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

Geologic units in Cassia county, Idaho

Tertiary (4) sedimentary rocks in western Utah (Middle Miocene to Late Pliocene) at surface, covers < 0.1 % of this area

Lithology: coarse-grained mixed clastic; alluvium; pyroclastic; basalt; evaporite

Coralline Limestone, sandstone, siltstone, shale, chert, and phosphorite; Mississippianshallow marine inner continental-shelf deposits; east-central Idaho, central Idaho (Mississippian ) at surface, covers 0.2 % of this area

Mississippian shallow-water coralline limestone interval of southern Idaho.

Lithology: limestone; sandstone; siltstone; shale; chert; phosphorite

Limestone, arenite, dolostone, chert, siltstone, shale; Upper Paleozoic marine continental-shelf deposits; southeastern Idaho (Late Paleozoic) at surface, covers 0.6 % of this area

Upper Paleozoic marine sediments in southern Idaho.

Lithology: limestone; arenite; dolostone (dolomite); chert; siltstone; shale

Sand; Holocene dunes; Snake River Plain (Holocene) at surface, covers < 0.1 % of this area

Recent active sand dunes and eolian deposits.

Lithology: dune sand; eolian

Gravel, sand, and silt; glacial outburst flood deposits, outwash, fanglomerate, and alluvium, undivided; Pleistocene (Pleistocene) at surface, covers 1 % of this area

Pleistocene outwash, fanglomerate, flood and terrace gravels; sudivisions are: (Qpug, Qpmg, and Qplg).

Lithology: stratified glacial sediment; alluvium; outwash; alluvial fan; alluvial terrace

Shale, limestone, and sandstone; Triassic marine to non-marine epicontinental deposits (subunits are TRl and TRu) (Triassic) at surface, covers < 0.1 % of this area

Triassic shallow-marine to non-marine sediments of eastern Idaho; subdivisions are (TRu and TRl).

Lithology: shale; limestone; sandstone; chert; conglomerate

Silt, clay, sand, and gravel; Quaternary-Tertiary alluvial and lacustrine deposits; western Snake River Plain (Early Pleistocene and Late Pliocene) at surface, covers 0.2 % of this area

Pleistocene and Pliocene stream and lake deposits.

Lithology: lake or marine deposit (non-glacial); alluvium; silt; clay; sand; gravel

Clastic debris; Quaternary colluvium, fanglomerate, talus, and glacial deposits; upland-valley margins (Quaternary) at surface, covers 11 % of this area

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

Lithology: alluvium; glacial drift; colluvium

Limestone, sandstone, shale, and chert; Pennsylvanian marine epicontinental-basin deposits; southeastern Idaho (Pennsylvanian) at surface, covers 1 % of this area

Pennsylvanian beds; lowermost portion of the southern Idaho sequence (PPNs).

Lithology: limestone; sandstone; shale; chert

Chert, shale, phosphorite, and carbonates; Permian restricted marine epicontinental-basin deposits; southeastern Idaho (Permian) at surface, covers 2 % of this area

Permian phosphatic sandstone, mudstone and chert of east-central Idaho.

Lithology: chert; shale; phosphorite; dolostone (dolomite); arenite; limestone

Granodiorite and muscovitic monzogranite; Oligocene Almo pluton; south-central Idaho, Albion Range metamorphic core complexIdaho (Oligocene) at surface, covers 0.5 % of this area

Oligocene granodiorite to muscovite pegmatite, pegmatitic granite, and mylonitized granitic injection gneiss

Lithology: granodiorite; peraluminous granite

Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits (Miocene) at surface, covers 0.6 % of this area

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

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

Siltstone, sandstone, and dolostone; Early Permian marine epicontinental-basin deposits; southeastern Idaho (Early Permian) at surface, covers 2 % of this area

Lower Permian beds; uppermost portion of the southern Idaho sequence (PPNs).

Lithology: siltstone; arenite; dolostone (dolomite)

Quaternary alluvium and colluvium (Quaternary) at surface, covers < 0.1 % of this area

Lithology: alluvium; colluvium

Tertiary (4) sedimentary rocks in northwestern Utah (Middle Miocene to Late Pliocene) at surface, covers < 0.1 % of this area

Lithology: mudstone; sandstone; conglomerate

Moenkopi Formation, Thaynes Formation, and related rocks (Early Triassic to Middle Triassic) at surface, covers < 0.1 % of this area

MOENKOPI FORMATION, THAYNES FORMATION, AND RELATED ROCKS (Lower Triassic)-Marine deposits of siltstone, limestone, and sparse conglomerate

Lithology: shale; limestone; siltstone; sandstone; gypsum; dolostone (dolomite); conglomerate

Siltstone, shale, and limestone; Early Triassic marine to non-marine epicontinental deposits; southeastern Idaho (Early Triassic) at surface, covers 0.4 % of this area

Lower Triassic shallow-marine to non-marine sediments; limestone and chert above shaley sandstone, siltstone, and limestone of eastern Idaho.

Lithology: siltstone; shale; limetstone; chert; dolostone (dolomite)

Gravel, sand, and silt; Quaternary; alluvium (Quaternary) at surface, covers 6 % of this area

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

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

Basalt flows (Late Miocene to Middle Miocene) at surface, covers < 0.1 % of this area

BASALT FLOWS

Lithology: basalt

Dolostone, limestone, sandstone, shale, and conglomerate; Devonian marine continental-shelf deposits; east-central and southeastern Idaho (Devonian) at surface, covers < 0.1 % of this area

Devonian bedded dolomite and limestone interval of eastern and southern Idaho.

Lithology: dolostone (dolomite); limestone; sandstone; shale; conglomerate

Basalt and gravel; Late Pleistocene basalt flows and interlayered gravel of subunit 2b; Snake River Plain (Late Pleistocene) at surface, covers 4 % of this area

Upper Pleistocene Snake Plain basaltic lava flows, unit 2.

Lithology: tholeiite; lava flow; gravel

Welded and nonwelded silicic ash-flow tuffs (Middle Miocene to Late Miocene) at surface, covers < 0.1 % of this area

WELDED AND NONWELDED SILICIC ASH-FLOW TUFFS-Locally includes thin units of air-fall tuff and sedimentary rock

Lithology: rhyolite

Limestone, sandstone, dolostone, and chert; Permian to Pennsylvanian marine epicontinental-basin deposits; southeastern Idaho; (Early Permian to Early Pennsylvanian) at surface, covers 4 % of this area

Lower Permian to Lower Pennsylvanian chert, limestone, and sandstone of southern Idaho; subdivisions are (Ps, and PNs).

Lithology: limestone; sandstone; dolostone (dolomite); chert; siltstone; shale

Sandstone, conglomerate, siltstone, tuff, claystone, limestone, and diatomite; Pliocene tuffaceous alluvial and lacustrine deposits; Snake River Plain and vicinity, southeastern Idaho (Pliocene ) at surface, covers 5 % of this area

Pliocene stream and lake deposits; may be due to volcanic and block-faulting events.

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

Pennsylvanian and Permian sedimentary rocks in northwestern Utah (Pennsylvanian to Permian) at surface, covers < 0.1 % of this area

Lithology: limestone; sandstone

Older Quaternary alluvial deposits (Quaternary) at surface, covers < 0.1 % of this area

Lithology: alluvium

Glacial debris; Late Pleistocene glacial till, outwash, and alluvium of continental glaciers; northern Idaho (Late Pleistocene ) at surface, covers 2 % of this area

Pleistocene till, moraines and similar unsorted glacial debris.

Lithology: till; outwash; alluvium

Gravel, sand, and silt; Quaternary basin-filling alluvium; Snake River Plain, Basin and Range provinces (Quaternary) at surface, covers 25 % of this area

Quaternary detritus; generally basin-filling deposits of central and southern Idaho.

Lithology: alluvium; alluvial fan; alluvial terrace

Open Water (Holocene) at surface, covers 0.4 % of this area

Lakes and streams

Lithology: water

Tuffaceous sedimentary rocks (Late Eocene to Late Miocene) at surface, covers < 0.1 % of this area

TUFFACEOUS SEDIMENTARY ROCKS-Locally includes minor amounts of tuff

Lithology: sandstone; limestone; siltstone; conglomerate; mudstone; dolostone (dolomite); felsic volcanic rock; intermediate volcanic rock; mafic volcanic rock; tuff

Rhyolite, quartz latite, and latite ignimbrites and flows; Miocene felsic volcanics; Owyhee Plateau; (Miocene) at surface, covers 16 % of this area

Miocene silicic flows, tuffs; most common in southwestern Idaho.

Lithology: rhyolite; latite; quartz latite; ignimbrite; lava flow

Rhyolite ot trachyte ignimbrites and flows; Pliocene felsic volcanics; eastern Snake River Plain and vicinity (Pliocene) at surface, covers < 0.1 % of this area

Pliocene silicic welded tuff, ash, and flow rock; most common in southwestern Idaho.

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

Dolostone, limestone, arenite, chert, and conglomerate; Ordovician marine continental-shelf deposits; southeastern Idaho (Ordovician) at surface, covers 1 % of this area

Ordovician marine dolomite, quartzite, and limestone; subdivisions are (Ou and Ol).

Lithology: dolostone (dolomite); limestone; arenite; chert; conglomerate

Clay, silt, sand, and gravel; Late Pleistocene glacial-lake sediments; Basin and Range province (Late Pleistocene) at surface, covers 1 % of this area

Pleistocene glacial-lake, ponded-water, and shoreline sediments.

Lithology: glaciolacustrine; silt; sand; gravel

Quartzite, mica schist, and marble; Cambrian and Late Proterozoic metasedimentary rocks; south-central Idaho, Albion-Range metamorphic core complex (Cambrian to Late Proterozoic) at surface, covers 2 % of this area

Schist, quartzite and other metasediments of probable Lower Ordovician to Cambrian age.

Lithology: quartzite; mica schist; marble

Basalt flows, pumice, and tuff; Early Pleistocene to Pliocene basaltic volcanics; Snake River Plain (Early Pleistocene) at surface, covers 5 % of this area

Lower Pleistocene to Pliocene basalts with associated tuffs and volcanic detritus.

Lithology: tholeiite; lava flow; pumice; tuff

Basalt flows, pyroclastic debris, clastic sediments, and diatomite; Pliocene basaltic volcanics and clastic sediments; Snake River Plain and vicinity (Pliocene) at surface, covers 0.1 % of this area

Pliocene olivine basalt flows and associated tuff and detritus of southern Idaho.

Lithology: basalt; lava flow; tuff; mixed clastic/volcanic

Surficial sediments; Quaternary alluvial, lacustrine, eolian, and glacial-outwash deposits, undivided; Snake River Plain, and Basin-and-Range provinces (Quaternary) at surface, covers 4 % of this area

Quaternary surficial cover; Snake Plain stream, lake, wind and glacial-flood mantle.

Lithology: loess; colluvium

Orthogneiss, mica schist, and amphibolite; Early Proterozoic to Late Archean metamorphic rocks; south-central Idaho; Albion Range metamorphic core complex (Early Proterozoic to Late Archean) at surface, covers 1 % of this area

Precambrian, high-grade metamorphic rock; metasediment subdivisions are (PC3, PC2, PC1).

Lithology: orthogneiss; mica schist; amphibolite

Migmatite, or injection gneiss; Oligocene granite in Late Proterozoic metasedimentary rocks; south-central Idaho, Albion Range metamorphic core complex (Oligocene and Cambrian to Late Proterozoic, mixed) at surface, covers 0.5 % of this area

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

Lithology: migmatite