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[100,null,100,"Qs","HC002","Surficial deposits, undifferentiated","Includes flood plain deposits of silt, sand, and gravel, and fluvial, colluvial, and eolian terrace and slope deposits of silt and very fine sand.","Quaternary (Holocene and Pleistocene)",null,null,"Holy Cross","Unconsolidated",null]
[100,null,104,"Qof","BL002","Old flood-plain deposits","Flood-plain deposits of silt, sandy silt, and bog deposits","Quaternary",null,null,"Black","Unconsolidated",null]
[100,null,108,"Qof","HP002","Old flood-plain and delta deposits","Old flood-plain and delta deposits; silt, sandy silt, and bog deposits","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[100,null,108,"Qof","SC002","Old flood-plain deposits","Old flood-plain deposits, mostly silt and sandy silt","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[100,null,109,"Qoa","HP002","Old alluvial deposits","Old alluvial deposits; mostly silt and sand; clay and minor amounts of fine gravel at depth.  Mostly fluvial with some wind deposits","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[100,null,109,"Qoa","SC002","Old alluvial deposits","Alluvial deposits of silt and sandy silt overlying sand and gravel.  Includes terrace and fan gravel and colluvial deposits","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[100,null,110,"Qgc","HP002","Glacial and colluvial deposits","Glacial and colluvial deposits; sand, gravel, boulders, and angular talus blocks.  Includes steep recent fans of gravel and boulders","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[100,null,126,"Qu","RM004","Quaternary deposits, undifferentiated","Unconsolidated alluvial, colluvial, and eolian deposits","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[100,null,200,"Qac","HP003","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[100,null,200,"Qac","SC003","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[100,null,205,"Qac","MA003","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Marshall","Unconsolidated",null]
[100,null,303,"Qac","HC003","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Holy Cross","Unconsolidated",null]
[100,null,503,"Qac","RM005","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[100,null,902,"Qac","KW003","Alluvial, colluvial, and glacial drift deposits, undivided","Alluvial and colluvial deposits consist mainly of silt, sandy silt, and peat.  Alluvium is chiefly fluvial in origin, but locally includes reworked windblown deposits.  Glaical drift composed of sand, gravel, and boulder morainal and outwash deposits","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[105,null,18,"Qoa","KW002","Old alluvial deposits","Alluvial deposits of silt and sandy silt on the delta with sand and gravel at depth; also includes terrace and fan gravel and colluvial deposits in and near mountains","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[105,null,25,"Qyf","BL002","Younger flood-plain deposits","Flood-plain depoits of silt and sandy silt on sand delta; also includes gravel and boulders in and near mountains","Quaternary",null,null,"Black","Unconsolidated",null]
[105,null,25,"Qyf","KW002","Younger flood-plain deposits","Flood-plain depoits of silt and sandy silt on sand delta; also includes gravel and boulders in and near mountains","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[105,null,100,"Qf","RM002","Flood Plain Alluvium","Flood plain alluvium","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[105,null,104,"Qof","KW002","Old flood-plain deposits","Flood-plain deposits of silt, sandy silt, and bog deposits","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[105,null,105,"Qyf","MA002","Young flood-plain deposits","Young flood-plain deposits; silt and sandy silt, minor sand and gravel","Quaternary",null,null,"Marshall","Unconsolidated",null]
[105,null,105,"Qyf","SC002","Young flood-plain deposits","Beach and lagoon deposits, mostly silt and sandy silt on the delta; includes gravel and boulders in and near Nulato Hills","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[105,null,105,"Qa","RM003","Alluvium","Unconsolidated alluvial, colluvial, glacial outwash, lucustrine, and eolian conglomerate, sand, silt, and mudrock","Quaternary (Holocene and Pleistocene)",null,null,"Russian Misson","Unconsolidated",null]
[105,null,106,"Qe","HP002","Estuarine deposits","Estuarine deposits; fluvial silt and sandy silt, reworked and deposited by tidal currents and wave action","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[105,null,107,"Qof","MA002","Old flood-plain deposits","Old flood-plain deposits; silt and sandy silt","Quaternary",null,null,"Marshall","Unconsolidated",null]
[105,null,109,"Qoa","MA002","Old alluvial deposits","Old alluvial deposits; chiefly silt and sandy silt with sand and gravel at depth.  Includes terrace and colluvial deposits near mountains","Quaternary",null,null,"Marshall","Unconsolidated",null]
[105,null,110,"Qa","RM004","Sandy flood-plain alluvium","Sandy flood-plain alluvium.  Unconsolidated, well stratified, gray- to tan-weathered fine-grained sand, silty sand, and silt deposited by modern streams","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[105,null,111,"Qag","RM004","Coarse-grained, gravel-rich alluvium","Coarse-grained, gravel-rich alluvium.  Unconsolidated, moderately- to well stratified silt, sand, and gravel deposited by modern streams","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[105,null,112,"Qas","RM004","Flood-plain alluvium with extensive overbank deposits","Flood-plain alluvium with extensive overbank deposits.  Alluvium composed of interbedded, dark-brown-gray, organic-rich sand and sandy silt.  Masks Qa and Qag","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[105,null,115,"Qgr","RM004","Reworked glacial outwash and till deposits","Reworked glacial outwash and till deposits.  Well sorted, moderately well-stratified sand and pebble gravel reworked from coarser outwash gravel and diamicton by perennial streams","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[105,null,201,"Qf","MA003","Floodplain, tidal flats, and estuarine deposits","Unit composed cheifly of silt, fine sand, and peat.  Some gravel and coarse sand depoists occur locally along the tributary streams draining upland areas.  Estuarine deposits conists of fluvial silt and sandy silt that has been reworked and redeposited b","Quaternary",null,null,"Marshall","Unconsolidated",null]
[105,null,300,"Qf","HC003","Floodplain, tidal flats, and estuarine deposits","Unit composed cheifly of silt, fine sand, and peat.  Some gravel and coarse sand depoists occur locally along the tributary streams draining upland areas.  Estuarine deposits conists of fluvial silt and sandy silt that has been reworked and redeposited b","Quaternary",null,null,"Holy Cross","Unconsolidated",null]
[105,null,500,"Qf","RM005","Floodplain, tidal flats, and estuarine deposits","Unit composed cheifly of silt, fine sand, and peat.  Some gravel and coarse sand depoists occur locally along the tributary streams draining upland areas.  Estuarine deposits conists of fluvial silt and sandy silt that has been reworked and redeposited b","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[105,null,900,"Qf","KW003","Floodplain, tidal flats, and estuarine deposits","Unit composed cheifly of silt, fine sand, and peat.  Some gravel and coarse sand depoists occur locally along the tributary streams draining upland areas.  Estuarine deposits conists of fluvial silt and sandy silt that has been reworked and redeposited b","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[106,null,114,"Qaf","RM004","Alluvial fan deposits","Alluvial fan deposits.  Generally poorly sorted, partially stratified sand and coarse gravel deposits","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[106,null,119,"Qctf","RM004","Fan and terrace deposits","Fan and terrace deposits.  Composite unit of poorly sorted, partially stratified silt, sand, and gravel of alluvial and colluvial fans","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[107,null,103,"Qc","RM002","Colluvium","Chiefly frost-rived rubble, locally includes stream alluvium, terrace gravel, glacial deposits, and wind blown silt","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[107,null,117,"Qca","RM004","Colluvial-alluvial deposits","Colluvial-alluvial deposits.  Poorly to moderately well-sorted silt, sand, gravel, and diamictin of alluvial, colluvial, and locally, glacial origin","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[107,null,118,"Qct","RM004","Talus","Talus.  Angular fragments of frost-riven bedrock transported downslope by gravity and deposited as apron or fans at toe of slope.","Quaternary",null,null,"Russian Mission","Unconsolidated",1071]
[110,null,116,"Qat","RM004","Terrace alluvium","Terrace alluvium.  Well-sorted, moderately stratified gravelly sand and silt","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[113,null,104,"Qrs","RM002","Reworked Silt","Silt, sandy silt, and bog deposits","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[115,null,69,"Qyb","BL002","Younger beach deposits","Beach deposits of marine silt and sandy silt and younger flood-plain and estuarine deposits along streams","Quaternary",null,null,"Black","Unconsolidated",null]
[115,null,69,"Qyb","KW002","Younger beach deposits","Beach deposits of marine silt and sandy silt and younger flood-plain and estuarine deposits along streams","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[115,null,105,"Qyb","HP002","Young beach deposts","Young beach deposts; marine silt, sandy silt, and sand.  Forms beaches, spits, bars, dunes, and islands","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[115,null,106,"Qbl","SC002","Beach and lagoon deposits","Beach and lagoon deposits, mostly silt and sandy silt","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[115,null,107,"Qob","HP002","Old beach deposits","Old beach deposits; marine silt and sandy silt forming older beach ridges and intervening swales","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[115,null,201,"Qbl","HP003","Beach and lagoonal deposits","Silt and sandy silt.  Deposits form the modern offshore bars, spits, and beach ridges.","Quaternary",null,null,"Hooper Bay","Unconsolidated",null]
[115,null,729,"Qob","BL002","Old beach deposits","Beach deposits of marine silt and sandy silt","Quaternary",null,null,"Black","Unconsolidated",null]
[115,null,729,"Qob","KW002","Old beach deposits","Beach deposits of marine silt and sandy silt","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[115,null,800,"Qbl","BL003","Beach and lagoonal deposits","Silt and sandy silt.  Deposits form the modern offshore bars, spits, and beach ridges.","Quaternary",null,null,"Black","Unconsolidated",null]
[115,null,901,"Qbl","KW003","Beach and lagoonal deposits","Silt and sandy silt.  Deposits form the modern offshore bars, spits, and beach ridges.","Quaternary",null,null,"Kwiguk","Unconsolidated",null]
[116,null,106,"Qe","MA002","Estuarine deposits","Estuarine deposits; silt and sandy silt","Quaternary",null,null,"Marshall","Unconsolidated",null]
[120,null,108,"Qw","MA002","Wind-blown deposits","Wind-blown deposits; silt and sandy silt","Quaternary",null,null,"Marshall","Unconsolidated",null]
[120,null,203,"Qw","MA003","Wind-blown deposits","Silt and sandy silt.  Deposits form broad partly dissected stabilized dune fields in the lowlands of the Yukon and Kuskokwim Rivers.  The dune fields overlie the alluvial and colluvial deposits of unit Qac and predate the floodplain deposits of unit Qf.","Quaternary",null,null,"Marshall","Unconsolidated",null]
[120,null,504,"Qw","RM005","Wind-blown deposits","Silt and sandy silt.  Deposits form broad partly dissected stabilized dune fields in the lowlands of the Yukon and Kuskokwim Rivers.  The dune fields overlie the alluvial and colluvial deposits of unit Qac and predate the floodplain deposits of unit Qf.","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[121,null,105,"Qsw","RM002","Wind-deposited Silt","Wind-deposited silt","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[122,null,108,"Qs","RM002","Silt Deposits","Light- to dark-gray silt and sandy silt","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[122,null,113,"Qsp","RM004","Silt and peat","Silt and peat.  Poorly stratified, black to brown, organic-rich alluvial, lacustrine, or bog silt.","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[125,null,106,"Qd","RM002","Glacial Drift","Poorly sorted sand, gravel, and boulders; stipples (of original map) indicate well defined end and lateral moraines","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[125,null,125,"Qt","RM003","Glacial till","Unconsolidated glacial till; ground lateral and end moraines","Quaternary (Pleistocene)",null,null,"Russian Mission","Unconsolidated",null]
[127,null,120,"Qrg","RM004","Rock-glacier deposits","Rock-glacier deposits.  Stable, tongue-shaped mass of unsorted, angular frost-shattered boulders and cobbles.","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[130,null,121,"Qgt4","RM004","Till","Till.  Unmodified till from Crater Mountain glaciation of early Holocene(?) age","Quaternary (Holocene)",null,null,"Russian Mission","Unconsolidated",null]
[135,null,122,"Qgt3","RM004","Till, Tolstoi Lake glaciation","Till consisting of fresh, undissected moraines from Tolstoi Lake glaciation of late Wisconsin age","Quaternary (Late Pleistocene)",null,null,"Russian Mission","Unconsolidated",null]
[135,null,123,"Qgt2","RM004","Till, Bifurcation Creek glaciation","Till consisting of dissected moraines from Bifurcation Creek glaciation of late Wisconsin age","Quaternary (Late Pleistocene)",null,null,"Russian Mission","Unconsolidated",null]
[140,null,107,"Qo","RM002","Outwash Deposits","Poorly- to well-sorted silt, sand, gravel, and boulders in terraces and outwash fan-plains","Quaternary",null,null,"Russian Mission","Unconsolidated",null]
[140,null,125,"Qgf","RM004","Outwash-fan deposits","Outwash-fan deposits.  Poorly consolidated, moderately well-stratified sand and gravel deposited as large fans proximal to ice-marginal meltwater streams during Late Pleistocene","Quaternary (Late Pleistocene)",null,null,"Russian Mission","Unconsolidated",null]
[190,null,124,"Qgt1","RM004","Till, Beaver Creek glaciation","Till.  Reworked, highly dissected till from Beaver Creek glaciation of pre-Wisconsin age","Quaternary (Early Pleistocene)",null,null,"Russian Mission","Unconsolidated",null]
[330,null,115,"Qb","MA002","Basalt","Basalt; undeformed flows and associated cones and craters.  Includes pyroclastic rock","Quaternary",null,"Age based on magnetic polarity","Marshall","Igneous",null]
[330,null,115,"Qby","SC002","Basalt","Basalt; Younger flows and cones","Quaternary",null,null,"Saint Michael","Igneous",null]
[330,null,330,"Qb","HC002","Basalt flows","Columnar-jointed flows of fine-grained tholeiitic and alkaline-olivine basalt","Quaternary (Pleistocene)",null,null,"Holy Cross","Igneous",null]
[330,null,398,"Qb","KW002","Basalt","Horizontal basalt flows and associated colcanic craters","Quaternary",null,null,"Kwiguk","Igneous",null]
[350,null,110,"QTb","RM002","Basalt","Horizontal vesicular basalt flows","Quaternary and Tertiary",null,null,"Russian Mission","Igneous",null]
[350,null,115,"Qb","HP002","Basalt","Olivine basalt and associated scoria","Quaternary",null,"Age determined from paleomagnetic","Hooper Bay","Igneous",null]
[350,null,116,"Qbo","SC002","Basalt","Basalt; Older flows, cones, maars, tuffs, and breccias","Quaternary",null,null,"Saint Michael","Unconsolidated",null]
[350,null,207,"QTb","MA003","Basalt","Part of the late Cenozoic Bering Sea basalt province.  Vesicular tholeiitic and alkali basalt lava flows, cones, and maar craters.  The flows are interlayered with subordinate amounts of pyroclastic deposits that range from fine ash to coarse breccia.  T","Quaternary and latest Tertiary",null,"K-Ar ages ranging from 3.25 Ma to 0.19 Ma from samples in the Unalakleet quadrangle","Marshall","Igneous",null]
[350,null,903,"QTb","KW003","Basalt","Part of the late Cenozoic Bering Sea basalt province.  Vesicular tholeiitic and alkali basalt lava flows, cones, and maar craters.  The flows are interlayered with subordinate amounts of pyroclastic deposits that range from fine ash to coarse breccia.  T","Quaternary and latest Tertiary",null,"K-Ar ages ranging from 3.25 Ma to 0.19 Ma from samples in the Unalakleet quadrangle","Kwiguk","Igneous",null]
[1001,null,121,"Tr","RM002","Albite Rhyolite","Light- to medium-gray, fine-grained, porphyritic rhyolite; occurs as small stock or pluglike intrusive bodies","Tertiary",null,null,"Russian Mission","Igneous",null]
[1004,null,532,"Tb","RM005","Basalt","Three small areas of basalt lava flows.  Two on the Yukon River in the northwestern part of the quadrangle and one on the Owhat River in the northeastern part of the quadrangle.  Flat-lying vesicular basalt","Late Tertiary",null,"Whole-rock K-Ar ages of 19.35 Ma and 6.19 Ma","Russian Mission","Igneous",null]
[1025,null,130,"Tvb","RM004","Basalt","Medium- to dark-gray, vesicular olivine-clinopyroxene basalt and minor basaltic andesite","late Tertiary (late Pliocene)",null,"Whole rock K/Ar of 6.19 Ma","Russian Mission","Igneous",null]
[1103,null,1103,"Tm","HC002","Mafic volcanic and subvolcanic rocks, undifferentiated","Wide variety of of basaltic and andesitic flows, agglomerate, coarse breccia, fine-grained tuff, and subordinate hypabyssal intrusive rocks.  Most common is olivine basalt and pyroxene andesite","Tertiary (Eocene and Paleocene)",null,null,"Holy Cross","Igneous",null]
[1120,null,1120,"Tfu","HC002","Felsic volcanic and subvolcanic rocks, undifferentiated","Flows, tuffs, breccias, and fine-grained hypabyssal intrusions, ranging in composition from rhyolite to dacite.","Tertiary (Eocene and Paleocene)",null,"K-Ar in the Unalakleet quadrangle","Holy Cross","Igneous",null]
[1121,null,1121,"Tfi","HC002","Felsic hypabyssal intrusives","Known or strongly suspected fine-grained felsic hypabyssal intrusive rocks of unddifferentiated unit Tfu","Tertiary (Eocene and Paleocene)",null,null,"Holy Cross","Igneous",null]
[1200,null,122,"Tg","RM002","Granitic Rocks","Medium- to coarse-grained, pink and gray granitic-textured rocks.  Forms stocks chiefly of quartz monzonite, but ranges from granodiorite to granite; minor facies include gabbro, diabase, and aplite.","Tertiary",null,null,"Russian Mission","Igneous",null]
[1200,null,123,"Ti","RM002","Intrusive Rocks (?)","Probable stocks of granitic rocks; interpreted and mapped by photogeologic methods.","Tertiary",null,null,"Russian Mission","Igneous",null]
[1207,null,120,"Tm","RM002","Mafic Rocks","Medium- to coarse-grained, light- to dark-gray gabbro and diabase.  Occurs as small stocklike bodies, dikes, and sills.","Tertiary",null,null,"Russian Mission","Igneous",null]
[1300,null,1300,"Tgr","HC002","Shallow granitic intrusives","Small epizonal granitic intrusive rocks, inferred to range from granite to tonalite, be fine- to coarse-grained, and having varying textures.  Locally sheared or brecciated..","Tertiary (Eocene and Paleocene)",null,null,"Holy Cross","Igneous",null]
[1600,null,111,"TKuv","RM002","Volcanic Rocks","Probably andesitic lava for the most part, with some interbedded sedimentary rocks; interpreted and mapped by photogeologic methods.","Tertiary and Cretaceous",null,null,"Russian Mission","Igneous",null]
[1600,null,135,"TKvt","RM004","Andesite to dacite flows and tuff","Andesite to dacite flows and tuff.  Medium-green-gray, very fine-grained, porphyritic biotite andesite to dacite flows.  Light-green-gray, platy-weathering, fine- to medium-grained crystal-lithic tuff.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1600,null,137,"TKva","RM004","Volcanic agglomerate","Volcanic agglomerate. Medium- to dark-green-gray, lapilli tuff and agglomerate containing elliptical bombs and subangular to rounded fragments of andesite.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1600,"ALT",310,"TKad","HC003","Dacite, rhyolite, andesite, and basalt lava flows, and volcaniclastic and hypabyssal rocks, undivided","Dacite, rhyolite, andesite, and basalt lava flows, and volcaniclastic and hypabyssal rocks, undivided\rConfined to the Holy Cross quadrangel and northern part of the Russian Mission quadrangle where field data are insufficient to map units TKa and TKd sep","early and late (?) Tertiary and latest Cretaceous",null,null,"Holy Cross","Igneous",null]
[1600,null,510,"TKad","RM005","Dacite, rhyolite, andesite, and basalt lava flows, and volcaniclastic and hypabyssal rocks, undivided","Dacite, rhyolite, andesite, and basalt lava flows, and volcaniclastic and hypabyssal rocks, undivided.  Confined to the Holy Cross quadrangel and northern part of the Russian Mission quadrangle where field data are insufficient to map units TKa and TKd s","early and late (?) Tertiary and latest Cretaceous",null,null,"Russian Mission","Igneous",null]
[1600,"HFS",513,"TKhf","RM005","Hornfels","Formed in the thermal aureole bordering the granitic cores of the Fox Hills and Russian Mountains.  Consists of metasiltstone, metasandstone, metaconglomerate and subordinate amounts of metavolcanic rocks","early Tertiary and latest Cretaceous",null,null,"Russian Mission","Metamorphic",null]
[1602,null,153,"TKdf","RM004","Dikes and small hypabyssal intrusions","Dikes and small hypabyssal intrusions.  Fine-grained, locally porphyro-aphanitic biotite quartz porphyry.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1602,null,211,"TKi","MA003","Shallow intrusive rocks of intermediate and silicic composition","Composed of rhyolite, dacite and lesser amounts of trachyte and andesite.  The typical rock is composed of a fine-grained felsic groundmass with phenocrysts of plagioclase, quartz, biotite, and hornblende.","early Tertiary and latest Cretaceous",null,"U/Pb zircon age of 63.6 Ma, 40Ar/39Ar age of 67.3 Ma, 40Ar/39/Ar age of 65.7 Ma","Marshall","Igneous",null]
[1602,null,307,"TKi","HC003","Shallow intrusive rocks of intermediate and silicic composition","Composed of rhyolite, dacite and lesser amounts of trachyte and andesite.  The typical rock is composed of a fine-grained felsic groundmass with phenocrysts of plagioclase, quartz, biotite, and hornblende.","early Tertiary and latest Cretaceous",null,"U/Pb zircon age of 63.6 Ma, 40Ar/39Ar age of 67.3 Ma, 40Ar/39/Ar age of 65.7 Ma","Holy Cross","Igneous",null]
[1602,null,507,"TKi","RM005","Shallow intrusive rocks of intermediate and silicic composition","Composed of rhyolite, dacite and lesser amounts of trachyte and andesite.  The typical rock is composed of a fine-grained felsic groundmass with phenocrysts of plagioclase, quartz, biotite, and hornblende.","early Tertiary and latest Cretaceous",null,"U/Pb zircon age of 63.6 Ma, 40Ar/39Ar age of 67.3 Ma, 40Ar/39/Ar age of 65.7 Ma","Russian Mission","Igneous",null]
[1602,null,905,"TKi","KW003","Shallow intrusive rocks of intermediate and silicic composition","Composed of rhyolite, dacite and lesser amounts of trachyte and andesite.  The typical rock is composed of a fine-grained felsic groundmass with phenocrysts of plagioclase, quartz, biotite, and hornblende.","early Tertiary and latest Cretaceous",null,"U/Pb zircon age of 63.6 Ma, 40Ar/39Ar age of 67.3 Ma, 40Ar/39/Ar age of 65.7 Ma","Kwiguk","Igneous",null]
[1604,null,138,"TKvi","RM004","Andesite to dacite","Andesite to dacite.  Poorly exposed, light- to medium-green-gray, porphyro-aphanitic pyroxene andesite to dacite flows.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1625,null,309,"TKd","HC003","Dacite and rhyolite lava flows, domes, and volcaniclasic and hypabyssal rocks","Dacite, rhyolite, and subordinate trachyandesite lava flows, sills, dikes, and interlayered tuffs, ash-flow tuffs, and breccias.  Flows generally are porphyritic and composed of phenocrysts of plagioclase, sanidine, quartz, and biotite in a fine-grained","early Teritiary and latest Cretaceous",null,"K-Ar ages of 67.0 Ma and 64.7 Ma from an area mapped as TKad","Holy Cross","Igneous",null]
[1625,null,509,"TKd","RM005","Dacite and rhyolite lava flows, domes, and volcaniclasic and hypabyssal rocks","Dacite, rhyolite, and subordinate trachyandesite lava flows, sills, dikes, and interlayered tuffs, ash-flow tuffs, and breccias.  Flows generally are porphyritic and composed of phenocrysts of plagioclase, sanidine, quartz, and biotite in a fine-grained","early Teritiary and latest Cretaceous",null,"K-Ar ages of 67.0 Ma and 64.7 Ma from an area mapped as TKad","Russian Mission","Igneous",null]
[1631,null,523,"TJb","RM005","Whitefish Lake Volcanic Field","Altered basaltic lava flows and subordinate altered andesite, dacite, rhyolite, and gabbro.  Inferred to be the extrusive equivalent of the mafic intrusive rocks of unit TJm.  Regional relationships suggest unit could be as old as Jurassic or as young as","early Tertiary to Jurassic",null,null,"Russian Mission","Metamorphic",null]
[1631,"ALT",2870,"TJwl","RM003","Whitefish Lake volcanic field, Nyac terrane","Highly altered basaltic flows, subordinate altered andesite, dacite, rhyolite, and gabbro.  Lavas believed to be extrusive equivalent of parts of diorites and gabbros (TJim) of Nyac Terrane","early Tertiary?, Cretaceous, and Jurassic?",null,null,"Russian Mission","Sedimentary",null]
[1635,"Q",308,"TKa","HC003","Andesite and basalt flows and volcanicclasitc rocks","Composed primarily of andesite and basalt lava flows and volcaniclastic rocks.  Flows are generally porphyritic and composed of phenocrysts of plagioclase and pyroxene in a groundmass of plagioclase microlites.  Volcaniclastic rocks include breccia, tuff","early Tertiary and latest Cretaceous",null,"K-Ar ages of 50.8 and 42.9 Ma\rFive K-Ar ages of 65.2 to 51.9 Ma in the Unalakleet quadrangle","Holy Cross","Igneous",null]
[1635,"Q",508,"TKa","RM005","Andesite and basalt flows and volcanicclasitc rocks","Composed primarily of andesite and basalt lava flows and volcaniclastic rocks.  Flows are generally porphyritic and composed of phenocrysts of plagioclase and pyroxene in a groundmass of plagioclase microlites.  Volcaniclastic rocks include breccia, tuff","early Tertiary and latest Cretaceous",null,"K-Ar ages of 50.8 and 42.9 Ma.  Five K-Ar ages of 65.2 to 51.9 Ma in the Unalakleet quadrangle","Russian Mission","Igneous",null]
[1641,null,154,"TKda","RM004","Dikes and small hypabyssal intrusions","Dikes and small hypabyssal intrusions.  Medium-green-gray, very fine-grained to porphyro-phanitic biotite-axinite andesite porphyry.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1641,null,155,"TKdm","RM004","Dikes and small hypabyssal intrusions","Dikes and small hypabyssal intrusions.  Olivine-rich, fine-grained gabbro to picrite with distinctive columnar jointing.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1655,null,150,"TKmp","RM004","Porphyritic quartz monzonite","Porphyritic quartz monzonite.  Light gray, locally bleached, fine-grained to porphyro-aphanitic, clinopyroxene-bearing, biotite-rich quartz monzonite.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1655,null,209,"TKg","MA003","Granite, granodiorite, syenite, and monzonite","Composed of plutonic rocks that have been assigned a wide variety of petrographic names based largely on field inspection and examination of a few thin sections.  The most common rock type appears to be biotite granite, but other rock types include grano","early Tertiary and latest Cretaceous",null,"Seven K-Ar cooling ages from this unit range from 70.9 to 60.9 Ma","Marshall","Igneous",null]
[1655,null,306,"TKg","HC003","Granite, granodiorite, syenite, and monzonite","Composed of plutonic rocks that have been assigned a wide variety of petrographic names based largely on field inspection and examination of a few thin sections.  The most common rock type appears to be biotite granite, but other rock types include grano","early Tertiary and latest Cretaceous",null,"Seven K-Ar cooling ages from this unit range from 70.9 to 60.9 Ma","Holy Cross","Igneous",null]
[1655,null,506,"TKg","RM005","Granite, granodiorite, syenite, and monzonite","Composed of plutonic rocks that have been assigned a wide variety of petrographic names based largely on field inspection and examination of a few thin sections.  The most common rock type appears to be biotite granite, but other rock types include grano","early Tertiary and latest Cretaceous",null,"Seven K-Ar cooling ages from this unit range from 70.9 to 60.9 Ma","Russian Mission","Igneous",null]
[1657,null,151,"TKsy","RM004","Quartz syenite","Quartz syenite.  Medium-gray, medium-grained, equigranular, biotite-rich quartz syenite.","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Igneous",null]
[1660,null,152,"TKsym","RM004","Syenite to monzonite and quartz monzonite","Syenite to monzonite and quartz monzonite.  Medium-gray, subporphyritic, biotite-pyroxene syenite to monzonite and quartz monzonite.  Transitional between TKsy and TKmp.","early Tertiary and (or) Late Cretaceous",null,"Biotite-pyroxene quartz monzonite yielded K/Ar of 70.3 Ma","Russian Mission","Igneous",null]
[1665,null,1667,"TKip","RM003","Mt. Plummer pluton","Medium- to coarse-grained, erosionally resistant, hypidiomorphic granular augite-biotite mafic granodiorite, quartz monzodiorite, and quartz diorite pluton.  Intrudes and contact metamorphoses Kkmf, Kksh, and Kkcd of Kuskokwim group.","early Tertiary and (or) Late Cretaceous",null,"K/Ar ages of 65.5+2.0 Ma and 66.6+2.0 Ma from biotite","Russian Mission","Igneous",null]
[1681,null,311,"TJgd","HC003","Gabbro and diorite","Gabbro and diorite","Tertiary, Cretaceous, and Jurassic",null,null,"Holy Cross","Igneous",null]
[1682,"ALT",324,"TJm","HC003","Altered mafic plutonic rocks","Altered gabbro and diorite bodies.  Intrudes units Jab, Jvc, KJv, and KMu.  Age of unit is uncertain, but not older than Jurassic.  Some or all of the unit may be as young as Tertiary","early Tertiary to Jurassic",null,null,"Holy Cross","Metamorphic",null]
[1682,null,511,"TJgd","RM005","Gabbro and diorite","Gabbro and diorite   Unit dropped, now part of TJm (1682)","Tertiary, Cretaceous, and Jurassic",null,null,"Russian Mission","Igneous",null]
[1682,null,524,"TJm","RM005","Altered mafic plutonic rocks","Altered gabbro and diorite bodies.  Intrudes units Jab, Jvc, KJv, and KMu.  Age of unit is uncertain, but not older than Jurassic.  Some or all of the unit may be as young as Tertiary","early Tertiary to Jurassic",null,null,"Russian Mission","Metamorphic",null]
[1943,null,315,"Kym","HC003","Polymict conglomerate, sandstone, siltstone, and shale","Yukon-Koyukuk basin\rMarginal shelf and slope deposits\rComposed of pebble and cobble conglomerate interbedded with sandstone, siltstone, and shale.  Conglomerate contains clasts of chert, greenstone, quartz, and schist in variable amounts.  Sandstone vari","Cretaceous","Well-preserved leaf impressions of Cretaceous (Albian-Cenomanian ?) age (personal communication, J.A. Wolfe, 1962)",null,"Holy Cross","Sedimentary",null]
[1943,"HFS",315,"Kym","HC003","Polymict conglomerate, sandstone, siltstone, and shale","Yukon-Koyukuk basin\rMarginal shelf and slope deposits\rComposed of pebble and cobble conglomerate interbedded with sandstone, siltstone, and shale.  Conglomerate contains clasts of chert, greenstone, quartz, and schist in variable amounts.  Sandstone vari","Cretaceous","Well-preserved leaf impressions of Cretaceous (Albian-Cenomanian ?) age (personal communication, J.A. Wolfe, 1962)",null,"Holy Cross","Sedimentary",null]
[1943,null,322,"Kym","SC003","Polymict conglomerate, sandstone, siltstone, and shale, Yukon-Koyukuk basin, Marginal shelf and slope deposits","Composed of pebble and cobble conglomerate interbedded with sandstone, siltstone, and shale.  Conglomerate contains clasts of chert, greenstone, quartz, and schist in variable amounts.  Sandstone varies from poorly sorted graywacke turbidite to well-wash","Cretaceous","Well-preserved leaf impressions of Cretaceous (Albian-Cenomanian ?) age (personal communication, J.A. Wolfe, 1962)",null,"Saint Michael","Sedimentary",null]
[1943,null,515,"Kym","RM005","Polymict conglomerate, sandstone, siltstone, and shale, Yukon-Koyukuk basin, marginal shelf and slope deposits","Composed of pebble and cobble conglomerate interbedded with sandstone, siltstone, and shale.  Conglomerate contains clasts of chert, greenstone, quartz, and schist in variable amounts.  Sandstone varies from poorly sorted graywacke turbidite to well-wash","Cretaceous","Well-preserved leaf impressions of Cretaceous (Albian-Cenomanian ?) age (personal communication, J.A. Wolfe, 1962)",null,"Russian Mission","Sedimentary",null]
[1943,null,780,"Ks","KW002","Noncalcareous sandstone","Interbedded fine- to medium-grained noncalcareous sandstone and siltstone.  Local hornfels","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[1943,null,911,"Kym","KW003","Polymict conglomerate, sandstone, siltstone, and shale, Yukon-Koyukuk basin, Marginal shelf and slope deposits","Composed of pebble and cobble conglomerate interbedded with sandstone, siltstone, and shale.  Conglomerate contains clasts of chert, greenstone, quartz, and schist in variable amounts.  Sandstone varies from poorly sorted graywacke turbidite to well-wash","Cretaceous","Well-preserved leaf impressions of Cretaceous (Albian-Cenomanian ?) age (personal communication, J.A. Wolfe, 1962)",null,"Kwiguk","Sedimentary",null]
[1943,null,1943,"Ks","HC002","Sandstone, shale, conglomerate, and coal","Chiefly fluvial and shallow marine deposits of well-sorted, medium- to coarse-grained, light-gray to olive, cross-bedded sandstone, fine- to medium-grained, dark-gray to green silty sandstone, dark-gray micaceous shale, quart-chert pebble conglomerate, a","Late and Early Cretaceous (Cenomanian and Albian)","Cenomanian and Albian megafossils, including plants in Unalakleet quadrangle to north.",null,"Holy Cross","Sedimentary",null]
[1970,null,113,"Kks","RM002","Kuskokwim Group (siltstone)","Medium- to dark-gray siltstone and graywacke with interbeds of grit and conglomerate.","Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[1970,null,141,"Kus","RM004","Sedimentary rocks, undifferentiated","Sedimentary rocks, undifferentiated.  Heterogeneous unit of fine to coarse, generally noncalcareous, micaceous sandstone, siltstone, and minor shale.","Late to middle Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[1970,null,1970,"Kkcf","RM003","Kuskokwim Group; Chert-clast provence rocks; Outer-fan turbidite facies","Thin-bedded, fine-grained, quartzose sandstone and slate with lesser thin- and thick-bedded medium-grained sandstone.","Late Cretaceous (Turonian)","Age considered Turonian (Late Cretaceous) based on three megafossil collections",null,"Russian Mission","Sedimentary",null]
[1970,null,1972,"Kkmf","RM003","Kuskokwim Group; Mixed provence rocks; Outer-fan turbidite facies","Shale-rich sequence with lesser thin- to thick-bedded, medium-grained sandstone sections.","Late Cretaceous (Turonian)","Age considered Turonian (Late Cretaceous) based on two megafossil occurances",null,"Russian Mission","Sedimentary",null]
[1970,null,1974,"Kkv","RM003","Kuskokwim Group; Volcanic provenance rocks","Interbedded shale, siltstone, sandstone, and conglomerate composed of rounded clasts of volcanic, volcaniclastic, and plutonic rocks.","Late Cretaceous (Turonian)","Age considered Turonian (Late Cretaceous) based on megafossil occurances",null,"Russian Mission","Sedimentary",null]
[1970,null,1975,"Kksh","RM003","Kuskokwim Group; Shale and siltstone","Dark-gray to black, finely laminated shale, siltstone and thin-bedded, very fine grained sandstone.","Late Cretaceous (Early Turonian and (or) Late Cenomanian)","Age constrained by megafossil occurances of late Cenomanian and (or) early Turonian age low in section and by overlying units of Turonian age",null,"Russian Mission","Sedimentary",null]
[1985,null,140,"Ksl","RM004","Calcareous lithic sandstone","Calcareous lithic sandstone.  Gray to tan, subangular to rounded, fine- to coarse-grained calcareous lithic sandstone and interbedded micaceous siltstone, locally plant rich.  Sandstone equivalent to the calcareous clastic units of Kuskokwim Group.","Late to middle Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[1985,null,316,"Kks","HC003","Sandstone, siltstone, and shale","Kuskokwim basin\rDeltaic and submarine fan deposits, undivided\rComposed of both deltaic and submarine fan deposits, but the two different facies are not mapped separately owing to the lack of field data.  The deltaic deposits consist of well-sorted, quart","Cretaceous",null,null,"Holy Cross","Sedimentary",null]
[1985,null,516,"Kks","RM005","Sandstone, siltstone, and shale, Kuskokwim basin, deltaic and submarine fan deposits, undivided","Composed of both deltaic and submarine fan deposits, but the two different facies are not mapped separately owing to the lack of field data.  The deltaic deposits consist of well-sorted, quartz-rich, cross-bedded sandstone interbedded with siltstone and","Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[1985,"HFS",534,"TKhf","RM005","Hornfels Altered Kks and Tkd","Formed in the thermal aureole bordering the granitic cores of the Fox Hills and Russian Mountains.  Consists of metasiltstone, metasandstone, metaconglomerate and subordinate amounts of metavolcanic rocks","early Tertiary and latest Cretaceous",null,null,"Russian Mission","Metamorphic",null]
[1985,null,1971,"Kkcd","RM003","Kuskokwim Group; Chert-clast provence rocks; Deltaic facies","Thick bedded quartzose sandstone, pebbly sandstone, and subordinate siltstone and shale.","Late Cretaceous (Turonian)","Age considered Turonian (Late Cretaceous) based on megafossil occurances",null,"Russian Mission","Sedimentary",null]
[2020,null,114,"Ks","RM002","Shaktolik Group","Interbedded sandstone, shale, \"argillite,\" grit, and conglomerate.","Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[2020,null,125,"Ks","MA002","Noncalcareous sandstone","Interbedded fine- to medium-grained gray noncalcareous sandstone and siltstone.  Includes both marine and nonmarine strata, and biotite-hypersthene hornfels.","Cretaceous","Albian and Cenomanian age from plant fossils (Aralia wellingtoniana and Credneria grewiopsoides) and mollusks (Cultellus kokolikensis",null,"Marshall","Sedimentary",null]
[2021,null,213,"Kys","MA003","Sandstone and siltstone, Yukon-Koyukuk basin, deltaic deposits","Fluvial and shallow marine deltaic depoists of sandstone, siltstone, and shale.  Locally crossbedded and ripple marked.  Yukon-Koyukuk basin, deltaic deposits","Cretaceous","Plant debris and fresh- and brackish-water mollusks",null,"Marshall","Sedimentary",null]
[2021,null,329,"Kys","HC003","Sandstone and siltstone","Yukon-Koyukuk basin\rDeltaic deposits\rFluvial and shallow marine deltaic depoists of sandstone, siltstone, and shale.  Locally crossbedded and ripple marked","Cretaceous","Plant debris and fresh- and brackish-water mollusks",null,"Holy Cross","Sedimentary",null]
[2021,null,529,"Kys","RM005","Yukon-Koyukuk Basin, Sandstone and siltstone","Sandstone and siltstone.","Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[2021,null,906,"Kys","KW003","Sandstone and siltstone, Yukon-Koyukuk basin, Deltaic deposits","Fluvial and shallow marine deltaic depoists of sandstone, siltstone, and shale.  Locally crossbedded and ripple marked.  Yukon-Koyukuk basin, deltaic deposits","Cretaceous","Plant debris and fresh- and brackish-water mollusks",null,"Kwiguk","Sedimentary",null]
[2023,null,314,"Kys","HC003","Sandstone and siltstone","Yukon-Koyukuk basin\rDeltaic deposits\rSandstone and siltstone intruded by numerous small hypabyssal bodies of rhyolite and dacite (TKi)","Cretaceous",null,null,"Holy Cross","Sedimentary",null]
[2023,null,514,"Kys (dot)","RM005","Sandstone and siltstone","Sandstone and siltstone. Dot pattern where intruded by numerous small hypabyssal bodies of rhyolite and dacite (TKi)","Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[2023,null,912,"Kys","KW003","Sandstone and siltstone and hypabyssal intrusions, Yukon-Koyukuk basin, deltaic deposits","Sandstone and siltstone intruded by numerous small hypabyssal bodies of rhyolite and dacite (TKi).  Yukon-Koyukuk basin, deltaic deposits","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2102,null,321,"Kygc","SC003","Highly calcareous graywacke sandstone and mudstone turbidites, Yukon-Koyukuk basin, submarine fan deposits","Turbidites composed of highly calcareous sandstone interbedded with noncalcareous micaeous siltstone and shale.  No fossils found, but elsewhere in the Yukon-Koyukuk basin similar assemblages have yielded marine mollusks of probable late Early Cretaceou","Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2102,null,331,"Kygc","HC003","Highly calcareous graywacke sandstone and mudstone turbidites","Yukon-Koyukuk basin\rSubmarine fan deposits\rTurbidites composed of highly calcareous sandstone interbedded with noncalcareous micaeous siltstone and shale.  No fossils found, but elsewhere in the Yukon-Koyukuk basin similar assemblages have yielded marine","Cretaceous",null,null,"Holy Cross","Sedimentary",null]
[2102,null,909,"Kygc","KW003","Highly calcareous graywacke sandstone and mudstone turbidites, Yukon-Koyukuk basin, Submarine fan deposits","Turbidites composed of highly calcareous sandstone interbedded with noncalcareous micaeous siltstone and shale.  No fossils found, but elsewhere in the Yukon-Koyukuk basin similar assemblages have yielded marine mollusks of probable late Early Cretaceous","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2105,null,122,"Kls","SC002","Laumontitized sandstone","Mottled or spotted medium to dark gray laumontitized tuffaceous sandstone interbedded with equal or greater amounts of siltstone and sandstone and sandstone containing little or no laumontite","Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2105,null,892,"Kls","KW002","Laumontitized sandstone","Mottled or spotted medium- to dark-gray laumontitized sandstone interbedded with equal or greater amount of siltstone and sandstone","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2105,null,910,"Kygv","KW003","Graywacke sandstone and mudstone turbidites containing abundant laumontitized volcanic debris, Yukon-Koyukuk basin, Submarine fan deposits","Hard, well-indurated, fine- to medium-grained, locally tuffaceous, sandstone and micaceous mudstone.  No fossils found, but elsewhere in the Yukon-Koyukuk basin a lithologically similar unit has yielded marine mollusks of probable late Early Cretaceous a","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2152,null,121,"Kcs","SC002","Calcareous sandstone","Mostly fine- to medium-grained, gray highly calcareous sandstone interbedded with non-calcareous siltstone with calcareous concretions","Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2152,null,126,"Kcs","MA002","Calcareous sandstone","Mostly fine- to medium-grained gray, highly calcareous, thin-bedded sandstone interbedded with noncalcareous siltstone","Cretaceous",null,null,"Marshall","Sedimentary",null]
[2152,null,828,"Kcs","KW002","Calcareous sandstone","Fine- to medium-grained highly calcareous, thin-bedded sandstone interbedded with noncalcareous siltstone","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2180,null,120,"Ks","SC002","Non-calcareous sandstone","Mostly fine- to medium-grained gray, non-calcareous sandstone and dark gray to black siltstone","Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2180,"HFS",125,"Ks","HP002","Sandstone and siltstone","Interbedded sandstone and siltstone.  Thermally metamorphosed to hornfels.  Similar to Cretaceous rocks in the Kwiguk quad.","Cretaceous",null,null,"Hooper Bay","Sedimentary",null]
[2180,null,215,"Kyg","MA003","Graywacke sandstone and mudstone turbidites, undivided, Yukon-Koyukuk basin, submarine fan deposits","Sparse field data on this sedimentary rock unit suggests that it is composed largely of graywacke turbidites and includes both highly calcareous graywacke as in unit Kygc and graywacke containing abundant volcanic debris as in unit Kygv.  Yukon-Koyukuk b","Cretaceous",null,null,"Marshall","Sedimentary",null]
[2180,null,323,"Kyg","SC003","Graywacke sandstone and mudstone turbidites, undivided, Yukon-Koyukuk basin, submarine fan deposits","Sparse field data on this sedimentary rock unit suggests that it is composed largely of graywacke turbidites and includes both highly calcareous graywacke as in unit Kygc and graywacke containing abundant volcanic debris as in unit Kygv.  Yukon-Koyukuk b","Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2180,null,907,"Kyg","KW003","Graywacke sandstone and mudstone turbidites, undivided, Yukon-Koyukuk basin, Submarine fan deposits","Sparse field data on this sedimentary rock unit suggests that it is composed largely of graywacke turbidites and includes both highly calcareous graywacke as in unit Kygc and graywacke containing abundant volcanic debris as in unit Kygv.  Yukon-Koyukuk b","Cretaceous",null,null,"Kwiguk","Sedimentary",null]
[2210,null,120,"Ki","MA002","Intrusive rhyodacite, dacite, and aplite","Intrusive rhyodacite, dacite, and aplite forming small, light- to dark-gray, fine-grained porphyritic dikes and sills","Cretaceous",null,null,"Marshall","Igneous",null]
[2210,null,155,"Ki","KW002","Intrusive rhyodacite and dacite","Light- to medium-gray, fine-grained, porphyritic rhyodacite and dacite; intrucive, forming dikes and large sill-like bodies","Late Cretaceous",null,null,"Kwiguk","Igneous",null]
[2210,null,2210,"Ki","HC002","Shallow granodiorite intrusives","Shallow, dominantly sill-like bodies probably ranging in composition from granodiorite to diorite.","Late Cretaceous",null,"67.1 +/- 3 and 78.7 +/- 4 Ma K-Ar ages determined on similar rocks to west of quadrangle","Holy Cross","Igneous",null]
[2260,null,112,"Kkv","RM002","Kuskokwim Group (andesite)","Massive gray and greenish-gray porphyritic andesite lava flows, flow breccia, and agglomerate with some interbedded sedimentary rocks.","Cretaceous",null,null,"Russian Mission","Igneous",null]
[2260,null,136,"TKvm","RM004","Basaltic andesite and andesite","Basaltic andesite and andesite.  Medium- to dark-green-gray, aphanitic to fine-grained, pyroxene-rich basaltic andesite and andesite.","Early Tertiary and (or) Late Cretaceous",null,"K/Ar of 75.8 Ma","Russian Mission","Igneous",null]
[2320,null,2320,"Kv","HC002","Andesitic volcaniclastic rocks","Dark-greenish-gray crystal and lithic tuff, fine cherty tuff, and volcanic sandstone","Early Cretaceous (Valanginian)","Early Cretaceous (Valanginian) megafossils and radiolaria in Unalakleet quadrangle",null,"Holy Cross","Igneous",null]
[2330,null,123,"KJv","SC002","Volcanic rocks","Volcanic rocks consisting of dark gray and green andesitic flows and volcaniclastic rocks","Jurassic? and Cretaceous",null,null,"Saint Michael","Sedimentary",null]
[2330,"Q",318,"KJv","HC003","Andesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone","Koyukuk terrane\rHighly disrupted assemblage of mafic to intermediate tuff, breccia, agglomerate, volcanic-rich conglomerate and graywacke, cherty tuff, chert and mudstone and andesitic and basaltic pillow lava.  Age assigned based on sparse fossil and is","Early Cretaceous and Jurassic","Molluscks of Early Cretaceous (Hauterivian and Valanginian age)","K-Ar amphibole age of 128 Ma (Early Cretaceous)\rK-Ar amphibole age of 164 Ma (Middle Jurassic)","Holy Cross","Sedimentary",null]
[2330,"Q",518,"KJv","RM005","Andesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone, Koyukuk terrane","Highly disrupted assemblage of mafic to intermediate tuff, breccia, agglomerate, volcanic-rich conglomerate and graywacke, cherty tuff, chert and mudstone and andesitic and basaltic pillow lava of the Koyukuk terrane.  Age assigned based on sparse fossil","Early Cretaceous and Jurassic","Molluscs of Early Cretaceous (Hauterivian and Valanginian age)","K-Ar amphibole age of 128 Ma (Early Cretaceous)\rK-Ar amphibole age of 164 Ma (Middle Jurassic)","Russian Mission","Sedimentary",null]
[2330,null,705,"KJv","KW002","Volcanic rocks","Dark-gray and green andesite flows, volcanoclastic rocks, and minor interbedded graywacke","Early Cretaceous and Jurassic?",null,null,"Kwiguk","Sedimentary",null]
[2330,null,908,"KJv","KW003","Andesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone, Koyukuk terrane","Highly disrupted assemblage of mafic to intermediate tuff, breccia, agglomerate, volcanic-rich conglomerate and graywacke, cherty tuff, chert and mudstone and andesitic and basaltic pillow lava of the Koyukuk terrane.  Age assigned based on sparse fossil","Early Cretaceous and Jurassic","Molluscs of Early Cretaceous (Hauterivian and Valanginian age)","K-Ar amphibole age of 128 Ma (Early Cretaceous), K-Ar amphibole age of 164 Ma (Middle Jurassic)","Kwiguk","Sedimentary",null]
[2410,null,121,"Kg","MA002","Granitic rocks","Light-gray, medium-grained, weakly foliated granitic rocks","Cretaceous",null,null,"Marshall","Igneous",null]
[2480,null,120,"Kg","HP002","Granodiorite","Light gray, medium- to coarse-grained, locally porphyritic granodiorite","Late Cretaceous",null,"K/Ar age of 78.7 +/- 4.0 m.y. from biotite","Hooper Bay","Igneous",null]
[2480,null,512,"Kg","RM005","Granodiorite and granite","Composed chiefly of biotie granite and hornblende-biotite granodiorite.","Late and Early Cretaceous",null,"K-Ar and 40Ar/39Ar ages ranging from 101 to 120 Ma.  U/Pb age between 104 and 129 Ma (upper Concorida intercept).  K/Ar age of 80.6 +/- 4.0 Ma","Russian Mission",null,null]
[2480,null,2515,"Kis","RM003","Sawpit pluton","Recessively weathering, pink-colored, coarse-grained, seriate, leucocratic biotite granite pluton.","Early Cretaceous",null,null,"Russian Mission","Igneous",null]
[2530,null,2530,"Kinc","RM003","Nyac, Bonanza Creek, and Columbia Creek plutons, undivided","Rock is pale-pink weathering light-gray, coarse-grained porphyritic to seriate hornblende-biotite and biotite-hornblende granite, quartz monzonite, and lesser granodiorite and quartz-monzodiorite.  Nyac (~200 km) is crudely concentrically zoned from horn","Early Cretaceous",null,"Nyac: K/Ar age of 101.1+3.0 Ma from hornblende; 108.5+3.3 Maÿand 120.0+3.6 Ma from biotite; and U/Pb age of 104 to 129 Ma from zircon.  Bonanza Creek: Ar/Ar total-fusion age of 110+3.3 Ma from biotite.  Columbia Creek: K/Ar age of 115.0+3.5 Ma from bioti","Russian Mission","Igneous",null]
[2870,null,526,"KJb","RM005","Basaltic and andesitic lava flows, Nyak terrane","Variably altered basalt and andesite.  Conformably(?) overlies unit Jab and unconformably(?) overlain by unit TJb.  Nyak terrane","Early Cretaceous to Late Jurassic",null,null,"Russian Mission","Igneous",null]
[2870,null,2871,"KJba","RM003","Basaltic and Andesitic lava flows, Nyac terrane","Basaltic and andesitic lava flows.","Early Cretaceous and (or) Late Jurassic",null,null,"Russian Mission","Sedimentary",null]
[2885,null,525,"TJi","RM005","Hyabyssal felsic intrusive rocks","Altered rhyolite and dacite porphyries.  Age of unit is uncertain, but not older than Jurassic.  May be as young as Tertiary","early Tertiary to Jurassic",null,null,"Russian Mission","Metamorphic",null]
[2885,null,2885,"TJih","RM003","Hypabyssal felsic intrusive rocks","Highly altered rhyolite and dacite porphyries.","early Tertiary?, Cretaceous, and Jurassic",null,null,"Russian Mission","Igneous",null]
[3120,null,527,"Jvc","RM005","Volcaniclastic conglomerate, sandstone, and shale","Tuffaceous marine sandstone, shale, and conglomerate.  Minor basaltic and andesitic lava flows.  Felsic pyroclastic rocks locally near base of unit.  Unit rests conformably(?) on unit Jab and is conformably(?) overlain by unit KJb","Late and Middle Jurassic","Mollusks of Late Jurassic (late Kimmeridgian to early Tithonian) age",null,"Russian Mission","Sedimentary",null]
[3120,null,3120,"Jvc","RM003","Volcaniclastic conglomerate, sandstone, and shale, Nyac terrnae","Epiclastic sequence of tuffaceous marine sandstone, shale, and conglomerate with minor interbedded basaltic and andesitic lava flows","Late and Middle Jurassic","Marine pelecypods of Bajocian age (Middle Jurassic);  Marine pelecypods of Tithonian age (Late Jurassic)",null,"Russian Mission","Sedimentary",null]
[3380,null,319,"Jt","HC003","Trondhjemite, tonalite, and gabbro","Koyukuk terrane\rComposed chiefly of trondjhemite and tonalite plutonic bodies that locally have been metasomatized by potassium-rich fluids to a pink granite and granodiorite.  Also includes subordinate amounts of quarz diorite, diorite, and gabbro","Jurassic",null,"K-Ar ages from 173 to 130 Ma in the Unalakleet quadrangle (Patton and Moll-Stalcup, 1996)","Holy Cross","Igneous",null]
[3380,null,3380,"Jgr","HC002","Mafic granitoid rocks","Poorly known diorite, gabbro, and tonalite plutons intruding unit MzPzb in northern part of quadrangle","Late and Middle Jurassic",null,"Correlative rocks in Unalakleet quadrangle yielded K-Ar age of 154 +/- 6, 166 +/- &, qnd 173 +/- ( Ma","Holy Cross","Igneous",null]
[3406,"ALT",3406,"TJim","RM003","Altered mafic plutonic rocks","Small, erosionally neutral, texturally and compositionally diverse, partially to extensively altered diorite and gabbro bodies","Early Tertiary?, Cretaceous, and Jurassic",null,null,"Russian Mission","Igneous",null]
[3450,null,328,"Jab","HC003","Andesite and basalt, Nyac terrane","Andesite and basalt","Middle Jurassic",null,null,"Holy Cross","Igneous",null]
[3450,null,528,"Jab","RM005","Andesitic and basaltic lava flows and marine volcaniclastic rocks","Andesitic and basaltic lava flows and flow breccia.  Tuffaceous sandstone and conglomerate containing abundant clasts of mafic and intermediate volcanic and intrusive rocks.  Unit altered to low-grad metamorphic facies by variable replacement of primary","Middle Jurassic","Marine mollusks",null,"Russian Mission","Metamorphic",null]
[3450,null,3450,"Jab","RM003","Andesitic and Basaltic lava flows and marine epiclastic rocks, Nyac terrane","Andesitic and basaltic lava flows, flow breccias, and tuffaceous marine sedimentary rocks","Middle Jurassic","Marine pelecypods of Bajocian age (Middle Jurassic)",null,"Russian Mission","Sedimentary",null]
[3498,null,320,"MzPzum","HC003","Serpentinized ulramafic rocks","Koyukuk terrane\rPresumed to be composed of partly serpentinized harzburgbite and dunite.  May also include some gabbro","Mesozoic and Paleozoic?",null,null,"Holy Cross","Metamorphic",null]
[4710,null,115,"KCgu","RM002","Gemuk Group (mafic volcanics and sedimentary rocks)","Mafic lava flows, volcanic breccia, and agglomerate interbedded with siliceous siltstone, chert, graywacke, and a small amount of calcareous conglomerate and limestone","Carboniferous? to Cretaceous",null,null,"Russian Mission","Sedimentary",null]
[4710,null,130,"TrPvs","MA002","Metavolcanic and metasedimentary rocks","Chiefly gray and green, fine- to medium-grained schistose metavolcanic and metasedimentary rocks.  Includes contact metamorphosed hornfels","Permian and Triassic?",null,null,"Marshall","Metamorphic",null]
[4710,null,145,"MzPzvs","RM004","Metasandstone, argillite, and mafic meta-igneous rocks","Metasandstone, argillite, and mafic meta-igneous rocks.  Poorly exposed, highly deformed heterogeneous package of green, feldspathic, tuffaceous metasandstone.  Dark-gray to brown argillite.  Dark-green, fine- to coarse-grained metabasalt and metadiorite","early Mesozoic to middle Paleozoic",null,null,"Russian Mission","Metamorphic",null]
[5235,null,322,"KMu","HC003","Andesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone (KJv) and altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone (TrMv), undivided","Undivided Koyukuk and Angayucham-Tozitna terranes\rAndesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone (KJv) and altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone (TrMv), undivided","Cretaceous to Mississippian",null,null,"Holy Cross","Metamorphic",null]
[5235,null,522,"KMu","RM005","Andesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone (KJv) and altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone (TrMv), undivided","Undivided Koyukuk and Angayucham-Tozitna terranes\rAndesitic and basaltic volcaniclastic rocks, lava flows, chert, and mudstone (KJv, 2330) and altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone (TrMv, 5280), un","Cretaceous to Mississippian",null,null,"Russian Mission","Metamorphic",null]
[5280,null,217,"TrMv","MA003","Complexly deformed assemblage of altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone, Angayucham-Tozitna terrane","Composed of a wide variety of mafic and intermediate volcanic and intrusive rocks including basalt, and andesite, diabase, gabbro, and volcaniclastic rocks that are weakly metamorphosed to prehnite-pumpellyite and locally to greenshist facies assemblages","Triassic to Mississippian","Locally abundant fossil occurrences",null,"Marshall","Metamorphic",null]
[5280,null,321,"TrMv","HC003","Complexly deformed assemblage of altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone","Angayucham-Tozitna terrane\rComposed of a wide variety of mafic and intermediate volcanic and intrusive rocks including basalt, and andesite, diabase, gabbro, and volcaniclastic rocks that are weakly metamorphosed to prehnite-pumpellyite and locally to gr","Triassic to Mississippian","Locally abundant fossil occurrences",null,"Holy Cross","Metamorphic",null]
[5280,null,521,"TrMv","RM005","Complexly deformed assemblage of altered basalt, chert, chert breccia, argillite, tuff, volcaniclastic graywacke, and limestone, Angayucham-Tozitna terrane","Composed of a wide variety of mafic and intermediate volcanic and intrusive rocks including basalt, and andesite, diabase, gabbro, and volcaniclastic rocks that are weakly metamorphosed to prehnite-pumpellyite and locally to greenshist facies assemblages","Triassic to Mississippian","Locally abundant fossil occurrences",null,"Russian Mission","Metamorphic",null]
[5280,null,5280,"MzPzb","HC002","Altered basalt, diabase, and subordinate limestone","Dominantly dark-green to gray altered basalt and fine-grained diabase, containing subordinate cherty tuff and pods of recrystallized limestone.","early Mesozoic and Paleozoic","Unidentifiable crinoid stem fragments in limestone pod",null,"Holy Cross","Igneous",null]
[6320,null,330,"ls","HC003","Limestone","Scattered limestone bodies within unit TrMv","Triassic to Mississippian","Locally abundant fossil occurances",null,"Holy Cross","Sedimentary",null]
[6320,null,530,"ls","RM005","Limestone","Scattered limestone bodies within unit TrMv","Triassic to Mississippian","Locally abundant fossil occurances",null,"Russian Mission","Sedimentary",null]
[6320,null,6320,"ls","HC002","Limestone pods in altered basalt, diabase, and subordinate limestone","Recrystallized limestone in unit MzPzb, consisting of dominantly dark-green to gray altered basalt and fine-grained diabase, containing subordinate cherty tuff and pods of recrystallized limestone.  Correlation highly tentative with unit MDl of Innoko se","early Mesozoic and Paleozoic","Unidentifiable crinoid stem fragments in limestone pod",null,"Holy Cross","Sedimentary",null]
[6412,null,116,"KCgg","RM002","Gemuk Group (altered mafic volcanics and sedimentary rocks)","Mafic volcanic rocks altered to gneissoid and schistose rocks in some areas.  Light grreenish gray tuff with interbedded siltstone, overlain by volcanic agglomerate, impure limestone, graywacke, and chert","Cretaceous to Carboniferous?",null,null,"Russian Mission","Metamorphic",null]
[12950,"HFS",160,"TKhf","RM004","Hornfels","Hornfels.  Brown to gray, massive to locally porphyroblastic chlorite-biotite hornfels, partly tourmaline rich","early Tertiary and (or) Late Cretaceous",null,null,"Russian Mission","Metamorphic",null]
[12950,"HFS",313,"TKhf","HC003","Hornfels","Formed in the ternal aureole bordering the granitic cores of the Fox Hills and Russian Mountains.  Consists of metasitlstone, metasandstone, metaconglomerate and subordinate amounts of metavolcanic rocks","early Tertiary and latest Cretaceous",null,null,"Holy Cross","Metamorphic",null]