{"text_format":"dbase-jsonl-2026-09-30","columns":[{"name":"NSACLASS","type":"number","width":4,"decimals":0},{"name":"NSAMOD","type":"character","width":3},{"name":"CLASS","type":"number","width":5,"decimals":0},{"name":"MAP_UNIT","type":"character","width":18},{"name":"SOURCE","type":"character","width":5},{"name":"UNIT_NAME","type":"character","width":76},{"name":"DESCRIPTIO","type":"character","width":254},{"name":"AGE","type":"character","width":49},{"name":"FOSSIL","type":"character","width":197},{"name":"RADIOMETRI","type":"character","width":147},{"name":"QUADRANGLE","type":"character","width":15},{"name":"ROCK_CLASS","type":"character","width":14},{"name":"QCLASS","type":"number","width":4,"decimals":0},{"name":"LABEL","type":"character","width":4}],"n_rows":284,"rows_kept":284,"cut":false,"deleted_skipped":0,"read_ended":"whole","bounds":"16MiB/16384/4096/first_that_fit","version":"dbase_level_three","encoding_class":"enc_absent","reader":"statdb_count/9"}
[99,null,500,"Bx","AD012","Undifferentiated","May include minor amounts of talus and colluvium. In areas away from Mount Moffett and Mount Adagdak, most of the bedrock consists of Finger Bay Volcanics (Coats, 1956). These rocks are extensively fractured and faulted, and locally exhibit some weatheri","Quaternary and Tertiary",null,null,"Adak","Igneous",99,null]
[100,null,100,"Qal","AD002","Alluvial and other deposits","Unconsolidated beach, delta, lagoon, and alluvial deposits","Quaternary",null,null,"Adak","Unconsolidated",1000,"Qs"]
[100,null,401,"Qal","AD004","Alluvium","Alluvium, dune and beach sands","Quaternary",null,null,"Adak","Unconsolidated",1000,"Qs"]
[100,null,447,"Qas","AD006","Ash, soil, and tundra mantle","Ash, soil, and tundra mantle","Quaternary",null,null,"Adak","Unconsolidated",1000,"Qs"]
[100,null,509,"Qal","AT004","Alluvium and beach deposits","Alluvium and beach deposits","Quaternary",null,null,"Attu","Unconsolidated",1000,"Qs"]
[100,null,1,"Qal","KK002","Surficial deposits","Alluvium, colluvium, landslide deposits, and beach deposits","Holocene",null,null,"Kiska","Unconsolidated",1000,"Qs"]
[100,null,3,"Qal","RI002","Alluvium, eluvium, and talus","Alluvium, eluvium, and talus","Holocene",null,null,"Rat Islands","Unconsolidated",1000,"Qs"]
[100,null,39,"Qal","RI003","Alluvium","Alluvium - Sand, gravel, and boulders.","Quaternary",null,null,"Rat Islands","Unconsolidated",1000,"Qs"]
[100,null,300,"Qas","GI003","Ash and soil cover, Kavalaga Island","Ash and soil cover","Quaternary",null,null,"Gareloi Island","Unconsolidated",1000,null]
[100,null,306,"Qas","GI003","Surficial deposits, ash and soil cover, Ogliuga and Skagul Islands","Ash and soil cover","Quaternary",null,null,"Gareloi Island","Unconsolidated",1000,null]
[100,null,500,"Qal","RI005","Alluvial deposits, Amchitka Island","Unconsolidated material in valley floors","Quaternary, Holocene",null,null,"Rat Islands","Unconsolidated",1000,null]
[100,null,600,"Qt","RI006","Talus, alluvium, and landslide deposits, Segula Island","Talus, alluvium, and landslide deposits, primarily landslide deposits","Quaternary",null,null,"Rat Islands","Unconsolidated",1000,null]
[100,null,707,"Qtsc","AD009","Tephra, soil and colluvium","Accumulations of organic-rich soil, peat and tephra mainly on the southern part of the island. Thickness ranges between 1 and 5 meters. Tephra deposits consist of light colored, fine silt-size ash beds to pebble and granule size lapilli beds mostly deriv","Quaternary",null,null,"Adak","Unconsolidated",1000,null]
[100,null,603,"Qhpt","AD007","Peat, tephra, and colluvium","Accumulations of peat and tephra on the slopes of ancestral Mount Kanaton typically between 1 and 5 meters thick. Tephra deposits consist of light-colored, fine silt-sized ash beds to lapilli beds mostly derived from eruptions of Kanaga volcano. Colluvia","Quaternary",null,null,"Adak","Unconsolidated",1000,null]
[100,null,400,"al","GI006","Ash and soil cover, Tanaga volcano","Ash and soil cover","Quaternary, Holocene",null,null,"Gareloi Island","Unconsolidated",1000,null]
[100,null,400,"al","AD013","Ash and soil cover, Tanaga volcano","Ash and soil cover","Quaternary, Holocene",null,null,"Adak","Unconsolidated",1000,null]
[105,null,101,"Qal","AT002","Alluvium","Valley-fill aluvium; includes old beach deposits in lower parts of some valleys","Quaternary",null,null,"Attu","Unconsolidated",1050,"Qa"]
[105,null,105,"Qal","AD003","Alluvial deposits","Alluvial deposits","Quaternary",null,null,"Adak","Unconsolidated",1050,"Qa"]
[105,null,425,"Qal","AD005","Alluvium","Alluvium, beach gravel, and wqater-sorted pumice deposits.  Rocks younger than caldera.","Quaternary",null,null,"Adak","Unconsolidated",1050,"Qa"]
[105,null,301,"Qal","KK003","Alluvium","Sand and silt","Quaternary, Holocene",null,null,"Kiska","Unconsolidated",1050,null]
[105,null,501,"Qal","AD012","Alluvial of modern streams","Well to moderately sorted angular to rounded gravel, sand and minor silt along present day streams and creeks. Generally less than 1 m thick and forms longitudinal bars, point bars, and transverse bars along stream channels. Generally stable, but may bec","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1050,null]
[106,null,102,"Qf","AT002","Alluvial fan deposits","Alluvial fan deposits","Quaternary",null,null,"Attu","Unconsolidated",1060,"Qaf"]
[106,null,502,"Qaf","AD012","Alluvial fan deposits","Moderately to poorly sorted subangular cobble gravel, sand, and minor silt in small fan-shaped bodies at the mouths of some streams with steep (more than 20 percent) gradients. May contain variable amounts of debris-flow sediment and talus, and usually m","Quaternary",null,null,"Adak","Unconsolidated",1060,null]
[107,null,45,"Qc","RI003","Colluvium","Colluvium - Boulders and bouldery debris in slope wash, talus, landslide, and mudflow deposits.","Quaternary",null,null,"Rat Islands","Unconsolidated",1070,"Qc"]
[107,"ALT",20045,"Qc","RI003","Colluvium","Colluvium - Boulders and bouldery debris in slope wash, talus, landslide, and mudflow deposits.  Contains areas of kaolinized, silicified, and pyritized rock.","Quaternary",null,null,"Rat Islands","Unconsolidated",1070,"Qc"]
[107,null,702,"Qct","AD009","Talus and coarse colluvial deposits","Accumulations of poorly sorted, angular rock debris on hillslopes below bedrock outcrops.","Quaternary",null,null,"Adak","Unconsolidated",1071,null]
[107,null,605,"Qhtc","AD007","Talus and coarse colluvial deposits","Accumulations of poorly sorted, angular rock debris on hillslopes below bedrock outcrops.","Quaternary",null,null,"Adak","Unconsolidated",1071,null]
[107,null,503,"Qcc","AD012","Coarse-grained colluvial deposits","Poorly sorted to fall-sorted, angular blocks, boulders, and gravel on steep hillslopes. Includes all forms of talus, rockfall avalanche debris, and may include some debris-flow deposits. Extremely porous and permeable, but generally not water bearing.","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1071,null]
[107,null,504,"Qcf","AD012","Fine-grained colluvial deposits","Reworked volcanic ash, eolian sediment, and other fine-grained deposits on hillslopes. Somewhat porous and permeable and locally water bearing.",null,null,null,"Adak","Unconsolidated",1073,null]
[107,null,505,"Qc","AD012","Colluvial deposits, undifferentiated","Reworked, unconsolidated sediment of all particle sizes on hillslopes. Typically unsorted to poorly sorted and forms a thin blanketing layer on bedrock or other surficial deposits. Porosity and permeability dependent on composition. May be water bearing.","Quaternary",null,null,"Adak","Unconsolidated",1070,null]
[107,null,525,"Qcd","AD012","Debris-flow deposits","Poorly sorted, matrix and clast-supported, angular bouldery gravel. May consist of reworked lahar deposits, colluvium, and talus. Deposits usually exhibit lobate fronts and levee-like ridges along their margins.","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1071,null]
[107,null,401,"co","GI006","Colluvium, Tanaga volcano","Colluvium","Quaternary, Holocene",null,null,"Gareloi Island","Unconsolidated",1070,null]
[108,null,403,"Qmf","AD004","Mudflow","Mudflow","Quaternary",null,null,"Adak","Unconsolidated",1080,"Qls"]
[108,null,423,"Qls","AD004","Landslide","Landslide","Quaternary",null,null,"Adak","Unconsolidated",1080,"Qls"]
[108,null,701,"Qls","AD009","Landslide deposits","Poorly sorted accumulations of gravel, sand and silt in slumps, and localized debris-flow deposits.","Quaternary",null,null,"Adak","Unconsolidated",1080,null]
[108,null,604,"Qhls","AD007","Landslide deposits","Poorly sorted accumulations of gravel, sand, and silt in slumps and debris-flow deposits.","Quaternary",null,null,"Adak","Unconsolidated",1080,null]
[108,null,506,"Qcl","AD012","Landslide deposits","Discrete bodies of reworked unconsolidated sediment formed by slumping, sliding, or short-distance debris flow. Consists of poorly sorted to intact blocks of sediment that are generally found a short distance from their source. Common on the lower slopes","Quaternary",null,null,"Adak","Unconsolidated",1080,null]
[110,null,507,"Qat","AD012","Alluvial terrace deposits","Moderately to well-sorted gravel, sand, and silt in low benches and unpaired terraces along streams and creeks. Usually mantled by tephra. Generally of limited extent in the map area, and most common along large drainages. Porous and permeable and may be","Quaternary",null,null,"Adak","Unconsolidated",1100,null]
[112,null,508,"Qlk","AD012","Deposits of former lakes, ponds, and bogs","Consists of varying amounts of sand, silt, clay, peat, and reworked or primary tephra. Almost always overlain by tephra deposits. Somewhat porous and permeable and generally water bearing.","Quaternary",null,null,"Adak","Unconsolidated",1120,null]
[113,null,509,"Qobb","AD012","Organic deposits over beach gravel","Peat, silty peat, and sand peat developed on uplifted beach gravel. Usually consists of 1 to 3 m thick sequences of compact, fibrous peat resting on well-rounded beach gravel. May contain multiple thin, fine-grained tephra layers. Common along the Clam L","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1130,null]
[115,null,103,"Qb","AT002","Beach deposits","Includes some narrow stretches of bare rock shore platform","Quaternary",null,null,"Attu","Unconsolidated",1150,"Qb"]
[115,null,449,"Qb","AD006","Surficial beach deposits","Surficial beach deposits","Quaternary",null,null,"Adak","Unconsolidated",1150,"Qb"]
[115,null,41,"Qb2","RI003","Beach deposits","Beach deposits - Sand, pebbles, gravel, and boulders.","Quaternary",null,null,"Rat Islands","Unconsolidated",1150,"Qb"]
[115,null,43,"Qb1","RI003","Beach deposits","Beach deposits - Boulders and boulder conglomerate.","Quaternary",null,null,"Rat Islands","Unconsolidated",1150,"Qb"]
[115,null,307,"Qb","GI003","Surfical deposits, beach deposits, Ogliuga and Skagul Islands","Beach deposits","Quaternary",null,null,"Gareloi Island","Unconsolidated",1150,null]
[115,null,515,"Qb","RI005","Beach deposits, Amchitka Island","Beach deposit of sand, cobbles, boulders, and shells of marine fauna characteristic of warmer water.  Inferred late interglacial age","Quaternary, Pleistocene",null,null,"Rat Islands","Unconsolidated",1150,null]
[115,null,615,"Qb","RI006","Beach deposits, Segula Island","Primalrily wave rounded boulders and and minor fine gravel.  Beach at head of cove on north coast is only one that contains appreciable sand.","Quaternary",null,null,"Rat Islands","Unconsolidated",1150,null]
[115,null,700,"Qbe","AD009","Beach and coastal eolian deposits","Pocket beaches and steep berms of rounded cobble and boulder gravel, and sand. Eolian deposits consists mostly of well-sorted medium to coarse sand.","Quaternary",null,null,"Adak","Unconsolidated",1150,null]
[115,null,600,"Qhbe","AD007","Beach and eolian deposits","Beach deposits consist of sandy pocket beaches to steep berms of rounded cobble and boulder gravel. Eolian deposits consist mostly of well-sorted medium to coarse sand.","Quaternary",null,null,"Adak","Unconsolidated",1150,null]
[115,null,300,"Qb","KK003","Beach deposits","Sand, gravel, pebbles, and boulders","Quaternary, Holocene",null,null,"Kiska","Unconsolidated",1150,null]
[115,null,510,"Qb","AD012","Beach sand","Fine to medium-grained, well-sorted sand found on modern and former beaches. Contains variable amounts of heavy minerals (for example, magnetite) that form discrete beds and lenses (placer deposits). Porous, permeable, and water bearing.","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1150,null]
[115,null,511,"Qbb","AD012","Boulder beaches","Moderately sorted, rounded to well-rounded boulder and cobble gravel on high energy beaches. Common in the Clam Lagoon and Andrew Bay area where deposits are found on uplifted wave-cut terraces. Porous and permeable, but not water bearing.","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1150,null]
[115,null,512,"Qbr","AD012","Beach ridges and beach-ridge complexes","Moderately to well-sorted coarse to fine sand, and minor fine gravel in nested sets of ridges that are generally parallel to the present coastline. Deposits probably form during storms but are no longer affected by wave action. Indicative of recent tecto","Quaternary",null,null,"Adak","Unconsolidated",1151,null]
[115,null,513,"Qbbo","AD012","Older boulder beaches","Moderately sorted, rounded to well-rounded boulder and cobble gravel with a sand matrix on uplifted wave-cut platforms and terraces. Former zone of high-energy wave action now isolated from the coastline by tectonic uplift. Overlain by as much as 2.5 m o","Quaternary",null,null,"Adak","Unconsolidated",1151,null]
[115,null,514,"Qbby","AD012","Younger boulder beaches","Moderately sorted, rounded to well-rounded boulder and cobble gravel with a sand matrix on uplifted wave-cut platforms and terraces. Forms prominent benches in the area between Clam Lagoon and Lake Andrew. Former zone of high-energy wave action now isola","Quaternary",null,null,"Adak","Unconsolidated",1151,null]
[116,"Q",529,"Qlg","AD012","Lagoonal deposits","Lagoonal deposits","Quaternary",null,null,"Adak","Unconsolidated",1160,null]
[117,null,117,"Qtg","AD002","Marine terrace boulder gravel","Marine terrace boulder gravel","Quaternary",null,null,"Adak","Unconsolidated",1170,"Qmt"]
[120,null,120,"Qs","AD002","Sand dunes","Sand dunes","Quaternary",null,null,"Adak","Unconsolidated",1200,"Qd"]
[120,null,3,"Qd","KK002","Surficial deposits, sand dunes","Sand dunes","Holocene",null,null,"Kiska","Unconsolidated",1200,"Qd"]
[120,null,1,"Qd","RI002","Dune sand","Dune sand - Chiefly in beach ridges.","Holocene",null,null,"Rat Islands","Unconsolidated",1200,"Qd"]
[120,null,47,"Qes","RI003","Eolian deposits","Dune sand.","Quaternary",null,null,"Rat Islands","Unconsolidated",1200,"Qd"]
[120,null,308,"Qd","GI003","Surficial deposits, dunes, Ogliuga and Skagul Islands","Dunes","Quaternary",null,null,"Gareloi Island","Unconsolidated",1200,null]
[120,null,520,"Qd","RI005","Eolian deposits, Amchitka Island","Cliff top dunes","Quaternary, Holocene",null,null,"Rat Islands","Unconsolidated",1200,null]
[120,null,515,"Qes","AD012","Eolian sand","Fine to medium-grained, well-sorted and locally cross-bedded, wind-deposited sand. Usually found in dunes and sand sheets along the coastline. May contain multiple thin (less than 5 cm thick) volcanic ash and peat layers. Porous and permeable and commonl","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",1200,null]
[125,null,104,"Qt","AT002","Glacial till - ground moraine","Ground moraine deposits","Quaternary",null,null,"Attu","Unconsolidated",1250,"Qm"]
[125,null,105,"Qt","AT002","Glacial till - lateral and end moraine","Terminal or lateral moraine deposits","Quaternary",null,null,"Attu","Unconsolidated",1250,"Qm"]
[125,null,125,"Qd","AD002","Glacial drift","Glacial drift, including till, lateral moraines, and mudflows","Quaternary",null,null,"Adak","Unconsolidated",1250,"Qm"]
[125,null,405,"Qmo","AD004","Glacial moraine","Glacial moraine","Quaternary",null,null,"Adak","Unconsolidated",1250,"Qm"]
[125,null,525,"Qg","RI005","Glacial deposits, Amchitka Island","Till, outwash gravel, and silt with varve=like bedding that contains constituents not of local origin.","Quaternary, Pleistocene",null,null,"Rat Islands","Unconsolidated",1250,null]
[125,null,516,"Qgm","AD012","Morainal deposits (till)","Unsorted, massive, matrix-supported, cobble and boulder gravel. Matrix consists of silt, clay, and fine sand. Contains abundant faceted, soled, and striated subangular to subrounded clasts. Typically found as irregular, discontinuous layers and lenses ov","Quaternary (also see description)",null,null,"Adak","Unconsolidated",1250,null]
[125,null,402,"gh","GI006","Glacial deposits, Tanaga volcano","Glacial deposits","Quaternary, Holocene",null,null,"Gareloi Island","Unconsolidated",1250,null]
[170,null,517,"Qld","AD012","Delta deposits","Moderately sorted sand and gravel deposits at the mouths of small streams and creeks that enter standing bodies of water. Usually mantled by 1 to 2 m of tephra and are indicative of higher lake levels. Porous and permeable, and may be water bearing.","Quaternary",null,null,"Adak","Unconsolidated",1700,null]
[282,null,206,"Tc","AD002","Bouldery conglomerate","Bouldery conglomerate, mapped as Tertiary by Coats (1956), is probably Quaternary, certainly Pliocene or younger.","Tertiary",null,null,"Adak","Sedimentary",2820,"QTmb"]
[282,null,205,"Ts","AD002","Fossiliferous marine sandstone","Soft yellow-to-gray sandstone containing lenses of dark pebble conglomerate","Tertiary",null,null,"Adak","Sedimentary",2820,"Tmr"]
[282,null,503,"QTg","RI005","Gravel of hornblende andesite, Amchitka Island","Sand and gravel, nonindurated, bedded, composed of fragments of hornblende andesite.  Inferred beach and nearshore marine deposit","Quaternary or Tertiary",null,null,"Rat Islands","Unconsolidated",2820,null]
[284,null,502,"QTs","RI005","Tilted sedimentary rocks at South Bight, Amchitka Island","Sand, silt, and gravel in tilted beds, truncated at 90-foot altitude, overlain by fossiliferous beach deposit (Qb).  Consist, from base, of 200 feet of layers in random order, a few inches to 2-feet-thick, of carbonaceous sandy silt, fine- to medium-sand","Quaternary or Tertiary","Fragments of carbonized wood common in silt layers",null,"Rat Islands","Unconsolidated",2840,null]
[290,null,106,"QTf","AT002","Faneto Formation","Coarse red sandstone and conglomerate","early Pleistocene or Late Tertiary",null,null,"Attu","Sedimentary",2900,"QTf"]
[295,null,518,"Qdl","AD012","Disturbed land","Areas affected by human disturbance. Includes filled or reclaimed land, present and former housing developments, and other facilities that locally obscure primary surficial deposits. May be porous and permeable and may be water bearing.","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",2950,null]
[300,null,413,"Tgs","AD004","Great Sitkin Volcanics - Basalt flows","Basalt flows on Sitkin Creek","Tertiary",null,null,"Adak","Igneous",3000,"Tb"]
[300,null,415,"Tgc","AD004","Great Sitkin Volcanics - Composite cone","Composite cone of Great Sitkin Volcano.  Principally basalt and andesite flows, but includes some tuff layers.","Tertiary",null,null,"Adak","Igneous",3000,"Tvu"]
[300,null,429,"Qkv","AD005","Older volcanic rocks of Kanaga Volcano","Basalt and andesite flows, scoria, and tuff breccia.   Rocks younger than caldera.","Quaternary",null,null,"Adak","Igneous",3000,"Qv"]
[300,null,431,"Qva","AD005","Older volcanic rocks of Kanaga Volcano","Vent agglomerate and minor intrusive rocks of later stage.  Rocks younger than caldera.","Quaternary",null,null,"Adak","Igneous",3000,"Qv"]
[300,null,7,"Qk","KK002","Rocks of Kiska Volcano","Lava flows and interbedded pyroclastic rocks forming Kiska Volcano.","Pleistocene",null,null,"Kiska","Igneous",3000,"Qv"]
[300,null,29,"Qbt","RI002","Basaltic tuff","Basaltic tuff  breccia and tuffaceous sand with minor basaltic flows.","Quaternary",null,null,"Rat Islands","Igneous",3000,"Qv"]
[300,null,406,"Qv","GI005","Composite volcanic cones","Composite volcanic cones","Quaternary",null,null,"Gareloi Island","Igneous",3000,null]
[300,null,650,"Qv","RI006","Composite volcanic material, Segula Island","Interbedded lava and pyroclastic material.  Lavas are in lenticular tongues and sheets from a few to about 100 feet thick.  Pyroclastic layers are comparable in thickness but cover much wider areas","Quaternary",null,null,"Rat Islands","Igneous",3000,null]
[300,null,651,"Qv","RI006","Composite volcanic material, Davidof and Khvostof Islands","Interbedded lava and pyroclastic material.  Lavas are in lenticular tongues and sheets from a few to about 100 feet thick.  Pyroclastic layers are comparable in thickness but cover much wider areas","Quaternary",null,null,"Rat Islands","Igneous",3000,null]
[300,null,717,"Qcbf","AD009","Cone building lava flows and volcaniclastic rocks","Medium to dark grey, massive, and thickly bedded, andesite and basaltic andesite lava flows, interbedded with thin accumulations of pyroclastic and laharic debris. Makes up the remaining sector of the ancestral edifice that was partially destroyed by fla","Quaternary (Pleistocene and Holocene )",null,null,"Adak","Igneous",3000,null]
[300,null,801,"Qpv","AD008","Precaldera glaciated or dissected remnants of volcanic cones","Precaldera glaciated or dissected remnants of volcanic cones","Quaternary",null,null,"Adak","Igneous",3000,null]
[300,null,304,"Qtbv","KK003","Buldir Volcanics","Olivine basalt flows and pyroclastic rocks","Quaternary",null,null,"Kiska","Igneous",3000,null]
[300,null,404,"sop, sol, tol, tko","GI006","Older volcanic rocks, Sajaka, Takawangha, and Tanaga volcanoes","Undivided older volcanic rocks on informally named Sajaka, Tanaga, and Takawangha volcanoes","Quaternary",null,null,"Gareloi Island","Unconsolidated",3000,null]
[300,null,405,"Qv","GI006","Pre-Tanaga volcanic rocks","Undivided older volcanic rocks that predate Tanaga volcano","Quaternary",null,null,"Gareloi Island","Unconsolidated",3000,null]
[300,null,202,"Qvo","GI006","Older volcanic rocks, Gareloi volcano","Undivided older volcanic rocks associated with Gareloi volcano","Quaternary",null,null,"Gareloi Island","Unconsolidated",3000,null]
[300,null,405,"Qv","AD013","Pre-Tanaga volcanic rocks","Undivided older volcanic rocks that predate Tanaga volcano","Quaternary",null,null,"Adak","Unconsolidated",3000,null]
[305,null,155,"Tmb","AD002","Basalt flow, Moffett Volcano",null,"Tertiary",null,null,"Adak","Igneous",3050,"Hv"]
[305,null,153,"Tyc","AD002","Younger composite cone, Mt. Adagdak Volcano","Younger composite cone, Mt. Adagdak Volcano, principally hornblende andesite tuff breccia, but includes some hornblende andesite flows.","Quaternary",null,null,"Adak","Igneous",3050,"Hv"]
[305,null,427,"Qkb","AD005","Basalt flows","Historic and late prehistoric basalt flows from Kanaga Volcano.  Rocks younger than caldera.","Quaternary",null,null,"Adak","Igneous",3050,"Hv"]
[305,null,5,"Qkr","KK002","Rocks of Kiska Volcano","Lava flows and interbedded pyroclastic rocks forming Kiska Volcano.  The most recent lava flows, Qkr, are mapped separately.","Pleistocene",null,null,"Kiska","Igneous",3050,"Hv"]
[305,null,5,"Qbc","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,7,"Qbc1","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,9,"Qbc2","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,11,"Qbc3","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,13,"Qbc4","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,15,"Qbc5","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,17,"Qbc6","RI002","Basalt","Mount Cerberus :  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,19,"Qbl","RI002","Basalt","Lakeshore Cone:  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,21,"Qbl1","RI002","Basalt","Lakeshore Cone:  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,23,"Qbl2","RI002","Basalt","Lakeshore Cone:  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,25,"Qbs","RI002","Basalt","Sugarloaf Peak:  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,27,"Qbs1","RI002","Basalt","Sugarloaf Peak:  Basalt - Lava flows in part separately mapped and numbered in probable order of eruption.","Holocene",null,null,"Rat Islands","Igneous",3050,"Hv"]
[305,null,201,"Qby","GI002","Younger basalt flows","Olivine basalt flows, ranging from fine-grained to porphyritic","Quaternary",null,null,"Gareloi Island","Igneous",3050,null]
[305,null,200,"Ql","GI002","Lava of 1929 eruption","Black to dark-reddish brown basaltic lava and scoria and viscous andesitic flows","Quaternary, Holocene",null,null,"Gareloi Island","Igneous",3050,null]
[305,null,605,"Qf","RI006","Surface flows of porphyritic feldspathic basalt, Segula Island","Flows are generally dark-gray, glassy or fine-grained, compact or diktytaxitic, all porphyritic and feldspathic.  Flows are 2-pyroxene andesite and olivine basalt and have uneroded flow forms","Quaternary",null,null,"Rat Islands","Igneous",3050,null]
[305,null,708,"Qld74","AD009","Lava dome emplaced during 1974 eruption","Dark gray to black, basaltic andesite with highly fractured and blocky carapace. Occupies most of the summit crater.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,709,"Qld45","AD009","Lava dome emplaced during 1945 eruption","Dark gray to black, glassy, porphyritic basalt. Largely removed by 1974 eruption.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,712,"Qllf","AD009","Lava flows of Holocene age with well developed lateral levees","Medium to dark gray andesite and basaltic andesite aa lava flows on the northwest flank of the volcano. Characterized by well developed, steep, nearly linear lateral flow levees of blocky aa lava.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,713,"Qmlf","AD009","Massive lava flows of Holocene age","Medium to dark gray, massive, thickly bedded, andesite and basaltic andesite lava flows erupted from the summit crater on the north flank of the volcano.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,714,"Qlf","AD009","Younger lava flows of Holocene age erupted from flank vents","Medium to dark grey andesite and basaltic andesite aa lava flows erupted from flank vents on the west flank of the volcano.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,715,"Qolf","AD009","Older lava flows of Holocene age erupted from flank vents","Medium to dark grey andesite and basaltic andesite aa lava flows erupted from flank vents on the west flank of the volcano.","Quaternary (Holocene)",null,null,"Adak","Igneous",3050,null]
[305,null,609,"Qhlf1994","AD007","Lava flows of 1994 eruption","Two-pyroxene porphyritic andesite; light to dark gray, unvegetated, fresh.\rPhenocrysts of plagioclase, clinopyroxene, orthopyroxene, and Fe-oxides with trace amounts of olivine and hornblende in a glassy groundmass. Abundant mafic inclusions. Forms block","Quaternary",null,null,"Adak","Igneous",3050,null]
[305,null,610,"Qhlf1906","AD007","Lava flows of 1906 eruption","Two-pyroxene porphyritic andesite; light to dark gray, unvegetated, fresh.\rPhenocrysts of plagioclase, clinopyroxene, orthopyroxene, and Fe-oxides with trace amounts of olivine and hornblende in a glassy groundmass. Abundant mafic inclusions. Forms block","Quaternary",null,null,"Adak","Igneous",3050,null]
[305,null,611,"Qhlfh","AD007","Lava flows formed by historical eruptions","Two-pyroxene porphyritic andesite; light to dark gray, unvegetated, fresh.\rPhenocrysts of plagioclase, clinopyroxene, orthopyroxene, and Fe-oxides with trace amounts of olivine and hornblende in a glassy groundmass. Abundant mafic inclusions. Overlapping","Quaternary",null,null,"Adak","Igneous",3050,null]
[305,null,612,"Qhlf","AD007","Lava flows of Holocene age","Two-pyroxene porphyritic andesite; light to dark gray, unvegetated to sparsely vegetated, fresh. Phenocrysts of plagioclase, clinopyroxene, orthopyroxene, and Fe-oxides with trace amounts of olivine and hornblende in a glassy groundmass. Abundant mafic i","Quaternary",null,null,"Adak","Igneous",3050,null]
[305,null,800,"Qv","AD008","Composite volcanic zone","Composite volcanic zone, currently or recently active.","Quaternary",null,null,"Adak","Igneous",3050,null]
[305,null,302,"Qtecd","KK003","Volcanic dome on flank of East Cape Volcano","Hornblende basalt","Quaternary, Holocene",null,null,"Kiska","Igneous",3050,null]
[305,null,303,"Qtecv","KK003","East Cape Volcanics","Hornblende basalt and basaltic andesite","Quaternary, Holocene",null,null,"Kiska","Igneous",3050,null]
[305,null,500,"Ql","GI005","Lava of 1929 eruption","Lava of 1929 eruption","Quaternary",null,null,"Gareloi Island","Igneous",3050,null]
[305,null,403,"Hv","GI006","Young volcanic rocks, Sajaka, Takawangha, and Tanaga volcanoes","Undivided young volcanic rocks on informally named Sajaka, Tanaga, and Takawangha volcanoes","Quaternary, Holocene",null,null,"Gareloi Island","Unconsolidated",3050,null]
[305,null,203,"Hv","GI006","Younger volcanic rocks, Gareloi volcano","Undivided younger volcanic rocks associated with Gareloi volcano, including historic rocks derived from 1929 eruption","Quaternary, Holocene",null,null,"Gareloi Island","Unconsolidated",3050,null]
[305,null,403,"Hv","AD013","Young volcanic rocks, Sajaka, Takawangha, and Tanaga volcanoes","Undivided young volcanic rocks on informally named Sajaka, Tanaga, and Takawangha volcanoes","Quaternary, Holocene",null,null,"Adak","Unconsolidated",3050,null]
[306,null,407,"Qgd","AD004","Basalt dome","Basalt dome extruded in crater of Great Sitkin Volcano in 1945, as exposed in September 1946.","Quaternary, Holocene",null,null,"Adak","Igneous",3060,"Qbd"]
[306,null,711,"Qld","AD009","Lava domes of Holocene age","Medium to dark gray andesite and basaltic andesite that form resistant knobs and hills on the northwest and east flanks of the volcano. Retain little original surface morphology, and blocky exteriors largely removed by erosion.","Quaternary (Holocene)",null,null,"Adak","Igneous",3060,null]
[310,null,156,"Toc","AD002","Older composite cone, Mt. Adagdak Volcano","Principally hornblende andesite lapilli tuff, but includes some hornblende andesite flows.","Quaternary",null,null,"Adak","Igneous",3100,"Qpd"]
[310,null,409,"Qga","AD004","Ash","Ash, Great Sitkin Volcanics - Probably from flank vent northwest of crater.","Quaternary",null,null,"Adak","Igneous",3100,"Qpd"]
[310,null,433,"Qat","AD005","Andesite tuff","Andesite tuff - Rocks formed at time of caldera.","Quaternary",null,null,"Adak","Igneous",3100,"Qpd"]
[310,null,31,"Qlp","RI002","Lava flows and pyroclastic rocks","Lava flows and pyroclastic rocks - Later than or interbedded with dacite pumice of caldera eruption, largely from Anvil Peak, but also from 914-foot cone near Tuman Head and Threequarter Cone on west rim of caldera.","Late Pleistocene",null,null,"Rat Islands","Igneous",3100,"Qpd"]
[310,null,55,"Qp","RI003","Patterson Point Formation","Dacitic ash and pumice and dacitic and andesitic pyroclastic debris.","Quaternary",null,null,"Rat Islands","Igneous",3100,"Qpd"]
[310,null,704,"Qpf","AD009","Pyroclastic-flow deposits","Moderate to poorly sorted, non-welded, pumice-flow deposits with rounded to subrounded pumice clasts up to 75 cm in diameter. Ash-rich matrix and abundant angular to subangular lithic clasts up to 25 cm in diameter. Deposits in Glacier Creek valley conta","Quaternary",null,null,"Adak","Igneous",3100,null]
[310,null,706,"Qat","AD009","Talus, avalanche debris and tephra","Poorly sorted, loose rock rubble derived from fragmentation of lava flows and ejecta. Also includes variable amounts of reworked lapilli tephra.","Quaternary",null,null,"Adak","Igneous",3100,null]
[310,null,602,"Qhts","AD007","Talus, avalanche debris, and tephra","Loose, accumulations of poorly sorted rock rubble derived from fragmentation of lava flows and ejecta on upper slopes of Kanaga Volcano. Also includes variable amounts of reworked  lapilli tephra. Lower contact gradational.","Quaternary",null,null,"Adak","Igneous",3100,null]
[310,null,608,"Qhpf","AD007","Pyroclastic-flow deposits","Moderate to poorly sorted, pumice- and lithic-bearing gravelly deposits with ash-rich matrix.","Quaternary",null,null,"Adak","Igneous",3100,null]
[311,null,203,"Ql(p)","GI002","Lava of 1929 eruption, pyroclastic deposits","Pyroclastic apron derived from 1929 eruption","Quaternary, Holocene",null,null,"Gareloi Island","Igneous",3110,null]
[311,null,611,"Qp","RI006","Surface pyroclastic deposits, Segula Island","A pyroclastic mantle forms constructional surfaces on much of Segula and possibly Davidof and Khvostof Islands.  Consists of light-gray debris at least 150 feet thick.  Fragments range from fine sand to large blocks of lava several feet across, fragments","Quaternary",null,null,"Rat Islands","Igneous",3111,null]
[311,null,519,"Qptg","AD012","Tephra mantling glacial deposits","Deposits of tephra that overlie morainal deposits. Tephra deposits are the same as those mantling bedrock (Qptb).","Quaternary",null,null,"Adak","Unconsolidated",3111,null]
[311,null,520,"Qptb","AD012","Tephra mantling bedrock","Deposits of tephra that overlie bedrock, but generally do not obscure bedrock topography and structure. Tephra deposits are usually 1.5 to 3.0 m thick and consist of thin beds of fine-grained (mostly silt and clay size particles) ash and 3 to 5 beds of l","Quaternary (Holocene)",null,null,"Adak","Unconsolidated",3111,null]
[311,null,521,"Qptc","AD012","Tephra mantling colluvial deposits","Deposits of tephra that overlie undifferentiated colluvial deposits. Tephra deposits are the same as those mantling bedrock (Qptb).","Quaternary",null,null,"Adak","Unconsolidated",3111,null]
[311,null,522,"Qptbc","AD012","Tephra mantling beach deposits","Deposits of tephra that overlie beach deposits. Tephra deposits are the same as those mantling bedrock (Qptb).","Quaternary",null,null,"Adak","Unconsolidated",3111,null]
[311,null,523,"Qptl","AD012","Tephra mantling lacustrine deposits","Deposits of tephra that overlie lacustrine deposits. Tephra deposits are the same as those mantling bedrock (Qptb).","Quaternary",null,null,"Adak","Unconsolidated",3111,null]
[311,null,524,"Qpta","AD012","Tephra mantling alluvial deposits","Deposits of tephra that overlie undifferenciated alluvial deposits. Tephra deposits are the same as those mantling bedrock (Qptb).","Quaternary",null,null,"Adak","Unconsolidated",3111,null]
[311,null,527,"Qptbbo","AD012","Tephra deposits mantling older boulder beach deposits","Tephra deposits mantling older boulder beach deposits","Quaternary",null,null,"Adak","Unconsolidated",3110,null]
[311,null,528,"Qptbby","AD012","Tephra deposits mantling younger boulder beach deposits","Tephra deposits mantling younger boulder beach deposits","Quaternary",null,null,"Adak","Unconsolidated",3110,null]
[313,null,703,"Ql","AD009","Lahar deposits","Poorly sorted gravel, sand, silt, and boulders in fan-shaped deposits. Present in most major valleys. One to five meters thick. Products of eruptive activity and likely formed when pyroclastic flows and lava flows encountered and mixed with snow or ice o","Quaternary",null,null,"Adak","Igneous",3130,null]
[313,null,606,"Qhla","AD007","Lahar deposits","Poorly-sorted gravel, sand and silt in fan-shaped deposits mainly on the southeast flank of Kanaga Volcano. Products of eruptive activity and likely formed when pyroclastic flows and lava flows encountered and mixed with snow or ice on the upper flanks o","Quaternary",null,null,"Adak","Igneous",3130,null]
[313,null,607,"Qhla","AD007","Pumice-rich lahar deposits","Massive, 10-to-20 meter-thick deposit on southwest side of volcano. Very coarse with cream-colored dacitic pumice clasts to 1 meter diameter and lava clasts 2 to 4 meters diameter. In places, deposit is composed almost entirely of pumice clasts and sandy","Quaternary",null,null,"Adak","Igneous",3130,null]
[313,null,526,"Qpl","AD012","Lahar deposits","Poorly sorted, matrix-supported, angular, cobble and boulder gravel of volcanic origin found on the slopes of Mount Moffett and Mount Adagdak. Matrix consists primarily of silt and fine sand. Coarse clasts are angular to subangular and often exhibit brea","Quaternary",null,null,"Adak","Unconsolidated",3130,null]
[314,null,705,"Qdl","AD009","Debris-avalanche and lahar deposits","Poorly sorted, massive accumulations of volcanic rock rubble, sand and gravel. Associated with the older edifice.","Quaternary",null,null,"Adak","Igneous",3140,null]
[317,null,61,"Qs","RI003","Sitkin Point Formation","Waterlaid pyroclastic material; tuffaceous graywacke, dacite-boulder tuff-breccia, andesitic tuff, and pumiceous tuff.","Quaternary",null,null,"Rat Islands","Igneous",3170,"Qvs"]
[317,"ALT",20061,"Qs","RI003","Sitkin Point Formation","Waterlaid pyroclastic material; tuffaceous graywacke, dacite-boulder tuff-breccia, andesitic tuff, and pumiceous tuff.  Contains areas of kaolinized, silicified, and pyritized rock.","Quaternary",null,null,"Rat Islands","Igneous",3170,"Qvs"]
[317,null,617,"Qs","RI006","Moderately well-bedded volcanic detritus, Segula Island","Unconsolidated, rudely sorted, moderately well-bedded volcanic detritus at least 500 feet thick.  Fragments are compositionally similar to other rocks on the island and range from fine sand to blocks several feet across.  Fragments between one-eighth inc","Quaternary",null,null,"Rat Islands","Igneous",3170,null]
[320,null,171,"Tmt","AD002","Tuff-breccia cone of Mt. Moffett Volcano","Tuff-breccia cone of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",3200,"Qcs"]
[320,null,620,"Qcv","RI006","Surface flows of porphyritic feldspathic basalt, central vent, Segula Island","Central vent form of flows, which are generally dark-gray, glassy or fine-grained, compact or diktytaxitic, all porphyritic and feldspathic.  Flows are 2-pyroxene andesite and olivine basalt and have uneroded flow forms","Quaternary",null,null,"Rat Islands","Igneous",320,null]
[320,null,621,"Qrv","RI006","Surface flows of porphyritic feldspathic basalt, rift vent, Segula Island","Rift vent flows, which are generally dark-gray, glassy or fine-grained, compact or diktytaxitic, all porphyritic and feldspathic.  Flows are 2-pyroxene andesite and olivine basalt and have uneroded flow forms","Quaternary",null,null,"Rat Islands","Igneous",320,null]
[320,null,710,"Qsd","AD009","Spatter and agglutinate deposits","Poorly sorted, oxidized, scoriaceous ejecta, bombs and bomb aggregates on the rim of the summit crater.","Quaternary",null,null,"Adak","Igneous",3200,null]
[320,null,601,"Qhs","AD007","Tephra and spatter from recent eruptions","Mostly coarse near-vent ejecta, including volcanic bombs, blocks, and scoriaceous debris on and around the rim of the modern crater.","Quaternary",null,null,"Adak","Igneous",3200,null]
[330,null,157,"Tmc","AD002","Composite cone of Mt. Moffett Volcano","Composite cone of Mt. Moffett Volcano, principally basalt flows and tuff breccia","Quaternary",null,null,"Adak","Igneous",3300,"Qb"]
[330,null,158,"Tpc","AD002","Composite cone of Parasitic cone of Mt. Moffett Volcano","Composite cone of Parasitic cone of Mt. Moffett Volcano, principally basalt lava flows, but includes subordinate tuff breccia.","Quaternary",null,null,"Adak","Igneous",3300,"Qb"]
[330,null,159,"Tls","AD002","Interbedded basalt lava flows and tuffaceous sandstone","Interbedded basalt lava flows and tuffaceous sandstone","Quaternary",null,null,"Adak","Igneous",3300,"Qb"]
[330,null,716,"Qyb","AD009","Basalt lava flow","Short, stubby flow of dark grey basalt erupted from flank vent at the head of Sitkin Creek.","Quaternary",null,null,"Adak","Igneous",3300,null]
[330,null,501,"Qby","GI005","Younger basalt flows","Younger basalt flows","Quaternary",null,null,"Gareloi Island","Igneous",3300,null]
[335,null,59,"Qe","RI003","East Point Formation","Sequence of andesite and basalt flows.","Quaternary",null,null,"Rat Islands","Igneous",3350,"Qva"]
[335,null,613,"Qholf","AD007","Lava flows of the cone-building sequence","Two-pyroxene porphyritic andesite; light to dark gray, mostly vegetated but not extensively weathered. Phenocrysts of plagioclase, clinopyroxene, orthopyroxene, and Fe-oxides with trace amounts of olivine and hornblende in a glassy groundmass. Abundant m","Quaternary",null,null,"Adak","Igneous",3350,null]
[336,null,49,"Qlw","RI003","Little Sitkin dacite","Sequence of low-silica dacite flows; West Cove member.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qva"]
[336,null,51,"Qls","RI003","LIttle Sitkin dacite","Rhyodacite flow unit.  Low-silica dacite flows with minor amounts of associated pyroclastic material.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qvda"]
[336,null,53,"Qlp","RI003","LIttle Sitkin dacite","Low-silica dacite flows associated with youngest major eruption.  Pratt Point member.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qva"]
[336,null,57,"Qd","RI003","Double Point dacite","Sequence of high-silica dacite flows containing many miarolitic inclusions of labradorite andesite; minor amounts of associated pyroclastic material.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qvda"]
[336,"ALT",20049,"Qlw","RI003","Little Sitkin dacite","Sequence of low-silica dacite flows; West Cove member.  Contains areas of kaolinized, silicified, and pyritized rock.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qva"]
[336,"ALT",20051,"Qls","RI003","LIttle Sitkin dacite","Rhyodacite flow unit.  Low-silica dacite flows with minor amounts of associated pyroclastic material.  Contains areas of kaolinized, silicified, and pyritized rock.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qvda"]
[336,"ALT",20057,"Qd","RI003","Double Point dacite","Sequence of high-silica dacite flows containing many miarolitic inclusions of labradorite andesite; minor amounts of associated pyroclastic material.  Contains areas of kaolinized, silicified, and pyritized rock.","Quaternary",null,null,"Rat Islands","Igneous",3360,"Qvda"]
[350,null,411,"QTgp","AD004","Great Sitkin Volcanics - Basalt (?) plugs","Great Sitkin Volcanics - Basalt (?) plugs","Quaternary or Tertiary",null,null,"Adak","Igneous",3500,"QTb"]
[350,null,435,"QTb","AD005","Basalt flows and tuff breccia","Basalt flows and tuff breccia from ancient vent near west coast.  Rocks older than caldera of Mt. Kanaton","Quaternary or Tertiary",null,null,"Adak","Igneous",3500,"QTb"]
[350,null,501,"QTb","AT003","Basalt porphyry, Shemya Island","Basalt porphyry consisting of two basalt plugs of fine-grained basalt having excellent columnar joints","Tertiary or Quaternary",null,null,"Attu","Igneous",3500,"QTb"]
[355,null,445,"Tb","AD005","Basalt flows and tuff beds","Basalt flows and tuff beds from vent older than Mt. Kanaton near north coast.","Tertiary",null,null,"Adak","Igneous",3550,"Tb"]
[355,null,202,"Qbo","GI002","Older basalt flows","Olivine basalt flows and beds of scoria","Quaternary",null,null,"Gareloi Island","Igneous",3550,null]
[355,null,617,"Tb","AD007","Basalt flows and tuff beds older than Mt. Kanaton volcano","Basalt flows and tuff beds older than Mt. Kanaton volcano (Coats, 1956)","Tertiary",null,null,"Adak","Igneous",3550,null]
[402,null,182,"Tmtv","AD002","Andesite vent filling, tuff-breccia cone of Mt. Moffett Volcano","Andesite vent filling, tuff-breccia cone of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",4020,"Qanp"]
[402,null,186,"Td","AD002","Basalt and andesite domes, Mt. Adagdak Volcano","Basalt and andesite domes","Quaternary",null,null,"Adak","Igneous",4020,"Qanp"]
[402,null,614,"Qhld","AD007","Lava domes","Two-pyroxene silicic andesite lava domes; highly fractured, massive, slab-like, slightly weathered. Round mafic inclusions up to 10 cm across are common. Exposed at west end of intracaldera lake and on island in the lake. Alteration and fractured charact","Quaternary",null,null,"Adak","Igneous",4020,null]
[404,null,361,"Tmd","AD002","Basalt domes of Mt. Moffett Volcano","Basalt domes of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",4040,"Qbd"]
[404,null,183,"Tpd","AD002","Basalt dome of Parasitic cone of Mt. Moffett Volcano","Basalt dome of Parasitic cone of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",4040,"Qbd"]
[404,null,185,"Tpv","AD002","Basalt vent agglomerate of Parasitic cone of Mt. Moffett Volcano","Basalt vent agglomerate associated with fine-grained olivine gabbro plug of Parasitic cone of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",4040,"Qbd"]
[404,null,184,"Tpp","AD002","Olivine gabbro of Parasitic cone of Mt. Moffett Volcano","Fine-grained olivine gabbro plug of Parasitic cone of Mt. Moffett Volcano","Quaternary",null,null,"Adak","Igneous",4040,"Qbd"]
[450,null,107,"QTm","AT002","Massacre Bay Formation","Basaltic and andesitic lava and pyroclastic and coarse clastic rocks","early Pleistocene or Late Tertiary",null,null,"Attu","Igneous",4500,"QTv"]
[450,null,191,"Tav","AD002","Rocks of Andrew Bay volcano","Flows and tuff-breccia of olivine-, hypersthene-, and hornblende-bearing andesite","Tertiary",null,null,"Adak","Igneous",4500,"QTv"]
[450,null,419,"Tsa","AD004","Sand Bay Volcanics - Agglomerate","Agglomerate.  Includes a few thin flows.","Tertiary",null,null,"Adak","Igneous",4500,"Tvu"]
[450,null,435,"Tkb","AD005","Olivine and hypersthene basalt","Olivine and hypersthene basalt and andesite flows of ancient Mt. Kanton.  Rocks older than caldera of Mt. Kanaton.Tkb of Coats","Tertiary",null,null,"Adak","Igneous",4500,"Tb"]
[450,null,443,"Tva","AD005","Agglomerate","Agglomerate in vent older than Mt. Kanaton near north coast.","Tertiary",null,null,"Adak","Igneous",4500,"Tvu"]
[450,null,405,"Qpv","GI005","Precaldera glaciated and dissected remnants of volcanic cones","Precaldera glaciated and dissected remnants of volcanic cones","Quaternary",null,null,"Gareloi Island","Igneous",4500,null]
[450,null,718,"Tsbv","AD009","Sand Bay Volcanics","Undifferentiated agglomerate, pyroclastic rocks, and andesite and basaltic lava flows. The lower part of the sequence consists mostly of pyroclastic rocks with a few thin flows. The upper part of the sequence contains mostly lava flows. These two sequenc","Tertiary",null,null,"Adak","Igneous",4500,null]
[450,null,615,"TQKv","AD007","Mt. Kanaton volcanic rocks","Olivine and hypersthene basalt andesite flows of ancestral Mt. Kanaton volcano (Coats, 1956). Erupted from flank vents on the west flank of the volcano.","Quaternary-Tertiary",null,null,"Adak","Igneous",4500,null]
[450,null,null,"QTb","GI004","Late Tertiary and Quaternary basaltic rocks","Basaltic rocks","Quaternary and Late Tertiary",null,null,"Gareloi Island","Igneous",4500,null]
[450,null,1050,"QTb","AD010","Late Tertiary and Quaternary basaltic rocks","Basaltic rocks","Quaternary and Late Tertiary",null,null,"Adak","Igneous",4500,null]
[451,null,417,"Tsl","AD004","Sand Bay Volcanics-- Lava flows","Principally andesite, but includes a few basalt flows.","Tertiary",null,null,"Adak","Igneous",4510,"Ta"]
[451,null,63,"QTw","RI003","Williwaw Cove Formation","Sequence of andesite and bandaite flows with minor amounts of basalt and dacite flows and major amounts of pyroclastic material.  Dikes of andesite and basalt shown in some areas.","Tertiary or Quaternary",null,null,"Rat Islands","Igneous",4510,"QTv"]
[451,"ALT",20063,"QTw","RI003","Williwaw Cove Formation","Sequence of andesite and bandaite flows with minor amounts of basalt and dacite flows and major amounts of pyroclastic material.  Dikes of andesite and basalt shown in some areas.  Contains areas of kaolinized, silicified, and pyritized rock.","Tertiary or Quaternary",null,null,"Rat Islands","Igneous",4510,"QTa"]
[454,null,437,"QTob","AD005","Olivine basalt flows","Olivine basalt flows from ancient vent near Round Head.  Rocks older than caldera of Mt. Kanaton.","Quaternary or Tertiary",null,null,"Adak","Igneous",4540,"QTob"]
[454,null,616,"QTob","AD007","Olivine basalt of Round Head","Olivine basalt of Round Head (Coats 1956)","Quaternary-Tertiary",null,null,"Adak","Igneous",4540,null]
[460,null,35,"QTp","RI002","Pyroclastic rocks and lava flows","Pyroclastic rocks and lava flows - Crystalline vent plugs of cones.","Quaternary or Tertiary (?)",null,null,"Rat Islands","Igneous",4600,"QTi"]
[462,null,120,"QTqk","AT002","Quartz keratophyre dikes","Quartz keratophyre dikes occur on widely separated parts of Attu Island.  The dikes consists of chalky white euhedral feldspar (albite) crystals and glassy quartz in a bluish-gray to light-gray groundmass, which is a felt of fine-grained albite and quart","Early Quaternary or Late Tertiary",null,null,"Attu","Igneous",4620,"QTqk"]
[463,null,110,"QTha","AT002","Hornblende andesite and dacite, Attu Island","Porphyritic dikes and stocks of hornblende andesite and dacite","Early Quaternary or Late Tertiary",null,null,"Attu","Igneous",4630,"QTad"]
[463,null,503,"QTp","AT003","Hornblende porphyry, Shemya Island","Hornblende porphyry - Includes some porphyry rich in plagioclase phenocrysts.","Tertiary or Quaternary",null,null,"Attu","Igneous",4630,"Qtad"]
[466,null,37,"QTpo","RI002","Pochnoi Volcanics","Pochnoi Volcanics - Tuff-breccia, lava flows, and agglomerate, largely basaltic, of shield-shaped volcano.  Locally sandstone from reworked pyroclastic deposits.","Tertiary (?) or Quaternary",null,null,"Rat Islands","Igneous",4660,"QTvb"]
[466,null,400,"QT","GI005","Interbedded flows, pyroclastic deposits, and sedimentary rocks","Interbedded flows, pyroclastic deposits, and sedimentary rocks, Unalga, Ogliuga, and Skagul Islands","Quaternary or Tertiary",null,null,"Gareloi Island","Igneous",4660,null]
[466,null,802,"QT","AD008","Interbedded flows, pyroclastic deposits, and sedimentary rocks","Interbedded flows, pyroclastic deposits, and sedimentary rocks. Includes fine-grained dikes and sills.","Quaternary-Tertiary",null,null,"Adak","Igneous",4660,null]
[470,null,505,"QTt","AT003","Andesitic and basaltic tuff and tuff-breccia, Shemya Island","Andesitic and basaltic tuff and tuff-breccia","Quaternary or Tertiary",null,null,"Attu","Igneous",4700,"QTva"]
[470,null,33,"QTpl","RI002","Pyroclastic rocks and lava flows","Pyroclastic rocks and lava flows - Listed clockwise from north: North Head Double Cone, Perret Ridge, north tip Fenner Lake, Ragged Top, 1405-foot cone, 1389-foot cone, Tuman Head younger, Tuman Head older.","Quaternary or Tertiary(?)",null,null,"Rat Islands","Igneous",4700,"QTva"]
[475,null,9,"QTk","KK002","Kiska Harbor Formation","Water-laid coarse- to fine-grained pumice and detritus derived from volcanic rock, interbedded with breccia, and flow rock.  Abundance of flow rock increases northward in the area.  One breccia layer, QTkb, and one lava flow, QTkf, are mapped as members","Quaternary and Late Tertiary",null,null,"Kiska","Igneous",4750,"QTk"]
[476,null,11,"QTkb","KK002","Kiska Harbor Formation, breccia member","Breccia layer contained within the Kiska Harbor formation.","Quaternary and Late Tertiary",null,null,"Kiska","Igneous",4760,"QTkb"]
[477,null,13,"QTkf","KK002","Kiska Harbor Formation, flow member","One lava flow within the Kiska Harbor formation.","Quaternary and Late Tertiary",null,null,"Kiska","Igneous",4770,"QTkf"]
[572,null,200,"Tch","AT002","Chuniksak Formation","Fine-grained laminated siliceous, argillitic, and limy marine sedimentary rocks","Tertiary -- Miocene(?)","Mollusks and plants.  Also diatoms and foraminifera.  Best inferred ages are probably Miocene",null,"Attu","Sedimentary",null,"Tta"]
[572,null,507,"Tb","AT003","Basement rocks, Shemya Island","Basement rocks - Siliceous and limy argillite and conglomerate; includes some tuff-breccia.","Tertiary",null,null,"Attu","Sedimentary",null,"TMzf"]
[610,null,210,"Tc","AT002","Chirikof Formation","Conglomerate, sandstone, carbonaceous shale, and possibly one lava flow; small outcrop on Chirikof Point.  May be same age as Nevidiskov Formation","middle Tertiary -- Miocene(?)","Plants -- leaves in coaly beds, similar species to Chuniksak Formation, hence probably Miocene",null,"Attu","Sedimentary",null,"Tu"]
[650,null,220,"Tn","AT002","Nevidiskov Formation","Coarse graywacke and conglomerate","Tertiary -- early Miocene(?) or late Oligocene(?)","Single indeterminate Pecten",null,"Attu","Sedimentary",null,"Th"]
[750,null,65,"Tg","RI004","Gunners Cove Formation","Tuffaceous conglomerate and sandstone, crystal-vitric basaltic tuff, thin basalt flows, and basaltic dikes.  Unit age revised to late Eocene or Oligocene, (Carr and others, 1970, RI007)","Tertiary, Oligocene or early Miocene","Barnacles, crinoids, echinoids, and pectens.  Crinoid Isocrinus aff. I. oregonensis (Moore and Volkes) and pecten Chlamys aff. C. washburnei Arnold of probable middle Tertiary age.",null,"Rat Islands","Sedimentary",null,"Tgc"]
[751,null,506,"Tbp","RI005","Banjo Point Formation","Sandstone, conglomerate, tuffaceous shale, and lapilli tuff of basaltic composition.  Bedded nearshore marine deposits containing sparse fauna of middle Tertiary age, Amchitka Island. Unit definition and age revised to late Eocene or Oligocene, (Carr and","Tertiary","36 species of Formas and poorly preserved mollusks suggest a late Oligocene or early Miocene age.",null,"Rat Islands","Sedimentary",null,null]
[751,null,706,"Tb","RI007","Banjo Point Formation","Bedded marine sandstone, conglomerate, tuffaceous shale, and lapilli tuff of basaltic composition.  Carr and others (1970) slightly revised the unit and the defined outcrop area and indicated that minor pillow lava was present in the unit","Tertiary, Oligocene or late Eocene",null,null,"Rat Islands","Sedimentary",null,null]
[800,null,401,"Ts","GI005","Altered tuffaceous sedimentary beds with some coarse pyroclastic deposits","Altered tuffaceous sedimentary beds with some coarse pyroclastic deposits with fine-grained dikes and sills and coarse-grained dikes.  Rocks are composed of volcanic debris; are dark-gray, greenish-gray, olive-green, bluish-gray, and light brown tuffaceo","Tertiary",null,null,"Gareloi Island","Sedimentary",null,null]
[800,null,1100,"Tal","AD011","Andrew Lake Formation","Tuffaceous sandstone and siltstone and siliceous and cherty shale interbedded with  mafic flows or penecontemporaneous sills.  \"Graded sandstone beds as much as 0.3-m-thick are common and alternating beds of sandstone and shale, ***, form graded sequence","Tertiary, late Eocene","Fossils reported to be Annularia stellata of Pennsylvanian or Permian age along with mollusks, fish skeletal remains and scales, foraminifera, dinoflagellates, and pectens, all others of Eocene age",null,"Adak","Sedimentary",null,null]
[860,null,null,"MZg","GI004","Graywacke and graywacke breccia","Graywacke and graywacke breccia","Mesozoic",null,null,"Gareloi Island","Sedimentary",null,null]
[1010,null,19,"Ti","KK002","Dikes and intrusive rocks","Dikes and small intrusive bodies are related to both the Kiska Harbor and Vega Bay Formations.  Relation not differentiated.","Tertiary",null,null,"Kiska","Igneous",null,"Thf"]
[1011,null,527,"Tp","AT004","Dacite porphyry","Dacite porphyry","Tertiary",null,null,"Attu","Igneous",null,"Thf"]
[1012,null,1012,"d","AD003","Andesite and dacite","Andesite and dacite, probably includes basalt in small dikes and sills.  Generally altered.  Includes some dikes older than unit gd","Tertiary?",null,null,"Adak","Igneous",null,"Thf"]
[1012,null,441,"Tbd","AD005","Basalt dome","Basalt dome.  Rocks older than caldera of Mt. Kanaton.","Tertiary",null,null,"Adak","Igneous",null,"Thm"]
[1012,null,457,"Tp","AD006","Porphyritic andesite sills","Porphyritic andesite sills","Tertiary",null,null,"Adak","Igneous",null,"Thf"]
[1012,null,459,"Tab","AD006","Andesite and basalt dikes","Andesite and basalt dikes","Tertiary",null,null,"Adak","Igneous",null,"Thm"]
[1012,null,305,"Tab","GI003","Andesite or basalt dikes, Kavalaga Island","Andesite or basalt dikes","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1012,null,312,"Tab","GI003","Intrusive rocks, andesite or basalt dikes, Ogliuga and Skagul Islands","Andesite or basalt dikes","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1012,null,313,"Tpi","GI003","Intrusive rocks, Ogliuga and Skagul Islands","Intrusion of porphyritic andesite, irregular shape, with feldspar and hornblende conspicuous","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1050,null,504,"QTc","RI005","Chitka Point Formation, Amchitka Island","Flows, flow breccias, and dikes of porphyritic andesite and feldspathic basalt, in part interbedded with marine conglomerate, in part with subaerial deposits, Amchitka Island.  Thickness exceeds 1000 feet.  Conglomerate confined to lower part of unit.  U","Quaternary(?) or middle or late Tertiary","Conglomerate contains carbonized frangments of woody material",null,"Rat Islands","Igneous",null,null]
[1050,null,704,"Tc","RI007","Chitka Point Formation","Subaerial hornblende- and pyroxene-andesite flows, breccia, tuff, and conglomerate on the northwestern 2/3 of Amchitka Island","Tertiary, Miocene, probably late to middle",null,null,"Rat Islands","Igneous",null,null]
[1051,null,311,"Ta","AD002","Andesite porphyry domes","Includes andesite porphyry, dacite porphyry, hornblende basalt porphyry, quartz-hornblende basalt porphyry, and hornblende-biotite basalt porphyry","Tertiary",null,null,"Adak","Igneous",null,"Tab"]
[1066,null,451,"Tt","AD006","Extrusive rocks, tuff dominant","Extrusive rocks, tuff dominant","Tertiary",null,null,"Adak","Igneous",null,"Tvu"]
[1066,null,453,"Ttb","AD006","Extrusive rocks, tuff-breccia dominant","Extrusive rocks, tuff-breccia dominant","Tertiary",null,null,"Adak","Igneous",null,"Tvu"]
[1066,null,455,"Tvl","AD006","Extrusive rocks, lava dominant","Extrusive rocks, lava dominant","Tertiary",null,null,"Adak","Igneous",null,"Ta"]
[1066,null,309,"Tvl","GI003","Lavas and pyroclastic deposits, predominantly lava and flow breccia","Predominantly lava and flow breccia, but includes minor pyroclastic deposits on Ogliuga and Skagul Islands","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,null,310,"Tvp","GI003","Lavas and pyroclastic deposits, predominantly pyroclastic deposits","Predominantly pyroclastic deposits; tuff and breccia, but includes minor sedimentary rocks, lava and flow breccia, Ogliuga and Skagul Islands","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,null,311,"Tvu","GI003","Lavas and pyroclastic deposits, undifferentiated","Lavas and pyroclastic deposits, undifferentiated, along untraversed coastline on Ogliuga and Skagul Islands","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,"ALT",402,"Tp","GI005","Altered pyroclastic deposits and pillow lavas with minor sedimentary beds","Altered pyroclastic deposits and pillow lavas with minor sedimentary beds, with fine-grained dikes and sills, Ulak Island","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,null,301,"Tvl","GI003","Lavas and pyroclastic deposits, predominantly lava and flow breccia","Predominantly lava and flow breccia, but includes minor pyroclastic deposits on Kavalga Island","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,null,302,"Tvp","GI003","Lavas and pyroclastic deposits, predominantly pyroclastic deposits","Predominantly pyroclastic deposits; tuff and breccia, but includes minor sedimentary rocks, lava and flow breccia, Kavalga Island","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1066,null,304,"Tvu","GI003","Lavas and pyroclastic deposits, undifferentiated","Lavas and pyroclastic deposits, undifferentiated, along untraversed coastline on Kavalga Island","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1080,null,17,"Tv","KK002","Vega Bay Formation","Marine deposits of volcanic breccia, tuff, and a few pillow lava flows, all of basaltic composition, with a few interbeds of conglomerate and sandstone of similar material.","Middle Tertiary",null,null,"Kiska","Igneous",null,"Tpb"]
[1081,null,336,"PPaf","AD002","Finger Bay Volcanics","Finger Bay Volcanics of Adak and Kagalaska Islands (Fraser and Snyder, 1959).  Unit mapped as Paleozoic by Coats (1956), since revised.  Consists of basalt and hornblende basalt tuff, flow breccia, agglomerate, and basalt dikes, and subordinate rhyolite","Permian and Pennsylvanian",null,null,"Adak","Igneous",null,"Tvb"]
[1081,null,3336,"fb","AD003","Finger Bay Volcanics","Finger Bay Volcanics of Adak and Kagalaska Islands (Fraser and Snyder, 1959).  Unit mapped as Paleozoic by Coats (1956), since revised.  Consists of altered andesite and basaltic pyroclastic deposits and lavas: minor amounts of pillow lava, volcanic wack","Tertiary",null,null,"Adak","Igneous",null,"Tvb"]
[1081,"HFS",337,"mr","AD003","Finger Bay Volcanics, mixed rocks","Mixed rocks of the Finger Bay Volcanics intimately injected by Miocene(?) granodiorite, quartz diorite, and gabbro on Kagalaska Island (Fraser and Snyder, 1959).","Tertiary",null,null,"Adak","Igneous",null,"Tvb"]
[1081,null,421,"PlPf","AD004","Finger Bay Volcanics, undifferentiated","Finger Bay volcanics - Undifferentiated flows, flow breccia, tuff, and dikes.","Permian (?) or Pennsylvanian (?)",null,null,"Adak","Igneous",null,"Tvb"]
[1081,null,67,"Tr","RI004","Rat Formation","Rat Formation - Flows and flow breccias of porphyritic andesite, and minor amounts of conglomerate composed of andesitic debris.","Tertiary",null,null,"Rat Islands","Igneous",null,"Tvb"]
[1081,null,507,"a","RI005","Amchitka Formation, Amchitka Island","Volcanic agglomerate, tuff-breccia, tuff, and pillow lave flows of andesitic to latitic composition.  Tilted, jointed, and slightly metamorphosed in many areas.  Thickness several thousand feet","early Tertiary or older",null,null,"Rat Islands","Igneous",null,null]
[1081,null,719,"Tfbv","AD009","Finger Bay Volcanics","Undifferentiated andesite and basalt lava flows, flow breccia, tuff and dikes. Deformed and altered to greenstone. See Coats, 1956 for additional information.","Tertiary",null,null,"Adak","Igneous",null,null]
[1081,null,1081,"Tb","AD010","Early Tertiary basaltic rocks","Basaltic rocks","Early Tertiary",null,null,"Adak","Igneous",null,null]
[1081,null,null,"Tb","GI004","Early Tertiary basaltic rocks","Basaltic rocks","Early Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1081,null,null,"PPaf","GI004","Finger Bay Volcanics","Basaltic rocks, argillite, and graywacke","Paleozoic",null,null,"Adak","Igneous",null,null]
[1081,null,707,"Tak","RI007","Amchitka Formation, pillow lavas and breccias of Kirilof Point","Glassy, generally monolithologic breccia, and tuff breccia, subordinate pillow lava, and very minor bedded volcsanic sedimentary rocks probably deposited in a submarine environment.  Less mafic than other rocks on Amchitka Island, as felsic as latite","Tertiary, Oligocene or late Eocene",null,null,"Rat Islands","Igneous",null,null]
[1081,"ALT",708,"Tao","RI007","Amchitka Formation, older breccias","Coarse to fine-grained sedimentary breccia and minor interbedded sandstone, siltstone, and claystone composed of volcanic debris; generally propolitically altered.  May be as much as 4,000 feet thick, although estimated is considered high.","Tertiary, Oligocene or late Eocene",null,null,"Rat Islands","Igneous",null,null]
[1094,null,513,"TMzkb","AT004","Krugoli Formation - lava","Lava; chiefly basaltic and spilitic.","Late Mesozoic or Early Tertiary",null,null,"Attu","Igneous",null,"Tpb"]
[1095,null,515,"TMzkt","AT004","Krugoli Formation, tuff and tuff-agglomerate.","Krugoli Formation, tuff and tuff-agglomerate.","Late Mesozoic or Early Tertiary",null,null,"Attu","Igneous",null,"TMza"]
[1096,null,320,"TMzv","AT002","Basement rocks -- volcanic rocks","Volcanic rocks, including basaltic, spilitic, and keratophyric lava and tuff.  Pillow lava very common.","Early Tertiary or Late Mesozoic",null,"A series of radiometric dates were done on samples from the original mapping in the mid-1970's.  Ages typically were no older that 30 Ma, Oligocene","Attu","Igneous",null,"Tpb"]
[1096,null,521,"TMzl","AT004","Basement rocks - Agattu","Basement rocks - lava","Late Mesozoic or Early Tertiary",null,null,"Attu","Igneous",null,"TMzl"]
[1096,null,523,"TMzt","AT004","Basement rocks - Agattu","Basement rocks - tuff and tuff-agglomerate","Late Mesozoic or Early Tertiary",null,null,"Attu","Igneous",null,"TMzt"]
[1203,null,250,"Tgr","AT002","Albite granite","Albite granite.  It occurs in irregular masses at Steller Cove and as a small stock east of Mikhail Point.  The granite is gray, pale-pink, or purplish and has widely varying grain size.  Locally euhedral gray-green feldspar (albite) phenocrysts up to 5","Tertiary",null,null,"Attu","Igneous",null,"Tagr"]
[1207,null,230,"Td","AT002","Diabase and gabbro dikes, sills and small plutons","Diabase and gabbro dikes, sills and small plutons, Attu Island","Tertiary",null,null,"Attu","Igneous",null,"Tgb"]
[1207,null,364,"PPag","AD002","Gabbro","Gabbro intruding Finger Bay volcanics of Adak Island (Fraser and Snyder, 1959).  Unit mapped as Paleozoic by Coats (1956), since revised.  Consists of gabbro, locally including hornblende gabbro and augite-quartz syenite","Permian and Pennsylvanian",null,null,"Adak","Igneous",null,"Tgb"]
[1207,null,529,"Td","AT004","Diabase and gabbro","Diabase and gabbro, Agattu Island","Tertiary",null,null,"Attu","Igneous",null,"Tgb"]
[1207,null,15,"Tg","KK002","Gabbro","Medium- to coarse-grained intrusive gabbro and related rock types.","Middle Tertiary",null,null,"Kiska","Igneous",null,"Tgb"]
[1250,null,365,"gd","AD003","Granodiorite, quartz diorite, and gabbro","Granodiorite, quartz diorite, and gabbro in stocks, sills, and dikes.  Younger plutons","Tertiary",null,"K-Ar dates 10-13 Ma","Adak","Igneous",null,"Ti"]
[1250,null,403,"Ti","GI005","Granodiorite and quartz diorite","Granodiorite and quartz diorite, Ilak and Amatignak Islands, includes andesite dikes on Ilak Island","Tertiary",null,null,"Gareloi Island","Igneous",null,null]
[1250,null,505,"Tqd","RI005","Quartz diorite, Amchitka Island","Medium-grained quartz diorite and related rock in dikes, sillls, and a small stock.  Intrudes Amchitka and Banjo Point Formations","Tertiary",null,"Reported K-Ar age on biotite of 15.8 Ma (Marlow and others, 1973)","Rat Islands","Igneous",null,null]
[1250,null,null,"gr","GI004","Granite?","Granite?","Paleozoic",null,null,"Gareloi Island","Igneous",null,null]
[1292,null,370,"gd","AD003","Granodiorite, quartz diorite, and gabbro","Granodiorite, quartz diorite, and gabbro in stocks, sills, and dikes.  Older plutons","Tertiary",null,"K-Ar dates in the range of 30-33 Ma","Adak","Igneous",null,"Toem"]
[1530,null,511,"TMzk","AT004","Krugoli Formation, undifferentiated - Agattu","Undifferentiated; includes bedded argillite, siltstone, and chert.","Late Mesozoic or Early Tertiary",null,null,"Attu","Sedimentary",null,"TMzf"]
[1540,null,517,"TMzkc","AT004","Krugoli Formation - conglomerate Agattu","Conglomerate.","Late Mesozoic or Early Tertiary",null,null,"Attu","Sedimentary",null,"TMzc"]
[1550,null,519,"TMzu","AT004","Basement rocks - Agattu","Basement rocks - undifferentiated","Late Mesozoic or Early Tertiary",null,null,"Attu","Igneous",null,"TMzu"]
[1552,null,300,"TMzf","AT002","Basement rocks - fine-grained banded sedimentary rocks - Attu","Fine-grained thin-bedded, sedimentary rocks, chert silicious siltstone, argillite, limestone, and fine tuffaceous graywacke.  Some graded beds.  Turbidite characteristics, evidence of soft-sediment deformation","Early Tertiary or Late Mesozoic","Undetermined Foraminifera, diatoms, and radiolaria",null,"Attu","Sedimentary",null,"TMzf"]
[1553,null,310,"TMzc","AT002","Basement rocks - coarse-grained and conglomeratic sedimentary rocks - Attu","Coarse graywacke and conglomerate, interbedded with pillow lavas, pyroclastic rocks, and fine siliceous rocks.","Early Tertiary or Late Mesozoic","Undetermined Foraminifera, diatoms, and radiolaria",null,"Attu","Sedimentary",null,"TMzc"]
[1553,null,525,"TMzc","AT004","Basement rocks - Agattu","Basement rocks - conglomerate, argillite, siltstone, and chert.","Late Mesozoic or Early Tertiary",null,null,"Attu","Sedimentary",null,"TMzs"]