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

Geologic units in Clearwater county, Idaho

[Additional scientific data in this geographic area]

Tertiary volcanic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Tertiary volcanic rocks: Flows and associated pyroclastic deposits, with subordinate amounts of intercalated sedimentary beds and lignite. The volcanic material is mostly latite, quartz latite, and andesite but includes some rhyolite and basalt. The distinction between Tertiary and pre-Tertiary volcanic rocks was not made in some of the reports used in the complilation. Hence in the less well-known areas some pre-Tertiary volcanic rocks may be included.

Lithology: volcanic rock (aphanitic); mixed clastic/volcanic; coal

Rhyolite ignimbrites, latite and basalt lava flows, late Eocene rhyolitic ignimbrite cauldron complex; east-central Idaho, northern Challis volcanic field (Eocene) at surface, covers 0.4 % of this area

Eocene mixed silicic and basaltic volcanic ejecta, flows and reworked debris.

Lithology: rhyolite; latite; ignimbrite; lava flow; mixed clastic/volcanic; basalt

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

Wallace formation (Proterozoic | Mesoproterozoic) at surface, covers < 0.1 % of this area

Wallace formation: A heterogeneous unit that includes dark-gray argillite, arenaceous and argillaceous limestone, in part dolomitic, and gray limy quartzite, with shale and sandstone in large areas. The argillaceous and sandy or quartzitic rocks are commonly slightly calcareous. The dominantly carbonate-rich rocks contain "molar tooth" or segregation structures. Commonly characterized by thin laminae. Locally red rocks near the top may represent a transition into the Missoula group.

Lithology: meta-argillite; carbonate; quartzite

Silt; Pleistocene wind-blown loess dunes; northwestern Idaho, Palouse Hills (Pleistocene) at surface, covers 0.6 % of this area

Pleistocene wind-blown loess of northern Idaho.

Lithology: loess

Metamorphosed granodiorite, quartz monzonitek tonalite, quartz diorite; mostly Cretaceous orthogneiss and migmatite; northern and Atlanta batholith; margins of Bitterroot and Atlanta batholiths (Cretaceous) at surface, covers 0.8 % of this area

Metamorphosed granitic intrusive rock; associated with pluton margins and stress areas.

Lithology: granodiorite; quartz monzonite; tonalite; quartz diorite; orthogneiss; migmatite

Quartzite and muscovite schist; Middle Protrerozoic metasedimentary rocks of the Ravalli Group; northern Belt province (Middle Proterozoic) at surface, covers 3 % of this area

Intermediate Precambrian age metasediments; dominantly quartzite with minor micaceous layers and mica schists of northern Idaho.

Lithology: quartzite; mica schist

Idaho batholith and associated masses (Phanerozoic | Mesozoic Cenozoic | Cretaceous-Late Tertiary) at surface, covers < 0.1 % of this area

Idaho batholith and associated masses: faintly gneissic quartz monzonite, granodiorite, and similar rocks. The extreme eastern part of the Idaho batholith extends into Ravalli County, Mont. This and nearby masses of similar rocks are shown as associated with the Idaho batholith and designated Ki. Future studies may show that some granitoid masses further east are also allied to the Idaho batholith or that a few of the masses now grouped with that batholith are younger. Precise dating is impossible at present.

Lithology: granitoid

Basalt, andesite, diorite, lamprophyre intrusions; Tertiary to Cretaceous, undivided; northern Idaho, central Idaho (Cretaceous or Eocene) at surface, covers < 0.1 % of this area

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

Lithology: gabbro; diabase; diorite; lamprophyre

Garnet-mica schist, gneiss, and quartzite; Proterozoic high-grade metasedimentary rocks; trans-Idaho metamorphic province (Late to Early Proterozoic) at surface, covers 0.1 % of this area

Precambrian high-grade metamorphic rock; metasediment; Kyanite-sillimanite-garnet-mica schist and gneiss; minor quartzite

Lithology: mica schist; paragneiss; quartzite; orthogneiss

Amphibolite after gabbro, diabase, and diorite; Middle Proterozoic sill-like intrusions; southern and northern Belt provinces (Middle Proterozoic) at surface, covers < 0.1 % of this area

Younger or Intermediate Precambrian age intrusive rock undifferentiated; Intrusive rock of eastern Idaho; appears older than Cretaceous, possibly Precambrian; Highly metamorphosed rock of central Idaho; age and origin of rock questionable.

Lithology: amphibolite; gabbro; diabase; diorite

Open Water (Holocene) at surface, covers 1 % of this area

Lakes and streams

Lithology: water

Tuffaceous shale, sandstone, conglomerate, and lignite; Eocene to Pliocene alluvial and lacustrine deposits; central and southern Idaho (Tertiary) at surface, covers < 0.1 % of this area

Tertiary continental sediments; predominantly Upper Tertiary in age; subdivisions are:(Tpd, Tmd, and Ted).

Lithology: shale; sandstone; conglomerate; tuff; siltstone; lignite; bentonite; claystone; limestone

Basalt lava flows; Early Miocene valley-filling basalt flows of subunit 1b; Columbia Plateau (Miocene) at surface, covers 0.4 % of this area

Miocene basalt flows of western Idaho; commonly porphyritic and exposed on lower slopes.

Lithology: tholeiite; lava flow

Schist, phyllite, quartzite, and calc-silicate rock; Middle Proterozoic metasedimentary rocks of Wallace Formation; northern Belt province (Middle Proterozoic) at surface, covers 10 % of this area

Intermediate Precambrian age metasediments; generally low-to-medium grade; carbonate bearing argillite and siltite of northern Idaho.

Lithology: mica schist; phyllite; quartzite; calc-silicate rock

Garnet-sillimanite-biotite schist; Middle Proterozoic Prichard Formation, northern Belt province (Early Middle Proterozoic) at surface, covers 7 % of this area

Precambrian high-grade metamorphic rock; metasediment; kyanite-sillimanite-garnet-mica coarse-grained schist and gneiss; minor quartzite

Lithology: schist; gneiss; quartzite

Anorthosite (folded sill-like intrusive or metasomatic bodies); Middle Proterozoic; northern Idaho, Boehls Butte metamorphic core complex (Middle Proterozoic) at surface, covers 0.8 % of this area

Highly metamorphosed, probably Precambrian, intrusive rock; anorthosite common

Lithology: anorthosite

Mica schist, quartzite, and calc-silcicate rock; Proterozoic high-grade metasedimentary rocks; trans-Idaho metamorphic province (Proterozoic) at surface, covers 16 % 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

Basalt lava flows; Middle to Late Miocene local basalt flows of subunit 3b; Columbia Plateau (Late Miocene) at surface, covers 0.6 % of this area

Upper Miocene valley-filling basalt flows of western Idaho.

Lithology: basalt; lava flow

Gravel, sand, and clay; Quaternary-Tertiary colluvium and fanglomerate; western Idaho (Pleistocene and Pliocene) at surface, covers 10 % 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 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 1 % of this area

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

Lithology: quartzite; mica schist; calc-silicate rock

Clastic debris; Quaternary colluvium, fanglomerate, talus, and glacial deposits; upland-valley margins (Quaternary) at surface, covers 0.2 % of this area

Quaternary colluvium, fanglomerate, and talus plus some glacial debris in upland valleys.

Lithology: alluvium; glacial drift; colluvium

Quartz diorite, tonalite, granodiorite, orthogneiss, migmatite; Cretaceous to Jurassic quartz dioritic plutons; western Idaho, Blue Mountains island-arc complex (Early Cretaceous to Late Jurassic) at surface, covers 1 % of this area

Lower Cretaceous to Upper Jurassic intrusions in west-central Idaho.

Lithology: quartz diorite; tonalite; granodiorite; orthogneiss; migmatite; gabbro; trondhjemite; aplite

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

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)

Gabbroic intrusions; probably Cretaceous; mostly satellitic to the Idaho batholith (Cretaceous ) at surface, covers < 0.1 % of this area

Cretaceous plutons; basaltic or mafic; as gabbro; probably includes unmapped older and younger crystalline bodies.

Lithology: gabbro

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 1 % of this area

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

Lithology: granite; quartz monzodiorite; granodiorite

High-grade metasedimentary biotite schist, biotite gneiss, and calc-silicate gneiss; Middle Proterozoic northern Belt province near Idaho batholith (Middle Proterozoic) at surface, covers 6 % of this area

Precambrian high-grade metamorphic rock; kyanite-sillimanite calc-silcate bearing schist and gneiss; scapolite common

Lithology: mica schist; paragneiss; calc-silicate rock

Basalt lava flows; Middle Miocene flood-basalt flows of subunit 2b; Columbia Plateau (Miocene) at surface, covers 6 % of this area

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

Lithology: basalt; lava flow

Monzogranite, syenogranite, and syenite; Eocene phaneritic to porphro-aphanitic intrusions of the pink monzogranite suite; Challis magmatic belt (Eocene) at surface, covers 9 % of this area

Eocene intrusions of predominantly felsic (pink granite) composition

Lithology: granite; quartz syenite

Gravel, sand, and silt; Quaternary; alluvium (Quaternary) at surface, covers < 0.1 % of this area

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

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