It is subdivided into four members (below), whose sediments are thought to have eroded from the rising Uinta Mountains to the north and deposited in river, floodplains and small lakes.

Volcanic ash in the formation, derived from volcanoes in the Wasatch Range, East Tintic, and Oquirrh Mountains to west, have provided radiometric dates.

Minor beds of green-gray to red brown, silty to sandy, thin to very thin bedded, poorly sorted claystone, red brown, thin-bedded, nodular, poorly sorted mudstone, yellow brown, very thin bedded, nodular, poorly sorted, horizontally stratified siltstone, and red-purple, sandy, clayey, thin-bedded, medium to coarse crystalline limestone.

acer CopeMammalia LagomorphaMytonolagus petersoni BurkeRodentiaLeptotomus kayi Burke ?Sciuravid or Myomorph sp.

Consists of pale red, olive gray to yellow brown, coarse, medium, fine to very fine grained, thin-, thick to very thick bedded, massive, moderately to poorly sorted sandstone that may be horizontally or cross stratified and red, gray to brown, very thin, thin- to thick-bedded, moderately to poorly sorted claystone that may be nodular, micaceous, or laminated.

CarnivoraEosictis avinoffi ScottPerissodactylaEpihippus (Duchesnehippus) intermedius PetersonLapoint Member: Named for the town of Lapoint, Uintah County.

Consists of: 1) red- to yellow-brown, light gray, gray- to yellow-orange, pale red to gray red sandstone that ranges from coarse, medium, fine to very fine grained, thin, thick to very thick bedded, sandy, silty, to clayey, cross-stratified to horizontally stratified, flaggy, blocky, massive, brown-gray, gray-red to olive, sandy to silty; 2) very thin bedded, poorly sorted, platy, laminated, nodular to massive claystone; and 3) gray red, sandy, poorly sorted, thin-bedded, nodular, massive siltstone.