"NSALCASS", "LABEL", "NAME", "AGE", "DESCRIPTION", "SOURCES", "SYMBOL", "OVERPRINT"
"2530","Kg","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).  About 200 km2 in size, pluton is crudely concentrically zoned from hornblende-biotite granodiorite and granite at margin to hornblende-biotite granite at core (Box and others, 1993).  K/Ar age determinations yield a range of ages, from 101.13.0 Ma (Decker and others, 1984; Box and others, 1993) on hornblende in the Russian Mission quadrangle north of the map area to 120.03.3 Ma on biotite (Wilson, 1977; Box and others, 1993), also in the Russian Mission quadrangle as well as a K/Ar biotite age of 1153.5 Ma from within the Bethel quadrangle (sample 87ATf 30, table 1) and a U/Pb crystallization age reported as a range of 104 to 129 Ma (upper Concordia intercept) on zircon (see table 1, also for additional data see Box and others, 1993; Patton and others, in press(b); Wilson and others, 2006a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","6",""
"1625","TKr","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 rhyolitic ash-flow tuff, black glassy vitrophyre, and pale pink to orange, fine-grained, porphyritic albite-bearing rhyolite.  The rhyolite commonly has well-developed flow structures and forms rhyolite domes found as small knobs or large domal hills as much as 4 km in diameter having 300 to 500 m of relief (Box and others, 1993), as well as small stock-like intrusions, dikes, and sills (Hoare and Coonrad, 1959a).  The block-and-ash flow in the Tulip volcanic field consists of broken blocks of dacite in an ashy dacitic matrix and was interpreted to be a hot avalanche deposit formed during dome collapse.  Dacite and subordinate andesite flows in the Tulip volcanic field, which crop out as columnar-jointed cliffs, are also included here.  K/Ar ages range from 54.71.6 Ma on a whole-rock to 62.51.9 Ma on biotite (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","15",""
"1603","TKr","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 rhyolitic ash-flow tuff, black glassy vitrophyre, and pale pink to orange, fine-grained, porphyritic albite-bearing rhyolite.  The rhyolite commonly has well-developed flow structures and forms rhyolite domes found as small knobs or large domal hills as much as 4 km in diameter having 300 to 500 m of relief (Box and others, 1993), as well as small stock-like intrusions, dikes, and sills (Hoare and Coonrad, 1959a).  The block-and-ash flow in the Tulip volcanic field consists of broken blocks of dacite in an ashy dacitic matrix and was interpreted to be a hot avalanche deposit formed during dome collapse.  Dacite and subordinate andesite flows in the Tulip volcanic field, which crop out as columnar-jointed cliffs, are also included here.  K/Ar ages range from 54.71.6 Ma on a whole-rock to 62.51.9 Ma on biotite (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","15",""
"1604","TKr","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 rhyolitic ash-flow tuff, black glassy vitrophyre, and pale pink to orange, fine-grained, porphyritic albite-bearing rhyolite.  The rhyolite commonly has well-developed flow structures and forms rhyolite domes found as small knobs or large domal hills as much as 4 km in diameter having 300 to 500 m of relief (Box and others, 1993), as well as small stock-like intrusions, dikes, and sills (Hoare and Coonrad, 1959a).  The block-and-ash flow in the Tulip volcanic field consists of broken blocks of dacite in an ashy dacitic matrix and was interpreted to be a hot avalanche deposit formed during dome collapse.  Dacite and subordinate andesite flows in the Tulip volcanic field, which crop out as columnar-jointed cliffs, are also included here.  K/Ar ages range from 54.71.6 Ma on a whole-rock to 62.51.9 Ma on biotite (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","15",""
"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; Coonrad, 1957).  Locally includes reworked volcanic debris including block and ash flows.  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","20",""
"1053","Tfi","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 13.000.50 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","28",""
"3380","JTrot","Dismembered 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 Goodnews Bay quadrangles by Hoare and Coonrad (1978).  Box (1985a) indicated that in addition to the mapped bodies, other small bodies occur within altered diabase near Cape Newenham.  At Tokomarik Mountain, Box (1985a) described the trondhjemite as ""a northeast-dipping slab faulted above and below against schistose rocks ***.""  Box (1985a) tentatively assigned a Late Triassic age based probable co-genesis with the Upper Triassic pillow basalt (Trob) and other components of the ophiolite whereas Hoare and Coonrad (1978) assigned a Jurassic age based on the association of the trondhjemite with Jurassic gabbro and ultramafic rocks","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","34",""
"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, 1959a, 1961a; 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","40",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","42",""
"1658","TKqm","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 hornblende ratio is variable but generally sub-equal (Wilson, 1977).  These plutons are the most common of the Tertiary and (or) Cretaceous plutons of the map area.  Includes Crooked Mountain and Canyon Creek plutons of Box and others (1993) in the Bethel quadrangle.  As described by Box and others (1993), Crooked Mountain is a large composite pluton having a thin gabbro and diorite margin that partially rims a massive core of augite-biotite-hornblende and (augite-) hornblende-biotite granodiorite, quartz monzonite, and granite.  Canyon Creek pluton is a small (~1 km2), medium- to coarse-grained, intergranular to hypidiomorphic-granular augite-biotite quartz diorite to hornblende-biotite granodiorite.  K/Ar and 40Ar/39Ar ages range from 63.7 to 71.1 Ma (table 1); the Togiak Lake pluton of Wilson (1977) yielded a discordant K/Ar age of 63.72.0 Ma on biotite and 69.53.0 Ma on hornblende (74AHr 118, table 1).  40Ar/39Ar total-fusion ages of 69.82.1 Ma were determined on biotite from Crooked Mountain pluton and 70.32.1 Ma  on biotite from Canyon Creek pluton (87ATf 51 and 87AJm 36a, respectively, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","48",""
"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 beach ridges and may underlie the marine terraces farther inland.  Along the Nushagak Peninsula, wind blown sand derived from the adjacent tidal flats forms ridges interspersed with reworked glacially derived gravels","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","50",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","54",""
"1120","Tvep","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 island, chiefly light-colored rhyolite and dacite hypabyssal rocks (Patton and others, 1975).  These felsic rocks appear to overlie mafic flows and volcaniclastic rocks mapped herein as unit Kv and may be extrusive and hypabyssal cogenetic equivalent of granodiorite mapped herein as unit TKm (Patton and others, 1975).  Age thought to be Eocene or Paleocene (see Wittbrodt and others, 1989)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","54",""
"1301","Tad","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.  Radiometric dating (Hopkins and Silberman, 1978; table 1 herein) indicates an age range of about 49.52.0 to 57.22.3 Ma","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","55",""
"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 Island, impressive dunes occur (Barth, 1956).  Also widely distributed on the Nushagak Peninsula, where they overlie glacial, estuarine, and beach deposits.  Lea (1989) described widespread  eolian sand sheets in the Nushagak Lowland and these have also been shown locally on the Nushagak Peninsula (W.L. Coonrad, 2007, unpublished data)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","61",""
"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 Island, impressive dunes occur (Barth, 1956).  Also widely distributed on the Nushagak Peninsula, where they overlie glacial, estuarine, and beach deposits.  Lea (1989) described widespread  eolian sand sheets in the Nushagak Lowland and these have also been shown locally on the Nushagak Peninsula (W.L. Coonrad, 2007, unpublished data)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","61",""
"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, b; Box and others, 1993).  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","61",""
"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 0.03.02 to 0.74.09 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","64",""
"2900","TJis","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 to 25 percent quartz, along with green hornblende, plagioclase, and opaque oxides (Box and others, 1993).  Pluton erodes similarly to country, hence is not prominent and was considered ""erosionally neutral"" by Box and others (1993).  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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","69",""
"1656","TKgr","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) as well as Aniak Lake pluton of Box and others (1993) and the Nayorurun River intrusive complex of Hoare and Coonrad (1978) consisting of granite porphyry dikes, sills, and related tuff and breccia.  The Aniak Lake pluton is a coarse-grained, porphyritic to seriate leucocratic biotite granite pluton 10 km2 in area in the Bethel quadrangle (Box and others, 1993).  It has a distinctive speckled appearance due to randomly oriented microperthite feldspar phenocrysts.  Porphyritic rhyolite dikes common in the uppermost part of this pluton and in surrounding biotite hornfels.  K/Ar and 40Ar/39Ar total-fusion ages for this unit range from 60.71.8 Ma to 69.62.1 Ma (table 1).  The Akuluktok pluton yielded unusually discordant ages with biotite at 69.62.1 Ma and hornblende at 63.43.0 Ma (Wilson, 1977; sample 74B57, table1 herein).  To the east of the map area, rocks of this map unit range from 54.5  1.6 Ma on hornblende, considered a minimum age and not an emplacement age by Wallace and others (1989) to 66.640.08 Ma on mica (Wilson and others, 2003)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","88",""
"1655","TKg","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; muscovite is uncommon.  K/Ar and 40Ar/39Ar ages range from 60.7 to 75 Ma throughout the map area for rocks of this unit and its sub-divisions (table 1) and 68.73.0 and 75.02.9 Ma for dated rocks that are in this undivided unit.  Unit includes the Fisher Dome and Marvel Creek plutons of Box and others (1993).  Also includes map unit TKg of Hoare and Coonrad (1978) except where subdivision of these rocks is possible on the basis of composition.  Rocks assigned to this map unit by Hoare and Coonrad (1978) on Hagemeister Island were subsequently assigned to map unit Jmf of Middle Jurassic age by Box (1985a).  Subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","89",""
"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, dark-gray to black and contain fine microcrysts of labradorite, augite, olivine, and accessory magnetite in a diktytaxitic texture (Hoare and Coonrad, 1980).  Includes the Togiak Basalt of Hoare and Coonrad (1980) on the floor of the Togiak River valley as well as flows in the Bethel, Nunivak Island, Cape Mendenhall, Pribilof Islands, and Baird Inlet quadrangles.  The Togiak Basalt is divisible into a lower unit of low-lying horizontal flows, less than 100 m thick, and an upper unit, about 300 m thick, comprising an isolated volcanic edifice, regarded by Hoare and Coonrad (1978) as a tuya (subglacial volcano).  Whole-rock K/Ar age on lower unit was 0.7580.2 Ma (Hoare and Coonrad, 1978, 1980, Box, 1985a, sample 74AHr 77, table 1, herein).  In the Bethel quadrangle, includes fresh olivine tholeiite basalt flows having diktytaxitic texture and containing olivine, subophitic clinopyroxene, plagioclase and iron oxides as well as sparse interstitial volcanic glass yielding a whole-rock K/Ar age of 0.4180.016 Ma (Box and others, 1993, sample 87ASb 9a, table 1, herein).  Unit also includes Tholeiitic Basalt of Mekoryuk on Nunivak Island (Hoare and others, 1968); massive, columnar-jointed flows including both normally polarized rocks of the Brunhes polarity epoch and reversely magnetized rocks of the Matuyama polarity epoch (shown as unit Qvbm).  Samples dated by K/Ar for this unit on Nunivak Island yielded ages as old as 1.69.09 Ma (table 1).  In the Pribilof Islands, widespread olivine hylobasanite (containing normative nepheline) flows and sills range in thickness from 20 cm to 7 m or more (Barth, 1956).  These rocks can be vesicular or dense and many eruptive features, such as hornitos, chimneys surrounded by foam and splatters, blowholes, diatremes, and miniature craters (Barth, 1956) suggesting very recent eruption.  Other flows lack these features and are overgrown with vegetation.  A K/Ar whole-rock age of 1.63.06 Ma (sample P21, table 1) was determined on basalt from the Pribilof Islands.  Locally subdivided on Nunivak Island","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","125","21"
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","125",""
"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 (Barth, 1956) which range in thickness from 20 cm to 7 m or more on Saint Paul and Saint George Islands; on Otter Island, hylobasanite flows are at least 100 m thick.  Dated samples in the Pribilof Islands range from less than 0.10 to 2.25.10 Ma (table 1); elsewhere no dates are available on rocks of this unit.  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","133",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","140",""
"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 erosional scarp 3 to 15 m high (Hoare and Coonrad, 1959a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","142",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","143",""
"1605","TKa","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 obsidian and siliceous tuff (Hoare and Coonrad, 1959a).  Primarily exposed on the west side of the Bethel quadrangle along ridges and in river cuts in the Eek volcanic field; however, the Swift Creek volcanic field also contains exposures of columnar jointed andesite capping small hills in the southeastern part of the Bethel quadrangle (Box and others, 1993).  According to Hoare and Coonrad (1959a) this map unit is moderately folded and unconformable on steeply dipping rocks of Cretaceous age and older.  A 40Ar/39Ar total fusion age of 59.512.3 Ma was determined on plagioclase from andesite in the central Bethel quadrangle (Box and others, 1993, sample 88Al 12, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","143",""
"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, sediments overlie a glaciated surface of peridotite upon which Pleistocene fossil shells have been cemented.  The sediments are quite varied; however, a basal conglomerate has boulders of peridotite but primarily consists of basalt boulders.  Overlying the basal conglomerate is a sand layer containing casts of fossil shells; however no CaCO3 is left and the casts disintegrate on contact (Barth, 1956).  Locally cross-bedded","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","153",""
"2885","TJih","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 percent phenocrysts of plagioclase and biotite in a groundmass plagioclase, quartz, and opaque oxides (Box and others, 1993).  Some of these rocks have similar trace element signatures to the Slate Creek pluton (unit TJis) of Box and others (1993).  Age is uncertain though rocks intrude the rocks of map units Jab and Jvc","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","157",""
"1024","Ttb","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).  Multiple samples yielded ages between 3.24.10 and 5.01.15 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","162",""
"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 members in some areas.  Organic muck containing mammoth remains and nonmarine gastropods is found locally near top of deposits (Hoare and Coonrad, 1959a, 1961b)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","162",""
"1023","Talb","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 ages of 5.19.15 and 6.28.18 Ma (samples A15 and A1, respectively, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","174",""
"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.  Range in elevation from less than 8 m on the west to as much as 12 m on the east","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","183",""
"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 163 20'W longitude in the Kuskokwim Bay quadrangle is an artifact of the topographic maps; it is likely that the tidal flats continue along the coast to the west","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","210",""
"466","QTab","Older alkalic basalt of Karon Lake","Quaternary, Pleistocene and Tertiary, Pliocene","Cinder 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 0.67.07 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","222",""
"2021","Kys","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 that extends from northwest of the map area into the northern edge of the Marshall quadrangle (see Patton and others, in press(a) in press(b); Wilson and others, 2006a, c).  Shallow water marine mollusks of mid-Cretaceous age found in the Kwiguk quadrangle (table 2)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","230",""
"1660","TKgd","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 62.32.0 Ma K/Ar age on hornblende (Patton and others, 1975, 71AMm 45, table 1 herein).  In the Goodnews Bay quadrangle, the Sunday Creek and Mt. Waskey plutons of Wilson (1977) are medium- to coarse-grained tonalite and granodiorite.  The Sunday Creek pluton yielded a K/Ar age on biotite of 72.52.2 Ma (GC1-1381, table 1), whereas the Mt. Waskey pluton yielded slightly discordant K/Ar ages of 62.51.9 and 65.22.0 Ma on biotite and hornblende (GD1-3154, table 1).  In the Bethel quadrangle, includes the two phase North Fork pluton of Box and others (1993) and the Cripple Mountain pluton.  Aplite dikes are common near these plutons.  Main felsic phase of the North Fork pluton is seriate to hypidiomorphic granular (augite-) hornblende-biotite quartz monzodiorite, granodiorite, and minor biotite granite.  The North Fork mafic phase is a coarse-grained, cumulate-textured augite quartz gabbro and quartz diorite.  Cripple Mountain pluton is an elliptical, coarse-grained, hypidiomorphic-granular hornblende-biotite granodiorite and granite, and lesser quartz monzodiorite and quartz monzonite covering about 40 km2 in the Bethel quadrangle (Box and others, 1993).  The pluton is erosionally recessive wherein the contact aureole and surrounding country rock are more resistant to erosion than the pluton.  North Fork and Cripple Mountain plutons yield 40Ar/39Ar total-fusion ages of 64.31.9 and 62.2  1.9 Ma, respectively (87ATf 56 and 87ATf 72, respectively, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","248",""
"2872","KTrvs","Volcanic 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 and trachytic flows, tuffs, and breccias.  Interbedded with the volcanic rocks are thick sections of tuffaceous siltstone, tuffaceous cherts, and massive or thin-bedded argillite.  Tuffs and tuffaceous sedimentary rocks associated with the intermediate composition volcanic rocks are commonly laumontized.""  Radiolarians of Late Jurassic to Early Cretaceous age and fragmentary ammonites of Jurassic age have been collected from this unit in the Goodnews Bay quadrangle (Hoare and Coonrad, 1978).  The unit may include some areas of rocks of Triassic and Permian age.  In the Bethel quadrangle Box and others (1993) suggested that this unit may be subdivided into the units KJc, KJb, Ja, and Jvs, whereas the mapping of Box (1985a) in the Hagemeister Island and southern Goodnews Bay quadrangles resulted in the subdivisions Jlt, Jvt, and JTrcv.  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","250",""
"8610","P_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 marginal rocks of the complex and rarely in the high-grade core.  Locally may contain incipient diopside, white mica, phlogopite, quartz, plagioclase, and epidote as minor phases (Turner and others, in prep.)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","263",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","271",""
"4880","TJik","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","276",""
"1111","Tnba","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","307",""
"3892","JTrot","Dismembered 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 Goodnews Bay quadrangles by Hoare and Coonrad (1978).  Box (1985a) indicated that in addition to the mapped bodies, other small bodies occur within altered diabase near Cape Newenham.  At Tokomarik Mountain, Box (1985a) described the trondhjemite as ""a northeast-dipping slab faulted above and below against schistose rocks ***.""  Box (1985a) tentatively assigned a Late Triassic age based probable co-genesis with the Upper Triassic pillow basalt (Trob) and other components of the ophiolite whereas Hoare and Coonrad (1978) assigned a Jurassic age based on the association of the trondhjemite with Jurassic gabbro and ultramafic rocks","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","328",""
"1665","TKqd","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 fine- to coarse-grained monzodiorite and diorite, but locally include gabbro.  Eek River pluton is a sill 50 to 500 m thick cropping out in discontinuous exposures over 10 km length which intruded and contact-metamorphosed rocks of the Kuskokwim Group (Kk).  It is dominantly medium- to coarse-grained, porphyritic to diabasic (hornblende) augite diorite, quartz diorite, and mafic quartz monzodiorite.  Gemuk Mountain pluton is elongate, north-trending, erosionally resistant, mafic to intermediate quartz gabbro to mafic granodiorite pluton.  The pluton also intruded and contact-metamorphosed the Kuskokwim Group as well as Lower Cretaceous marine volcaniclastic sandstone, conglomerate, shale, and interbedded tuff of map unit Kvm.  Mt. Plummer pluton is medium- to coarse-grained, erosionally resistant, hypidiomorphic granular augite-biotite mafic granodiorite, quartz monzodiorite, and quartz diorite; it intruded and contact metamorphosed the Kuskokwim Group.  The Mt. Plummer pluton has yielded K/Ar biotite ages of 65.12.0 Ma (87ACz 61, table 1) and 66.62.0 Ma in the adjacent Russian Mission quadrangle north of the map area (Box and others, 1993).  Hornblende diorite stocks and dikes are small, extensively altered, and contain relict euhedral plagioclase; samples yielded a 40Ar/39Ar total-fusion age of 68.02.0 Ma on hornblende (87AJm 271b, table 1) and a conventional K/Ar age of 71.32.1 Ma on biotite (GB7-1479a, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","337",""
"1970","Kk","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 pebbles.  Originally described by Cady and others (1955), the Kuskokwim Group is widespread in southwestern Alaska and although largely a flysch deposit, represents a range of local depositional environments.  Box and others (1993) subdivided upper part of unit in the Bethel quadrangle on the basis of provenance and depositional environment; however, data is insufficient to carry those distinctions throughout this map area.  They described three provenances called chert-clast, mixed, and volcanic, and described three depositional environments, outer-fan turbidite, inner-fan turbidite, and deltaic.  We have placed the deltaic environment, which is restricted to the chert-clast provenance, in the nearshore facies sub-division (Kkn) of this map.  The other chert-clast provenance rocks are described as outer-fan facies and consist of thin-bedded, fine-grained, quartzose sandstone and shale with lesser thin- and thick-bedded medium-grained sandstone (Box and others, 1993).  The mixed provenance rocks represent two depositional environments; an outer-fan turbidite facies consisting of a shale-rich sequence with lesser thin- to thick-bedded, medium-grained sandstone sections and an inner-fan-channel facies consisting of mixed shale-rich and sandstone-rich sections, with coarse sandstone and pebbly sandstone in thick-bedded, amalgamated sequences with minor interbedded shale (Box and others, 1993).  Volcanic provenance rocks consist of interbedded shale, siltstone, sandstone, and conglomerate composed of rounded clasts of volcanic, volcaniclastic, and plutonic rocks deposited in slope and inner-fan environments (Box and others, 1993).  The lower part of the Kuskokwim Group was divided into two units by Box and others (1993); an upper shale and siltstone unit consisting of dark-gray to black, finely laminated shale, siltstone, and thin-bedded, very fine-grained sandstone and a basal conglomerate unit of pebble to boulder conglomerate, coarse sandstone, and minor interbedded medium-grained sandstone, siltstone, and shale.  Box and others (1993) suggested the shale and siltstone represent sand-poor slope, interchannel, and distal basin-plain environments.  Basal conglomerate is assigned to map unit Kkn herein, described below.  The age of the Kuskokwim Group is not well constrained; multiple provenances and potentially multiple depositional systems are included within the map unit.  Cady and others (1955) assigned an early Late Cretaceous age in part, but acknowledged collections outside their map area that might indicate an age older than Late Cretaceous and as young as Tertiary.  Elder and Box (1992) and Box and others (1993) assigned an early Turonian to late Cenomanian age based on inoceramid fossil collections in the Bethel quadrangle, whereas Hoare and Coonrad (1959a) reported Albian and Cenomanian to Coniacian fossils from the same area and Murphy (1989) reported an Albian collection.  Other age assignments have ranged as young as Santonian (Decker and others, 1994) or Campanian(?) (Miller and Bundtzen, 1994).  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","340",""
"5225","MzPzm","Togiak-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 seams to centimeter-thick bands rich in fine-grained white mica.  Recrystallized radiolarian tests present in some horizons.  Thickness is uncertain.  Structurally overlies units }|s and }|v on north and is structurally overlain by unit MDm on south.  Unconformably overlain by conglomeratic rocks [Kkn] of Kuskokwim Group along Kisaralik River.  Age constrained by presence of radiolarians (Phanerozoic) and by Late [Early] Cretaceous age of overlying unit [Kkn].""  Unit is strongly foliated and metamorphosed to greenschist and transitional greenschist-blueschist facies","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","352",""
"4710","MzPzt","Togiak-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, and limestone.  Formerly called the Gemuk Group (Hoare and Coonrad, 1959a, 1961a, b), this unit consists of a wide variety of rock types in a structural collage of blocks.  The Gemuk Group as originally defined consists chiefly of dense, dark, massive siltstone having interbeds of chert, volcanic rocks, limestone, graywacke and breccia (Cady, 1955).  The assemblage was subsequently redefined as the Togiak-Tikchik Complex on the basis of  its structural character (Wilson and Coonrad, 2005).  Unit crops out in a wide belt through the Goodnews Bay quadrangle from the Eek Mountains in the north southwest to Goodnews Bay making up most of the northwestern Ahklun Mountains.  It is unconformably overlain by rocks of the Late Cretaceous Kuskokwim Group (Kk and Kkn) and Early Cretaceous (Valanginian) calcareous graywacke and siltstone (Kcgc).  Permian limestone (Pl) containing Atomodesma sp. is interbedded throughout the unit.  Hoare and Coonrad (1978, see also www.alaskafossil.org) collected samples containing corals of Permian age and crinoids, bryozoans and Halobia of Triassic age.  They also collected brachiopods (including several productoid forms, cleiothyridinoid genus, and a spiriferoid), a pleurotomarian gastropod, and pelecypods of late Paleozoic (probably Permian) age.  Hoare and Coonrad (1978) mentioned the unit contains volcanic rocks of Triassic, Permian, and Devonian ages.  Unit was included in the Goodnews terrane by Box (1985a) and Box and others (1993); however, rocks also mapped as unit MzPz by Hoare and Coonrad (1978) and included in the Togiak-Tikchik Complex were assigned to the Togiak terrane by Box and others (1993; see also Decker and others, 1994).  Unit was subdivided by Box (1985a) in the Hagemeister Island and southernmost of the Goodnews Bay quadrangles into units JTrcs (JPcs, herein), JTrmvs (JPmvs, herein), JTrmb (JPmb, herein), Pvs, and Pmv.  Where possible, sub-unit assignments were extrapolated from the Box (1985a) map area into the Hoare and Coonrad (1978) map area.  Unit }| of Hoare and Coonrad (1978) was further subdivided into two mlange units (MzPza; Mzm) by Box and others (1993) in the Bethel quadrangle","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","354",""
"3510","Jlgd","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 rocks (map unit Jlvs) with a narrow contact metamorphic zone of hornblende-biotite-plagioclase hornfels.  Box (1985a) reported that clasts of similar granodiorite occur in conglomerate of adjacent interbedded volcanic and sedimentary rocks of map unit Jmv.  An age reported variously by Box (1985a) as on biotite (p. 26) or hornblende (p. 18) yielded K/Ar age of 1837 Ma (B78-1152G, table 1); the reported K2O content for this sample is well below that typical for biotite and conversely, very high for hornblende.  As presented, the date must be considered suspect.  No similar age granitic rocks are known elsewhere in southwestern Alaska, but rocks of this age are common in the Alaska-Aleutian Range batholith to the east (Wilson and others, 2006b).  Pluton originally mapped as part of map unit TKg by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","357",""
"3406","Jgb","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 altered, containing sericitized plagioclase, hornblende partially replaced by actinolite and chlorite, and prehnite-quartz veinlets.  Hoare and Coonrad (1978) reported that these gabbroic intrusions are commonly associated with ultramafic rocks.  Five K/Ar amphibole and hornblende ages have a bimodal distribution, having peaks at about 187 and 161 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","369",""
"4950","Mzm","Togiak-Tikchik Complex - Melange","Mesozoic","Mlange 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 by Hoare and Jones (1981) as gray and thin-bedded with shale partings or red siliceous silt; and massive or thick-bedded gray, black, white and brownish.  They also described calcareous sandstone and shale, white crystalline limestone, and pyroclastic rocks altered to greenstone.  Consists of unit ^|m of Box and others (1993) in the Bethel quadrangle and subdivided from unit }| of Hoare and Coonrad (1978) in the Goodnews Bay and adjacent Dillingham and Taylor Mountains quadrangles based on work reported in Wilson and others (2006b).  Unit crops out in the Tikchik Lakes area of the Bethel and Goodnews Bay quadrangles and extends into the adjacent Taylor Mountains and Dillingham quadrangles.  The mlange may contain rocks of multiple map units, including the argillite and graywacke (KTrag), volcanic rock (Pv and Trv), clastic rocks (Pcs), limestone (Pls), greenstone and schist (MDv), and chert (Pzc and TrPzc) of Wilson and others (2006b).  Unit is structurally complex and is dismembered along anastomosing cleavage (Box and others, 1993).  According to Hoare and Jones (1981) ""***the rocks were deformed twice by isoclinal folding and offset by northwest trending high-angle faults and northwest-dipping low- and high-angle reverse faults.  The older folds trend west or northwest; the younger folds are post-Cretaceous in age, trend northeast, and are commonly recumbent to the southeast.""  Unit structurally underlies greenstone and schist (MDv) to the northwest beneath a low-angle(?) fault; and is juxtaposed against volcanic and sedimentary rocks (KTrvs) along the high-angle Togiak-Tikchik fault (Box and others, 1993).  Where units, such as the limestone of Permian age can be distinguished, they are mapped separately.  Reported are Late Triassic and Permian megafossils and radiolarians of Paleozoic(?), Devonian, pre-Late Devonian, and Triassic age including the radiolarians Eucyrtis sp., Mirifusus(?), Parvicingula blowi Pessagno, Parvicingula sp., Ristola(?) altissima Rust, Ristola sp., Spongocapsula sp.(?) of Early Cretaceous (Berriasian/early Valanginian) to Late Jurassic (late Tithonian) age; and conodonts Epigondolella, Epigondolella abneptis, Neogondolella, Neogondolella navicula, Xaniognathus sp. indet of Late Triassic, Norian age (Hoare and Jones, 1981; Box and others, 1993; see www.alaskafossil.org).  Unit was included in the Tikchik terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","375",""
"5090","MzPza","Togiak-Tikchik Complex - Argillaceous mlange","Mesozoic to Paleozoic","Rock unit described by Box and others (1993) as a weakly to intensely fractured foliated black to green argillaceous mlange containing discontinuous phacoids of radiolarian chert, limey sandstone, blocks of limestone, and subphyllitic, amygdaloidal basalt.  Unit crops out in the Eek mountains near the southern boundary of the Bethel quadrangle.  Unit is unconformably overlain by Cretaceous rocks of the Kuskokwim Group (Kk) and calcareous graywacke and siltstone (Kcgc).  Conodonts Neogondolella bitteri and Neogondolella phosphoriensis of Permian age were found in limy siltstone (Box and others, 1993; see also www.alaskafossil.org).  Box and others (1993) reported Permian pelecypods (Atomodesma sp. fragments) from a basalt-limestone block originally reported by Murphy (1989) and Permian conodonts recovered from limy siltstone in the matrix of the unit.  Unit was included in the Goodnews terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","378",""
"3005","Jvs","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 plutonic rock fragments, felsic volcanic and hypabyssal, sedimentary rock fragments and low-grade metamorphic rock fragments are a persistent component (Box and others, 1993).  According to Box and others (1993), age control is based on stratigraphic position above Early Jurassic and Late Triassic phyllite and chert of map unit JTrp and below Early Cretaceous and (or) Late Jurassic argillite and tuffaceous chert of map unit KJc","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","382",""
"1657","TKgs","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 similar Okstukuk Hills and Kulik Lake plutons occur in the adjacent Dillingham quadrangle (Wilson, 1977; Wilson and others, 2006b).  Potassium content is high relative to SiO2, as high as 4.50 percent K2O at a SiO2 value of 57.4 percent (Wilson, 1977).  A K/Ar age of 71.92.0 Ma (sample 74AHr 51, table 1) was determined on a pluton in the Nushagak Bay quadrangle, whereas the Okstukuk Hills pluton in the adjacent Dillingham quadrangle yielded an age of 84.490.05 Ma (Iriondo and others, 2003; Wilson and others, 2006b) which is unusually old for this region","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","396",""
"2150","Klg","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 green and maroon lithic fragments and a few well-rounded quartz pebbles"" (Hoare and Coonrad, 1983) cemented by gray bioclastic limestone consisting of tiny shell fragments.  Lithic clasts are fine-grained tuff and volcanogenic sedimentary rocks metamorphosed to phyllite and low-grade quartz-chlorite-sericite schist (Hoare and Coonrad, 1983).  Lithic fragments thought to be derived from ""nearby strata that were tectonically metamorphosed by movement on the Ungalikthluk fault"" (Hoare and Coonrad, 1983); the matrix does not have a metamorphic fabric suggesting that metamorphism and therefore fault movement were pre-Early Cretaceous (Hoare and Coonrad, 1983).   Bioclastic limestone is composed mostly of microscopic shell fragments.  Buchia crassicollis is found in some limestone beds and Hoare and Coonrad (1983) suggested that the shell fragments in the bioclastic limestone were derived from Buchia.  The presence of Buchia crassicollis indicates these rocks are coeval with the graywacke of Buchia Ridge (Kbr)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","401",""
"5730","Pls","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, Box, 1985a).  Unit is widely distributed throughout the map area and is commonly intercalated in the Togiak-Tikchik Complex and mlange units (MzPzt, MzPza, Mzm).  Hoare and Coonrad (1978) reported the unit ""commonly closely associated with mafic volcanic rocks into which it grades through medium of calcareous breccias and tuffs.""  Commonly contains the pelecypod Atomodesma of Permian age as well as crinoid stems, brachiopods, other pelecypods, and possible bryozoan reported (J.M. Hoare and W.H. Condon, unpub. data; Box, 1985a; see also www.alaskafossil.org).  Unit included in the Goodnews terrane by Box (1985a); however, rocks of this unit are also found within his Togiak terrane (Box and others, 1993; Decker and others, 1994)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","413",""
"3990","TrPmb","Metabasaltic 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 chert (Box, 1985a).  Mineral assemblages indicate greenschist to transitional greenschist-blueschist facies metamorphism (Box, 1985a).  Unit crops out on the south and west side of Goodnews Bay and near Cape Peirce.  Low-angle faults separate unit from overlying nonfoliated mafic rocks (ophiolite units Trob, Trod, Trog) and from underlying schistose clastic rocks (TrPvs).   Schistose fabric indicates multiple deformation events including:  moderately to shallowly dipping foliation and a locally developed lineation; sporadically developed crenulation cleavage and crenulation microfolds; and northeast-trending open folds folding both deformation fabrics (Box, 1985a).  Metamorphic fabric is similar to that of structurally underlying meta-volcaniclastic glaucophane-hornblende epidote schist (TrPvs) and calcareous schist (TrPcs) (Box, 1985a).  Similarity of metamorphic fabrics suggests all three units were deformed during the same event (Box, 1985a).  West of Goodnews Bay, the unit structurally overlies Permian volcaniclastic rocks (Pvs) and underlies Permian limestone (Pls).  Metamorphic age is constrained between Middle Jurassic and Middle Triassic based on age constraints as described for unit ^Pvs below.  Intruded by nonfoliated Middle Jurassic hornblende gabbro (Jgb).  Schist yielded K/Ar mica ages of 1508 and 1558 Ma (table 1), possibly related to a Late Jurassic thermal event suggested by Box (1985a); however, the ages are suspect because the K2O content of the mica (2.94 and 1.71 percent) is much lower than typical for mica (8 to 10 percent), suggesting alteration.  Box (1985a) suggests the protolith age is similar to the structurally overlying ophiolite (units Trob, Trod, and Trog) because the lithologic similarity of the protolith.  However, on the basis of Box's (1985a) terrane model, the similarity of protolith may not be relevant, as he assigned this unit to his Goodnews terrane and the ophiolite to his Togiak terrane.  An alternative protolith age assignment could be Permian or older, based on metamorphic ties to unit TrPvs and association with Permian rocks of the Goodnews terrane","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","425",""
"2832","KJc","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 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","450",""
"5239","Jgs","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); overlain by crystalline limestone, phyllite, and minor amounts of chlorite, graphite, and quartz-sericite schist (Hoare and Coonrad, 1959a).  Mapped as Mesozoic to Paleozoic metabasalt and minor meta-chert (MzPzb) by Box and others (1993); protolith was diabase and basalt having MORB trace-element (REE) signature (Box and others, 1993).  Although protolith age is unknown, it was suggested to be Devonian to Ordovician by Hoare and Coonrad (1959a).  Greenstone Ridge near the center of the Bethel quadrangle is composed of this map unit.  Unit is bounded on west by Golden Gate fault; nearshore facies Kuskokwim Group rocks (Kkn) depositionally overlie unit at the north end of its exposure.  Age of metamorphism may be Late Jurassic because of 146.015.0 Ma age of an actinolite (sample B78-1213, Table 1).  Unit was included in the Goodnews terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","452",""
"5810","Pv","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 Goodnews Bay area, unit is interbedded with volcaniclastic sedimentary rocks (unit Pvs herein; Box,  1985).  Hoare and Coonrad (1978) did not separate these rocks from their undivided }| unit in the vicinity of Goodnews Bay.  In the Nuyakuk Lake area, unit lies stratigraphically above and grades downward into the Permian limestone (unit Pls herein; Mertie, 1938, p. 45-46).  Near lowest part of section north of Nuyakuk Lake fossils identified in an interbed or fault sliver of limestone include brachiopods Calliprotonia sp., Neochonetes(?), Neophricadothyris sp., Neospirifer(?) sp., Thamnosia sp., Waagenoconcha(?) sp., and Yakovlevia sp. of Permian age; foraminifera Schwagerina jenkinsi Thorsteinnson of Permian age; stenoporoid bryozoans of Permian age; and echinoderm debris of Permian age (see sample 79AHr 2, www.alaskafossil.org).  Outcrops in vicinity of Goodnews Bay were included in the Goodnews terrane by Box (1985a), outcrops near Nuyakuk Lake lie within his Togiak terrane","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","454",""
"5050","MzPzs","Togiak-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 (30 to 50 percent), plagioclase (10 percent), and potassium feldspar (5 percent), and minor mica, slate, and volcanic rock fragments.  Alteration products include secondary prehnite, calcite, quartz, and white mica.  Turbidite depositional features locally preserved.  Thickness is uncertain.  Intercalated (structurally?) over 100-m-thick zones with thin-bedded chert-argillite sections (MzPzm); unconformably overlain by conglomeratic rocks [Kkn] of Kuskokwim Group.  Age is uncertain, but older than Late [Early] Cretaceous age of unit [Kkn].""  Unit has a slaty cleavage and is metamorphosed to the prehnite-pumpellyite facies (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","455",""
"2265","Kpd","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 conglomerate, and andesite and dacite porphyritic and vitrophyritic plugs, dikes, sills, and flows (Patton and others, 1975).  K/Ar ages of 76.02.0 and 76.32.0 Ma on biotite and hornblende (samples 4-16 and 5-33, table 1).  Late Cretaceous pollen assemblages from carbonaceous tuffs (R.A. Scott, oral commun., 1973; reported in Patton and others, 1975)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","464",""
"1110","Tnr","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 54.71.6 Ma (Box and others, 1993, sample 87ACz 75m, 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","466",""
"4215","Trv","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 eastward into the adjacent Taylor Mountains quadrangle.  West of Milk Creek fault, basalt is hydrothermally altered, containing secondary chlorite, quartz, and calcite, but it retains original subophitic and fine-grained plagioclase porphyritic textures (Box and others, 1993).   East of Milk Creek fault, a strong foliation and recrystallization has produced fine-grained schist or phyllite composed of chlorite, epidote, calcite, and pumpellyite (Box and others, 1993).  ""Whole-rock trace-element chemistry is characterized by flat to light REE-depleted chondrite-normalized REE pattern, and by high La/Nb elemental ratios, characteristic of island-arc tholeiitic basalts"" (Box and others, 1993).  Box and others (1993) linked the units on either side of the Milk Creek fault on the basis of similar stratigraphic position and trace-element chemistry.  Box and others (1993) reported interbedded shale yielded pelecypods of Late Triassic age just east of Aniak Lake as well as in the Taylor Mountain quadrangle east of map area (W.L. Coonrad, written commun., 1991 cited in Box and others, 1993).  In the Taylor Mountains quadrangle, unit is associated with a limestone that yields Monotis and Halobia fossils of Late Triassic age (Wilson and others, 2006b).  Unit was included in the Togiak terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","468",""
"2180","Kvm","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 range widely in color, mostly green and gray but also red, yellow, brown, or black (Hoare and Coonrad, 1983).  Most distinctive rock type in the belt according to Hoare and Coonrad (1983) is the massive andesitic crystal-lithic tuff, which is at least 1,000 m thick.  Fine-grained tuff and some graywacke is commonly laumontized.   Buchia crassicollis of Early Cretaceous, Valanginian age is found in calcareous graywacke, conglomerate and impure limestone.  In cherty tuff, Radiolaria of Early Cretaceous age has been found at 3 localities (Hoare and Coonrad, 1983).  As in unit Klg above, the presence of Buchia crassicollis indicates these rocks are coeval with the graywacke of Buchia Ridge (Kbr)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","473",""
"2261","Kv","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  rhyolite domes and flows, Swift Creek volcanic field lithic air-fall tuff, Kipchuk volcanic field andesite and basalt flows, tuff, tuffaceous sandstone, and rhyolite domes and flows (Box and others, 1993).  Also includes moderately to steeply dipping, fresh to weakly altered porphyritic basaltic andesite flows of calc-alkaline affinity and interbedded sandy to boulder-rich volcaniclastic rocks mapped by Globerman (1985) and Box (1985a) in the Hagemeister Island quadrangle originally mapped as unit Tv by Hoare and Coonrad (1978).  Associated dikes cut underlying units.  In the Hagemeister Island and southern Goodnews Bay quadrangles, unit overlies Upper Cretaceous Summit Island Formation on Summit Island and adjacent mainland.  On Hagemeister Island, consists of individual 2 to 5 m thick subaerial flows aggregating at least 2 km thick with very minor fluvial sandstone interbeds.  On Crooked Island, it has similar flows but has more voluminous (25 percent) interbedded epiclastic volcanic sandstone and coarse boulder conglomerate.  On mainland coast, northwest of Right Hand Point, consists almost entirely of boulder-rich volcaniclastic sedimentary rocks of probable debris flow origin and very minor flows.  On Saint Matthew Island, consists of flat-lying to gently dipping mafic flows of andesite and basalt, and volcaniclastic rocks consisting of andesitic and basaltic tuff and conglomerate.  K/Ar and 40Ar/39Ar ages range from 64.52.0 Ma to 79.22.4 Ma (table 1); however, a basalt sill from Saint Matthew Island yielded a whole-rock K/Ar age of 52.21.6 Ma (Wittbrodt and others, 1989, sample 12-106, table 1 herein).  As this sample yields a significantly younger age than other dated rocks from Saint Matthew Island, Wittbrodt and others (1989) suggested that the basalt sill was derived from a significantly younger event, which intruded this map unit, Kv. In the Bethel quadrangle, internal contacts reflect distinction between flow and tuff units of Box and others (1993); pyroclastic and felsic sub-units are shown with overprint patterns","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","485",""
"2210","Kv","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  rhyolite domes and flows, Swift Creek volcanic field lithic air-fall tuff, Kipchuk volcanic field andesite and basalt flows, tuff, tuffaceous sandstone, and rhyolite domes and flows (Box and others, 1993).  Also includes moderately to steeply dipping, fresh to weakly altered porphyritic basaltic andesite flows of calc-alkaline affinity and interbedded sandy to boulder-rich volcaniclastic rocks mapped by Globerman (1985) and Box (1985a) in the Hagemeister Island quadrangle originally mapped as unit Tv by Hoare and Coonrad (1978).  Associated dikes cut underlying units.  In the Hagemeister Island and southern Goodnews Bay quadrangles, unit overlies Upper Cretaceous Summit Island Formation on Summit Island and adjacent mainland.  On Hagemeister Island, consists of individual 2 to 5 m thick subaerial flows aggregating at least 2 km thick with very minor fluvial sandstone interbeds.  On Crooked Island, it has similar flows but has more voluminous (25 percent) interbedded epiclastic volcanic sandstone and coarse boulder conglomerate.  On mainland coast, northwest of Right Hand Point, consists almost entirely of boulder-rich volcaniclastic sedimentary rocks of probable debris flow origin and very minor flows.  On Saint Matthew Island, consists of flat-lying to gently dipping mafic flows of andesite and basalt, and volcaniclastic rocks consisting of andesitic and basaltic tuff and conglomerate.  K/Ar and 40Ar/39Ar ages range from 64.52.0 Ma to 79.22.4 Ma (table 1); however, a basalt sill from Saint Matthew Island yielded a whole-rock K/Ar age of 52.21.6 Ma (Wittbrodt and others, 1989, sample 12-106, table 1 herein).  As this sample yields a significantly younger age than other dated rocks from Saint Matthew Island, Wittbrodt and others (1989) suggested that the basalt sill was derived from a significantly younger event, which intruded this map unit, Kv. In the Bethel quadrangle, internal contacts reflect distinction between flow and tuff units of Box and others (1993); pyroclastic and felsic sub-units are shown with overprint patterns","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","485",""
"2260","Kv","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  rhyolite domes and flows, Swift Creek volcanic field lithic air-fall tuff, Kipchuk volcanic field andesite and basalt flows, tuff, tuffaceous sandstone, and rhyolite domes and flows (Box and others, 1993).  Also includes moderately to steeply dipping, fresh to weakly altered porphyritic basaltic andesite flows of calc-alkaline affinity and interbedded sandy to boulder-rich volcaniclastic rocks mapped by Globerman (1985) and Box (1985a) in the Hagemeister Island quadrangle originally mapped as unit Tv by Hoare and Coonrad (1978).  Associated dikes cut underlying units.  In the Hagemeister Island and southern Goodnews Bay quadrangles, unit overlies Upper Cretaceous Summit Island Formation on Summit Island and adjacent mainland.  On Hagemeister Island, consists of individual 2 to 5 m thick subaerial flows aggregating at least 2 km thick with very minor fluvial sandstone interbeds.  On Crooked Island, it has similar flows but has more voluminous (25 percent) interbedded epiclastic volcanic sandstone and coarse boulder conglomerate.  On mainland coast, northwest of Right Hand Point, consists almost entirely of boulder-rich volcaniclastic sedimentary rocks of probable debris flow origin and very minor flows.  On Saint Matthew Island, consists of flat-lying to gently dipping mafic flows of andesite and basalt, and volcaniclastic rocks consisting of andesitic and basaltic tuff and conglomerate.  K/Ar and 40Ar/39Ar ages range from 64.52.0 Ma to 79.22.4 Ma (table 1); however, a basalt sill from Saint Matthew Island yielded a whole-rock K/Ar age of 52.21.6 Ma (Wittbrodt and others, 1989, sample 12-106, table 1 herein).  As this sample yields a significantly younger age than other dated rocks from Saint Matthew Island, Wittbrodt and others (1989) suggested that the basalt sill was derived from a significantly younger event, which intruded this map unit, Kv. In the Bethel quadrangle, internal contacts reflect distinction between flow and tuff units of Box and others (1993); pyroclastic and felsic sub-units are shown with overprint patterns","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","485",""
"5045","MzPzv","Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Volcaniclastic sandstone and argillite","Mesozoic 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 quadrangle].  Detrital grains include volcanic rock fragments containing plagioclase phenocrysts, plagioclase, and minor potassium feldspar, clinopyroxene, and quartz.  Thickness is uncertain.  Structurally overlain and underlain by unit MzPzs; structurally overlain by unit MzPzm along Kisaralik River; unconformably overlain by conglomeratic strata [Kkn] of Kuskokwim Group north of Kisaralik River.  Age is uncertain, but older than Late [Early] Cretaceous age of unit [Kkn].""  Unit has a slaty cleavage and is metamorphosed to the prehnite-pumpellyite facies (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","485",""
"9420","P_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, biotite-hornblende gneisses, garnetiferous amphibolites, quartz-mica schists, and marble"" (Hoare and Coonrad, 1978).  It is an antiformal crystalline complex cored by high-grade orthogneiss intercalated with metavolcanic and metasedimentary rocks, and flanked by greenschist-facies rocks (Turner and others, in prep.).  Rocks in core of complex include varieties of orthogneiss whose protoliths may have ranged in composition from granite to diorite (Turner and others, in prep.; Moll-Stalcup and others, 1996).  As described by Turner and others (in prep.), orthogneiss of the core is intercalated with pyroxene granulite, garnet amphibolite, garnet-mica schist (locally kyanite-bearing), and rare quartzite and marble (marble locally mapped separately as unit P_km).  The core of amphibolite facies rocks which apparently grade into greenschist facies rocks that dip away from the core on the northwest and southeast.  These lower grade rocks contain a variety of schist and quartzite, as well as calc-phyllite, marble, and meta-conglomerate (Turner and others, in prep.).  Mineral foliation tends to parallel compositional layering and both consistently strike northeast; ""*** dip of the foliation changes from northwest to southwest two to four times across the width of the complex"" (Hoare and Coonrad, 1979) south of Kanektok River.  Compositional layering and foliation are disrupted by northwest trending faults including a significant left lateral offset at the Kanektok River.  North of the river, the rocks are more highly deformed, there the dip and trend of foliation are more variable (Hoare and Coonrad, 1979). The Kanektok metamorphic complex is fault bounded on the southeast against calcareous schist (unit TrPcs), the Kuskokwim Group (unit Kk), and the undivided Togiak-Tikchik Complex (unit MzPzt) in the Goodnews Bay quadrangle, and green amphibole-bearing schist (Jgs) in the Bethel quadrangle.  It is depositionally overlain by the Kuskokwim Group (unit Kkn) in the Bethel quadrangle.  The Kanektok metamorphic complex was originally assigned a Precambrian age because it was more metamorphosed than nearby Paleozoic rocks (Hoare and Coonrad, 1959a; 1961b).  Turner and others (in prep.) measured 77 K/Ar ages on 58 samples (table 1 herein) as well as dating zircon and sphene by the population-based U/Pb method.  Most K/Ar ages were Mesozoic and discordant when multiple minerals from the same sample could be dated.  If these are considered simply as cooling ages, they suggest a latest Jurassic or Early Cretaceous thermal event affected the metamorphic complex.  However, multiple K-Ar analyses of biotite from three pyroxene granulite samples yielded average ages between 2255 and 2474 Ma (table 1).  Hornblende from a garnet amphibolite yielded 177053 Ma (sample DT76-69a, table 1) which is identical to a sphene U/Pb age of 1770 Ma (sample DT75-86, table 1).  U/Pb ages of zircon from granite gneiss and tonalite gneisses cluster around 2050 Ma (Turner and others, in prep.; Box and others, 1990, Moll-Stalcup and others, 1996; table 1, herein).  The Kanektok metamorphic complex crops out as a narrow belt trending northeast extending from near Jacksmith Bay in the Goodnews Bay quadrangle northward 160 km to the southern part of the Bethel quadrangle.  The Idono complex of Gemuts and others (1983; Miller and others, 1991; Miller and Bundtzen, 1994; Wilson and others, 1998) is similar in some respects to the Kanektok metamorphic complex and crops out north of the map area in the Iditarod quadrangle.  The Kanektok metamorphic complex is the Kilbuck terrane of Jones and others (1981).  Locally subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","486",""
"3893","Trod","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 mapped 0.3 to 1.0-m-wide diabase sills and dikes containing basalt and chert screens west of Matogak River mouth, thick diabase sills intruding chert at Pyrite Point, and diabase dikes cutting gabbro south of Chagvan Bay, which are not shown.  Box (1985a) described the unit as ""mostly massive and highly altered to low greenschist facies assemblage.""   Unit is altered to hornblende hornfels west of Matogak River mouth, which Box (1985a) reported is due to an underlying, but not shown, gabbroic pluton; a K/Ar amphibole age on the hornfels was 18710 Ma (sample 81SB 116b, table 1).  Unit believed to be co-genetic with associated, overlying Upper Triassic pillow basalt (^ob) (Box, 1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","514",""
"2105","Kygv","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 others, 1975).  Argillite is siliceous, dense, breaks with conchoidal fracture, shows small-scale crossbedding and convolute laminations, and is interpreted to be a distal facies of a marine turbidite.  No fossils are known in this unit; however, it is thermally altered by granodiorite (map unit TKgd) which yielded an age of 62.22.0 Ma (71AMm 45, table 1).  Unit appears to stratigraphically underlie pyroclastic rocks, which yield K/Ar ages of 76.02.0 and 76.32.0 Ma on biotite and hornblende, respectively (71AMm 50, table 1) which, in part, led Patton and others (1975) to assign a Cretaceous(?) age for the unit.  Unit may correlate with unit Kygv of Patton and others, in press(a), in press(b); Wilson and others, 2006a, c)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","532",""
"1640","TMzp","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 polished, has glacial striae and a brownish-black varnish (Barth, 1956, p. 117).  Intruded by an aplite dike of unit Tad, suggesting age is greater than 57 Ma","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","546",""
"1960","Ks","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 about 200 m of massive and thick-bedded pebble [to] cobble conglomerate overlain by about 650 m of interbedded sandstone, siltstone, and mudstone and a few conglomerate beds"" (Hoare and others, 1983).  At the reference section of the unit, its character changes to consist of ""about 75 percent carbonaceous mudstone, siltstone, and shale and 25 percent interbedded sandstone and pebble grit"" (Hoare and others, 1983).  Bedding is discontinuous and best developed in lower part of formation where thick conglomerate beds grade into pebble sandstone and sandstone beds (Hoare and others, 1983).  Conglomerate clasts are well-rounded, generally not larger than 10 cm, and primarily derived from flows, tuffs, and sedimentary rocks of Jurassic and Early Cretaceous age (Hoare and others, 1983).  Hoare and others (1983) also reported white quartz clasts and sparse schist and plutonic clasts; they suggest the schist clasts are derived from tectonically metamorphosed rocks that occur locally along major faults in this region.  Sandstone and siltstone consists of 60 to 70 percent lithic fragments and 10 to 15 percent each of quartz and feldspar (Hoare and others, 1983).  Lithic component of the sandstone and siltstone is very fine-grained cherty tuff and other volcanic rock fragments, as well as, argillite, quartzite, and chert (Hoare and others, 1983).  Hoare and others (1983) indicated that the hardness of the rocks in the unit varies with their structure and, by implication, location.  At the west end of Summit Island and on the west side of the unnamed adjacent headland on the mainland, the rocks dip 45 to 80 and are hard and well indurated.  On the east end of the island and elsewhere on the mainland, dips are shallow and the rocks are less well indurated.  Box (1985a) divided the unit into two sub-basins along the trace of the Togiak-Tikchik fault, based on contrasting sandstone compositions.  Sandstone of his Summit sub-basin (southeast of Togiak-Tikchik fault) is composed mostly of slaty sedimentary lithic fragments, similar to underlying Jurassic sedimentary rocks.  Rocks in this sub-basin are more than 1 km thick and consist of a lower conglomeratic member (200 m) of probable alluvial fan to braided stream origin, and an upper carbonaceous shale member, of probable meandering stream-flood plain origin, having channelized sandstone bodies, that become finer-grained and thinner upward.  Paleocurrent indicators in the upper member generally indicate transport to the northeast.  Sandstone of Box's Hagemeister sub-basin (northwest of Togiak-Tikchik fault) is composed of nonfoliated volcanic detritus similar to underlying Jurassic rocks.  This sub-basin section is also more than 1 km thick, consisting of a lower channelized sandstone member (600 m) of probable meandering stream origin, and an upper sandy member (400 m) having coarsening and thickening upward cycles beginning with laminated siltstone-coal intervals which are possibly lacustrine delta deposits.  Paleocurrent indicators in the Hagemeister sub-basin generally indicate transport to the northwest (Box, 1985a).  Plant fossils from the base of the reference section indicate a latest Cretaceous or early Tertiary age (Jack Wolfe, USGS, oral commun. 1974, cited in Hoare and others, 1983).  A dike that cuts the formation yielded an age of 64.62 (74ACd 14d, table 1); which suggested to Hoare and others (1983) that a Late Cretaceous age for the Summit Island Formation was more probable.   Subsequent dating of a dike cutting the formation by Box (1985a) yielded an older age of 76.64.5 Ma (B78-1125G, table 1), further supporting the age assignment for the unit.  Pollen identified by R.H. Tschudy (USGS, written commun, 1975, cited in Hoare and others, 1983) formed a unique assemblage.  Several of the taxa had been reported from Arctic Canada and western Siberia, but the complete assemblage was unique and therefore he was reluctant to assign the unit a definite Late Cretaceous age.  However, on the basis of the fossil and radiometric evidence, Hoare and others (1983) assigned a Late Cretaceous, possibly Maastrichtian 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","552",""
"1985","Kkn","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-grained sandstone, siltstone, and shale of the basal conglomerate of Box and others (1993).  This informal sub-division of the Kuskokwim Group was originally defined by Platt and Muller (USGS unpublished data, 1957, cited in Wilson and others, 2006b) in the northeastern Taylor Mountains quadrangle; subsequent mapping in the Iditarod quadrangle to the north (Miller and Bundtzen, 1994) also described a nearshore facies.  As described by Hoare and Coonrad (1959a), chiefly consists of conglomerate facies of interbedded graywacke and siltstone, with lesser amounts of pebble grit conglomerate and a small amount of coal.  Well-indurated, commonly light- to dark-gray, and weathers brown.  Varies from volcanic wacke to quartz-chert-feldspar-rich sandstone.  Fossils collected from basal conglomerate of Box and others (1993) zone are considered Late Cretaceous (Cenomanian) age and fossils from the deltaic facies of Box and others (1993) considered Late Cretaceous (Turonian).  Murphy (1989) reported an Albian ammonite, Paragastroplites, from this unit in the Bethel quadrangle","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","553",""
"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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","554",""
"2125","Kgbr","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.  In lowest part of section, beds range from 0.1 to 3 to 4 m thick; the upper part of this lower section consists of 1,400 m of increasingly massive conglomerate (Hoare and Coonrad, 1983).  Well-rounded clasts, as large as 10 cm, consist of ""graywacke and siltstone, cherty tuff, and less abundant porphyritic volcanic rocks"" (Hoare and Coonrad, 1983); the graywacke clasts resemble the graywacke of Kulukak Bay (map unit Jkw:  Jln, Jmm).  The conglomerate, near the top of Buchia Ridge, contains coquinas of Buchia crassicollis shells (Hoare and Coonrad, 1983).  Box (1985a) interpreted this part of the unit to be of shallow marine origin.  Upper part of unit, about 2,500 m thick, is ""mostly shale and thin-bedded sandstone"" (Hoare and Coonrad, 1983), which is poorly exposed.  It is ""dominantly fine-grained *** calcareous black shale, thin-bedded calcareous siltstone, sandstone, calcarenite, and minor gritstone"" (Hoare and Coonrad, 1983).  Box (1985a) interpreted this upper part of the section to be of probable offshore marine origin.  According to Hoare and Coonrad (1983), the graywacke of Buchia Ridge ""is the thickest, least deformed section of Lower Cretaceous sedimentary rocks known in southwestern Alaska.""  Outcrop area covers approximately 350 km2 in a thrust plate separated from its neighbors by reverse faults (Hoare and Coonrad, 1983).  Lower part of section contains abundant Valanginian fauna, primarily Buchia; upper part of section yields sparse Inoceramus, Belemnites, and a single Hauterivian ammonite according to Hoare and Coonrad (1983)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","560",""
"3150","Jkw","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.  Compositionally, ""varies from quartz- and plagioclase-rich wackes to quartz-poor volcanic wackes.  Generally contains black argillite or tuff chips"" (Hoare and Coonrad, 1978).  These rocks are the thick marine sedimentary unit referred to as the ""Weary graywacke"" by Hoare and others (1975).  Unit is widely exposed in the southern Goodnews Bay and the Nushagak Bay quadrangles as well as the adjacent southeastern Dillingham quadrangle (Hoare and Coonrad, 1978).  Buchia, Inoceramus, belemnites, and rare ammonite fragments ranging from Middle to early Late Jurassic age have been found in this unit.  Locally sub-divided by Box (1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","562",""
"3120","Jvc","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 thick; coarser parts are composed primarily of rounded clasts of basalt and andesite and minor mafic to intermediate composition plutonic rock fragments (Box and others, 1993).  Felsic pyroclastic rocks are found locally in the middle part of the unit within the map area and in the lower part of the unit north of the map area (Box and others, 1993).  Marine pelecypods of Bajocian age (Middle Jurassic) are found near the base of the sequence and marine pelecypods of late Kimmeridgian to early Tithonian age (Late Jurassic) were reported from the Russian Mission quadrangle north of map area (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","606",""
"5746","Pcs","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 locally north and east of Goodnews Bay.  Age constrained by several occurrences of fragmentary Atomodesma sp.  Prehnite-pumpellyite facies"" (Box, 1985a).  Interbedded with Permian mafic volcanic rocks (Pv).  Unit included in the Platinum subterrane of the Goodnews terrane by Box (1985a); however, rocks that are similar and stratigraphically correlated, associated with map units Pls and Pv, are found in the western Taylor Mountains quadrangle and apparently extend into the eastern Bethel quadrangle (map unit Pcs of Wilson and others, 2006b).  These rocks were assigned to the Togiak terrane by Box (1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","615",""
"2870","KJba","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 Jab","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","623",""
"3255","JTrcv","Coarse 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 aquagene tuff and crystal tuff commonly having devitrified glass shards.  Rocks are altered to prehnite-pumpellyite facies mineral assemblages and locally altered to hornblende and biotite hornfels around gabbroic plutons.  Unit is exposed on both sides of Togiak-Tikchik and Kulukak faults; age northwest of Togiak-Tikchik fault constrained by underlying Upper Triassic basalt and crosscutting plutons of early Middle Jurassic age; southeast of Togiak-Tikchik fault, constrained only to pre-Valanginian age (Box, 1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","665",""
"3310","Jlt","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 unit Jpb).  Highly deformed, commonly having folded slaty or spaced cleavage.  Partially altered to prehnite-pumpellyite facies mineral assemblage.  Several chert samples have yielded Radiolaria of Jurassic age, one of which is identified as upper Kimmeridgian to upper Tithonian (latest Jurassic) (see Box, 1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","682",""
"3891","Trob","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 in an intergranular to subophitic groundmass of plagioclase, clinopyroxene, and secondary replacement minerals.  Basalt is commonly amygdaloidal; abundant vesicles are filled with a combination of chlorite, clinozoisite, prehnite, pumpellyite, and calcite.  Box (1985a) reported a number of radiolarian collections; however, only 2 were age diagnostic, yielding Middle Triassic to Early Jurassic and Middle to Late Triassic.  Box (1985a) considered the pillow basalt to be Late Triassic","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","708",""
"3130","Ja","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 clinopyroxene, in contrast to sandstone of map unit Jvs, which had a largely volcanic source (Box and others, 1993).  Age inferred based on stratigraphic position above Early Jurassic and Late Triassic phyllite and chert (map unit JTrp) and on strike position relative to map unit Jvs","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","715",""
"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 Newenham which are here included in map unit Jum.  Hoare and Coonrad (1978) mapped the trondhjemite as a distinct map unit, but included the remaining lithologies in their }| or Jum units.  Box (1985a) placed these rocks in his Hagemeister subterrane of the Goodnews terrane.  As described by Hoare and Coonrad (1978), little information is available about specific lithologies and there distribution in the }| unit, hence the ophiolite may also occur outside of the area covered by Box's dissertation area and therefore be more extensive than shown.  Box (1985a) inferred the igneous rocks of the complex to be cogenetic and inferred the ophiolite complex to be Late Triassic in age on the basis of the Radiolaria in the included chert.  Subdivided","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","717",""
"2890","KJb","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 from enclosing map unit","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","718",""
"3450","Jab","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 the unit is interbedded graywacke, siltstone, impure limestone, and pebble conglomerate (Hoare and Coonrad, 1959a).  The rock unit forms a belt in low rolling hills on the west flank of the Kuskokwim Mountains from the Kwethluk River and northward (Hoare and Coonrad, 1959a).  Marine pelecypods of Bajocian (Middle Jurassic) age occur in sedimentary strata of this unit (Hoare and Coonrad, 1959a; Box and others, 1993).  Assigned to Nyac terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","744",""
"6580","MDm","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 feldspar, quartz, and plutonic rock fragments.  Rare metamorphic blue amphiboles (magnesioriebeckite) in metabasaltic dikes indicate relatively high-pressure, low-temperature metamorphism (Sarah Roeske, written commun., 1988).  Ranges from 100 to 300 m thick.  Unit found structurally above unit MzPzm and structurally below unit MzPzp; original depositional relations are uncertain.  Age constrained by conodonts of latest Devonian to earliest Mississippian age (Stephen Box and others, unpublished data, reported in Box and others, 1993)""  Unit is strongly foliated and metamorphosed to greenschist and transitional greenschist-blueschist facies","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","745",""
"3894","Trog","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 albite, epidote, chlorite, calcite and iron oxides.  Compositional layering is rare in contrast to gabbro of map unit Jg.  Locally grades into diabase (Trod) south at Chagvan Mountain due to increasing proportion of crosscutting diabasic dikes.  Box (1985a) mapped gabbro as a thrust sheet above the Osviak fault emplaced over schistose rocks of map unit TrPcs around Security Cove and Cape Peirce.  Locally, mylonite is found along contact and similar mylonite is found sporadically along contact between gabbro and structurally underlying diabase near Cape Newenham.  Box (1985a) believed gabbro was co-genetic with associated diabase (Trod), pillow basalt (Trob), trondhjemite (JTrot) and serpentinized ultramafic rocks, all part of a dismembered ophiolite","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","747",""
"3451","Jmv","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  hornblende porphyritic rocks, more common in lower third of exposed section.  Interbedded clastic rocks composed almost entirely of volcanic lithic detritus, except lower conglomerate, which contains a minor proportion granitic plutonic rock clasts similar to adjacent pluton.  Sedimentary facies range from fluvial deltaic to nearshore marine to subwave base turbidites.  Box (1985a) mapped the contact between this unit and similar older volcanic and sedimentary rocks (unit Jlvs) structurally and stratigraphically below it as a low-angle thrust(?) which he suggested is probably a faulted unconformity.  Fossils of Middle Jurassic age are locally common (Box, 1985a).  Conglomerate includes clasts of granitic rocks similar to nearby Middle Jurassic Hagemeister pluton (Box, 1985a); mapped herein as unit Jlgd","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","751",""
"3230","Jln","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 preserved and indicate deposition from turbidity currents and other mass flow processes"" (Box, 1985a).  Partially altered to prehnite-pumpellyite mineral assemblages, the unit is divisible into two structural facies types, which occur as alternating, fault-bounded blocks (Box, 1985a).  One structural facies is characterized by generally well-bedded sections showing varying degrees of disruption prior to lithification; the second structural facies is distinguished by pervasive cleavage and occurrence of sandstone boudins in an argillaceous matrix (Box, 1985a).  Poorly preserved Radiolaria from structural facies 1 have been identified as post-Triassic Mesozoic forms (Box, 1985a).  Clasts of slate similar to structural facies 2 occur stratigraphically below Bajocian fossil occurrence in adjacent Middle Jurassic turbidite facies sedimentary rocks (map unit Jmm).  Box (1985a) interprets this to indicate that deposition and deformation of these rocks were therefore Early Jurassic in age.  This unit and map unit Jmm above are found southeast of the Kulukak fault, their outcrop area corresponds to the area shown by Hoare and Coonrad (1978) for the graywacke of Kulukak Bay","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","793",""
"4712","Pls","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, Box, 1985a).  Unit is widely distributed throughout the map area and is commonly intercalated in the Togiak-Tikchik Complex and mlange units (MzPzt, MzPza, Mzm).  Hoare and Coonrad (1978) reported the unit ""commonly closely associated with mafic volcanic rocks into which it grades through medium of calcareous breccias and tuffs.""  Commonly contains the pelecypod Atomodesma of Permian age as well as crinoid stems, brachiopods, other pelecypods, and possible bryozoan reported (J.M. Hoare and W.H. Condon, unpub. data; Box, 1985a; see also www.alaskafossil.org).  Unit included in the Goodnews terrane by Box (1985a); however, rocks of this unit are also found within his Togiak terrane (Box and others, 1993; Decker and others, 1994)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","805",""
"1670","TKm","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 64.62 Ma on biotite (74ACd 14d, table 1) from the western Nushagak Bay quadrangle.  Also includes medium- to coarse-grained pyroxene gabbro dike(?) on Saint Matthew Island (Patton and others, 1975)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","839",""
"6995","DOl","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 quartzite and quartz-chlorite schist  ***"" Hoare and Coonrad (1978).  Algal mounds indicate shallow water deposition (Decker and others, 1994).  Unit is in scattered outcrops along a north-northeasterly trend from Goodnews Bay to the northern edge of the Goodnews Bay quadrangle.  Unit thrust over Permian limestone (Pls) and calcareous schist unit (^Pcs) and intruded by gabbro of Jurassic age (Jgb).  Hoare and Coonrad (1978) reported sparse fossils of Middle Devonian to Early(?) Ordovician age  One sample collected by Stephen Box in northern part of the Goodnews Bay quadrangle boundary contains the conodonts Acanthodus lineatus (Furnish), Drepanoistodus sp., Variabiliconus bassleri (Furnish), ""Scolopodus"" cf. ""S."" sulcatus Furnish, Eucharodus parallelus (Branson and Mehl), and Rossodus(?) sp. of Early Ordovician age (see sample 89AJM 60a,  www.alaskafossil.org).  A sample collected by J.M. Hoare contained ostracodes, echinoderms, fragments of brachiopods, algae, and small colonies of tabulate coral, possibly the genus Dania of Silurian age (A.K. Armstrong, written commun., 1975)   Unit was included in the Goodnews terrane by Box (1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","842",""
"6412","MDv","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 volcanic protolith have whole-rock trace-element signatures indicating an arc-alkaline arc affinity.  In the adjacent Taylor Mountains quadrangle, Wilson and others (2006b) described ""Fine- to coarse-grained, massive green to purple altered greenstone, occasionally calcareous or schistose, rarely interbedded with green chert, argillite, and tuff.  Greenschist with occasional chert boudins is a minor part of unit as is shale-chip agglomerate.  Greenstone is locally cut by quartz and calcite veins containing epidote and copper sulfides"" based on the 1969 and 1970 field notes of J.M. Hoare and W.H. Condon.  Unit crops out near the head of Chikuminuk Lake.  Unit is interbedded with the basal part of unit Pcs, clastic rocks and phyllite of map unit J^p may overlie this map unit (Wilson and others, 2006b).  Age inferred by Box and others (1993) on the basis of conodonts of Late Devonian to Early Mississippian age near the base of unit shown herein as Pcs (Note, the Pcs unit was mapped as of Triassic to Devonian age by Box and others, 1993).  Age assignment questionable because conodont-bearing samples may have been collected from redeposited clasts or ""interweaved"" tectonic slices (see comments by Anita Harris for sample 87AMM 69, www.alaskafossil.org).  Unit may be Permian in age because of association with clastic rocks of presumed Permian age due to association with Permian limestone (Pls) interbeds in the Taylor Mountains quadrangle (Wilson and others, 2006b)  Unit included in the Tikchik terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","846",""
"3991","TrPvs","Volcaniclastic 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, 1985a).  Rounded cobble meta-conglomerate contains mostly plagioclase-phyric amygdaloidal volcanic clasts (Box, 1985a).  Mineral assemblages indicate greenschist to transitional greenschist-blueschist facies metamorphism (Box, 1985a).  Unit shows evidence of multiple metamorphic events and has a more pronounced structural fabric to the southwest (Box, 1985a).  The latest metamorphic event created a strong fabric by syn-metamorphic flattening or mylonitization and a lineation formed by clast elongation and mineral alignment (Box, 1985a).  This latest metamorphic fabric deformed non-coplanar isoclinal folds and slaty cleavage of a previous metamorphic event (Box, 1985a).  Metamorphic fabric is similar to the structurally overlying metabasaltic schist (^Pmb) and underlying calcareous schist (TrPcs) suggesting all three units were deformed during the same Late Jurassic metamorphic event (Box, 1985a).  However, this is contradicted by K/Ar cooling age of amphibole of 231.26.9 Ma (sample 82SB-147, Table 1) suggesting Middle Triassic metamorphism; age is constrained to be older than the intrusion of Middle Jurassic gabbroic rocks (unit Jgb).  On and adjacent to Susie Mountain, unit is intruded by pyroxenite and hornblende gabbro bodies which yielded Middle Jurassic K/Ar amphibole ages.  Box (1985a) indicates unit structurally overlies Permian mafic volcanic rocks (Pv) and volcaniclastic rocks (Pcs), which he concludes suggests the protolith age could be as old as Permian.  Unit crops out near Cape Peirce and on the south and west sides of Goodnews Bay.  Unit was included in the Cape Peirce subterrane of the Goodnews terrane by Box (1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","847",""
"2102","Kcgc","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 sandstone and shale intervals 5 to 20 m thick, locally has thin-bedded sections (Hoare and Coonrad, 1983).  The base of the unit is not recognized and as such Hoare and Coonrad (1983) suggested that rocks of Jurassic age may be present in the unit.  Rocks are strongly folded and commonly overturned (Hoare and Coonrad, 1983).  Box and others (1993) reported the presence of lithic clasts likely derived from the Kanektok metamorphic complex, as well as other local units.  Buchia crassicollis is found in several areas on the northwest side of the belt.  Unit is exposed in the Bethel and Goodnews Bay quadrangles and appears to correspond with similar rocks that extend in a broad belt from the southeast corner of Saint Michael quadrangle and the northwest corner of the Holy Cross quadrangle to the south-central part of the Kwiguk quadrangle (map unit Kygc, Patton and others, in press(a), in press(b); Wilson and others, 2006a, c).  No fossils have been found in this similar unit in the Saint Michael and Holy Cross quadrangles, but in the Yukon-Koyukuk Basin to the north, similar rock assemblages have yielded marine mollusks of probable late Early or early Late Cretaceous age (Patton and others, in press(a); Wilson and others, 2006c), slightly younger than within this map area","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","852",""
"5217","MzPzp","Togiak-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 age.  Whole-rock major- and trace-element chemical compositions are similar to those of modern mid-ocean ridge basalts and strikingly similar to those of lavas from unit MzPzb.  Structurally overlies unit MDm and is intruded by serpentinite (Ksp).  Depositionally overlain by conglomeratic rocks [Kkn] of Kuskokwim Group.  Age is uncertain, but older than Late Cretaceous age of unit [Kkn].""  Unit is strongly foliated and metamorphosed to greenschist and transitional greenschist-blueschist facies.  (Note, on this map, the Kuskokwim Group nearshore facies rocks of map unit Kkn are assigned an age that includes Albian or late Early Cretaceous)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","872",""
"5026","MzPzc","Togiak-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 quadrangle].  Structurally(?) intercalated with unit }|s; unconformably overlain by conglomeratic rocks [Kkn] of Kuskokwim Group.  Age constrained by presence of recrystallized radiolarian (Phanerozoic) and Late [Early] Cretaceous age of overlying unit [Kkn].""  Unit has a slaty cleavage and is metamorphosed to the prehnite-pumpellyite facies (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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","872",""
"2510","Ksp","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 intrusion during Late Cretaceous tectonism","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","878",""
"3950","TrPcs","Calcareous 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).  Turbidite characteristics are locally preserved in clastic metasedimentary rocks (Box, 1985a).  Mineral assemblages indicate greenschist to transitional greenschist-blueschist facies metamorphism (Box, 1985a); however, structurally the unit shows evidence of multiple metamorphic events (Box, 1985a).  The latest metamorphic event created a strong fabric by syn-metamorphic flattening or mylonitization and a lineation formed by clast elongation and mineral alignment (Box, 1985a).  This latest metamorphic fabric deformed tight folds and axial planar slaty cleavage of a previous deformation event (Box, 1985a).  Metamorphic fabric is similar to the structurally overlying meta-volcaniclastic glaucophane-hornblende epidote schist (TrPvs) and metabasaltic schist (TrPmb) suggesting all three units were deformed during the same metamorphic events (Box, 1985a).  Metamorphic age is constrained as described above for unit TrPvs.  Unit crops out in two locations, near Cape Peirce and near Jacksmith Bay.  Near Jacksmith Bay, unit is structurally overlain by Devonian to Ordovician limestone (DOl) and the Kanektok metamorphic complex (P_k and P_km).  Intruded by nonfoliated Middle Jurassic gabbroic rocks (Jgb).  Age of protolith may be Permian or older (Hoare and Coonrad, 1978; Box, 1985a) because of metamorphic ties to unit TrPvs and association with Permian rocks of the Goodnews terrane.  Unit was included in the Cape Peirce subterrane of the Goodnews terrane by Box (1985a)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","884",""
"3151","Jmm","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 section, which he divided into four turbidite environment units (using criteria of Walker and Mutti, 1973, cited in Box, 1985a) from bottom to top:  1.) conglomeratic inner-fan; 2.) well-bedded, outer-fan lobe; 3.) sandy, typically massive, middle-fan channel; and 4.) conglomeratic inner-fan unit.  According to Box (1985a), ""sandstone compositions almost entirely derived from plagioclase-rich volcanic sources.  Minor slaty clasts near base of lowest unit, and minor component of slate, dioritic plutonic and chert detritus in upper unit.  Interbedded slump folds suggest southeast-facing paleoslope. *** Tightly folded around gently northeast-plunging axes and sub vertical axial planes.""  Box (1985a) suggested deformation was probably during latest Jurassic to earliest Cretaceous time, based on occurrence of clasts of similar lithology in the lower unit of the graywacke of Buchia Ridge (map unit Kbr).  Unit located southeast of map unit Jln; separated from by the Right Hand fault of Box (1985a); unit Kgbr located northwest of the Kulukak fault and northwest of map unit Jln; hence units Jmm and Kgbr are not in contact","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","895",""
"3260","JTrp","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 into the adjacent Taylor Mountains quadrangle.  Unit depositionally overlies map unit ^b in the southeastern Bethel quadrangle and is overlain by map units Jvs and Ja (Box, 1985a).  Box and others (1993) constrained age based on unit overlying ^b and an Early Jurassic age derived from the single radiolarian collection.  On the basis of field notes of J.M. Hoare and W.H. Condon in the adjacent Taylor Mountains quadrangle, the unit could also be described as gray to black cherty phyllitic shale, highly contorted thin-bedded siliceous argillite and local cherty dark calcareous phyllite in association with greenstone of map unit MDv.  The phyllite is occasionally sulfide-bearing along fault zones according to the field notes of J.M. Hoare and W.H. Condon (USGS unpublished data, 1969, 1970)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","896",""
"4035","Trv","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; however, locally may be dark gray and only finely crystalline.  Possibly occurs in fault bounded settings.  Unit crops out in two areas, one near the head of Lake Chauekuktuli in the northeast corner of the Goodnews Bay and adjacent Dillingham quadrangle and a second area near where the Kanektok River has cut through the Ahklun Mountains.  Fossils include the ammonite Arcestes sp. of Late Triassic age, and pelecypods Monotis subcircularis Gabb and Monotis(?) sp. of Norian age (see www.alaskafossil.org).  Similar rocks are included in the }| unit of Hoare and Coonrad (1978, unit }|t, herein) as well as in the ^|m melange unit of Box and others (1993, unit }m in part, herein).  Hoare and Coonrad (1978) mapped these rocks as a separate unit only in the vicinity of fossil localities ""because the rocks resemble other rocks of Paleozoic and Mesozoic ages with which they are tectonically associated.""  Unit included both in the Goodnews and Tikchik terranes by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","924",""
"5060","Pcs","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 volcanic clasts; shale-rich section have thin limestone turbidite beds and thin sand to gravel beds of volcaniclastic composition"" (Box and others, 1993).  Unit crops out in the Bethel quadrangle north and south of the head of Upnuk Lake and extends outside the map area into the adjacent Taylor Mountains quadrangle where it is mapped as the clastic rocks unit (Pcs) of Wilson and others (2006b).  Unit depositionally overlies the greenstone and schist unit (MDv) (Box and others, 1993).  Permian limestone (Pls) is interbedded with this unit in many places in the Taylor Mountains quadrangle to the east (Wilson and others, 2006b).  Conodonts of Middle(?) Triassic and Early Mississippian to Late Devonian age were reported by Box and others (1993).  With respect to the Devonian conodonts, Anita Harris (USGS, written commun. 1989) suggested they may have been derived from redeposited clasts or ""interweaved"" tectonic slices (see comments for sample 87AMM 69 at www.alaskafossil.org).  Unit was included in the Tikchik terrane by 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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","937",""
"3495","Jum","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).  At Red and Susie Mountains, south of Goodnews Bay, the rocks consist of medium-grained, partially serpentinized dunite, wehrlite, and clinopyroxenite (Box, 1985a); Hoare and Coonrad (1978) reported websterite rather than wehrlite.  The margins of these bodies are cut by numerous coarsely pegmatitic hornblendite dikes which have contact metamorphic zones as much as 800 m wide (Box, 1985a).  Unit, as mapped herein, also includes serpentinite at Cape Newenham, which apparently had a protolith that was predominately harzburgite, subordinate dunite, and rare clinopyroxenite (Box, 1985a).  This serpentinite ""varies from blocky, unsheared protoliths [harzburgite?] to slickensided serpentinite enclosing blocks with original fabrics"" (Box, 1985a).  According to Box (1985a), the northeast flank of the ultramafic body at Susie Mountain appears to grade into hornblende gabbro of map unit Jgb, which yielded an age of 162.44.9 Ma (GA7-1450, table 1), significantly younger than the dated dikes which cut the ultramafic body at Red Mountain.  K/Ar dates were 176.45.3 and 186.95.6 Ma (HD6-2272a and HD6-1453e, respectively, table 1) on amphibole from the cross-cutting hornblendite dikes","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","937",""
"3895","Jum","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).  At Red and Susie Mountains, south of Goodnews Bay, the rocks consist of medium-grained, partially serpentinized dunite, wehrlite, and clinopyroxenite (Box, 1985a); Hoare and Coonrad (1978) reported websterite rather than wehrlite.  The margins of these bodies are cut by numerous coarsely pegmatitic hornblendite dikes which have contact metamorphic zones as much as 800 m wide (Box, 1985a).  Unit, as mapped herein, also includes serpentinite at Cape Newenham, which apparently had a protolith that was predominately harzburgite, subordinate dunite, and rare clinopyroxenite (Box, 1985a).  This serpentinite ""varies from blocky, unsheared protoliths [harzburgite?] to slickensided serpentinite enclosing blocks with original fabrics"" (Box, 1985a).  According to Box (1985a), the northeast flank of the ultramafic body at Susie Mountain appears to grade into hornblende gabbro of map unit Jgb, which yielded an age of 162.44.9 Ma (GA7-1450, table 1), significantly younger than the dated dikes which cut the ultramafic body at Red Mountain.  K/Ar dates were 176.45.3 and 186.95.6 Ma (HD6-2272a and HD6-1453e, respectively, table 1) on amphibole from the cross-cutting hornblendite dikes","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","937",""
"3254","Jlvs","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) who described the unit as grading from a lower massive, sub-wave-base, angular pebbly mudstone to upper abundantly fossiliferous, shallow marine, well-bedded, locally cross-bedded sandstone and shale.  Unit only exposed on Hagemeister Island.  An impure sandy limestone that outcrops in the Taylor Mountains quadrangle to the east of map area was originally included in this unit by Hoare and Coonrad (1978) because of the common occurrence of Weyla pelecypods of Early Jurassic age; however, the limestone was mapped as a distinctive unit by Wilson and others (2006b)","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","943",""
"3152","Jvt","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, 1 km thick, and a bright green upper member, 0.7 km thick.  Lower unit consists of thin-bedded fine-grained sandstone and siltstone turbidites and channelized medium- to coarse-grained sandstone and minor chaotic interbeds indicating down-slope mass movement, which suggests an inner- to middle-fan environment (fig. 10, Walker and Mutti, 1973).  Upper, more tuffaceous member  is mostly thin-bedded fine-grained sandstone and siltstone turbidites, having coarse conglomerate beds in upper part showing poorly defined thinning and fining upward cycles.  ""Entire sequence interpreted as deposited on proximal channelized portion (i.e., upper to midfan) of turbidite basin fill complex"" (Box, 1985a).  Similar conglomerate intruded by gabbro at Aeolus Mountain; gabbro yielded 1748 Ma K/Ar age on amphibole (B78-1171G, table 1).  ""A few tool marks and interbedded slump folds suggest ENE-directed paleocurrents. *** Unit is folded around sub-horizontal, northeast-trending axes and steep axial planes, and lacks a penetrative cleavage"" (Box, 1985a).   Box (1985a) constrained the age to Middle Jurassic on the basis of Bajocian pelecypods northeast of his map area in Togiak River valley reported by Hoare and Coonrad (1978).  These rocks were included in map unit KJvs of Hoare and Coonrad (1978) and are likely to be present in undivided parts of that unit as shown herein in unit KTrvs","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, Kuskkwim Bay, Nunivak Island, saint Matthew, and Pribilof Islands 1:250,000-scale quadrangles:  U.S. Geological Survey Scientific Investigations Series Map, SIM-XXXX, scale 1:500,000.","982",""