Pliocene olivine basalt flows and associated tuff and detritus of southern Idaho.
Upper Pleistocene Snake Plain basaltic lava flows, unit 4.
Miocene silicic flows, tuffs; most common in southwestern Idaho.
Recent, relatively unweathered Snake Plain basalt flows and cinder cones.
Upper Pleistocene Snake Plain basaltic lava flows, unit 1.
Upper Pleistocene Snake Plain lava flows; local stratigraphic position shown by (Qpu4b, Qpu3b, Qpu2b, Qpu1b).
Middle Pleistocene plateau and canyon-filling basalt in and near Snake Plain.
Upper Pleistocene Snake Plain basaltic lava flows, unit 2.
Quaternary alluvium; may contain some glacial deposits and colluvium in uplands
Pleistocene and Pliocene stream and lake deposits.
Pliocene stream and lake deposits; may be due to volcanic and block-faulting events.
Lower Pleistocene to Pliocene basalts with associated tuffs and volcanic detritus.
Middle Pleistocene lava-dammed Snake Plain lake beds of silt, clay and diatomite.
Pleistocene outwash, fanglomerate, flood and terrace gravels; sudivisions are: (Qpug, Qpmg, and Qplg).
Quaternary colluvium, fanglomerate, and talus plus some glacial debris in upland valleys.
Upper Pleistocene deposits; outwash, fanglomerate, flood and terrace gravels.
Eocene mixed silicic and basaltic volcanic ejecta, flows and reworked debris.