A few small exposures of tuffaceous Oligocene sediments are exposed along the eastern flank of the Toiyabe and central Shoshone Ranges where they are 32.4-30 Ma, based upon K-Ar dating of surrounding tuffs (Stewart and McKee, 1977). Tuffaceous siltstone, sandstone, conglomerate, and air-fall tuffs were deposited in small-unconnected lacustrine basins making correlation of units between basins impossible. Rapid facies changes from sediments into ignimbrites make correlations within basins difficult (Stewart and McKee, 1977).

In the Grant and Quinn Canyon Ranges the Oligocene Blind Spring Formation is about 700 feet of shale, limestone lenses, and green and red conglomerate and sandstone derived from the Oligocene Railroad Valley Rhyolite (Kleinhampl and Ziony, 1985).

In the Duckwater Hills, and along the southern and eastern margins of Little Smoky Valley, small outcrops of porcelaneous bedded tuff and light-gray tuffaceous sandstone, and reddish limestone conglomerate are tentatively assigned an Oligocene age. They may in part represent local Eocene strata correlative with the Sheep Pass Formation. To the east in the Park Range, grayish-orange to pink siliceous siltstone, shale, conglomerate and fine-grained sandstone are also considered Oligocene in age (Kleinhampl and Ziony, 1985).

In the Hot Creek Range, unnamed Oligocene sediments are composed of yellowish and greenish, tuffaceous, locally laminated, fine to coarse grained sandstone, siltstone, and mudstone which are intercalated with various rhyolite and rhyodacite flows. These sediments attain a thickness of 300 feet (Quinlivan and Rogers, 1974). Brown and gray, medium to thick bedded, chert pebble and cobble conglomerate are exposed in the Morey Peak area of the northern Hot Creek Range. These sediments are also considered Oligocene in age. Most of the Oligocene sediments exposed in the Hot Creek Range are assigned to the Gilmore Gulch Formation, which is described below.