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
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, Ku
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
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
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 13.00ñ0.50 Ma (Hoare and Coonrad, 1978, sample 74AHr 26, table 1, herein)
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 Goo
Qa
Alluvial deposits
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, 195
Qgo
Outwash deposits
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)
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 hor
Qb
Beach deposits
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 beac
Qpd
Pyroclastic rocks
Pyroclastic rocks in the Pribilof Islands, largely basaltic tuff (Barth, 1956)
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 islan
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.
Qed
Eolian deposits
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
Qg
Glacial deposits, undivided
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,
Qcs
Alkalic basalt of Karon Lake
Cinder cones, flows, and tephra; normally polarized rocks of Brunhes polarity epoch (Hoare and others, 1968).  K/Ar ages range from 0.03ñ.02 to 0.74ñ.09 Ma (table 1)
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
TKgr
Granite
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) a
TKg
Granitic rocks, undivided
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;
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
Qvbm
Basalt flows, Matuyama polarity epoch
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
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 (B
Qes
Estuarine deposits
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
Qrs
Reworked silt
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 erosiona
Qgm
Glacial moraine
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
TKa
Eek and Swift Creek volcanic fields of Box and others (1993); andesite flows
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 obsid
Qvs
Volcaniclastic sediment
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, sediment
TJih
Hypabyssal felsic intrusive rocks
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 per
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).  Multipl
Qsd
Silt deposits
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 membe
Talb
Alkalic basalt of Ahzwiryuk Bluff
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
Qmt
Marine terraces
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.  R
Qtf
Tidal flat and active estuarine deposits
Quaternary, Holocene
Fine-grained silt and mud in tidal flats and active estuaries as shown on topographic maps.  Also includes older, topographically higher deposits on land.  The abrupt ending of the tidal flat deposits at approximately 163ø 20'W longitude in the Kuskokwim
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 0.67ñ.07 Ma (sample A50, table 1)
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 tha
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 62.3ñ2.0 Ma K/Ar age on hornblende (Patton and others, 1975, 71AMm 45, table 1 herein).  I
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
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 m
QTs
Semiconsolidated marine beach deposits
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
TJik
Little Kasigluk River pluton of Box and others (1993)
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
Tnba
Nukluk Volcanic Field, basalt and andesite
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)
TKqd
Monzodiorite and quartz diorite
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 f
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 pebb
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 se
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,
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 rock
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 alte
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 b
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 basa
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 pl
TKgs
Monzonite
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 si
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 gree
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, Bo
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 c
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
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); overlai
Pv
Togiak-Tikchik Complex - Volcanic rocks
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 Good
MzPzs
Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Arkosic sandstone and slate
"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
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 conglome
Tnr
Nukluk Volcanic Field, rhyolite
Moderately altered rhyolite flows, domes, and ash-flow tuff.  Rhyolite of the main volcanic field contains phenocrysts of sanidine, riebeckitic amphibole, and rare quartz.  A 40Ar/39Ar total-fusion age on riebeckite was 54.7ñ1.6 Ma (Box and others, 1993,
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
Kvm
Volcanic and sedimentary rocks of the Mount Oratia belt of Hoare and Coonrad (1983)
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 ra
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  rhy
MzPzv
Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Volcaniclastic sandstone and argillite
"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 quadrang
P_k
Kanektok metamorphic complex, undivided
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, biot
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 m
Kygv
Volcanic graywacke and argillite
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
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
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 abo
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-g
um
Not mapped
Small areas on Saint Matthew Island and much of Hall Island shown as not mapped by Patton and others (1973)
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.
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
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 thi
Pcs
Togiak-Tikchik Complex - Volcaniclastic sedimentary rocks
"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 locall
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
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 aq
Jlt
Laminated tuff and associated rocks of Box (1985a)
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 uni
Trob
Dismembered ophiolite of Box (1985a) - Pillow basalt
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
Ja
Marine arkosic sandstone and argillite
"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 clinopy
Dismembered ophiolite of Box (1985a)
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 N
KJb
Pillow basalt
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
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 th
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 feldsp
Trog
Dismembered ophiolite of Box (1985a) - Pyroxene gabbro
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
Jmv
Interbedded volcanic and sedimentary rocks
Basaltic and andesitic volcanic and volcaniclastic rocks on Hagemeister Island (Hoare and Coonrad, 1978; Box, 1985a); extensively altered to prehnite-pumpellyite facies mineral assemblage.  Volcanic rocks, characterized by plagioclase + clinopyroxene ñ h
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 preser
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 64.6ñ2 Ma on biotite (74ACd 14d, table 1) from the western Nushagak Bay quadrangle.  Also includes medium- to coarse-
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 quartzi
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 vol
TrPvs
Volcaniclastic glaucophane-hornblende-epidote schist
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
Kcgc
Calcareous graywacke and siltstone of the Eek Mountains belt of Hoare and Coonrad (1983)
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 san
MzPzp
Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Chloritic phyllite
"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
MzPzc
Togiak-Tikchik Complex - Rock units of the Kisaralik anticlinorium of Box and others (1993) - Chert and argillite
"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 quad
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 int
TrPcs
Calcareous schist
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).
Jmm
Turbidites of Metervik Bay of Box (1985a)
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 secti
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 i
Togiak-Tikchik Complex - Volcanic and sedimentary rocks
"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
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 v
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
Jlvs
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) w
Jvt
Volcaniclastic turbidites of Togiak Bay of Box (1985a)
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,