JQu
Glacial deposits and volcanic and plutonic rocks, undivided
Quaternary, Tertiary to Jurrassic
KN007
Kenai
Igneous
bu
Possible bedrock of unknown character
Unknown
Areas that air photo interpretation suggest as being underlain by bedrock.  Typically are of higher elevation than surrounding glacial deposits and show hints of structure.  In one case, an apparent strike and dip of bedding is perceptible on air photos.
KN008
Sedimentary
Bedrock, undivided
Qs
Surficial deposits
Holocene and Pleistocene
SV002
Seldovia
Unconsolidated
KN002
KN003
Unconsolidated surficial deposits
Holocene
Undifferentiated boulders, cobbles, gravel, sand, silt, and clay of present streams; angular clasts of talus and locally, landslide deposits; stratified sand, silt, and clay of alluvial fan and flood-plain deposits; well-sorted stratified sand and gravel
BS004
Blying Sound
SR004
Seward
Qu
Surficial deposits, undivided
Predominantly alluvium deposited by nonglacial streams and outwash deposited by glacial meltwater.  Consists of sand and gravel; terminal, lateral, and ground moraine composed of unsorted deposits of boulders, cobbles, gravel, and sand left by the retrea
BS002
MI002
Middleton Island
SR002
none
Drift River delta
Quaternary, Holocene
Drift river delta, no description
Quaternary surficial deposits
Quaternary
Undivided surficial deposits
KN009
Surficial deposits, undifferentiated
Surficial deposits, undifferentiated -- Alluvium deposited by nonglacial streams and outwash deposited by glacial meltwater.
CV003
Cordova
CV002
yellow
Recent glacio-fluvial deposits
glacio-fluvial deposits
CV005
Glacio-fluvial deposits
CV006
Undifferentiated surficial deposits
Mainly unsorted gravel, sand, and silt produced, deposited, and reworked by action of wind, water, glaciers, and frost, including solifluction.  In many areas of the map, this unit is a mixture of surrounding surficial deposit units that could not be rea
Qcaf
Colluvium, alluvium, lacustrine, and floodplain deposits
SV005
KN011
Unconsolidated deposits
KN012
Q
Predominantly glacial moraine and outwash deposits and beach and terrace deposits. Consists of sand and gravel; terminal, lateral, moraine composed of unsorted deposits of boulders, cobbles, gravel, and sand left by retreat of alpine and valley glaciers;
SR005
Qag
Includes stream and beach deposits, glacial till and outwash gravels, colluvium, and landslide debris
KN014
Qaf
Floodplains and alluvial fans, Alluvial fans and alluvial fan complexes
Quaternary, Pleistocene
Alluvial fans and alluvial fan complexes.  Southernmost polygons recoded as Quaternary deposits, undivided.
SV007
Qtf
Modern tidal flat and estuarine deposits
Well-sorted, stratified silt and some sand and local gravel deposited in shallow embayments.  Sub-tidal.
Qas
Tidal silt and beach deposits
KN013
Qal
Alluvial deposits -- Floodplain deposits
Floodplain deposits, inferred to be largely moderately to well-sorted sand and gravel.  Some silt locally.
KN006
Alluvial deposits, Flood-plain alluvium
Quaternary, Recent
Flood-plain alluvium, poorly- to well-sorted silt, sand, pebbles, cobbles, and boulders.  Mainly cobbles and boudlers except near tidewater.  Includes some glacial outwash.
KN005
Stream-channel deposits
Stream channel deposits
Alluvium
Mainly gravel and coarse sand, consists in part of glacial and glaciofluvial material reworked by postglacial streams.  Forms flood plains along major streams and rivers.
SV004
Qa
In active streambeds and lowest terraces along larger streams and active alluvial fans.  Chiefly well sorted gravel and sand; minor silt and boulders
CV004
Qft
Floodplains and alluvial fans
Flood plains and associated higher terraces along major streams and abandoned drainage lines
Alluvial fans and alluvial fan complexes.  Northern polygons in Kenai quadrangle recoded as alluvium.
Alluvial deposits -- Alluvial fans
Deposits of large flat alluvial fans, inferred to be moderately sorted sand and gravel
Qcf
Alluvial deposits -- Small alluvial-colluvial fans
Dposits of small, steep alluvial-colluvial fans, inferred to be non-sorted silt, sand, and gravel
Qf
Alluvial deposits, Alluvial fans and cones
Alluvial fans and cones, unsorted rock talus, in part colluvial in origin.
Qfs
Alluvial deposits, Partially submerged alluvial fans and cones
Partially submerged alluvial fans consisting of sand and gravel; exposed at low tide
Qcf?
Fan deposits
Alluvial fan deposits of Cresecent River
Alluvial fan deposits
Gravel, silt, and sand, commonly occur at mouth of small side canyons.  Includes some colluvial deposits.
Alluvial fans and alluvial fan complexes
Qct
Deposits of Mass Wasting -- talus
Cone-shaped deposits of talus beneath steep bedrock slopes
Qpr
Deposits of Mass Wasting -- protalus ramparts
Deposits of protalus ramparts
Qlc
Landslide and colluvial deposits
Unsorted deposits of fine to coarse rubble
Qt
Talus
Talus-- Boulder- to pebble-sized, angular rock debris.
tan
Qc
Colluvial deposits
Chiefly rubble, gravel, sand, silt, and clay.  Talus and other slope debris deposits, also includes alluvium of minor streams, and locally glacial, rock glacier, and mass-wasting deposits.  May include older glacial drift and locally grades into glacial
Slope deposits, undifferentiated
Quaternary, Holocene and Pleistocene
Colluvium consisting of talus and small landslides, also includes small glacial, rock glacier, and alluvial deposits.  Sand, gravel, boulders, diamicton, and rubble
Qls
Deposits of Mass Wasting -- landslide deposits
Deposits of landslides, including falls, slumps, slides, and failures by lateral spreading.  Assigned NSA = 312 in vicinity of Polly Creek where this unit consists of debris flows from Mount Redoubt.
Qcm
Deposits of Mass Wasting -- mudflow and debris-flow deposits
Mudflow and debris flow deposits, may include some volcanic mudflow (lahar) deposits
Qls?
Deposits of landslides, including falls, slumps, slides, and failures by lateral spreading
Qcm?
Landslides
Landslides-- Unsorted, angular rock debris derived by failure of bedrock slopes.
Landslide deposits
Chiefly rubble, gravel, sand, silt, and clay.  Most extensive in Jurassic sedimentary rock northeast of Mount Iliamna
Qra
Rock avalanche deposits
Ql
Slumps, earth-debris flows, block glides, and debris avalanches.  Diamicton and rubble
Landslide
Landslide debris near Bluff Point
Qao
Older alluvium
Older alluvial deposits found in larger stream valleys at levels higher than modern alluvium.  Grades into terrace deposits
In higher terraces along larger streams and in inactive alluvial fans.  Predominantly of Pleistocene age, but may include localized Holocene deposits.  Chiefly well sorted gravel and sand; minor silt and boulders
Qtg
Terrace deposits
Terrace gravels in outwash above modern floodplains.  Air photo interpretation
Symbol
Abandoned or underfit stream channel
Quaternary?
Abandoned or underfit stream channel, inferred to be relict glacial meltwater channel.  Shown by symbol on map
Qac
Abandoned channel deposits
Abandoned channel deposits in outwash above modern floodplains.  Air photo interpretation
lt green
Recent Lacustrine deposits
Lacustrine deposits
Qfl
Fine-grained deposits
In ponds, swamps, lagoons, and along low-gradient streams.  Chiefly silt, clay, fine sand, peat, and other organic material
Qm
Other unconsolidated deposits -- swamp and muskeg
Swamp and muskeg deposits, mainly organic material, but may include clay, silt, or sand
Qsw
Swamp deposits
Silt, sandy silt, and bog deposits, interpreted from air photos
Qlv
Natural levee deposits
Natural levee deposits on deltaic or fan delta deposits.
Qb
Beach deposits
Sand, gravel, and cobbles of present and former beaches, beach ridges, spits, and tidal flats
Qbv
Other unconsolidated deposits -- vegetated beach deposits
Vegetated beach deposits consisting mainly of mixed sand and gravel
Qbn
Other unconsolidated deposits -- nonvegetated beach deposits
Nonvegetated beach deposits consisting mainly of mixed sand and gravel
Qbe
Beach deposits, Elevated beach ridges
Elevated beach ridges, well-sorted well-stratified, well-drained sand and gravel
Qbv?
Beaches, spits, and offshore bars
Beaches, spits, and offshore bars -- Constructional shoreline deposits of well-sorted gravel and sand.
Moderately well-stratified and sorted sand and gravel on beaches
Beach and delta deposits
Wave-deposited, coarse-grained material and driftwood along seacoast; fine-grained sediment in mud flats of Copper River Delta; and marine uplift terraces.  Successive spit-building episodes of progressive gradation are preserved in beach sequences along
Qifv
Other unconsolidated deposits -- vegetated tidal marsh deposits
Vegetated tidal marsh deposits, consist of organic material mixed with sand and gravel
Qifn
Other unconsolidated deposits -- nonvegetated tidal marsh deposits
Nonvegetated tidal marsh deposits, consist of organic material mixed with sand and gravel
Qida
Other unconsolidated deposits -- delta deposits
Delta deposits, representing the intertidal parts of fans and contain coarser material than adjacent tidal flats
Qbm
Beach deposits, Salt marsh
Salt- marsh, well-stratified silt and small pebbles, poorly drained
Lagoonal deposits
Lagoonal deposits--Fine-grained silt rich in organic material, mud, and peat.
Qes
Estuarine deposits
Well-sorted, stratified silt and some sand deposited in shallow embayments, supra-tidal, hence probably uplifted
Qts
Elevated tidal silt and beach deposits
Elevated tidal silt and beach deposits.  Record high sea level stand about 10 - 15 feet above present datum during late Tanya time
Qtm
Marine terrace deposits
Quaternary, Pleistocene and Holocene
Qad
Cliff-head dune sand
Cliff-head dune sand.  Near Point Possession; of "Alaskan" age
Qd
Dunes
Dunes-- Well sorted, fine grained sand and silt aligned in longitudinal ridges.
Qe
Eolian deposits
Dunes on tops of river bluffs, windblown flats, and river bars.  Includes informally named Bremner sand dunes, a large barchan field, located at confluence of Bremner and Copper Rivers.  Fine-grained sand
Qld
Hanging delta deposits of Naptowne age
Hanging deltaic complexes associated with one or more strandline levels and deposited at mouth of streams draining into proglacial lakes of Naptowne age
Qds
Glacial deposits -- Proglacial stratified drift
Includes stratified and locally foreset-bedded sand and gravel that occur below 125 m elevation on West Foreland and from Katchin Creek to Redoubt Point; these deposits are probable emerged delta and glaciolacustrine deposits.  Also includes active outwa
Qds?
Qglf
Glaciolacustrine deposits
Ephemeral glacial lake deposits.  Well-sorted, well-stratified clay, silt, and fine sand deposited in ephemeral glacial and postglacial lakes.  Thought to be typically covered by several feet of muck and peat
Qlb
Proglacial lake bottom sediments of Naptowne age
Proglacial lake bottom sediments underlying terraced and channeled surfaces between major morainal belts in lowland and mountain valleys
Moraine
Morainal deposits
Glacial deposits -- Undifferentiated glacial drift
Inferred to consist of lodgement till, ablation till, and stratified drift.  Thickness ranges widely.
Qdt
Glacial deposits -- Lateral or terminal moraines
Till deposits in the form of lateral or terminal moraines
Qdi
Glacial deposits -- Stratified drift
Stratified drift in ice-contact deposits (kame terraces or deltas).  Identified by high local relief and steeply sloping margins.
Qd?
Qdt?
Qdi?
lime
Older glacial deposits
Glacial deposits
Undifferentiated glacial drift
Qmi
Moraine on ice
Superglacial and endglacial till on present glaciers
Qsm
Supraglacial moraine
Supraglacial moraine-- Unweathered, poorly sorted, debris on surfaces of glaciers.
Qsg
Superglacial drift
Consists of unsorted boulder to fine-grained debris on the surface of modern glaciers.  In the vicinity of Mount Redoubt and Mount Iliamna, may include a significant component of ash and other air-fall debris from eruptions
Qrg
Rock glacier deposits
Rock glaciers
Active and recently active rock glaciers.  Chiefly rubble and coarse rock debris, interpreted from air photos
Qsf
Solifluction deposits
Solifluction mantle, interpreted from airphotos.  Thought to be poorly sorted sand, silt, and clay derived from local upslope bedrock sources.
Qgtn
Glacial deposits, Tunnel Stade Alaskan Glaciation
Barren moraine as much as 1-mile in front of present glaciers.  Tunnel Stade, Alaskan Glaciation
Qgt
Glacial deposits, Tustumena Stade Alaskan Glaciation
Partially dissected moraine 1-6-mile in front of present glaciers; spruce and brush covered.  Tustumena Stade, Alaskan Glaciation
Terminal, lateral, and ground moraine
Terminal, lateral and ground moraine-- Unsorted boulders, cobbles, gravel and sand deposited during retreat of glaciers.
Glacial deposits, undivided
Younger glacial deposits, undivided
glacial deposits
Alaskan glaciation, till, Cirque glaciations
Quaternary, Holocene?
Unsorted boulder to clay-size  particles.  Morainal landforms common as are till deposits along the margins of modern glaciers.
Qmh
Glacial deposits of Holocene age, primarily ice-stagnation drift, outwash, and end moraine
Glacial deposits of holocene age, primarily ice-stagnation drift, outwash, and end moraine
Drift of Alaskan glaciation
Neoglacial deposits of end, lateral, and ground moraines, kames and outwash proximal to present glaciers; includes small rock glaciers.  Diamicton, local gravel, and sand
Moraines of Alaska Glaciation
Unmodified moraine deposits or mantled by loess, generally 2 to 6 feet thick
Glacial deposits -- Proglacial stratified drift (active outwash part)
Qdf
Glacial deposits -- Outwash fans
Moderately to heavily vegetated parts of outwash fans
Qo
Outwash deposits
Poorly- to well-sorted silt, sand, and gravel in terraces and outwash fans plains
Alaskan Glaciation, outwash
Outwash deposits associated with modern and Holocene glaciers
Outwash and valley train deposits
Graded to moraines of Alaskan age and to existing glacier fronts
Qgn
Glacial deposits, Naptowne Glaciation
Moderately weathered moraine along shoreline; heavily spruce and brush covered; Naptowne Glaciation
Qbl
Glacial deposits of the Naptowne glaciation
Loop, recessional, lateral, and medial moraine and other deposits of the Brooks Lake glaciation
Glacial deposits of the Naptowne glaciation - ground moraine?
Probably ground moraine deposits of the Brooks Lake glaciation
Qn
Moraines of Naptowne Glaciation
Prominent and little modified morainal deposits, mantled by 2 to 6 feet of loess
Qw4
Brooks Lake drift, Iliuk Stade
Qnt
Moraines of Naptowne Glaciation, Tanya advance
Qbln
Brooks Lake, Newhalen moraine
End moraine of the Newhalen advance of the Brooks Lake glaciation
Qns
Moraines of Naptowne Glaciation, Skilak advance
Qblil
Brooks Lake, Iliamna moraine
End moraine of the Iliamna advance of the Brooks Lake glaciation
Qnk
Moraines of Naptowne Glaciation, Killey advance
Qntm
Moraines of Naptowne Glaciation, terraced moraines
Discontinuously mantled below about the 500-ft strandline level with proglacial lake sediments of post Moosehorn, pre-Skilak age.  Mantled by various thicknesses of glaciolacustrine deposits
Qnm
Moraines of Naptowne Glaciation, Moosehorn advance
Qblo
Outwash, Brooks Lake glaciation, undivided
Qno
Graded to moraines of Naptowne age
Qdl
Deltaic deposits
Deltaic deposits, including outwash and alluvial deposits.
Qdc
Glacial deposits -- Pebble- and boulder-bearing diamicton
Pebble- and boulder-bearing diamicton.  Observed at one upland location at West Foreland and in sea cliffs along West Foreland and from Katchin Creek south to near Redoubt Point.
Qdc?
Qk
Moraines of Knik Glaciation
Moraines of Knik Glaciation.  Prominent but modified
Moraines of Eklutna Glaciation
Moraines of Eklutna Glaciation.  Subdued and moderately modified
Qkt
Terraced moraines of Knik age
Terraced moraines of Knik age.  Discontinuously manlted below the about 750 foot strandline level
Qet
Terraced moraines of Eklutna age
Terraced moraines of Eklutna age.  Discontinuously manlted below the about 1,000 foot strandline level with proglacial lake sediments of Knik and Naptowne age
Qko
Outwash and valley train deposits.  Graded to moraines of Knik age
Qeo
Outwash and valley train deposits.  Graded to moraines of Eklutna age
Moraines of Caribou Hills Glaciation
Moraines of Caribou Hills Glaciation.  Greatly modified
Terraced moraines of Caribou Hills age
Terraced moraines of Caribou Hills age.  Discontinuously mantled below the about 1,000 foot strandline level with proglacial lake sediments of Eklutna?, Knik, and Naptowne age
Qsb
Scoured bedrock
Glacially scoured bedrock; may be covered with thin glacially derived deposits; air-photo interpretation.
Other unconsolidated deposits -- artificial fill
Artificial fill at Drift River and West Foreland facilities
Qv
Volcanic rocks, undivided
Lava flows and associated pyroclastic rocks associated with Iliamna Volcano
Volcanic rocks
Quaternary (with mixed Tertiary?)
Lava, breccia, and associated pyroclastics.  May include Tertiary volcanic rocks
Volcanic rocks of Redoubt Volcano
Consists of volcanic rocks and deposits associated with Iliamna, Redoubt, and Double Glacier volcanoes.  Typically restricted to immediate vicinity of these volcanic centers, however locally, debris flows and air-fall material may be somewhat distal.  Lo
Quaternary volcanic rocks
Volcanic rocks of Iliamna and Redoubt volcanoes
Qil
Iliamna Lava flows
Light-gray hypersthene-augite andesitic lava, breccia, and associated pyroclastic debris
Hv
Holocene volcanic rocks
Holocene volcanic rocks, primarily associated with Redoubt Volcano
Qtv
Lava flows, North and South Twin volcanic center
Lava flows from the North and South Twin volcanic center.  Probably andesitic
Qca
Ash-rich colluvium
Consists of tephra-rich colluvium in the vicinity of and west of Redoubt volcano.  Similar to other volcanoes, these deposits probably consist of ash and larger-sized pyroclasts.  On the flank of Redoubt Volcano, these deposits mantle and are incorporate
Debris flow deposits
Debris flow deposits of Crescent River valley.  Includes several small (older?) deposits in the upper valley and the 3,500-year-old debris flow in the lower valley
Qdf2
Debris flow deposits, older Redoubt flows
Debris flow deposits of North Fork, Crescent River.  Deposits of multiple debris flows off the west and southwest flanks Redoubt Volcano.  Oldest(?) deposit is derived from west flank of Redoubt.  Next oldest deposit appears derived from presently glacia
Radiocarbon date of about 3,500 yrs. BP on youngest and most extensive debris flow.
Qdf1
Debris flow deposits, younger Redoubt flows
Debris flow deposits of North Fork, Crescent River.  Deposits of the youngest, most extensive, and probably most fluid debris flow derived from southwest flank of Redoubt Volcano.  Flow was apparently derived from a presently glacier free valley draining
Lahar deposits
Qdfn
Debris flow deposits on the north flank of Redoubt Volcano in the Drift River valley
Areas in Drift River valley subjected to flood scour or deposition by 1966 floods
pattern
Areas on Drift River delta subjected to flood scour or deposition prior to 1966
Areas on Drift River delta subjected to flood scour or deposition in the several decades before 1966
Qdr1
Younger Drift River delta mudflow deposits prior to 1957
Areas of mudflow deposits, tending to be minimally vegetated and relatively close to channel of Drift River
Qdr2
Older Drift River delta mudflow deposits
Areas of mudflow deposits, tending to be more heavily vegetated and tending to control location of Drift River channels
Qdr
Drift River delta mudflow deposits, undifferentiated
Areas of mudflow deposits, not easily separatable into the Younger and Older events
Qav
Volcanic avalanche deposits
Volcanic avalanche deposits consisting of poorly sorted mixture of angular sand, cobbles, and boulders.  All deposits contain clasts of gray andesitic lava and yellow-orange hydrothermally altered rocks.  Estimated age is less than 1,000 years and some m
Composite dome complex consisting of medium- to coarsely porphyritic hornblende andesite and dacite.
Three K-Ar whole-rock ages, two considered minimum ages at 627 and 763 ka and one of 887 ka.
Ts
Sterling Formation
Tertiary, Pliocene and Miocene
Interbedded, weakly lithified sandstone, siltstone, mudstone, carbonaceous shale, lignite coal, and minor volcanic ash.
Tks
Sandstone, siltstone, and some coal
SV010
Tb
Beluga Formation
Tertiary, Miocene
Interbedded, weakly lithified sandstone, siltstone, mudstone, carbonaceous shale, coal, and minor volcanic ash.
Tkb
Miocene
Sandstone, siltstone, and coal
Tk
Kenai Group
Tertiary
Coal-bearing semi-consolidated silt, sand, and gravel near Tustumena Glacier.  Possibly equivalent to the Sterling Formation?
Kenai Formation
Tertiary, Eocene
Semiconsolidated coal-bearing silt, sand, and gravel
Interbedded, poorly consolidated sandstone, siltstone, claystone, and minor amounts of conglomerate. Contains many beds of subbituminouos coal and lignite
bT
Tertiary bedrock
Kenai Group and West Foreland Formation; nonmarine sandstone, siltstone, shale, and claystone and local coal
bT?
Ty
Yakataga Formation
Consists of diverse marine and glaciomarine clastic rocks.  Interbedded gray to dark-gray and greenish-gray siltstone, mudstone, and sandstone predominate in the lower part of the formation.  Till-like diamictite is interbedded with siltstone in all but
mollusks, foraminifers
QTy
Quaternary, Pleistocene to Tertiary, Miocene
Consists of diverse marine and glaciomarine clastic rocks.  Interbedded gray to dark-gray and greenish-gray siltstone, mudstone, and sandstone predominate in lower third of formation.  Till-like diamictite dominant rock type in upper part of formation.
MI003
Tt
Tyonek Formation
Tertiary, Miocene and Oligocene
Conglomerate and subordinate sandstone, siltstone, and coal
Tkt
Miocene and Oligocene
Sandstone, siltstone, coal, and conglomerate
Tkth
Tyonek Formation and Hemlock Conglomerate (undivided)
Sandstone, conglomerate, and siltstone
Tr
Redwood Formation
Tertiary, Pliocene to Oligocene?
Lower sandstone member: about two-thirds thick-bedded sandstone and one-third silty sandstone and siltstone. Upper member: about one-half siltstone, mudstone and claystone, the rest is conglomerate and sandstone.
Tertiary, Oligocene (?) and Miocene
Marine siltstone, sandstone, and conglomerate.  The sandstone member consists of about two-thirds thick-bedded sandstone and one-third silty sandstone and siltstone.  The characteristic conglomeratic beds show complete gradation from coarse, clast-suppor
mollusks, and foraminifera
Tps
Sedimentary rocks, undivided (Poul Creek Formation)
Tertiary, Miocene, Oligocene, and Eocene
Concretionary pyritic, and glauconitic reddish-weathering, dark-gray to greenish-gray siltstone, claystone, and sandstone with subordinate dark-brown, laminated organic-rich shale, and gray calcareous sandstone; also includes thin interbeds of basaltic t
Poul Creek Formation: Sedimentary rocks, undivided
Concretionary, pyritic, glauconitic, reddish-weathering, dark-gray to greenish-gray siltstone, claystone, and sandstone; shale that is rich in organic material; gray calcareous sandstone; local thin interbeds of basaltic tuff.
Poul Creek Formation:  Sedimentary rocks, undivided
Concretionary pyritic, and glauconitic reddish-weathering, ark-gray to greenish-gray siltstone, claystone, and sandstone with subordinate dark-brown, laminated organic-rich shale, and gray calcareous sandstone; also includes thin interbeds of basaltic tu
Tokun Formation
Consists predominantly of concretionary siltstone and lesser, variable amount of interbedded sandstone. Siltstone is medium to dark gray and nearly massive. Spheroidal calcareous concretions as much as 1 m in maximum dimension are distributed randomly or
Tertiary, Oligocene and Eocene
A transgressive marine sequence.  Consists predominantly of concretionary siltstone with a lesser and variable amount of interbedded sandstone, chiefly in the lower part of the formation.  The siltstone generally is medium to dark gray and nearly massive
crabs, and mollusks
Stillwater Formation
Dense hard dark-gray siltstone. Where siltstone is carbonaceous, it has a coalike appearance; where its calcareous, it may be variegated from reddish brown to pale green
foraminifers
The dominant lithology is dense hard dark-gray siltstone.  Where the siltstone is carbonaceous, it has a coaly appearance; where it is calcareous, the siltstone may be variegated in shades of reddish brown to pale green and usually contains foraminifers.
foraminifers, and mollusks
Twf
West Foreland Formation
Poorly sorted polymictic conglomerate, graywacke, and siltstone; having interbedded tuff and local subaerial basalt flows.
Tertiary, Eocene and Paleocene
Conglomerate, sandstone, and siltstone; mostly tuffaceous
Tertiary, Miocene and Oligocene(?)
Tan to light-yellow-brown conglomerate, sandstone, and laminated siltstone; few thin coal beds
Twf?
Conglomerate, sandstone, and siltstone; mostly tuffaceous, inferred from air photos, covered by thin glacial deposits
Kulthieth Formation
Massive to thin-bedded, coal-bearing, arkosic sandstone, dark-gray to black carbonaceous siltstone and shale, and minor coal.  Sandstone and shale ratios in measured sections average about 1:1.  Sandstone varies from massive intervals as much as 150 m th
plants, and mollusks
Includes at least 1,500 m of interbedded, massive to thin-bedded, coal-bearing arkosic sandstone, dark-gray to black carbonaceous siltstone and shale, and minor coal. Commonly intensely deformed into imbricated stacks of fault-bounded chevron folds.
Tos
Orca Group -- Sedimentary rocks, undivided
Tertiary, Paleocene and early Eocene (?)
Dark-gray flysch of thin- to thick-bedded sandstone, pebbly sandstone, siltstone, mudstone, and locally conglomerate and limestone; sandstone is composed chiefly of quartz and plagioclase; conglomerate clasts are mainly felsic porphyry and granite
Toss
Orca Group:  Siltstone
Dark-gray to black siltstone, mudstone, and minor fine-grained sandstone that is tightly folded and metamorphosed to slate; medium-gray and green lenses of micritic limestone as much as 2 m thick present locally in slate; olistostromes of siltstone prese
Tertiary, Eocene (?) and Paleocene
A sequence of thin- to thick-bedded sandstone, siltstone, and mudstone.  Abundant sedimentary structures, such as graded bedding, crossbedding, and ripple marks, along with flute, groove, and load casts, indicate deposition from turbidity currents.  Sand
Pollen:  Alnus (Alder)  Foraminifers: Globogerina sp., G. senni, Globogerina sp. (hispid), Globorotalia sp.  Echinoids:  Holaster sp. ?Hypsopygaster sp., Nucleopygus
Very thick, complexly deformed monotonous sequence of thin- to thick-bedded turbidites consisting of sandstone, siltstone, and mudstone; metamorphosed to zeolite or prehnite-pumpellyite facies. Abundant sedimentary features indicate deposition from sedim
planktonic foraminifers, fossil crabs, pelecypods and gastropods
Pollen:  Alnus (Alder), Foraminifers: Globogerina sp., G. senni, Globogerina sp. (hispid), Globorotalia sp., Echinoids:  Holaster sp., ?Hypsopygaster sp., Nucleopygus
Tosb
Orca Group - Massive sandstone (Lithofacies B)
Eocene and Paleocene
Gray to tan, massive bedded, fine to medium grained sandstone. Beds range in thickness from 2 m to over 5 m. Locally contains interbedded interval of well bedded turbidites of lithofacies C (Mutti and Ricci Lucchi, 1978). Massive sandstone is predominant
Tosc
Orca Group - "Typical" turbidites
Gray, well bedded, fine to medium grained, alternating layers of sandstone, siltstone, and shale. Beds are in layers less than or equal to 2 m thick. This lithologic association led to the original definition of turbidites (Mutti and Ricci Lucchi, 1978).
Tosd
Orca Group - Rythmite (sp.) (Lithofacies D)
Dark gray, well bedded, fine grained, siltstone, and shale in beds 5 cm or less in thickness. Probably represents a distal facies of Tosc. Occurs in local map scale outcrops on the southern side of Fairmount Island and the west side of Wells Bay
Tosf
Orca Group
Eocene and Paleocene - Chaotic deposits (Lithofacies F)
Dark gray, contorted, fine grained shale. Irregular blocks of rythmite (sp.) and sandstone in a chaotically folded shale host. Probably represent deposition of large slump blocks along submarine canyon walls or the slope environment. The outcrops along t
Tosg
Orca Group - Shale or argillite (Lithofacies G)
Dark gray, massive argillite or thin bedded shale. Outcrop occurs in a north-trending band north of Eickelberg Bay
Tosbd
Orca Group - Massive sandstone and rythmite (sp.)(Lithofacies B and D)
Interbedded intervals, undivided at map scale, of tan, massive channel sandstones and rythmite (sp.). Rythmite (sp.) interval probably represents overbank deposits
Tops
Orca Group:  Pillow basalt and sedimentary rocks
Areas composed of about equal amounts of pillow basalt and interbedded sedimentary rocks of sandstone and subordinate siltstone.  Present chiefly on Erlington, Evans, and Bainbridge Islands.
Foraminifers.  probably  Globigerina or   Subbotina   Probably Tertiary (specimens poorly preserved)
Togs
Orca Group:  Greenstone and sedimentary rocks
Basalt sills intrude metasedimentary rocks, chiefly slate, on Elrington, Evans, and Bainbridge Islands; basalt sills and dikes in slate and sandstone on Knight Island
Metamorphic
Basalt sills intrude metasedimentary rocks, chiefly slate, on Elrington, Evans, and Bainbridge Islands; basalt sills and dikes in slate and sandstone on Knight Island.  Greenstone and sedimentary rocks
Tosv
Orca Group -- Interbedded sedimentary and mafic volcanic rocks
Locally variable amounts of volcanic and sedimentary rocks.  In some cases unit is marginal to thicker sequences composed of pillowed and massive basalt flows.  The lithologies are quite variable throughout the study area.  In Ragged mountains volcanicla
Foraminifers: Globigerina or Subbotina;  Globigerina sp. (?) Globorotalia sp.; Globigerina cf. G. senni, Globorotalia sp., ?Eoconuloides parvulus, Globigerina sp. (high spired), Globigerina sp. (hispid)
HFS
Orca Group -- Pillow basalt and sedimentary rocks
Pillow basalt, massive basalt flows, minor volcanic breccia interbedded with sandstone, siltstone, and shale.  Distinguished from the interbedded sedimentary and mafic volcanic rocks unit on the basis of the predominance of pillow basalt in the section.
Tovs
Orca Group -- Interbedded sedimentary and volcanic rocks
Variable proportions of interbedded, tholeiitic basalt and turbidites. Basalt--pillowed and massive flows, pillow breccia, and tuff. Turbitdites--mudstone, siltstone, and fossiliferous volcanogenic sandstone. Metamorphosed to zeolite or prehnite-pumpelly
Pillow basalt, massive basalt flows, minor volcanic breccia interbedded with sandstone, siltstone, and shale.  Distinguished from the interbedded sedimentary and mafic volcanics rocks unit on the basis of the predominance of pillow basalt in the section.
Ophiolite of Glacier Island - Volcaniclastic rocks
Dark gray to green, moderate to well bedded volcanic mudstone and sandstone, poorly sorted, broken pillow breccia with angular clasts of pillow basalt, ranging in size from a few centimeters to 15-cm across, in a volcanic mudstone matrix, and rare pillow
Toc
Orca Group:  Conglomerate
ORCA GROUP:  Ranges from matrix-supported pebbly mudstone and sandstone to massive clast-supported pebble, cobble, and boulder conglomerate.  The generally well-rounded clasts consist of various lithologies that have locally predominant types as follows:
Crab:  Branchioplax washingtoniana Pelecypod:  Acila decisa
Orca Group: Conglomerate
Massive, clast-supported, well-rounded pebble, cobble, and boulder conglomerate. Variable clast composition.
Ranges from matrix-supported pebbly mudstone and sandstone to massive clast-supported pebble, cobble, and boulder conglomerate.  The generally well-rounded clasts consist of various lithologies that have locally predominant types as follows:  greenstone,
Tosa
Orca Group - Conglomerate (Lithofacies A)
Dark gray, poorly-bedded to massive, matrix-supported pebbly mudstone and sandstone to pebble, cobble, and boulder conglomerate. Minor lenses of sandstone and less or amounts of siltstone. Clasts are usually well-rounded and predominately sandstone and s
Tots
Orca Group -- Tuffaceous sedimentary rocks
Tuffaceous sedimentary rocks, volcaniclastic sandstone, and minor chert.  Locally, these rocks contain abundant radiolarians and diatoms of probable Tertiary age (table 2).  South of the Martin fault, this unit also includes minor pillow basalt and abund
Diatoms: Arachinodiscus cf., A. ehrenbergii, Trinacria ef., T. pileclus  Silicoflagellates:  ?Corbisema geometrica, ?Corbisema hastata, ?Corbisema triacontha, Dictyocha aspera, Navoculopgis constricta
Tf
Lava flows
Tertiary, middle to late?
Andesitic to basaltic lavas and associated pyroclastic rocks.
Td
Intermediate, felsic and mafic dikes
early Tertiary
Dikes of dacite, rhyolite, andesite, and rare basalt; stored in coverage as arcs, arc-code = 50, arc-para1 = 0
Ar-AR isochron(?) age on andesite(?) of 57.0 Ma
Dacite of Cape Saint Elias
Described by Winkler and Plafker (1981, p. 18) as follows:  "A prominent, very pale gray dacite plug complex forms the landmarks of Cape Saint Elias and Pinnacle Rock at the seward end of Kayak Island (Plafker, 1974).  The dacite is very dense and hard,
K-Ar date on dacite of 6.2 + or - 0.3 Ma.
Tertiary, Pliocene or Miocene
Prominent very pale gray dacite plug complex that forms Cape Saint Elias and Pinnacle Rock at southwestern end of Kayak Island. Dacite is very dense and hard and is conspicuously jointed. Microgranitic and porphyritic texture.
Whole-rock K-Ar age of 6.2 Ma
Tpv
Poul Creek Formation -- Volcanic rocks, undivided
Basaltic pyroclastic and flow rocks including minor pillowed flows; locally interbedded with marine sedimentary rocks, including tuffaceous or glauconitic strata, probably genetically related to mafic dikes, sills, and plugs of the mafic plugs unit (Tm)
K/Ar date on whole rock of 31.2 + or - 1.3 Ma
Poul Creek Formation: Volcanic rocks, undivided
Tertiary, Miocene to Eocene
Basaltic pyroclastic and flow rocks; locally interbedded with marine sedimentary rocks. Probably related genetically to mafic dikes, sills and plugs unit (Tm).
Poul Creek Formation:  Volcanic rocks, undivided
Basaltic pyroclastic and flow rocks including minor pillowed flows; locally interbedded with marine sedimentary rocks, including tuffaceous or glauconitic strata, probably genetically related to mafic dikes, sills, and plugs of the mafic plugs unit (Tm).
Tm
Mafic dikes, sills, and plugs
Tertiary, Oligocene
Mafic dikes, sills, and plugs. Strongly altered intrusions of diabase, alkalic basalt, olivine basalt, and lamprophyre. Probably related genetically to extrusive volcanic rocks (Tpv) in Poul Creek Fm.
Mafic plugs
Tertiary, Oligocene (?)
Only includes mafic plugs in the eastern Cordova quadrangle west of Nichawak Mountain; mainly in the Blying Sound quadrangle.  Miller (1975) and Winkler and Plafker (1981) described the mafic plugs as coarse grained and diabasic with 45 percent euhedral
Only includes mafic plugs in the eastern Cordova quadrangle west of Nichawak Mountain mainly in the Blying Sound quadrangle.  Miller (1975) and Winkler and Plafker (1981) described the mafic plugs as coarse grained and diabasic with 45 percent euhedral p
Tog
Orca Group:  Greenstone, undivided
Probably pillow basalt, basaltic tuff, and sills. Few small areas of mafic igneous rock were also included in this map unit because classification of rocks is uncertain; they include an outcrop on Outpost Island not visited by authors, rocks with uncerta
Tov
Orca Group:  Volcanic rocks, undivided
Mostly tabular or lenticular bodies of mafic volcanic rocks altered to greenstone and not examined in detail.  As mapped, may include pillowed or massive flows, broken pillow breccia, tuff, and dikes.
Thick and thin tabular bodies of altered tholeiitic basalt. Pillowed, massive or crudely columnar flows; pillow breccia, aquagene tuff, and diabase or gabbro sills. Local interbedding of mudstone and siltstone. Metamorphosed to zeolite or prehnite-pumpel
Top
Orca Group:  Pillow basalt
Pale- to dark-green aphyric to porphyritic, commonly amygdaloidal, pillow basalt composed of plagioclase and clinopyroxene; plagioclase is generally replaced by albite and(or) chloritie; vesticles mostly filled with chlorite; pillow basalt in some areas
Kvp
Valdez Group:  Pillow basalt
Late Cretaceous
Pale- to dark-green aphyric to porphyritic, frequently amygdaloidal, pillow basalt composed to plagioclase and clinopyroxene; plagioclase commonly replaced by albite and epidote, and clinopyroxene by hornblende, actinolite, and(or) chlorite; vesticles mo
Pillow breccia and massive flows are subordinate in quantity to pillow basalt.  Minor intercalated sedimentary rocks are predominantly siliceous mudstone and argillite.  Interpillow material consists of silicious mudstone, sandstone, or carbonate rocks.
Pillow basalt and lesser massive basalt and broken pillow breccia make up most of the western flank of the mafic complex on the Resurrection Peninsula.  These pillow basalts from a west-dipping sequence and contain minor amounts of interbedded siliceous
Ophiolite of Glacier Island - Pillow basalt
Tertiary, Eocene (?) and Paleocene (added)
Dark gray or green pillow basalt flows and minor massive basalt flows. Basalts are fine to medium grained, porphyritic with phenocrysts of plagioclase and clinopyroxene; olivine is present but not abundant. Pillows average 0.3 m in diameter. Altered brow
Kvd
Valdez Group:  Sheeted basalt dikes
Dark-green, gray, and brown aphyric to porphyritic and locally gabbroic dikes composed mainly of plagioclase and clinopyroxene; olivine present in a few dikes; plagioclase generally is replaced by albite, and clinopyroxene commonly replaced by hornblende
Tod
Orca Group:  Sheeted basalt dikes
Dark-green, gray, and brown aphyric to porphyritic and gabbroic dikes composed mainly of plagioclase and clinopyroxene; plagioclase and clinopyroxene; felsic plagioclase-quartz dikes occur locally; plagioclase-clinopyroxene-olivine dikes are present but
Orca Group:  Sheeted dikes
ORCA GROUP:  Mafic sheeted-dike complexes in the Orca Group occur on Knight and Glacier Islands.  The dikes are basaltic in composition and display diabasic, equigranular, and porphyritic textures.  Phenocrysts of plagioclase and clinopyroxene are common
Valdez Group:  Sheeted dikes
Mafic sheeted dikes forming the topographically rugged crest of the Resurrection Peninsula are similar to the sheeted dikes unit of the Orca Group on Knight Island.  Most dikes are 3 to 6 ft thick, vertical, and generally have a parallel north-south orie
Ophiolite of Glacier Island - Sheeted dikes
Mafic sheeted dikes are basaltic in composition and form the lower oceanic-crust part of the ophiolite of Glacier Island. The dikes are diabasic, equigranular, and porphyritic. Phenocrysts of plagioclase and clinopyroxene are common. Facings on chilled m
37.6Ma ñ0.6, plag, plateau age
Ti
Intrusive rocks
Dikes, sills, and stock-lke masses of felsic to mafic composition
Tgc
Cedar Bay granite
Tertiary, Eocene (?)
Light-gray and pink medium- and coarse-grained muscovite (biotite) granite; plagioclase ranges from oligoclase to andesine in composition, and biotite is commonly less than 1 percent.
Tg
Granite and granodiorite
The central part of the plutons are dominantly light-gray, medium- to coarse-grained granite with color index ranging from 3 to 8.  The plutons grade outward to fine- to medium-grained, more mafic mineral-rich (color indices of 10 to 20) margins of grani
K/Ar dates from 34.2 + or - 1.7 to 36.2 + or - 1 Ma.
Leucocratic Granite
Oligocene
Light colored, leucocratic biotite granite. Color index 5. Common textures are allotriomorphic granular and hypidiomorphic granular. Comprises several igneous bodies - plutons of Cedar Bay, Terentiev Lake, Granite Cove, and Columbia Glacier stock and an
Ar/Ar 25.4 ñ0.1 Ma, kspar, plateau age; 29.2 ñ0.3 Ma, microcline, isochron age; 31.7 ñ0.1 Ma, kspar, plateau age; 29.2 ñ0.1 Ma, kspar, plateau age
Granodiorite and granite
Light-gray medium- to coarse-grained biotite (hornblende) granodiorite and granite stocks of central part of map area; larger stocks commonly grade from marginal zones containing more biotite (and locally hornblende) inward to more leucocratic zones; lar
K/Ar dates on biotite of about 36.6 m.y., 35.5, 36.1, and 36.2 Ma; K/Ar date on hornblende of about 34.4 Ma.
Tgb
Gabbro
Tertiary, Oligocene, Eocene, or Paleocene
Dark-gray fine- to medium-grained locally porphyritic gabbro composed of subequal amounts of labradorite and clinopyroxene; locally contains olivine on Esther Island; pyroxene largely altered to hornblende north of Paddy Bay.
Tgd
Gabbro and diorite
Consists of mafic rocks belonging to one of the main intrusive events.  These rocks are dominantly medium- to coarse-grained gabbro (labradorite-bearing) and subordinate diorite (andesine-bearing) with finer grained borders of quartz gabbro and quartz di
K/Ar date of 36.6 +/- 1.01 Ma indicating a chronological relation to the granite and granodiorite unit (Tg).
Granitoid rocks
Granitoid rocks-- Biotite and biotite-hornblende granodiorite, granite, and minor tonalite; generally medium grained, hypidiomorphic, and equigranular; foliated in many places, especially near contacts with country rocks.
K-Ar ages from 50.5 to 53.5 Ma
Tgg
Generally medium- and medium- to coarse-grained hypidiomorphic-granular biotite granite with border phases of biotite + or - hornblende granite to granodiorite and tonalite.  Plutons of this unit are generally medium- and medium- to coarse-grained hypidi
Six K/Ar ages on hornblende, biotite, and phlogopite ranging from 50.5 to 53.5 Ma
Felsite Dikes
Includes two types: (1) leucocratic porphyry dikes with 20%-30% euhedral phenocrysts of potassium feldspar and quartz in a fine grained allotriomorphic groundmass. Intrudes only the Orca Group; (2) allotriomorphic granular, white weathering, fine grained
Ar/Ar 38.6 ñ0.6 Ma, biotite, plateau age; 40 ñ1 Ma, biotite, disturbed, wt. avg.; 31.1 ñ 0.2 Ma, kspar, isochron age
Ti3
Tonalite
Mostly biotite tonalite but also includes biotite-muscovite +/- garnet tonalite and trondhjemite.  Includes both weakly foliated, syn-D plutons (Ti3a) and unfoliated, post D plutons (Ti3b)
Ti2
Mostly hornblende-biotite tonalite but also includes biotite tonalite.  Strongly foliated and lineated plutons with fabrics subparallel to D2 in adjacent metamorphic rocks
Ti3b
Mostly biotite tonalite, but also some biotite-muscovite +/- garnet trondhjemite and granodiorite.  Unfoliated plutonic rocks
Ti3a
Mostly biotite tonalite, weakly foliated, syn-D plutons
Granodiorite
Medium- and coarse-grained biotite granodiorite
U-Pb monazite age of 56.0, Ar-Ar biotite ages of 54.2, 53.2, 53.4,53.7, and 54.0
Tgh
Granite of Harding Icefield region
Medium- to dark-gray foliated amdium- to coarse-grained biotite-muscovite-(hornblende) granite and granodiorite; marginal phases are locally biotite-muscovite-(hornblende) tonalite; mafic minerals, almost wholly biotite, constitute 20 to 30 percent of mi
K/Ar dates on biotite of about 59.2 m.y. and on muscovite of about 54.6 m.y.
Medium- to dark-gray foliated medium- to coarse-grained biotite-muscovite-(hornblende) granite and granodiorite; marginal phases are locally biotite-muscovite-(hornblende) tonalite; mafic minerals, almost wholly biotite, constitute 20 to 30 percent of mi
Medium- and coarse-grained biotite granodiorite of the Aialik pluton and Paguna stock -- assigned to granitic rocks of the Harding Icefield.  Same as NSA 1200 of source KN003
SV009
Granitic rocks of the Harding Icefield extrapolated from description of Tysdal and Case (1979) in the adjoining Seward quadrangle.  Nunataks were mapped by Magoon and others (1976) as Valdez Group.
KN015
Kvg
Valdez Group:  Gabbro
Green massive medium- to coarse-grained and locally pegmatitic gabbro composed chiefly of labradorite and clinopyroxene; commonly altered to varying degreens; pyroxene altered to green hornblende which is partly replaced by actinolite and(or) chlorite; p
Togb
Orca Group:  Gabbro and diorite
ORCA GROUP:  Medium- and dark-gray to green coarse-grained chiefly clinopyroxene-plagioclase rocks with ophitic to subophitic texture and gabbroic to dioritic composition; locally pegmatitic with clinopyroxene crystals as much as 5 cm long; clinopyroxene
Orca Group:  Gabbro
ORCA GROUP:  Several small intrusive bodies of gabbro occur on Knight Island.  The largest body crops out east of Drier Bay, where it intrudes sheeted dikes.  Other gabbro bodies that have been reported are too small to show at the scale of this map.  Mo
Kvgb
Two north-south-trending plutons of medium- to coarse-grained gabbro occur east of the sheeted dikes unit on the Resurrection Peninsula.  Several features are displayed in shoreline exposures of the westernmost pluton that were not observed in the easter
Tou
Orca Group:  Ultramafic rocks
ORCA GROUP:  Two of these peridotite bodies occur within or near major shear zones in the sheeted dikes unit; only the larger (650 by 1,300 ft body is shown in the Port Audry shear zone.  The third body occurs as a xenolith in sheeted dikes.  The ultrama
Tmu
Mafic and ultramafic plutonic rocks
Tertiary, Eocene and Paleocene?
Mafic and ultramafic plutonic rocks-- Compositionally and texturally variable unit consists mainly of medium grained gabbro, local diabase, hornblende gabbro, peridotite, and orthopyroxenite. Gabbro is slightly to moderately foliated except near contacts
Kvu
Valdez Group:  Ultramafic rocks
Serpentinized peridotite and dunite occur at three localities underlain by the Valdez Group:  two of these are on the Resurrection Peninsula and the third is near the head of Port Fidalgo.  This description represents the third at Port Fidalgo.  The thir
TKu
Plutonic rocks, undivided
Tertiary and Cretaceous
Plutonic rocks
TKgd
Granodiorite, quartz diorite, and diorite
Tertiary or late Cretaceous
Kk
Kaguyak Formation, nonmarine sedimentary rocks
Sandstone, conglomerate, siltstone and interbedded coal
(Not in Bradley, but cited in Magoon and others, 1980):  Sporomorphs:  Cranwellia striata Srivastava, Balmeisporites spp., Wodehouseia spinata Stanley, Proteacidites spp., Aquilapollenites bertillonites Funkhouser, A. reticulatus Mtchedlishvili, A delica
KPm
McHugh Complex, undivided
Cretaceous to Permian
Complexly deformed tectonic assemblage of diverse lithologies (melange).  Lithologies include argillite, tuff, graywacke, basalt, chert, outcrop-scale melange, conglomerate, gabbro, and limestone.  Rocks typically show prehnite-pumpellyite facies metamor
Permian conodonts and fusilinids.
Tectonite
KJm
McHugh Complex
Cretaceous and (or) Jurassic
Weakly metamorphosed siltstone, graywacke, arkose, and conglomeratic sandstone; greenstone (mostly basaltic), metachert, and argillite
Cretaceous and (or) Late Jurassic
Between Border Ranges fault and unnamed fault:  melange of siltstone, sandstone, mud-chip sandstone, conglomeratic sandstone, tuff, and less abundant gabbro, serpentinite, bedded chert, and pillow basalt; fine-grained sedimentary strata commonly streaked
KJm?
Late Jurassic and (or) Cretaceous
Between unnamed fault and Eagle River thrust fault (?):  massive sandstone that is brown, tan, and gray-green thick-bedded ridge-forming medium- and coarse-grained locally conglomeratic sandstone; abundantmud chips give rock a distinct spotted appearance
Km
Early Cretaceous
Description from Clark (1981, p. 3-4) "The McHugh Complex is a heterogeneous, chaotic assemblage that includes metamorphosed clastic and volcanic rocks of diverse ages.  The clastic rocks, which are the most abundant, comprise thick, fault-bounded sequen
Ju
Interstratified graywacke-argillite and volcanic rocks
Jurassic?
Interstratified graywacke-argillite and volcanic rocks.  Highly folded and fractured.  Exposed at surface or beneath thin discontinuous deposits of Quaternary age
KPms
McHugh Complex, graywacke and conglomerate
Early Cretaceous to Early Jurassic (Pliensbachian)
Fault-bounded slices of massive conglomerate and graywacke.
Pliensbachian radiolaria in underlying ribbon chert
KPmc
McHugh Complex, basalt and chert
Early Cretaceous (Albian) to Middle Triassic (Ladinian)
Pillow and massive basalt, depositionally overlain by radiolarian chert.
Cretaceous to Triassic radiolaria in bedded chert
Kd
Intermediate dike
Basalt-andesite dike intruding McHugh Complex.  Stored in coverage as arcs, arc-code = 50 and arc-para1 = 5
Ar-Ar hornblende plateau age of 115 Ma
Ku
Ki12
Cretaceous intrusive rocks -- Unit 12 Quartz diorite
Cretaceous
Locally foliated, seriate hornblende-biotite quartz diorite.  Biotite-hornblende rationis quite variable although color index remains constant.  Deuteric epidote common.  Extension from adjacent Lake Clark quadrangle
Kv
Valdez Group
Thick sequences of drab, rythmically alternating multiply deformed turbidites, including metasandstone, metasiltstone, argillite, slate, and phyllite, and rare beds of pebbly argillite and metasandstone;  generally beds are a few centimeters to a few met
Maestrichtian and Campanian(?) Inoceramus
KJv
Valdez Group (?)
Cretaceous and Jurassic (?)
Metawacke, metasiltstone, and argillite; locally phyllitic
Valdez Group:  Sedimentary rocks, undivided
Dark-gray thin- to thick-bedded sandstone, siltstone, and mudstone flysch; sandstone is fine to coarse grained and mainly is composed of plagioclase, quartz, and igneous rock fragments, the third ranging from a few percent to as much as 40 percent of roc
Mollusc.  Inoceramus kusiroensis  Maestrichtian   Late Cretaceou )
Kvs
Thick sequences of deformed and metamorphosed flysch consisting of metasandstone, metasiltstone, argillite, slate, and phyllite, with rare beds of conglomerate and pebbly argillite.  In many places primary internal sedimentary structures, consisting of g
Pelecypod:  Inoceramus kusiroensis, Inoceramus ulrichi, and Inoceramya concentrica
K/Ar date on biotite semischist of 51.5 + or - 1.5 Ma
Valdez Group: Metasedimentary rocks, undivided
Thick sequence of rhythmically alternating, multiply-deformed, metamorphosed turbidites that consist of metasandstone, metasiltstone, argillite, slate and phyllite and rare beds of pebbly argillite. Beds generally a few centimeters to a few meters thick.
Graywacke-argillite and other consolidated rocks
Graywacke-argillite and other consolidated rocks.  Highly folded and fractured.  Exposed at surface or beneath thin discontinuous deposits of Quaternary age
Kvvs
Valdez Group:  Interbedded volcanic and sedimentary rocks
This unit is composed of approximately equal amounts of interbedded volcanic rocks, consisting of volcanic breccia, tuff, tuffaceous sediment, and minor pillow basalt, and sedimentary rocks, consisting of sandstone, siltstone, shale, and chert.  The two
K-Ar date on amphibote-bearing greenschist of 47.6 + or - 1.4 Ma was reported, those source rocks are now assigned to Orca Group
Valdez Group: Interbedded metavolcanic and metasedimentary rocks
Equal proportions of interbedded metavolcanic and metasedimentary rocks. Metavolcanic--semischistose metatuff and breccia and minor pillow basalt. Metasedimentary--slate, phyllite, with metasilstone and metasandstone interbedding. Variable metamorphic gr
K-Ar date on amphibote-bearing greenschist of 47.6 +/- 1.4 Ma was reported, those source rocks are now assigned to Orca Group
Kvv
Valdez Group: Metavolcanic rocks, undivided
Tholeiitic metabasalt and basaltic metatuff, including local pillow lava, pillow breccia, and gabbroic dikes and sills. Metabasalt forms rugged, nearly massive outcrops, whereas semischistose metatuff forms more subdued outcrops. Variable metamorphic gra
Kvgr
Valdez Group:  Greenstone
This unit consists of massive greenstone, metamorphosed pillow basalt, and mafic dikes exposed near the heads of Woodworth and Schwan Glaciers.  Elsewhere in the Cordova and Valdez quadrangles, the unit includes lenticular bodies of chorite schist that m
Kvt
Tuff
Green to dark-gray fine-grained finely laminated tuff with plagioclase phenocrysts; metamorphosed to chlorite and biotite zones of greenschist facies; chlorite, epidote, and locally actinolite are abundant; remnants of glossy shards are present.
Dunite, locally with layers of chromite, moderately to mostly altered to serpentine, serpentine-talc, and talc schist; lustrous pale- to dark-green and black, locally reddish weathering rock that forms dike-like and irregularly shaped intrusive bodies
Serpentinized peridotite and dunite occur at three localities underlain by the Valdez Group:  two of these are on the Resurrection Peninsula and the third is near the head of Port Fidalgo.  On the Resurrection Peninsula small sparse inclusions of altered
Serpentinized peridotite and dunite occur at three localities underlain by the Valdez Group:  two of these are on the Resurrection Peninsula and the third is near the head of Port Fidalgo.  This description reflects the two localities on the Resurrection
Kvm
Melange of Iceworm Peak
Tectonic melange consisting of blocks of graywacke in a phacoidally cleaved matrix of slate having a Valdez Group protolith for both matrix and blocks.
Schist, Valdez Group
Schistose, interbedded siltstone, graywacke, and less abundant tuff, tufaceous sandstone, and basalt (pillow basalt?); igneous rocks are typically dark green, metasiltstone is shiny steel gray, and metasandstone is dark gray; metamorphosed chiefly to bio
Valdez Group: Schist
Homogenous pelitic schist and minor amphibolite; includes spotted biotite-plagioclase-quartz schist. Common banding probably represents original layering. Transitional into gneissose rocks to the east and into greenschist-facies rocks of metasedimentary
Valdez Group: Gneiss
Muscovite-biotite-quartz-plagioclase (+/- sillimanite and garnet) schist, banded gneiss, and migmatitic gneiss; many local intrusive stringers, dikes, and sills of granodiorite and granite. Transitional into schistose rocks to the north, south, and west.
Valdez Group:  Paragneiss
Predominantly metasedimentary rocks with well-developed gneissic foliation consisting of alternating quartz and feldspar-rich layers with biotite-rich layers.  The paragneiss is brown weathering, medium grained, and banded on a 2 to 4 mm scale.  However,
green
Schist
Cretaceous ?
Upper greenschist to amphibolite facies schist derived from metamorphism of interbedded graywacke and argillite of the Valdez Group
pink
Transitional gneiss
Age not given
Upper amphibolite facies schist and gneiss interlayered at scale of meters to centimeters.  Top of unit marked by appearance of quartofeldspathic segregations in metapelite and base of unit marked by loss of stratal continuity through development of gnei
gray
Gneiss
Gray, banded quartzofeldspathic gneiss
orange
Orthogneiss
Metamorphosed plutonic rocks.  Mostly Ti2 plutons within the gneissic core of the complex
Granodioritic rocks
Granodiorite and quartz diorite
Age assigned revised based on Nelson and others (1983)
Js
Sedimentary rocks
Jurassic
Sedimentary rocks, undifferentiated
Jn
Naknek Formation
Late Jurassic (Oxfordian to Kimmeridgian)
Arkose, conglomerate, sandstone, siltstone, and shale
Ammonites and pelecypods, especially Buchia which provides tight age control
Late Jurassic
Sandstone, arkose, conglomerate, and siltstone
Jnss
Naknek Formation, lower sandstone member
Thin-bedded to massive arkosic sandstone, graywacke, and siltstone, mainly restricted to central part of region
Jns
Naknek Formation, Snug Harbor Siltstone Member
Massive to thin-bedded dark-gray to black siltstone; laminated near base
Jnp
Naknek Formation, Pomeroy Arkose Member
Massive light-gray arkose and arkosic conglomerate; minor interbeds of siltstone
Jnc
Naknek Formation, Chisik Conglomerate Member
Massive cobble-boulder conglomerate, mainly restricted to area adjacent to Iniskin Bay and Tuxedni Bay
Jcp
Chinitna Formation, Paveloff Siltstone Member
Massive to thin-bedded gray arenaceous siltstone, weathers gray, large ellipsoidal concretions and lenticular beds of limestone, massive sandstone unit at base
Jc
Chinitna Formation
Late Jurassic (Callovian)
Primarily dark-gray to brown massive arenacous siltstone containing a few sandstone interbeds and numerous limestone concretions.  Unit is subdivided into members, however not on this map
Abundant fossils, including many species of ammonites:  Cadoceras, C. stenocadoceras, C. pseudocadoceras, Kepplerites, Kheraiceras, Lilloettia, and Gowericeras.  Also especially known for Iniskinites and Chinitnites
Siltstone, limestone concretions, and sandstone
Jct
Chinitna Formation, Tonnie Siltstone Member
Massive to thin-bedded brownish-gray arenaceous siltstone, weathers red-brown, small yellowish-brown limestone concretions in parallel bands, minor sandstone at base
Jtu
Tuxedni Formation
Middle to Late Jurassic (Bajocian to Callovian)
Light- to dark-gray and green graywacke, conglomerate, siltstone, and shale.  Graywacke ranges from feldspathic to lithic to laumontitic; conglomerate composed mainly of volcanic clasts in a graywacke matrix.  Unit is subdivided into Formation, however n
Abundantly fossiliferous, containing ammonites and pelecypods.  Key ammonites include Erycites, Tmetoceras, Sonninia, Stemmatoceras, Emileia, Stephanoceras, Chondroceras, and many others
Jt
Middle Jurassic
Sandstone, siltstone, and limy concretions
Jtb
Tuxedni Group, Bowser Formation
Middle and Late Jurassic
Heterogeneous assemblage of sandstone, conglomerate, shale and siltstone characterized by rapid facies changes.  Massive light- to dark-gray sandstone and conglomerate are the dominant lithologic types on the Iniskin Peninsula.  The sandstone and the con
Abundantly fossiliferous, containing ammonites and pelecypods, the units can be divided into two faunal zones which correspond to the break between the Middle and Upper Jurassic.  The lower faunal zone immediately overlies the unconformity with the Twist
Jtt
Tuxedni Group, Twist Creek Siltstone
Soft, poorly consolidated, thin-bedded to massive siltstone and silty shale as much 125-m-thick.  The siltstone is dark-gray, weathering to dark-rusty brown and contains many thin beds of volcanic ash that weather a bright orange color.  Small limestone
Abundant ammonite fauna which includes Oppelia (Liroxyites), Megasphaerceras, Leptoshinctes, Lissoceras, and Normannites (Dettermanites)
Jtc
Tuxedni Group, Cynthia Falls Sandstone
Massive to thick-bedded graywacke sandstone and pebble conglomerate about 200-m-thick.  The sandstone is medium- to coarse-grained, greenish-gray to dark-green, weathering mottled light-gray due to zeolites and has graded bedding.  The sandstone consists
The sparse fauna includes the ammonites Chondroceras and Stephanoceras as well as the pelecypods Inoceramus sp. and Mytilus sp.
Jtf
Tuxedni Group, Fitz Creek Siltstone
Thick sequence of massive, bluish dark-gray, arenaceous coarse- to fine-grained siltstone that commonly weathers rusty orange and contains many small limestone concretions.  Interbedded are fine-grained sandstone and, locally, conglomerate interbeds.  In
This unit is abundantly fossiliferous and is the first unit of the Tuxedini Group where ammonites are more numerous than pelecypods.  A few non-diagnostic brachiopods are also present.  The ammonites include Normannites, Teloceras, and Chondroceras and m
Jtg
Tuxedni Group, Gaikema Sandstone
Resistant, cliff-forming, massive to thin-bedded graywacke sandstone and cobble conglomerate showing graded bedding.  Conglomerate is confined to the Iniskin Peninsula, clasts in it consist of red and green felsic volcanic rocks, aphanitic igneous rocks
Fossiliferous throughout, containing pelcypods Meleagrinella, Trigonia, and Inoceramus and ammonites Witchellia(?), Stephanceras and locally, Sonninia (Papilliceras), Lissoceras, and Emileia
Jtr
Tuxedni Group, Red Glacier Formation
Thin-bedded to massive, red-brown weathering dark-gray to moderate olive-gray siltstone concentrated in the upper part of the unit and consisting of about 40 percent of the Formation.  The siltstone is highly arenaceous and locally contains lenticular in
The Red Glacier Formation is most abundantly fossiliferous in its upper parts, no fossils are known from the lower 2000 feet of the unit.  Pelcypods include Meleagrinella, Trigonia, Inoceramus, Camptonectes, and Pleuromya.  Ammonites occur in two distinc
Talkeetna Formation
Early Jurassic (Hettangian to Toarcian)
Mainly volcanic breccia, agglomerate, lava flows, and tuff.  Sedimentary rocks locally interbedded but are minor.  Informally divided into three members, which correlate with formal members elsewhere.  Includes informally named Pogibshi Formation on east
KJu
Metasedimentary rocks (undivided)
Weakly metamorphosed slate and graywacke; locally includes volcanic and intrusive rocks, undivided.  Consists of contact metamorposed Talkeetna Formation according to Detterman and others (1976, KN010).
Jtk
Early Jurassic
Volcanic breccia, tuff, agglomerate, and aphanitic lava flows; as mapped, locally includes Kamishak Formation in Ilianna Quad
bpT
Jurassic bedrock
Volcanic flows, tuffs, and breccias, metamorphic equivalents, and granodiorite.  Talkeetna Formation and other units
Jtku
Talkeetna Formation, undivided
Tuff, sandstone, agglomerate, breccia and some lava flows
Jv
Volcanic rocks, locally includes sedimentary rocks
Mz
Metamorphic rocks
Mesozoic
Schist, hornfels, and amphibolite, contact metamorphosed Talkeetna Formation
KN010
sv
Sedimentary and volcanic rocks
Cenozoic and Mesozoic
Cheifly Jurassic volcanic rocks; locally includes Mesozoic and Cenozoic sedimentary and volcanic rocks
Jtkh
Talkeetna Formation, Horn Mountain Tuff Member
Mottled andesitic tuff, tuffaceous sandstone, and siltstone, locally contains andesitic flows
Jtkp
Talkeetna Formation, Portage Creek Agglomerate Member
Massive pink agglomerate and some volcanic breccia; minor andesitic flows, locally metasedimentary rock
Jtkm
Talkeetna Formation, Marsh Creek Breccia Member
Massive green volcanic breccia, lava flows, in part of submarine origin, interbedded with argillite and meta tuff, low rank metamorphism mainly confined to lower part
Jt (east)
Talkeetna Formation (Pogibshi Formation)
Mainly volcanic breccia, agglomerate, lava flows, and tuff.  Sedimentary rocks locally interbedded but are minor.  Informally named Pogibshi Formation on east side of Cook Inlet
Jth
Trondjemite
Jg
Granitic rocks
Granitic rocks of the Alaska-Aleutian Range batholith
Jgd
Quartz monzonite
Jqm
Medium- to coarse-grained pink to gray granitic-textured quartz monzonite
Jqd
Quartz diorite, diorite, and granodiorite
Jd
Diorite of Point Bede
Jurassic(?)
Fine- to medium-grained nonfoliated quartz diorite.
Jto
Tonalite of Dogfish Bay
Medium-grained nonfoliated tonalite.
Quartz diorite
Mainly biotite-hornblende-quartz dioriite
di
Quartz diroite dikes
Quartz diorite dikes
Plutonic rocks, undivided; chiefly tonalite and trondhjemite
JT
Tonalite, includes hornblendite, hornblende-biotite quartz diorite, and rare granodiorite, quartz monzonite, and granite
la
Lamprophyre dikes
Jsm
Seldovia metamorphic complex
Marble, quartzite, garnet-mica schist, and glaucophane-bearing amphibolite
191.1 and 191.7 Ma Ar-Ar on white mica and 191.9 Ma Ar-Ar on hornblende
JTrp
Port Graham Formation of Kelley (1980)
Early Jurassic and Late Triassic
Dark-gray, carbonaceous limestone and silty limestone, also includes tuff, tuffaceous sedimentary rocks, and chert.  Most of unit considered Norian in age.
Bivalves of Late Triassic (Norian) age
Trk
Kamishak Formation
Late Triassic
Limestone, grey to black chert, and porcellanite
J(?)f
Felsite
Jurassic(?) or early Tertiary(?)
Fine-grained aphanitic, light gray felsite
Newly determined zircon age of approx. 206 Ma
SV008
Assigned new nsaclass based on date of Diorite of Point Bede by Dwight Bradley.
Mg
Dark-green, medium- to coarse-grained gabbro and minor leucogabbro and plagiogranite.  Associated with McHugh Complex as fault-bounded bodies.
Mu
Ultramafic plutonic rocks
Predominantly layered, variably serpentinized dunite containing rare to locally abundant layers of chromitite and pyroxenite and fault slices of garnet pyroxenite and serpintinite.  Associated with McHugh Complex as fault-bounded bodies.
Trm
Metamorphic rocks, undivided
Late(?) Triassic
Metalimestone, argillite, quartzite, metatuff, greenstone, and phyllite; may in part be equivalent to the Kamishak Formation
as
Amphibolite
Early Mesozoic(?)
Amphibolite, locally includes sedimentary rocks