rock unit,unit name,age,description,fossil,radiometric age,source,class,quadrangle,rock class,nsaclass,label,nsamod,qclass
Qs?,Surficial deposits,Quaternary,Undivided surficial deposits,,,KD002,100,Kodiak,Unconsolidated,100,,,
Qs,Surficial deposits,Quaternary,Consist of glacial and stream deposits inland and beach sediments along coast,,,KD004,400,Kodiak,Unconsolidated,100,,,
Qs?,Surficial deposits,Quaternary,Undivided surficial deposits,,,KR005,500,Karluk,Unconsolidated,100,,,
Qs?,Surficial deposits,Quaternary,Undivided surficial deposits,,,TI002,100,Trinity Islands,Unconsolidated,100,,,
Qs?,Surficial deposits,Quaternary,Undivided surficial deposits,,,KG002,100,Kaguyak,Unconsolidated,100,,,
Qs,Surficial deposits,Holocene and Pleistocene,"Unconsolidated, porrly to well-sorted, poorly to moderately well-stratified doeposits; consists predominatly of alluvial, colluvial, glacial, marine, lacustrine, eolian, and swamp deposits.  Also, locally includes reworked volcanic debris as well as block and ash flows.",,,KR002,100,Karluk,Unconsolidated,100,,,
Qs,"Surficial deposits, undivided",Quaternary,"Surficial deposits, undivided",,,AF002,100,Afognak,Unconsolidated,100,,,
,Alluvium and marine terrace deposits,Quaternary,Alluvium and marine terrace deposits,,,TI004,400,Trinity Islands,Unconsolidated,100,,,
,Surficial deposits,Quaternary,Consist of glacial and stream deposits inland and beach sediments along coast,,,KR006,600,Karluk,Unconsolidated,100,,,
,Surficial deposits,Quaternary,Consists of glacial and stream deposits inland and beach sediments along coast,,,AF004,100,Afognak,Unconsolidated,100,,,
Qmg,"Present stream gravel, sand, and silt","Quaternary, Pleistocene and Recent",Low terrace gravel; alluvial fans; beach deposits.  Glacial morainal material,,,AF010,1000,Afognak,Unconsolidated,100,,,1000
Qmg,"Present stream gravel, sand, and silt","Quaternary, Pleistocene and Recent",Low terrace gravel; alluvial fans; beach deposits.  Glacial morainal material,,,KD007,1000,Kodiak,Unconsolidated,100,,,1000
Qmg,"Present stream gravel, sand, and silt","Quaternary, Pleistocene and Recent",Low terrace gravel; alluvial fans; beach deposits.  Glacial morainal material,,,KR009,1000,Karluk,Unconsolidated,100,,,1000
Qmg,"Present stream gravel, sand, and silt","Quaternary, Pleistocene and Recent",Low terrace gravel; alluvial fans; beach deposits.  Glacial morainal material,,,KG007,1000,Kaguyak,Unconsolidated,100,,,1000
,Surficial deposits,Quaternary,Consists of glacial and stream deposits inland and beach sediments along coast,,,AF005,100,Afognak,Unconsolidated,100,,,
Qs?,Surficial deposits,Quaternary,Undivided surficial deposits,,,KD004,100,Kodiak,Unconsolidated,100
Qa,Alluvial deposits,Holocene and Pleistocene,"Ranges from coarse, subangular rock fragments to fine sand and silt in grainsize; locally includes considerable amounts of pumice near volcanic centers.",,,AF006,105,Afognak,Unconsolidated,105
Qaf,Alluvial fan and landslide deposits,Holocene and Pleistocene,"Locally mapped; grainsize in this unit ranges from coarse, subangular rock fragments to fine sand and silt.  Alluvial fans either typically have a well-developed cone shape, or multiple cones coalescing into aprons.  Landslide deposits have poorly developed to well-developed lobate morphology",,,AF006,106,Afognak,Unconsolidated,106
Qls,Landslide deposits,Quaternary,Lanslide deposits,,,KR003,108,Karluk,Unconsolidated,108
Qls,Landslide deposits,Quaternary,"Landslide deposits ranging from nonsorted, nonstratifed, coarse angular rubble forming lobes, to large discrete blocks that resemble undisturbed bedrock",,,AF002,108,Afognak,Unconsolidated,108
ls,Landslide deposits,Quaternary,"Landslide deposits ranging from nonsorted, nonstratifed, coarse angular rubble forming lobste masses at base of moderately steep to steep slopes.  Where derived from bedrock, deposits are chiefly coarse angular blocks; where derived from glacial deposits, deposits are mixture of silt, sand, gravel, and boulders",,,AF006,108,Afognak,Unconsolidated,108
Qb,Marine beach and estuarine deposits,Holocene and Pleistocene,Marine beach and estuarine deposits.  Moderately well stratified and sorted sand and gravel on beaches; mud and silt in estuaries,,,KR003,115,Karluk,Unconsolidated,115
be,Marine beach deposits,Holocene and Pleistocene,Moderately well stratified and sorted sand and gravel on beaches,,,AF006,115,Afognak,Unconsolidated,115
Qmt,Marine terrace deposits,Holocene and Pleistocene,Marine terrace deposits.  Stratified and moderately well sorted sand and gravel deposits that form nearly level plains that end locally at prominent wave-cut scarps.  Terraces occur at 15 to 18 m elevation along Bristol Bay and between 40 and 45 m elevation along Pacific Ocean,,,KR003,117,Karluk,Unconsolidated,117
mt,Marine terrace deposits,Holocene and Pleistocene,Marine terrace deposits.  Stratified and moderately well sorted sand and gravel deposits that form nearly level plains that end locally at prominent wave-cut scarps.  Terraces occur at 15 to 18 m elevation along Bristol Bay and between 40 and 45 m elevation along Pacific Ocean,,,AF006,117,Afognak,Unconsolidated,117
rg,Rock glacier deposits,Quaternary,Rock glacier deposits,,,AF006,127,Afognak,Unconsolidated,127
Qad,"Drift, Alaskan glaciation (Neoglacial)",Holocene,"Drift, Alaskan glaciation (Neoglacial)",,,KR003,130,Karluk,Unconsolidated,130
nd,"Drift, Neoglacial",Holocene,"Drift, Neoglacial",,,AF006,130,Afognak,Unconsolidated,130
Qblu,"Drift, undivided, Brooks Lake glaciation","Quaternary, Pleistocene","Drift, undivided, Brooks Lake glaciation",,,KR003,135,Karluk,Unconsolidated,135
blu,"Drift, undivided, Brooks Lake glaciation","Quaternary, Pleistocene","Drift, undivided, Brooks Lake glaciation",,,AF006,135,Afognak,Unconsolidated,135
Qbln,"Drift, Newhalen Stade, Brooks Lake Glaciation","Quaternary, Pleistocene","Drift, Newhalen Stade, Brooks Lake Glaciation",,,KR003,137,Karluk,Unconsolidated,137
Qblil,"Drift, Iliamna Stade, Brooks Lake Glaciation","Quaternary, Pleistocene","Drift, Iliamna Stade, Brooks Lake Glaciation",,,KR003,138,Karluk,Unconsolidated,138
Qmhd,"Drift, Mak Hill Glaciation","Quaternary, Pleistocene","Drift, Mak Hill Glaciation",,,KR003,139,Karluk,Unconsolidated,190
Qvi,Volcanic and shallow intrusive rocks,Holocene and Pleistocene,"Basalitc andesite to dacite lava flows, volcaniclastic deposits.  Includes air-fall tuffs, volcanic domes, block and ash-flow deposits, ash-flow tuffs, volcanic-rubble flows, debris flows and hot-blast avalanche deposits",,,KR002,150,Karluk,Igneous,300
Qv,Volcanic rocks,Holocene and Pleistocene,"Andesite, dacite, and leucobasalt lava flows, volcanic breccia, lahar deposits, and debris-flow deposits.  Lava flows and clasts in other volcanic deposits of unit are porphyritic, typically glassy, gray to black, and commonly vesicular.  Andesite is overwhelmingly dominant composition and probably constitutes 60 percent or more of rocks.  Unit typically forms volcanic edifices; it also forms isolated outcrops that cap ridges, providing a good example of topography reversal caused by erosion.  Individual flows are locally as thick as 30 m and are laterally continuous over large areas.  Unit also includes basaltic, basaltic andesite, and dacite parasitic cinder and spatter cones.  Cones are commonly 30 to 300 m high, are steep sided, and have small crater at top.  Basaltic scoria cones occur at three separate locations in the Mount Katmai 1:250,000-scale quadrangle (Riehle and others, 1993).  Rocks are highly scoriaceous to vitrophyric, ranging in size from cinder-size fragments to 1-m-long bombs (Detterman and others, 1981b; T.P. Miller, oral commun., 1991).",,,AF006,150,Afognak,Igneous,300
Qv,Volcanic rocks,Holocene and Pleistocene,"Andesite, dacite, and leucobasalt lava flows, volcanic breccia, lahar deposits, and debris-flow deposits.  Lava flows and clasts in other volcanic deposits of unit are porphyritic, typically glassy, gray to black, and commonly vesicular.  Andesite is overwhelmingly dominant composition and probably constitutes 60 percent or more of rocks",,,KR004,150,Karluk,Igneous,300
Qap,Ash-flow and ash-fall deposits,Holocene,"Nonsorted, variably indurated deposits of ash, vitrophyre blocks, and (or) pumiceous lapilli.  Mapped in Valley of Ten Thousand Smokes and  at Kaguyak Crater",,,AF006,161,Afognak,Igneous,311
Qad,Domes,Holocene,"Dacitic or rhyolitic vitrophyres having plagioclase, pyroxene, and (or) hornblende phenocrysts in a brown to grayish-brown glassy groundmass.",,,AF002,181,Afognak,Igneous,401
cvd,Domes,Holocene and Pleistocene,"Dacite at Snowy Mountain, Mount Cerberus,  Falling Mountain, and at Kaguyak Crater and rhyolite at Novarupta",,,AF006,681,Afognak,Igneous,401
QTv,Volcanic rocks,Quaternary and Pliocene?,"Andesite and basalt lava flows, sills, and plugs.  These primarily extrusive rocks typically cap ridges and include massive lava flows, agglomerate, and lahar deposits.",,,AF002,190,Afognak,Igneous,450
Ttg,Tugidak Formation,"Tertiary, Pliocene","Consists of 1,500 m of of interbedded sandstone and siltstone characterized by randomly distributed pebbles and cobbles.  A single 1 m thick cobble conglomerate bed reported 350 m above base of unit","Richly fossiliferous, marine fossils of Pliocene age.",,TI003,212,Trinity Islands,Sedimentary,550
Tp,Pliocene marine sedimentary rocks,"Tertiary, Pliocene","Consists of 1,500 m of of interbedded sandstone and siltstone characterized by randomly distributed pebbles and cobbles.  A single 1 m thick cobble conglomerate bed reported 350 m above base of unit","Richly fossiliferous, marine fossils of Pliocene age.",,TI002,212,Trinity Islands,Sedimentary,550
,Mainly Tertiary sandstone and shale,Tertiary,Mainly Tertiary sandstone and shale,,,TI006,,Trinity Islands,Sedimentary,500
,Albatross sedimentary sequence,"Tertiary, Pliocene or late Miocene","Diamictite, sandstone, and siltstone.  Conglomerate horizons contain clasts of granite, chert, melange, and slate.  Also contain distinctive calcareous shale clasts unlike any nearby exposed units",Calcareous shale clasts contain a late early Miocene fauna; enclosing unit is correlate with the Yakataga Formation,,TI004,401,Trinity Islands,Sedimentary,565
Tnc,Narrow Cape Formation,"Tertiary, Miocene","Formation is 700m thick, the lower 2/3 consisting of sandstone and a few conglomerate beds.  The upper third consists of siltstone.",,,KD003,223,Kodiak,Sedimentary,580
Tms,Miocene sedimentary rocks,"Tertiary, Miocene","Formation is 700m thick, the lower 2/3 consisting of sandstone and a few conglomerate beds.  The upper third consists of siltstone.",,,KD002,223,Kodiak,Sedimentary,580
Tms,Miocene sedimentary rocks,"Tertiary, Miocene","Formation is 700m thick, the lower 2/3 consisting of sandstone and a few conglomerate beds.  The upper third consists of siltstone.",,,TI002,223,Trinity Islands,Sedimentary,580
Tnc,Narrow Cape Formation,"Tertiary, Miocene","Formation is 700m thick, the lower 2/3 consisting of sandstone and a few conglomerate beds.  The upper third consists of siltstone.",,,TI003,223,Trinity Islands,Sedimentary,580
Tnc,Narrow Cape Formation,"Tertiary, Late Miocene",Narrow Cape Formation,,,KD006,61,Kodiak,Sedimentary,580
Tms,Marine sandstones of Narrow Point,,"Marine sandstones of Narrow Point, mildly folded and moderately indurated",,,KD007,,Kodiak,Sedimentary,580
,Siltstone of Trinity Islands,"Tertiary, earliest Miocene or late Oligocene","Siltstone deposited in cool-temperature climactic conditions at outer neritic water depths.  Originally included is the Narrow Cape Formation, is now considered a distinctive, older unit.",Molluscan fauna and benthic foraminifers,,TI004,402,Trinity Islands,Sedimentary,581
Tts,Siltstone of Trinity Island and Sitkinak Formation,"Tertiary, Oligocene and Early Miocene",Siltstone of Trinity Island and Sitkinak Formation,,,KD006,62,Kodiak,Sedimentary,581
Th,Hemlock Conglomerate,late Oligocene,"Composed primarily of fluvial sandstone and conglomerate that contain interbeds of siltstone, shale, and coal.  Chert, quartz, and granitic and metasedimentary rocks form most of clasts in conglomerate; volcanic rocks are small but significant proportion of clasts.  Minor tuff is present; however, erosion of underlying Mesozoic rocks is probably main source for Hemlock Conglomerate.  ","Megaflora fossils of broadleaf deciduous plants and evergreen needles suggest late Oligocene age (J.A. Wolfe, written commun., 1988, in Detterman and others, 1996)",,KR004,231,Karluk,Sedimentary,650
Th,Hemlock Conglomerate,late Oligocene,"Composed primarily of fluvial sandstone and conglomerate that contain interbeds of siltstone, shale, and coal.  Chert, quartz, and granitic and metasedimentary rocks form most of clasts in conglomerate; volcanic rocks are small but significant proportion of clasts.  Minor tuff is present; however, erosion of underlying Mesozoic rocks is probably main source for Hemlock Conglomerate.  ","Megaflora fossils of broadleaf deciduous plants and evergreen needles suggest late Oligocene age (J.A. Wolfe, written commun., 1988, in Detterman and others, 1996)",,AF002,231,Afognak,Sedimentary,650
Tsk,Sitkinak Formation,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,KD003,233,Kodiak,Sedimentary,660
To,Oligocene continental sedimentary rocks,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,KD002,233,Kodiak,Sedimentary,660
To,Oligocene continental sedimentary rocks,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,TI002,233,Trinity Islands,Sedimentary,660
Tsk,Sitkinak Formation,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,TI003,233,Trinity Islands,Sedimentary,660
To,Oligocene continental sedimentary rocks,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,KG002,233,Kaguyak,Sedimentary,660
Tsk,Sitkinak Formation,"Tertiary, Oligocene",Conglomerate and cross-bedded sandstone and siltstone containing coal fragments.,,,KG003,233,Kaguyak,Sedimentary,660
,Sitkinak Formation,"Tertiary, Oligocene","Conglomerate and sandstone alternating with fine-grained sandstone, siltstone, coal, and carbonaceous shale.  Primarily of terrestrial origin; deposited as channelized braided stream gravels interebedded with interchannel, lagoonal, and interdistributary bay deposits",,,TI004,403,Trinity Islands,Sedimentary,660
Tss,"Fresh-water sandstone, shale, and conglomerate, locally containing coly seams",,"Fresh-water sandstone, shale, and conglomerate, locally containing coly seams.  Generally steeply dipping and well indurated; locally highly contorted.  (Includes Sitkinak and Sitkalidak Formations)",,,KD007,,Kodiak,Sedimentary,640
Tss,"Fresh-water sandstone, shale, and conglomerate, locally containing coly seams",,"Fresh-water sandstone, shale, and conglomerate, locally containing coly seams.  Generally steeply dipping and well indurated; locally highly contorted.  (Includes Sitkinak and Sitkalidak Formations)",,,KG007,,Kaguyak,Sedimentary,640
Tsi,Sitkalidak Formation,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,KD003,241,Kodiak,Sedimentary,740
Teo,Eo-Oligocene marine sedimentary rocks,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,KD002,241,Kodiak,Sedimentary,740
Teo,Eo-Oligocene marine sedimentary rocks,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,TI002,241,Trinity Islands,Sedimentary,740
Tsi,Sitkalidak Formation,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,TI003,241,Trinity Islands,Sedimentary,740
Teo,Eo-Oligocene marine sedimentary rocks,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,KG002,241,Kaguyak,Sedimentary,740
Tsi,Sitkalidak Formation,"Tertiary, Oligocene to Eocene","Uniform sandstone and siltstone graded beds about 3,000 m thick  Rare conglomerate beds.",,,KG003,241,Kaguyak,Sedimentary,740
,"Sitkalidak Formation, slope-basin deposits","Tertiary, Eocene","Less deformed interbedded sandstone and siltstone, mudstone and conglomerate, representative of deep-sea fan deposition.",,,TI004,404,Trinity Islands,Sedimentary,740
,"Sitkalidak Formation, offscraped deposits","Tertiary, Eocene","More deformed interbedded sandstone and siltstone, mudstone and conglomerate, representative of deep-sea fan deposition.",,,TI004,405,Trinity Islands,Sedimentary,740
,"Sitkalidak Formation, offscraped deposits","Tertiary, Eocene","More deformed interbedded sandstone and siltstone, mudstone and conglomerate, representative of deep-sea fan deposition.",,,KG004,405,Kaguyak,Sedimentary,740
Ts,"Sitkalidak Formation, undivided","Tertiary, Eocene to Early Oligocene","Sitkalidak Formation, undivided",,,KD006,63,Kodiak,Sedimentary,740
Tsl,"Sitkalidak Formation, less deformed","Tertiary, Eocene to Early Oligocene","Sitkalidak Formation, less deformed",,,KD006,64,Kodiak,Sedimentary,740
Tsm,"Sitkalidak Formation, more deformed","Tertiary, Eocene to Early Oligocene","Sitkalidak Formation, more deformed",,,KD006,65,Kodiak,Sedimentary,740
Ts,"Sitkalidak Formation, undivided","Tertiary, Eocene to Early Oligocene","Sitkalidak Formation, undivided",,,TI005,63,Trinity Islands,Sedimentary,740
Tc,Copper Lake Formation,early Eocene and Paleocene?,"Consists of thick pebble-cobble conglomerate in its uppermost and lowermost parts and contains sandstone and siltstone in its middle part.  In measured section, conglomerate intervals are massive and have clasts that are mixture of volcanic, granitic, and metamorphic rocks in subequal proportions.  Sandstone and siltstone intervals of measured section vary from thin bedded to massive and are typically dark to medium gray; they are fine to medium grained lower in section and become medium to coarse grained toward top.  More fine grained clastic parts of formation contain considerable carbonaceous debris and minor coaly material.  ","Age of Copper Lake is not well constrained; sparse megaflora in type section in Iliamna area and abundant megaflora in map area are restricted to sandstone and siltstone intervals that are present in middle part of unit (Detterman and others, 1996).",,AF002,250,Afognak,Sedimentary,850
Tgc,"Ghost Rocks Formation, coherent","Tertiary, early Paleocene","Ghost Rocks Formation, coherent",,,KD006,69,Kodiak,Sedimentary,960
Tgc,"Ghost Rocks Formation, coherent","Tertiary, early Paleocene","Ghost Rocks Formation, coherent",,,KG006,69,Kaguyak,Sedimentary,960
Tgs,"Ghost Rocks Formation, sandstone-rich unit, undivided","Tertiary, early Paleocene","Massive sandstone beds and lesser amounts of argillite and medium- to thin-bedded sandstone.  Sandstone beds show Bouma sequences indicative of deposition be turbidity currents.  Locally, channelized conglomerate units up to 100-m-thick occur on the Aliulik Peninsula.  Clasts in the conglomerate are up to 30 cm in size and consist of chert, sandstone, limestone, and greenstone.  Andesite are also interbedded on the Aiulik Peninsula.",,,KD006,67,Kodiak,Sedimentary,961,,
Tgs,"Ghost Rocks Formation, sandstone-rich unit, undivided","Tertiary, early Paleocene","Massive sandstone beds and lesser amounts of argillite and medium- to thin-bedded sandstone.  Sandstone beds show Bouma sequences indicative of deposition be turbidity currents.  Locally, channelized conglomerate units up to 100-m-thick occur on the Aliulik Peninsula.  Clasts in the conglomerate are up to 30 cm in size and consist of chert, sandstone, limestone, and greenstone.  Andesite are also interbedded on the Aiulik Peninsula.",,,KG006,67,Kaguyak,Sedimentary,961,,
Tgs,"Ghost Rocks Formation, sandstone-rich unit, undivided","Tertiary, early Paleocene",Consists of thick sections of argillite and local massive sandstone and chert-rich pebble conglomerate.  Tuff beds.  Limestone containing pelagic forams locally occurs at depositional contacts with pillow basalt.  Unit typically occurs to southeast of sandstone-rich unit.,Pelagic forams yielding early Tertiary and Late Cretaceous ages (3 collections),,TI005,67,Trinity Islands,Sedimentary,961,,
Tga,"Ghost Rocks Formation, argillite-rich unit, undivided","Tertiary, early Paleocene",Consists of thick sections of argillite and local massive sandstone and chert-rich pebble conglomerate.  Tuff beds.  Limestone containing pelagic forams locally occurs at depositional contacts with pillow basalt.  Unit typically occurs to southeast of sandstone-rich unit.,Pelagic forams yielding early Tertiary and Late Cretaceous ages (3 collections),,KD006,68,Kodiak,Sedimentary,962,,
Tga,"Ghost Rocks Formation, argillite-rich unit, undivided","Tertiary, early Paleocene","Massive sandstone beds and lesser amounts of argillite and medium- to thin-bedded sandstone.  Sandstone beds show Bouma sequences indicative of deposition be turbidity currents.  Locally, channelized conglomerate units up to 100-m-thick occur on the Aliulik Peninsula.  Clasts in the conglomerate are up to 30 cm in size and consist of chert, sandstone, limestone, and greenstone.  Andesite are also interbedded on the Aiulik Peninsula.",,,TI005,68,Trinity Islands,Sedimentary,962,,
Tga,"Ghost Rocks Formation, argillite-rich unit, undivided","Tertiary, early Paleocene",Consists of thick sections of argillite and local massive sandstone and chert-rich pebble conglomerate.  Tuff beds.  Limestone containing pelagic forams locally occurs at depositional contacts with pillow basalt.  Unit typically occurs to southeast of sandstone-rich unit.,Pelagic forams yielding early Tertiary and Late Cretaceous ages (3 collections),,KG006,68,Kaguyak,Sedimentary,962,,
Tab,Volcanic rocks of Barrier Range,late Tertiary,"Breccia, lava flows, sills, and local pyroclastic and epiclastic tuff, southeast of active part of Aleutian Arc",,,AF002,311,Afognak,Igneous,1051,,
Tgva,"Ghost Rocks Formation, andesitic volcanic and hypabyssal rocks","Tertiary, early Paleocene","Ghost Rocks Formation, andesitic volcanic and hypabyssal rocks",,,KD006,602,Kodiak,Igneous,1150,,
Tgvb,"Ghost Rocks Formation, basaltic volcanic and hypabyssal rocks","Tertiary, early Paleocene","Tholeiitic basalt occurring within both sandstone- and argillite-rich units of the Formation.  Rocks are typically altered by shearing and low-grade metamorphism, yet ""* * * these lavas cannot have been derived from a single source and in many respect exhibit chemical affinities to magmas found in a variety of tectonic environments."" (Moore and others, 1983, p. 270)",,,KD006,603,Kodiak,Igneous,1151,,
TKg,Granular intrusive rocks,Latest Cretaceous or Early Tertiary,"Granular intrusive rocks, mainly quartz diorite, with some diorite, and minor amounts of gabbro",,,KD007,,Kodiak,Igneous,1200,,Q
TKg,Granular intrusive rocks,Latest Cretaceous or Early Tertiary,"Granular intrusive rocks, mainly quartz diorite, with some diorite, and minor amounts of gabbro",,,AF010,1002,Afognak,Igneous,1200,,Q
TKg,Granular intrusive rocks,Latest Cretaceous or Early Tertiary,"Granular intrusive rocks, mainly quartz diorite, with some diorite, and minor amounts of gabbro",,,KR009,,Karluk,Igneous,1200,,Q
Tqd,Quartz diorite,Pliocene and (or) Miocene,"Fine- to medium-grained, equigranular, quartz diorite, quartz monzodiorite, granodiorite and quartz monzonite.  Intrusive bodies are typically located along Pacific coast and include, but are not limited to, large plutons at Agripina Bay, Mount Becharof, Cape Kubugakli and between Wide and Portage Bay",,"Potassium-argon ages range from 2.3 to 3.2 Ma (Wilson and  others, 1981; F.H. Wilson and Nora Shew, unpub. data, 1990; Wilson and Shew, 1992)",KR002,362,Karluk,Igneous,1250,,
Ti,Intrusive rocks,Pliocene and late Miocene,"Medium- to coarse-grained, equigranular, granodiorite to quartz diorite plutons and stocks containing hornblende, biotite, and pyroxene as mafic minerals and typically are surrounded by well-developed hornfels zones and sporadic hydrothermal alteration in country rocks.  Intrusive bodies are typically located along Pacific coast and include, but are not limited to, large plutons at Moss Cape, American Bay, Pyramid Mountain, Mitrofania Island, Devils Bay (Devils batholith, Detterman and others, 1981), Agripina Bay, Mount Becharof, Cape Igvak, and Cape Douglas.  ",,"Potassium-argon ages range from 9.43 +/- 0.26 to 3.21 +/- 0.14 Ma (Wilson and  others, 1981; F.H. Wilson and Nora Shew, unpub. data, 1990; Wilson and Shew, 1992)",AF002,362,Afognak,Igneous,1250,,
Ti,Granitic plutonic rocks,"Tertiary, Eocene or younger","Small altered granitic plutons that intrude the Ghost Rocks Formation between Portage and Kaingnak Bays and north of Ugak Bay on the southeast coast of Kodiak Island.  Examination of a few thin-sections of these plutons show them to be distinctive from the Kodiak batholith (unit Tqm, this map) in that they are more altered and contain little biotite (W.L. Coonrad and F.H. Wilson, unpublished data).",,,KD005,500,Kodiak,Igneous,1300,,
Tqm,Biotite quartz monzonite,"Tertiary, Paleocene?",Kodiak batholith,,,KD002,391,Kodiak,Igneous,1320,,
Tqm,Biotite quartz monzonite,"Tertiary, Paleocene?",Kodiak batholith,,,KR005,391,Karluk,Igneous,1320,,
Tqm,Biotite quartz monzonite,"Tertiary, Paleocene?",Kodiak batholith,,,TI002,391,Trinity Islands,Igneous,1320,,
Tqm,Biotite quartz monzonite,"Tertiary, Paleocene?",Kodiak batholith,,"Mobil Oil dates of approximately 62 Ma cited in Byrne (1981, Ph.D.)",KG002,391,Kaguyak,Igneous,1320,,
Tgd,Granodiorite,"Tertiary, Paleocene",Granodiorite,,,KD006,66,Kodiak,Igneous,1320,,
Tg,Granitic rocks,early Tertiary,Inferred granitic rocks based on aeromagnetic evidence and unconfirmed reports.,,,AF005,801,Afognak,Igneous,1320,,Q
Tgh,Ghost Rocks Formation,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,KD003,261,Kodiak,Tectonite,1780,,
Tpe,Paleocene volcanic and sedimentary rocks,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,KD002,261,Kodiak,Tectonite,1780,,
Tpe,Paleocene volcanic and sedimentary rocks,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,TI002,261,Trinity Islands,Tectonite,1780,,
Tgh,Ghost Rocks Formation,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,TI003,261,Trinity Islands,Tectonite,1780,,
Tpe,Paleocene volcanic and sedimentary rocks,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,KG002,261,Kaguyak,Tectonite,1780,,
Tgm,"Ghost Rocks Formation, melange","Tertiary, early Paleocene","Ghost Rocks Formation, melange",,,KD006,601,Kodiak,Tectonite,1780,,
Tgh,Ghost Rocks Formation,"Tertiary, Paleocene to Eocene","Consists of zeolite-bearing tuffaceous sandstone, basalt, claystone, sandstone, tuff, and graded beds (wildflysch)",,,KG003,261,Kaguyak,Tectonite,1780,,
Kk,Kodiak Formation,Late Cretaceous,Consists of graded bed sequences an average 1-m-thick of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,KD003,417,Kodiak,Sedimentary,1917,,
Kkd,Kodiak Formation,Late Cretaceous,Consists of average 1 m thick graded bed sequences of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,KD002,417,Kodiak,Sedimentary,1917,,
Kk,Kodiak Formation,"Late Cretaceous, Maestrichtian","Medium- to thickly bedded arkosic wacke and shale having occaisional beds of pebbly conglomerate.  Flute casts and complete Bouma sequences indicate deposition by turbidity currents below wave base.  Strike NE and dips steeply NW, generally deformed in tight large scale folds",Inoceramus kusiroensis,,KD004,492,Kodiak,Sedimentary,1917,,
Kkd,Kodiak Formation,Late Cretaceous,Consists of average 1 m thick graded bed sequences of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,KR005,417,Karluk,Sedimentary,1917,,
Kkd,Kodiak Formation,Late Cretaceous,Consists of average 1 m thick graded bed sequences of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,TI002,417,Trinity Islands,Sedimentary,1917,,
Kk,Kodiak Formation,Late Cretaceous,Consists of graded bed sequences an average 1-m-thick of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,TI003,417,Trinity Islands,Sedimentary,1917,,
Kkd,Kodiak Formation,Late Cretaceous,Consists of average 1 m thick graded bed sequences of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,KG002,417,Kaguyak,Sedimentary,1917,,
Kk,Kodiak Formation,Late Cretaceous,Consists of graded bed sequences an average 1-m-thick of thick medium-grained sandstone grading to thin slate,Inoceramus of Late Cretaceous age,,KG003,417,Kaguyak,Sedimentary,1917,,
Kk,Kodiak Formation,Late Cretaceous,Kodiak Formation,,,KD006,604,Kodiak,Sedimentary,1917,,
Kk,Kodiak Formation,"Late Cretaceous, Maestrichtian",Medium to thickly bedded arkosic wacke and shale with occaisional beds of pebbly conglomerate.  Flute casts and complete Bouma sequences,,,AF004,417,Afognak,Sedimentary,1917,,Q
Ksg,Mainly Upper Cretaceous rocks,Late Cretaceous,"Slate, argillite, graywacke, and conglomerate, thoroughly indurated, and generally highly metamorphosed.",,,AF010,417,Afognak,Metamorphic,1917,,Q
Ksg,Mainly Upper Cretaceous rocks,Late Cretaceous,"Slate, argillite, graywacke, and conglomerate, thoroughly indurated, and generally highly metamorphosed.",,,KD007,417,Kodiak,Metamorphic,1917,,Q
Ksg,Mainly Upper Cretaceous rocks,Late Cretaceous,"Slate, argillite, graywacke, and conglomerate, thoroughly indurated, and generally highly metamorphosed.",,,KG007,417,Kaguyak,Metamorphic,1917,,Q
Ksg,Mainly Upper Cretaceous rocks,Late Cretaceous,"Slate, argillite, graywacke, and conglomerate, thoroughly indurated, and generally highly metamorphosed.",,,KR009,417,Karluk,Metamorphic,1917,,Q
Kk,Kaguyak Formation,Late Cretaceous; Maestrichtian and Campanian,"Measured thickness is more than 1,200 m of dark-gray to pale-brown, typically thin bedded shale, siltstone, and fine grained sandstone.  Proportion of sandstone in unit increases up-section.  Load and flute casts are common; in upper part of unit, graywacke is graded with numerous rip-up clasts.  Overall depositional environment of formation is near mid-fan within multi-channeled system; however, uppermost part of unit may have been deposited in upper-fan regime (Detterman and others, 1996).  ","In general, fossils are sparse; however, in lower part of unit they are locally abundant.  Ammonites are most common and may range in size to as much as 1-m-across.  Fossils allow age assignment of latest Campanian and early Maestrichtian for Kaguyak.",,AF002,415,Afognak,Sedimentary,1955,,
Kc,Cape Current terrane of Connelly (1978),Late Cretaceous,Informal unit consisting principally of medium- to thick-bedded arkosic and lithic sandstone containing occaisional sections of vesicular pillow lava and pillow breccia.  Slightly metamorphosed and moderately deformed.  Contains two bodies of red pelagic limestone.,Coccoliths of indeterminate age and Late Cretaceous foraminifera in limestone,,AF004,420,Afognak,Sedimentary,2130,,
Khe,Herendeen Formation,Early Cretaceous; Barremian and Hauterivian,"Originally described as limestone, rocks of formation are actually an unusually uniform calc-arenaceous sandstone.  Rocks are thin bedded, medium grained, and dusky yellow to pale yellowish brown on freshly broken surfaces and weather to conspicuous light gray.  They have distinct platy fracture upon weathering and strong petroliferous odor when freshly broken.","Inoceramus fragments form major component of formation, although complete specimens have only been found in the Mount Katmai area.  A belemnite similar to Acroteuthis sp. A (Jones and Detterman, 1966) was found in rocks of formation just east of Staniukovich Mountain between Port Moller and Herendeen Bay.  Ammonite fossils and other collections from Herendeen in Mount Katmai area allow an age assignment of Hauterivian and Barremian for formation (J.W. Miller, written commun., 1983-85; Detterman and others, 1996).  Herendeen conformably overlies Staniukovich Formation (Kst) and is unconformably overlain by Chignik (Kc) and Pedmar (Kp) Formations",,AF008,441,Afognak,Sedimentary,2150,,
Ku,Uyak Complex,Cretaceous,Lithologically chaotic assemblage of deep-sea rock types.  Includes: argilite and gray chert containing minor tuff; massive arkosic sandstone; pillowed and massive greenstone; bedded radiolarian chert; minor limestone; and tuffaceous argillite.,,,KD004,450,Kodiak,Tectonite,2190,,
Kuf,Uyak Formation,Triassic,Principally black shale and local schistose tuff.  A few shale and sandstone graded beds occur.  Middle third of Formation contains many beds of pillow basalt and red chert and the upper characterized by thick layers of light-gray chert.  Thin limestone lenses occur in 2 places,Triassic marine fossils in lower limestone lense,,KR007,457,Karluk,Tectonite,2190,,
Ku,Uyak Complex,Cretaceous,"Lithologically chaotic assemblage of deep-sea rock types.  Includes argillite and gray chert, massive arkosic sandstone, pillowed and massive greenstone, rhythmically bedded radiolarian chert, minor limestone, and tuffaceous argillite.",,,KR006,450,Karluk,Tectonite,2190,,
Ku,Uyak Complex,Cretaceous,Lithologically chaotic assemblage of deep-sea rock types.  Includes: argilite and gray chert containing minor tuff; massive arkosic sandstone; pillowed and massive greenstone; bedded radiolarian chert; minor limestone; and tuffaceous argillite.,,,AF004,450,Afognak,Tectonite,2190
sgs,Mainly Triassic and Jurassic rocks possibly some Paleozoic or older rocks,Mesozoic and Paleozoic?,"A structurally complex group of rocks of great lithologic diversity.  Includes ellipsoidal lava with associated slate, thin-bedded chert and slate, calcareous slate, graywacke, and limestone, and their metamorphic equivalents, represented by greenstone schists, knotty schists resulting from the kneading together of slates with with chert, graywacke, and greenstone; crystalline limestone, calcareous and sliicieous schist, and mica schist.  May include materials of a wide range of ages.  Includes Ghost Rocks and Uyak Complexes",,,AF010,1001,Afognak,Tectonite,2190
sgs,Mainly Triassic and Jurassic rocks possibly some Paleozoic or older rocks,Mesozoic and Paleozoic?,"A structurally complex group of rocks of great lithologic diversity.  Includes ellipsoidal lava with associated slate, thin-bedded chert and slate, calcareous slate, graywacke, and limestone, and their metamorphic equivalents, represented by greenstone schists, knotty schists resulting from the kneading together of slates with with chert, graywacke, and greenstone; crystalline limestone, calcareous and sliicieous schist, and mica schist.  May include materials of a wide range of ages.  Includes Ghost Rocks and Uyak Complexes",,,KD007,,Kodiak,Tectonite,2190
sgs,Mainly Triassic and Jurassic rocks possibly some Paleozoic or older rocks,Mesozoic and Paleozoic?,"A structurally complex group of rocks of great lithologic diversity.  Includes ellipsoidal lava with associated slate, thin-bedded chert and slate, calcareous slate, graywacke, and limestone, and their metamorphic equivalents, represented by greenstone schists, knotty schists resulting from the kneading together of slates with with chert, graywacke, and greenstone; crystalline limestone, calcareous and sliicieous schist, and mica schist.  May include materials of a wide range of ages.  Includes Ghost Rocks and Uyak Complexes",,,KR009,,Karluk,Tectonite,2190
KJm,McHugh Complex,Cretaceous,"Weakly metamorphosed siltstone, graywacke, arkose and conglomeratic sandstone; greenstone (mostly basaltic), chert and argillite",,,AF011,1450,Afognak,Tectonite,2190
Kuu,Uyak Complex- Gabbroic and ultramafic rocks,Cretaceous,"Lithologically chaotic assemblage of deep-sea rock types.  Gabbroic and ultramafic rock, including layered gabbro, clinopyroxenite, dunite, and plagioclase peridotite.",,,KD004,470,Kodiak,Tectonite,2197
Kuu,Uyak Complex - gabbroic and ultramafic rocks,Cretaceous,"Lithologically chaotic assemblage of deep-sea rock types.  Gabbroic and ultramafic rock, including layered gabbro, clinopyroxenite, dunite, and plagioclase peridotite.",,,KR006,470,Karluk,Tectonite,2197
Kuu,Uyak Complex- Gabbroic and ultramafic rocks,Cretaceous,"Lithologically chaotic assemblage of deep-sea rock types.  Gabbroic and ultramafic rock, including layered gabbro, clinopyroxenite, dunite, and plagioclase peridotite.",,,AF004,470,Afognak,Tectonite,2197
Jn,Naknek Formation,Late Jurassic; Tithonian to Oxfordian,"Originally named Naknek Series by Spurr (1900, p. 169-171, 179, 181) for exposures at Naknek Lake.  Detterman and others (1996; see also, Detterman and Hartsock, 1966; Martin and Katz, 1912) have subdivided unit into five members on Alaska Peninsula.  ","Megafossils, particularly pelecypod Buchia (Detterman and Reed, 1980, p. B38; J.W. Miller, written communs., 1982-88), are common, and fauna, which also includes ammonites, indicate age range of Oxfordian to late Tithonian (Late Jurassic).",,AF008,510,Afognak,Sedimentary,3010
Jns,Naknek Formation -- Sandstone member,Late Jurassic; late Oxfordian to Kimmeridgian,"Upper part consists of up to 759 m of mainly thin-bedded fine-grained, olive-brown sandstone.  Lower part mainly massive to thick bedded medium- to coarse-grained arkosic sandstone","Buchia fossils are  in upper of unit, sparse ammonites.",,KR002,512,Karluk,Sedimentary,3012
Jnn,Naknek Formation -- Northeast Creek Sandstone Member,Late Jurassic; Oxfordian,"Type section consists of 624 m of fine- to coarse-grained, light-brownish-gray arkosic sandstone and minor amounts of olive-gray to dark-gray, thin-bedded siltstone in lower part of section.  Sandstone is typically thick bedded and crossbedded and contains magnetite laminae and thin beds of conglomerate.  Depositional environment is mainly nonmarine.  Some sand beds are channeled with lag gravel at bases of channels.  Crossbedding is mostly high-angle and variable directional eolian type, some is small-scale, tabular crossbedding with clay drapes characteristic of point bar deposits (Detterman and others, 1996).  Lower contact is conformable on underlying Chisik Conglomerate Member and is placed where thick sandstone replaces conglomerate in section.  Upper contact is sharp and conformable with overlying Snug Harbor Siltstone Member.  At this contact, depositional environment shifts from mainly nonmarine to marine; position of contact varies temporally depending on local conditions",Fossils are uncommon in unit although carbonaceous debris is common locally.  ,,AF008,512,Afognak,Sedimentary,3012
Jnn,Naknek Formation -- Northeast Creek Sandstone member,Late Jurassic; Oxfordian,"Type section consists of 624 m of fine- to coarse-grained, light-brownish-gray arkosic sandstone and minor amounts of olive-gray to dark-gray, thin-bedded siltstone in lower part of section.  Sandstone is typically thick bedded and crossbedded and contains magnetite laminae and thin beds of conglomerate.  Fossils are uncommon in unit although carbonaceous debris is common locally.  Depositional environment is mainly nonmarine.  Some sand beds are channeled with lag gravel at bases of channels",Fossils are uncommon in unit although carbonaceous debris is common locally. ,,KR004,512,Karluk,Sedimentary,3012
Jnst,Naknek Formation -- Siltstone member,Late Jurassic; Oxfordian,"Medium- to dark-olive-gray, slightly calcareous to siliceous and micaceous siltstone with nodules, concretions, and thin, lenticular limestone beds",Main fossils present are Buchia Concentrica and a few ammonites.,,KR002,513,Karluk,Sedimentary,3013
Jns,Naknek Formation -- Snug Harbor Siltstone Member,Late Jurassic; Kimmeridgian and Oxfordian,"Reference section consists of more than 638 m of dark-yellowish-brown and dark-gray, thin-bedded siltstone and minor amounts of thin- to medium-bedded olive-gray sandstone.  Limestone nodules are locally abundant, and limestone beds are present in some siltstone intervals.  Depositional environment was interpreted by Detterman and others (1996) to have been moderately deep water, well below wave base and above carbonate compensation depth, in a basin that had restricted circulation.  As mapped on I-1685 (Ugashik-Karluk)",It is lowest abundantly fossiliferous member of Naknek; main fossils present are of genus Buchia.  ,,KR004,516,Karluk,Sedimentary,3013
Jns,Naknek Formation -- Snug Harbor Siltstone Member,Late Jurassic; Kimmeridgian and Oxfordian,"Reference section consists of more than 638 m of dark-yellowish-brown and dark-gray, thin-bedded siltstone and minor amounts of thin- to medium-bedded olive-gray sandstone.  Limestone nodules are locally abundant, and limestone beds are present in some siltstone intervals.  Depositional environment was interpreted by Detterman and others (1996) to have been moderately deep water, well below wave base and above carbonate compensation depth, in a basin that had restricted circulation.",It is lowest abundantly fossiliferous member of Naknek; main fossils present are of genus Buchia.  ,,AF008,513,Afognak,Sedimentary,3013
Jni,Naknek Formation -- Indecision Creek Sandstone Member,Late Jurassic; Tithonian and Kimmeridgian,"Consists of medium-gray, fine- to medium-grained arkosic sandstone and siltstone.  It is thin bedded to massive; where bedded, it is locally crossbedded.  Fresh biotite and hornblende are minor, but important, components of sandstone, as they are interpreted to indicate first-cycle erosion from Alaska-Aleutian Range batholith.  ","Indecision Creek Sandstone Member is abundantly fossiliferous; however, fossils are restricted almost exclusively to pelecypods of genus Buchia.",,KR004,514,Karluk,Sedimentary,3014
Jni,Naknek Formation -- Indecision Creek Sandstone Member,Late Jurassic; Tithonian and Kimmeridgian,"Consists of medium-gray, fine- to medium-grained arkosic sandstone and siltstone.  It is thin bedded to massive; where bedded, it is locally crossbedded.  Fresh biotite and hornblende are minor, but important, components of sandstone, as they are interpreted to indicate first-cycle erosion from Alaska-Aleutian Range batholith.  ","Indecision Creek Sandstone Member is abundantly fossiliferous; however, fossils are restricted almost exclusively to pelecypods of genus Buchia.",,AF008,514,Afognak,Sedimentary,3014
Jnc,Naknek Formation -- Conglomerate member,Late Jurassic,"Limited to northern half of Alaska Peninsula, consists of massive to thick-bedded conglomerate and interbedded, crossbedded, clean quartzose sandstone.  Clasts as large as 2 m.  Clast composition is mainly granitic rocks, and up to 20 percent metamorphic and volcanic rocks",,,KR002,511,Karluk,Sedimentary,3016
Jnc,Naknek Formation -- Chisik Conglomerate member,Late Jurassic (Oxfordian),"Limited to northern half of Alaska Peninsula, unit is composed of 614 m of massive to thick-bedded conglomerate and interbedded, crossbedded, clean quartzose sandstone.  Clasts range in size from maximum of 120 cm at bottom to 15 cm at top.  Clast composition is 30 percent granitic rocks, 30 percent quartzite, 20 percent metavolcanic rocks, 10 percent schist, and 10 percent chert and quartz.  Clasts are well-rounded and commonly decrease in size stratigraphically upward within each lithic interval of member.  Lower contact is unconformity with Shelikof Formation; upper contact is conformable and gradational with Northeast Creek Sandstone Member",,,KR004,511,Karluk,Sedimentary,3016
Jss,Shelikof Formation -- Sandstone member,Middle Jurassic; Callovian,"Massive to thick-bedded, medium to coarse-grained, dark-green to gray volcanogenic sandstone containing abundant magnetite grains  (Note, owing to rapid lateral facies changes, informal subdivisions of Capps (1923) have been found impractical for mapping and have been abandoned.)  Shelikof is interpreted to have been deposited in a deep- to shallow-water environment (Detterman and others, 1996).  ","Megafauna are locally abundant in Shelikof, although, in general, formation is unfossiliferous.  Vast majority of fossils collected from formation are ammonites of Callovian age; however, a few specimens suggest a Bathonian(?) age for some rocks (Allaway and others, 1984, p. A23; Detterman and others, 1985, and 1996).",,KR002,520,Karluk,Sedimentary,3020
Jk,Kialagvik Formation,Middle and Early Jurassic; Bajocian to Toarcian,"Olive-gray to green, medium-bedded, fine- to medium-grained graywacke, mudstone, siltstone, and shale; local lenses of volcanic pebble conglomerate.","Shallow-water deposits of Kialagvik Formation are abundantly fossiliferous; most megafauna indicate age of early and middle Bajocian, although overall age range of fossils collected from unit is late Toarcian to Callovian (Imlay, 1984; see also, Detterman and others, 1996).",,KR002,530,Karluk,Sedimentary,3190
Jt,Talkeetna Formation,Early Jurassic,"Lower part composed of dark-gray tuffaceous limestone, tuff, and dark siliceous shale.  Upper part thin to massive tuffaceous gray sandstone with minor siltstone and shale interbeds.","Age of unit, Early Jurassic (Hettangian and early Sinemurian), is based on abundant megafauna; however, this megafauna is present in great abundance in only a few horizons and may represent mass kills as a result of volcanic eruptions (Detterman and others, 1996).  Contact of Talkeetna with underlying Kamishak Formation is conformable and gradational; it is arbitrarily placed where clastic sedimentary rocks replace limestone as major constituents of rock sequence.  Contact of Talkeetna with overlying Kialagvik Formation is structurally conformable; however, it is considered a disconformity, as rocks of late Sinemurian, Pliensbachian, and most of Toarcian Stages are missing",,KR002,540,Karluk,Sedimentary,3250
Js,Schist of Kodiak Island,Jurassic,"Thinly layered and complexly folded quartz-mica schist, greenschist, crossite-epidote schist, and epidote amphibolite.",,,AF004,572,Afognak,Metamorphic,3610
Js,Schist of Kodiak Island,Jurassic,"Thinly layered and complexly folded quartz-mica schist, greenschist, crossite-epidote schist, and epidote amphibolite.",,,KR006,572,Karluk,Metamorphic,3610
Trls,Limestone,Late Triassic; Norian,"Medium- to thick-bedded dark-gray limestone and thin to shaly bedded light tan limestone; locally contains massive chert-pebble and limestone-cobble conglomerate.  Interbedded with basalt flows, volcanic rubble flows and agglomerate.",Locally abundant pelecypods and ammonites yield Norian age,"A 46-m-thick columnar-jointed basalt flow or sill from upper part of section has yielded a potassium-argon age of 197? +/- 12 Ma (Wilson and Shew, 1992); however, it remains to be determined whether basalt is sill from overlying Early Jurassic Talkeetna Formation or, alternatively, a flow from Kamishak that yields an analytically ""minimum"" age.",KR002,602,Karluk,Sedimentary,4020
Trk,Kamishak Formation,Late Triassic; Norian,"Detterman and Reed (1980) divided unit into three members, in descending order, Ursus Member, middle member, and Bruin Limestone Member.  On Alaska Peninsula (see inset A, pl. 1), Triassic limestone strata was assigned to Bruin(?) Limestone Member of Kamishak Formation by Detterman and others (1996).  Reference section of Kamishak was measured near Puale Bay by R.M. Egbert (U.S. Geological Survey, 1979, cited in Detterman and others, 1996, section in Karluk C-4 and C-5 1:63,360-scale quadrangles).  Section consists of approximately 800 m of light- to brownish-gray, thin- to medium-bedded limestone, minor amounts of brownish-gray, calcareous siltstone and mudstone, and limestone conglomerate.  An interval of brecciated and calcite-recemented basalt occurs near top of section, as does a volcanic breccia interval in lower part of the section.  ","Fossils that have been found yield Norian age (Detterman and Reed, 1980; C.D. Blome, U.S. Geological Survey, oral commun., 1981).","A 46-m-thick columnar-jointed basalt flow or sill from upper part of section has yielded a potassium-argon age of 197? +/- 12 Ma (Wilson and Shew, 1992); however, it remains to be determined whether basalt is sill from overlying Early Jurassic Talkeetna Formation or, alternatively, a flow from Kamishak that yields an analytically ""minimum"" age.",KR004,601,Karluk,Sedimentary,4020
Trss,"Shuyak Formation, sedimentary member",Late Triassic,"Volcaniclastic sequence consisting of thin- to medium-bedded lithic sandstone containing lesser conglomerate, argillite, and siliceous tuff intruded by mafic dikes and sills (unit Trm of Connelly, 1978).",,,AF004,610,Afognak,Sedimentary,4150
Trss,"Shuyak Formation, sedimentary member",Late Triassic,"Volcaniclastic sequence consisting of thin- to medium-bedded lithic sandstone containing lesser conglomerate, argillite, and siliceous tuff intruded by mafic dikes and sills (unit Trm of Connelly, 1978).",,,KR006,610,Karluk,Sedimentary,4150
Trv,Volcanic rocks,Late Triassic,"Columnar-jointed basalt flows, volcanic breccia, and agglomerate.  Chemical data (Hill, 1979; Wilson and Shew, 1992) indicate these rocks are of tholeiitic affinity.  Interbedded with Late Triassic Kamishak Formation (Trk)",,"Potassium-argon age determination on flow unit was 197 +/- 12 Ma (Wilson and Shew, 1992); age is thought to be minimum age, as it is younger than stratigraphic position suggests.",KR002,625,Karluk,Igneous,4230
Trm,"Mafic dikes, sills, and plugs",Triassic?,Diabasic bodies intruding Shuyak Formation,,,AF004,651,Afognak,Igneous,4240
Trsv,"Shuyak Formation, volcanic member",Late Triassic,"Vesicular pillowed greenstone, locally containing beds of pillow breccia agglomerate, tuff, and argillite.  Greenstone is tholeiitic in composition.",,,AF004,640,Afognak,Igneous,4250
Ja,Afognak Pluton,Jurassic,Hornblende diorite and hornblende quartz diorite,,"K-Ar ages on hornblende of 192.7, and 188.4 Ma; U-Pb age of about 210 Ma",KD004,630,Kodiak,Igneous,4310
Ja,Afognak Pluton,Jurassic,Hornblende diorite and hornblende quartz diorite,,"K-Ar ages on hornblende of 192.7, and 188.4 Ma; U-Pb age of about 210 Ma",KR006,630,Karluk,Igneous,4310
Ja,Afognak Pluton,Jurassic,Hornblende diorite and hornblende quartz diorite,,"K-Ar ages on hornblende of 192.7, and 188.4 Ma; U-Pb age of about 210 Ma",AF004,630,Afognak,Igneous,4310
Pls,Limestone,middle Permian,"Consists of 40 m of massive, light-gray, crystalline limestone containing thin interbeds of chert, located on a small islet (100 by 200 m) at entrance to Puale Bay.  No contacts are exposed, although highly contorted beds dip about 40 northwest, which places them structurally beneath Triassic rocks that are located on other islands about 1 km away","Hanson (1957) reported age of late middle Permian (early Guadalupian) for these rocks on the basis of poorly preserved and silicified coral, brachiopod, and foraminifer fossils.  ",,KR002,701,Karluk,Sedimentary,5730
Pls,Limestone,Permian; early Guadalupian,"Consists of 40 m of thin- to thick-bedded, medium-grained, crystalline tan to gray limestone containing thin interbeds of chert, located on a small islet (100 by 200 m) at entrance to Puale Bay.  No contacts are exposed, although highly contorted beds dip about 40 northwest, which places them structurally beneath Triassic rocks that are located on other islands about 1 km away","Hanson (1957) reported age of late mid-Permian (early Guadalupian) for these rocks on the basis of poorly preserved and silicified coral, brachiopod, and foraminifer fossils.  ",,KR004,701,Karluk,Sedimentary,5730
Pv,Volcanic rocks,Permian?,"Massive, dark-green to black volcanic breccia, agglomerate, and andesitic flows (Hanson, 1957; Hill, 1979).  These rocks are only exposed on offshore islets east of Puale Bay and were not examined during this study (see inset A, pl. 1).  Well-developed joint system has obscured original structure, and because of this, in part, thickness is unknown.  No definite age control exists; however, these rocks appear to structurally underlie mid-Permian limestone (Pls).  Hill (1979) briefly examined exposures and sampled rocks.  Limited chemical data from Hill (1979) suggest these volcanic rocks are of calc-alkaline affinity, in contrast to Late Triassic tholeiitic volcanic rocks of nearby mainland (Trv)",,,KR004,750,Karluk,Igneous,5810