting of abundant quartz, plagioclase, and minor chlorite, sericite, and clinozoisite (Hoare and Coonrad, 1978; Box, 1985a). Found in small bodies mapped in a number of areas of the Hagemeister Island and GooWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku328 1665TKqd Monzodiorite and quartz diorite Tertiary and [or] Cretaceous Consists of the Eek River, Gemuk Mountain, Mount Plummer plutons of Box and others (1993) and the hornblende diorite stocks and dikes assigned a Late Cretaceous age by Box and others (1993) as well as the Wattamuse pluton of Wilson (1977). Plutons are fWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku337 1970Kk Kuskokwim Group, undivided Cretaceous, Campanian? to Albian? Interbedded graywacke and shale, having local interbeds of argillite and conglomerate. Graywacke fine- to medium-grained, gray, commonly micaceous and locally silty; in places is crossbedded, or contains siltstone partings. Contains rare argillite pebbWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku340 5225MzPzmTogiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Metachert and phyllitic metachert Mesozoic and (or) Paleozoic "Finely crystalline, thin-bedded quartzites (metachert) and finely interlayered quartzite and black phyllite. Found east of southern part of Greenstone Ridge in central part of map area [Bethel quadrangle]. Composed of fine aggregates of quartz with seWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku352 4710MzPztTogiak-Tikchik Complex, undivided Lower Cretaceous to Lower Paleozoic Thick, marine unit consisting of volcanic and sedimentary rocks including pillow basalts, intermediate to mafic flows, breccia, crystal-lithic tuff, thin-bedded to massive tuffaceous chert and siltstone, argillite, graywacke, pebble-cobble conglomerate, Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku354 3510Jlgd Hagemeister pluton of Box (1985a) Early Jurassic? Medium-grained biotite-hornblende granodiorite of Hagemeister Island; slightly altered (i.e. sericitized plagioclase, chlorite partially replacing biotite and hornblende) as described by Box (1985a). Intrudes Lower Jurassic volcanic and sedimentary rockWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku357 3406Jgb Gabbroic rocks Middle and Early Jurassic Medium- to coarse-grained, locally pegmatitic hornblende gabbro to diorite (Hoare and Coonrad, 1978). Plutons locally contain olivine and commonly are compositionally layered (Hoare and Coonrad, 1978). Box (1985a) described these rocks as slightly alteWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku369 4950Mzm Togiak-Tikchik Complex - Melange Mesozoic M‚lange containing chert, cherty tuff, siliceous siltstone, limestone and dolostone, pillowed and massive basalt, gabbro, and graywacke in an argillite matrix (Box and others, 1993; Hoare and Jones, 1981; Wilson and others, 2006b). Chert was described bWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku375 5090MzPzaTogiak-Tikchik Complex - Argillaceous m‚lange Mesozoic to Paleozoic Rock unit described by Box and others (1993) as a weakly to intensely fractured foliated black to green argillaceous m‚lange containing discontinuous phacoids of radiolarian chert, limey sandstone, blocks of limestone, and subphyllitic, amygdaloidal basaWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku378 3005Jvs Marine volcaniclastic sandstone, conglomerate, and argillite Jurassic "Turbidite-facies volcaniclastic strata, locally as coarse as fine-grained pebble conglomerate" (Box and others, 1993). Clasts are predominantly intermediate volcanic rock fragments and detrital feldspar, quartz, clinopyroxene, and hornblende. Minor plWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku382 1657TKgs Monzonite Tertiary and [or] Cretaceous Medium-grained pyroxene-bearing monzonite. Biotite is the dominant mafic mineral; however, these plutons are characterized by the presence of orthopyroxene. Includes the Ualik Lake and Kulukak plutons of Wilson (1977). The chemically and texturally siWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku396 2150Klg Limy grit and limestone of the Ungalikthluk belt of Hoare and Coonrad (1983) Lower Cretaceous, Valanginian Chiefly "limestone, greenish limy grit, and conglomerate overlain by noncalcareous graywacke and grit" (Hoare and Coonrad, 1983) exposed in a small area a few kilometers northwest of Buchia Ridge. Limy grit and conglomerate consists of "sub rounded greeWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku401 5730Pls Togiak-Tikchik Complex - Limestone Permian Thin-bedded and massive light- to dark-gray, locally cream-colored fine-grained recrystallized limestone; unit Pl of Hoare and Coonrad (1978) and Box (1985a). Tuffaceous and locally cherty; unit has a fetid odor upon breaking (Hoare and Coonrad 1978, BoWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku413 3990TrPmbMetabasaltic schist Triassic? to Permian? Partially to completely recrystallized schistose rocks derived from mafic igneous and associated sedimentary rocks, including pillow basalt, angular volcanic breccia, pebbly mudstone, fine-grained tuffaceous sedimentary rocks, diabase, gabbro, and rare cWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku425 2832KJc Argillite and tuffaceous chert Lower Cretaceous and (or) Upper Jurassic Thin-bedded green to brown argillite having local 1 to 4 cm thick tuffaceous chert, siltstone, and fine-grained tuff interbeds (Box and others, 1993). A Late Jurassic and (or) Early Cretaceous age is suggested from poorly preserved radiolarians (Box andWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku450 5239Jgs Green amphibole-bearing schist Late Jurassic Schist recrystallized in part to greenschist metamorphic facies mineral assemblage of albite-epidote-chlorite-actinolite. Schist contains interbeds of thin-bedded, white or green, meta-chert having white mica-rich laminae (Box and others, 1993); overlaiWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku452 5810Pv Togiak-Tikchik Complex - Volcanic rocks Permian Pillow and columnar-jointed amygdaloidal, mildly altered basalt flows, breccia, diabasic intrusive, and a few sandy tuffs; unit Pb of Box (1985) and Pv of Hoare and Coonrad (1978). Unit crops out near Goodnews Bay and north of Nuyakuk Lake. In the GoodWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku454 5050MzPzsTogiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Arkosic sandstone and slate Mesozoic and (or) Paleozoic "Strongly cleaved, medium-grained, generally thin-bedded, arkosic sandstone and slate. Exposed on prominent ridge east of Greenstone Ridge in central part of map area [Bethel quadrangle]. Detrital grains in sandstones include monocrystalline quartz (30Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku455 2265Kpd Intermediate and silicic pyroclastic rocks Late Cretaceous Intermediate and silicic pyroclastic rocks on Saint Matthew Island including: dacite, andesite, and rhyolite nonwelded tuff breccia and crystal tuff, dacite and rhyolite welded tuff, massive dacite breccia (lahar ?), fine ash-fall tuff, volcanic conglomeWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku464 1110Tnr Nukluk Volcanic Field, rhyolite Tertiary, Eocene Moderately altered rhyolite flows, domes, and ash-flow tuff. Rhyolite of the main volcanic field contains phenocrysts of sanidine, riebeckitic amphibole, and rare quartz. A 40Ar/39Ar total-fusion age on riebeckite was 54.7ñ1.6 Ma (Box and others, 1993,Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku466 4215Trv Togiak-Tikchik Complex - Basalt and chert Upper Triassic "Massive and pillow basalt and basaltic breccia interbedded with thin-bedded tuffaceous chert and shale" (Box and others, 1993). Unit crops out near the heads of Upnuk and Nishlik Lakes along the southwestern edge of the Bethel quadrangle and continues Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku468 2180Kvm Volcanic and sedimentary rocks of the Mount Oratia belt of Hoare and Coonrad (1983) Lower Cretaceous, Valanginian Consists of a variety of lithologies including thin-bedded tuffaceous chert, massive graywacke, conglomerate, argillite, a few volcanic flows and impure limestone beds, and massive, coarse-grained crystal-lithic tuff (Hoare and Coonrad, 1983). Rocks raWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku473 2261Kv Volcanic rocks Late Cretaceous, Maastrichtian and Campanian Volcanic rocks ranging from rhyolite to olivine basalt flows, dacitic to andesitic tuff and tuffaceous sandstone, and rhyolitic domes (Hoare and Coonrad, 1978; Patton and others, 1975; Box 1985a; Box and others, 1993). Includes Tulip volcanic field rhyWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku485 2210Kv Volcanic rocks Late Cretaceous, Maastrichtian and Campanian Volcanic rocks ranging from rhyolite to olivine basalt flows, dacitic to andesitic tuff and tuffaceous sandstone, and rhyolitic domes (Hoare and Coonrad, 1978; Patton and others, 1975; Box 1985a; Box and others, 1993). Includes Tulip volcanic field rhyWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku485 2260Kv Volcanic rocks Late Cretaceous, Maastrichtian and Campanian Volcanic rocks ranging from rhyolite to olivine basalt flows, dacitic to andesitic tuff and tuffaceous sandstone, and rhyolitic domes (Hoare and Coonrad, 1978; Patton and others, 1975; Box 1985a; Box and others, 1993). Includes Tulip volcanic field rhyWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku485 5045MzPzvTogiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Volcaniclastic sandstone and argilliteMesozoic and (or) Paleozoic "Turbiditic, thin-bedded, medium- to fine-grained, volcaniclastic sandstones, and dark-green to black argillites with weak to nonexistent slaty cleavage. Exposed along prominent ridge east of Greenstone Ridge in central part of map area [Bethel quadrangWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku485 9420P_k Kanektok metamorphic complex, undivided Paleoproterozoic Gneiss and schist derived from sedimentary, volcanic, and plutonic rocks metamorphosed to upper greenschist and granulite facies (Hoare and Coonrad, 1978; Turner and others, in prep.). "Includes medium- to coarse-grained, massive and well-foliated, biotWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku486 3893Trod Dismembered ophiolite of Box (1985a) - Diabasic intrusive rocks Triassic Subophitic, holocrystalline plagioclase-clinopyroxene diabase (Box, 1985a). Shown herein west of Jagged Mountain at Cape Newenham, at Chagvan Mountain, on the coast south of Downdraft Mountain, and along the coast east of Cape Peirce; Box (1985a) also mWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku514 2105Kygv Volcanic graywacke and argillite Upper Cretaceous? Thinly interbedded fine-grained graywacke and siliceous argillite (Patton and others, 1975) on Saint Matthew Island. Graywacke composed of angular to sub-rounded feldspar, volcanic lithic, and quartz grains in an altered argillaceous matrix (Patton and Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku532 1640TMzp Peridotite on Saint George Island Tertiary or older Peridotite forming the basement of Saint George Island in the Pribilof Islands. The peridotite is massive, originally was dunite and now largely altered to serpentine and magnetite (Barth, 1956). The erosional surface of the peridotite appears polishedWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku546 1960Ks Summit Island Formation Upper Cretaceous, Maastrichtian? Consists of lenses and inter-tonguing beds of nonmarine conglomerate, sandstone, carbonaceous siltstone, mudstone, and shale containing abundant plant detritus and a few coal seams (Hoare and others, 1983). In the type section, the unit "consists of aboWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku552 1985Kkn Kuskokwim Group, nearshore facies Cretaceous, Turonian to Albian Thick-bedded quartzose sandstone, pebbly sandstone, and subordinate siltstone and shale of the deltaic facies chert-clast provenance of Box and others (1993). Also includes pebble to boulder conglomerate, coarse sandstone, and minor interbedded medium-gWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku553 98 um Not mapped Small areas on Saint Matthew Island and much of Hall Island shown as not mapped by Patton and others (1973) Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku554 2125Kgbr Graywacke of Buchia Ridge Lower Cretaceous, Valanginian and Hauterivian Lithic sandstone, conglomerate, and shale about 5 km thick (Hoare and Coonrad, 1983). Lower part of unit is about 2,400 m thick, composed mainly of well-bedded fine- to medium-grained sandstone with siltstone interbeds, and pebble-cobble conglomerate. Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku560 3150Jkw Graywacke of Kulukak Bay lower Upper to Middle Jurassic A thick marine sedimentary unit consisting of very hard dark-green or gray, massive graywacke and siltstone containing local conglomerate horizons. Typically consists of sandstone, although coarse pebble conglomerate is locally present. CompositionallyWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku562 3120Jvc Volcaniclastic conglomerate, sandstone, and shale Upper and Middle Jurassic Poorly to moderately exposed sequence of tuffaceous marine sandstone, shale, and conglomerate having minor interbedded basalt and andesite lava flows in the northwest part of the Bethel quadrangle (Box and others, 1993). Unit is as much as 1 to 2 km thiWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku606 5746Pcs Togiak-Tikchik Complex - Volcaniclastic sedimentary rocks Permian "Volcaniclastic sedimentary rocks, ranging from coarsely bedded volcanic breccias to finely bedded calcareous tuffaceous rocks. Limestone cobble conglomerate locally north of Goodnews Bay. Red to black laminated argillite with radiolarian ghosts locallWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku615 2870KJba Basaltic and andesitic lava flows Early Cretaceous and (or) Late Jurassic Poorly to moderately exposed basalt and andesite lava flows in the west central part of the Bethel quadrangle (Box and others, 1993). Overlies volcaniclastic sedimentary rocks of map unit Jvc and generally spatially associated with rocks of map unit JabWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku623 3255JTrcvCoarse volcaniclastic rocks Lower Jurassic to Upper Triassic Dense green tuff, tuff breccia, pillow breccia, minor pillow basalt, and associated sedimentary rocks (Box, 1985a). Breccia clasts are mostly angular aphanitic or plagioclase-clinopyroxene porphyritic rocks, which are commonly vesicular. Interbedded aqWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku665 3310Jlt Laminated tuff and associated rocks of Box (1985a) Jurassic Banded to finely laminated crystal-lithic tuff having interbedded green, white, and black tuffaceous chert (Box, 1985a). Unit contains minor interbedded sections of massive, coarse-grained lithic tuff and (or) pillow basalt (mapped by Box (1985a) as uniWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku682 3891Trob Dismembered ophiolite of Box (1985a) - Pillow basalt Triassic Aphanitic to porphyritic pillow basalt, containing interbedded pillow breccia, aquagene tuff, and inter-pillow and interbedded red and white radiolarian chert as described by Box (1985a). Porphyritic basalt has plagioclase and clinopyroxene phenocrysts Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku708 3130Ja Marine arkosic sandstone and argillite Jurassic "Turbidite-facies arkosic sandstone and shale" (Box and others, 1993). Sandstone apparently derived from weathering of plutonic rocks; consists primarily of detrital plagioclase, quartz, and potassium feldspar, and minor hornblende, biotite, and clinopyWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku715 3890 Dismembered ophiolite of Box (1985a) Lower Jurassic to Middle Triassic The following units, JTrot, Trob, Trod, Trog, were described as the Newenham ophiolite complex, a dismembered ophiolite, by Box (1985a; Decker and others, 1994). The defined ophiolite assemblage also included the serpentinized ultramafic rocks of Cape NWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku717 2890KJb Pillow basalt Lower Cretaceous and (or) Upper Jurassic Highly altered pillow basalt sequence exposed along a narrow trend about 1 km wide and 10 km long south of Crooked Mountain in the Bethel quadrangle (Box and others, 1993). Interbedded with argillite and thin-bedded chert of map unit KJc. Age inferred Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku718 3450Jab Andesite and basalt Middle Jurassic Massive andesitic and basaltic flows; minor trachyte, trachyandesite, and dacite; some interbedded tuffaceous sedimentary rocks; and, locally, several hundred feet of volcanic breccia at or near base (Box and others, 1993). An estimated 25 percent of thWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku744 6580MDm Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Marble and metabasaltic dikes Lower Mississippian and (or) Upper Devonian "Light-gray to white calcitic and dolomitic marble cut by pre-metamorphic basaltic dikes. Only found in small area east of Greenstone Ridge in central part of map area [Bethel quadrangle]. Locally contains as much as 20 percent clastic grains of feldspWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku745 3894Trog Dismembered ophiolite of Box (1985a) - Pyroxene gabbro Triassic Altered clinopyroxene gabbro, locally containing up to 5 percent orthopyroxene which is commonly kinked and fractured and locally rimmed or replaced by pale-green amphibole (Box, 1985a). Plagioclase partially to completely replaced by fine aggregate of Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku747 3451Jmv Interbedded volcanic and sedimentary rocks Middle Jurassic Basaltic and andesitic volcanic and volcaniclastic rocks on Hagemeister Island (Hoare and Coonrad, 1978; Box, 1985a); extensively altered to prehnite-pumpellyite facies mineral assemblage. Volcanic rocks, characterized by plagioclase + clinopyroxene ñ hWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku751 3230Jln Dismembered volcaniclastic turbidites Lower Jurassic? Predominately argillaceous, tuffaceous sandstone-shale sequence that is pervasively deformed and structurally dismembered (Box, 1985a). Sandstone is composed of volcanic detritus and a very minor chert component. "Sedimentary structures variably preserWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku793 4712Pls Togiak-Tikchik Complex - Limestone Permian Thin-bedded and massive light- to dark-gray, locally cream-colored fine-grained recrystallized limestone; unit Pl of Hoare and Coonrad (1978) and Box (1985a). Tuffaceous and locally cherty; unit has a fetid odor upon breaking (Hoare and Coonrad 1978, BoWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku805 1670TKm Mafic intrusive rocks Tertiary, Paleocene, and Cretaceous? Dark-colored dikes and sills of diabase, basalt, and dioritic, gabbroic, and biotite lamprophyre (Hoare and Coonrad, 1978). K/Ar age of 64.6ñ2 Ma on biotite (74ACd 14d, table 1) from the western Nushagak Bay quadrangle. Also includes medium- to coarse-Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku839 6995DOl Togiak-Tikchik Complex - Thin-bedded limestone Devonian to Ordovician "Thin-bedded to massive, fine-grained gray limestone, highly fractured and veined with white calcite, contains algal reefs and reef breccias. Locally contains interbedded tuffs and mafic volcanic rocks. Recrystallized to marble with interbedded quartziWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku842 6412MDv Togiak-Tikchik Complex - Greenstone and schist Lower Mississippian or Upper Devonian Box and others (1993) described unit as consisting of "Weakly to moderately foliated and flattened pillowed and massive basalt, andesite, dacite, rhyolite flows, and breccia with greenschist metamorphic-mineral assemblages." and the rocks that have a volWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku846 3991TrPvsVolcaniclastic glaucophane-hornblende-epidote schist Triassic? to Permian? Metamorphosed conglomerate, sandstone, and shale. Unit includes map units JTrmvss and JPvss of Box (1985a), which he reports grade together in the vicinity of Goodnews Bay. Protolith for both was derived from a feldspar-rich volcanic source (Box, 1985aWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku847 2102Kcgc Calcareous graywacke and siltstone of the Eek Mountains belt of Hoare and Coonrad (1983) Lower Cretaceous, Valanginian Turbidites composed of highly calcareous sandstone interbedded with non-calcareous micaceous siltstone and shale. Hoare and Coonrad (1983) inferred the unit to be coarsening upward to conglomerate. Generally thick-bedded to massive with alternating sanWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku852 5217MzPzpTogiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Chloritic phyllite Mesozoic and (or) Paleozoic "Relatively homogenous unit of finely foliated and crenulated phyllite ***. Found east of southern part of Greenstone Ridge in south-central part of the map area [Bethel quadrangle]. Protolith was probably fine-grained tuffaceous sediment of uncertain Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku872 5026MzPzcTogiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Chert and argillite Mesozoic and (or) Paleozoic "White, gray-green, and blue-green crystallized chert in 2- to 5-cm-thick beds interbedded with black to dark-green phyllite or slate beds of similar thickness. Exposed on prominent ridge east of Greenstone Ridge in central part of map area [Bethel quadWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku872 2510Ksp Serpentinite Late Cretaceous? Small, pervasively slickensided bodies of serpentinite, serpentinite-matrix melange, and silica-carbonate-altered serpentinite north of mouth of Crooked Creek (Box and others, 1993). Protolith and intrusion age uncertain; Box and others (1993) infer intWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku878 3950TrPcsCalcareous schist Triassic? to Permian? Recrystallized schistose and phyllitic calcareous sandstone, shale, limestone, limestone conglomerate, greenish tuffaceous rocks, mafic volcanic rocks, and volcanic conglomerate. Includes units JTrmc of Box (1985a) and Pzcs of Hoare and Coonrad (1978). Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku884 3151Jmm Turbidites of Metervik Bay of Box (1985a) Upper and Middle Jurassic Volcaniclastic turbidite-facies sedimentary rocks southeast of Right Hand fault of Box (1985a) which is roughly equivalent to unnamed fault of Hoare and Coonrad (1978) that parallels the valley of Ualik Lake. Box (1985a) reconstructed a 6 km thick sectiWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku895 3260JTrp Togiak-Tikchik Complex - Phyllite and chert Lower Jurassic and Upper Triassic? Gray, green, and black phyllite, fine-grained tuff, and tuffaceous chert (Box and others, 1993). Unit crops out in the southeast corner of the Bethel quadrangle near the heads of Upnuk and Chikuminuk Lakes and trends north-northeast where it continues iWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku896 4035Trv Togiak-Tikchik Complex - Volcanic and sedimentary rocks Upper Triassic "Marine unit consisting of chert, tuffaceous cherty rocks, argillite, siltstone, volcanic wackes, conglomerate, limestone, and mafic flows and breccias" (Hoare and Coonrad, 1978). Limestone is generally white to cream colored and recrystallized; howeverWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku924 5060Pcs Togiak-Tikchik Complex - Clastic rocks Permian? "Well-bedded, cleaved sandstone, shale thin limestone interbeds, and cobble conglomerate *** sandstone and conglomerate are composed predominantly chert clasts (containing radiolarian ghosts and internal quartz veins) and minor phyllite and porphyritic vWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku937 3495Jum Ultramafic rocks Jurassic? Serpentinite, serpentinized dunite, and other ultramafic rocks form a number of intrusive bodies and tectonic blocks(?) within fault zones separating pillow basalt (Trob) and pyroxene gabbro (Trog), respectively (Hoare and Coonrad, 1978; Box, 1985a). AtWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku937 3895Jum Ultramafic rocks Jurassic? Serpentinite, serpentinized dunite, and other ultramafic rocks form a number of intrusive bodies and tectonic blocks(?) within fault zones separating pillow basalt (Trob) and pyroxene gabbro (Trog), respectively (Hoare and Coonrad, 1978; Box, 1985a). AtWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku937 3254Jlvs Volcanic and sedimentary rocks Lower Jurassic Marine unit of mafic flows, some displaying pillow structure, volcanic breccia, and massive fine- to medium-grained volcanogenic sedimentary rocks (Hoare and Coonrad, 1978). Fractures commonly coated with laumontite. Mapped as unit Jlv by Box (1985a) wWilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku943 3152Jvt Volcaniclastic turbidites of Togiak Bay of Box (1985a) Middle Jurassic Volcaniclastic turbidite sandstone and conglomerate composed entirely of volcanic and hypabyssal igneous clasts; unit is at least 1.7 km thick (Box, 1985a). Box (1985a) divided tightly folded section along the seacoast into a buff-colored lower member, Wilson, F.H,, Hults, C.P., Mohadjer, Solmaz, and Coonrad, W.L., in press, Reconnaissance geologic map for the Kuskokwim Bay region of southwest Alaska, including the Bethel, Goodnews Bay, Nushagak Bay, Hagemeister Island, Baird Inlet, Cape Mendenhall, Ku982