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Mineral Resources > Online Spatial Data > Geology > by state > Idaho Geology

Geologic units in Latah county, Idaho

[Additional scientific data in this geographic area]

Monzogranite, granodiorite, syenite, monzodiorite, monzonite, and diorite; Eocene phaneritic to porphyro-aphanitic intrusions (subunits are Teif and Teii); northern Idaho to central Idaho (Eocene) at surface, covers < 0.1 % of this area

Eocene intrusions including large granitic plutons and dike swarms of central Idaho

Lithology: granite; quartz monzodiorite; granodiorite

Basalt lava flows; Middle Miocene flood-basalt flows of subunit 2b; Columbia Plateau (Miocene) at surface, covers 7 % of this area

Miocene basalt flows of western Idaho; commonly finely crystalline and exposed on upper slopes.

Lithology: basalt; lava flow

Quaternary nonmarine deposits (Pleistocene) at surface, covers < 0.1 % of this area

Periglacial eolian deposits. Buff to light-brown, massive, homogenous, unconsolidated loessial silt; some water-laid material locally. Probably early Pleistocene.

Lithology: loess; glaciolacustrine

Gravel, sand, and silt; Quaternary; alluvium (Quaternary) at surface, covers 2 % of this area

Quaternary alluvium; may contain some glacial deposits and colluvium in uplands

Lithology: alluvium; alluvial terrace; floodplain; alluvial fan; colluvium

Monzogranite, syenogranite, and syenite; Eocene phaneritic to porphro-aphanitic intrusions of the pink monzogranite suite; Challis magmatic belt (Eocene) at surface, covers 0.4 % of this area

Eocene intrusions of predominantly felsic (pink granite) composition

Lithology: granite; quartz syenite

Syenite, monzonite, quartz syenite; Late to Early Cretaceous syenitic intrusions; northern Idaho (Cretaceous) at surface, covers 0.4 % of this area

Cretaceous syenitic to monzonitic intrusions

Lithology: syenite; monzonite; quartz syenite; alkali syenite

Mica schist, quartzite, gneiss, and amphibolite; Late to Early Proterozoic high-grade metasedimentary rocks (subunits are ZXmhs, ZXmhq, and ZXmhc); trans-Idaho metamorphic province (Proterozoic) at surface, covers < 0.1 % of this area

Precambrian high-grade metamorphic rock; metasediment

Lithology: mica schist; quartzite; calc-silicate rock; paragneiss; amphiibolite

Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits (Miocene) at surface, covers 1 % of this area

Miocene stream and lake deposits; generally associated with volcanic episodes.

Lithology: tuff; arkose; claystone; conglomerate; siltstone; mixed clastic/coal

Intrusive rocks: mostly Late Cretaceous granodioritic to granitic plutons of the Idaho batholithic assemblage, but including some Eocene intrusions; northern Idaho and Atlanta batholith (Cretaceous to Eocene) at surface, covers 20 % of this area

Cretaceous plutons; probably includes unmapped older and younger crystalline bodies.

Lithology: granodiorite; peraluminous granite; quartz monzonite; quartz diorite; tonalite; trondhjemite; pegmatite; alkali-granite (alaskite)

Basalt flows and incidental andesite, and latite flows; Miocene mafic to intermediate volcanics; subunits are Tmib, Tm1b, Tm2b, Tm3b; Columbia Plateau, Owyhee Plateau (Miocene) at surface, covers < 0.1 % of this area

Miocene plateau basalt flows of western Idaho; subdivisions are (Tm3b, Tm2b, Tm1b).

Lithology: basalt; latite; lava flow

Gravel, sand, and clay; Quaternary-Tertiary colluvium and fanglomerate; western Idaho (Pleistocene and Pliocene) at surface, covers 0.2 % of this area

Pleistocene and Pliocene fanglomerate, colluvium, and poorly sorted gravel deposits.

Lithology: alluvial fan; colluvium; residuum; gravel; clay or mud; sand; silt

Intermediate intrusions; mostly Late Cretaceous dioritic to granodioritic plutons of the Idaho batholithic assemblage (Cretaceous) at surface, covers 0.2 % of this area

Cretaceous plutons; intermediate; as granodiorite or diorite; probably includes unmapped older and younger crystalline bodies.

Lithology: tonalite; granodiorite; quartz diorite; trondhjemite

Quartzite, mica schist, and calc-silicate rock; Proterozoic high-grade metasedimentary rocks; trans-Idaho metamorphic province (Proterozoic) at surface, covers 0.6 % of this area

Precambrian, high-grade metamorphic rock; metasediments; kyanite-sillimanite schist, and micaceous quartzite

Lithology: quartzite; mica schist; calc-silicate rock

Precambrian rocks, undivided (Proterozoic) at surface, covers < 0.1 % of this area

Predominantly phyllite with some schist, limestone, dolomite, quartzite, and volcanic rocks; northeastern Pend Oreille County. Mainly quartzite sandstone in upper part, dark-gray argillite with sandstone and limestone in middle part, and sandstone with argillite in lower part; southeastern Pend Oreille County. Banded slate with quartzite and dolomite; southwestern Stevens County. Quartzite, siliceous argillite, and argilliceous quartzite grading into argillite and quartz-mica schists form south ot north; southeastern Stevens County. Quartzite, argillite, quartz-feldspar gneiss, and other metamorphic rocks in northeastern Whitman and southeastern Spokane Counties are partly if not all extenstions of the Belt strata.

Lithology: argillite; siltstone; quartzite; dolostone; phyllite; limestone; gneiss; schist; sandstone

Basalt dikes; Miocene basaltic feeder dikes of subunit ib; Columbia Plateau (Miocene) at surface, covers < 0.1 % of this area

Miocene intrusions including basalt feeder dikes and sills of western Idaho.

Lithology: basalt

Mica schist, quartzite, and calc-silcicate rock; Proterozoic high-grade metasedimentary rocks; trans-Idaho metamorphic province (Proterozoic) at surface, covers 15 % of this area

Precambrian high-grade metamorphic rock; metasediment; kyanite-sillimanite calc-silicate schist and gneiss, scapolite common

Lithology: mica schist; quartzite; calc-silicate rock

Argillite, siltite, and quartzite; Middle Proterozoic Ravalli Group; northern Belt Province (Middle Proterozoic) at surface, covers 1 % of this area

Intermediate Precambrian sediments, multicolored siltite and argillite overlying quartzite and siltite of northern Idaho.

Lithology: meta-argillite; siltstone; quartzite

Basalt lava flows; Middle to Late Miocene local basalt flows of subunit 3b; Columbia Plateau (Late Miocene) at surface, covers < 0.1 % of this area

Upper Miocene valley-filling basalt flows of western Idaho.

Lithology: basalt; lava flow

Argillite, siltstone, quartzite, and dolostone; Middle Proterozoic Missoula Group; northern Belt province (Middle Middle Proterozoic) at surface, covers 14 % of this area

Intermediate Precambrian sediments, light-colored siltite overlying multicolored fine-grained detrital beds of northern Idaho.

Lithology: meta-argillite; siltstone; quartzite; dolostone (dolomite); limestone

Miocene volcanic rocks (Middle Miocene) at surface, covers < 0.1 % of this area

Dark-gray to black, dense aphanitic basalt flows; commonly columnar jointed, less commonly irregularly and platy jointed; some flows vesicular, grading to scoriaceous; includes minor pillow lava, palagonite beds, and interbedded soil profiles and sedimentary beds; contains diatomite beds locally. Maximum thickness in south-central Washington may be in excess of 10,000 feet; much thinner in western Washington, where flows are mostly associated with marine sedimentary rocks. Includes acidic and intermediate volcanic rocks in northern Cascade Mountains.

Lithology: tholeiite; andesite; dacite; rhyolite; sandstone; siltstone; conglomerate

Rhyolite, andesite, dacite, quartz latite; Oligocene to Eocene volcanics; northern Idaho; (Paleogene, possibly Oligocene) at surface, covers 1 % of this area

Lower Tertiary, possibly Oligocene, flows and tuffs of northern Idaho.

Lithology: rhyolite; andesite; ignimbrite; lava flow; volcanic breccia (agglomerate)

Silt; Pleistocene wind-blown loess dunes; northwestern Idaho, Palouse Hills (Pleistocene) at surface, covers 33 % of this area

Pleistocene wind-blown loess of northern Idaho.

Lithology: loess

Siltite, argillite, dolostone, and quartzite; Middle Proterozoic Wallace Formation; northern Belt province (Early Middle Proterozoic) at surface, covers 4 % of this area

Intermediate Precambrian sediments, dark-colored calcareous and dolomitic argillite and siltite of northern Idaho.

Lithology: siltstone; meta-argillite; dolostone (dolomite); quartzite

Mesozoic granitic rocks, undivided (Mostly Cretaceous-Jurassic) at surface, covers < 0.1 % of this area

Granite, quartz monzonite, quartz diorite, granodiorite, and trondhjemite. Includes diorite in southeastern Washington; diorite and gabbro near Concunully in Okanogan County; gneiss, schist, and migmatites in areas of Chelan, Colville, and Okanogan batholiths. Includes high-grade metamorphic rocks of Precambrian age in Spokane area.

Lithology: granite; granodiorite; quartz monzonite; tonalite; orthogneiss; trondhjemite; quartz diorite; diorite; gabbro; schist; migmatite; syenite

Peraluminous monzogranite, granodiorite, pegmatite, aplite, and migmatite; mostly Cretaceous intrusions of the Kaniksu batholithic assemblage, but with minor Eocene intrusions, undivided; northern Idaho (Cretaceous to Eocene) at surface, covers < 0.1 % of this area

Cretaceous plutons; felsic; as granite or quartz monzonite; probably includes unmapped older and younger crystalline bodies.

Lithology: peraluminous granite; granodiorite; granitoid; pegmatite; aplite; migmatite; orthogneiss

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Mostly unconsolidated silt, sand, and gravel valley fill with some clay; includes low-level terrace, marsh, peat, artificial fill, and glacial deposits locally.

Lithology: alluvium; alluvial terrace; peat; glacial drift