<Li> Quartermaster Formation: Permian in age, this comprises the red, lower slopes of the Canyon . This layer was deposited in a shallow marine environment that alternated with dry tidal flats, indicated by ripple marks and gypsum evaporite deposits, respectively . </Li> <Li> Tecovas Formation: Part of the Dockum Group with the Trujillo Formation, this multicolored Triassic unit consists of shale, siltstone, and sandstone . Deposited in streams and swamps, its colors indicate varying oxidizing conditions, and the alternating dry / wet cycles typical of such environments . These rocks are fossiliferous, containing the remains of phytosaurs, amphibians, and fish . </Li> <Li> Trujillo Formation: This Triassic formation is harder than the underlying Tecovas, and forms many of the Canyon's ledges . Composed of coarse sandstone, river cross-bedding indicates deposition in a stream environment . Fossils are rare . </Li> <Li> Ogallala Formation: This late Miocene to early Pliocene unit forms the cliffs and ledges at the very top of the canyon . Composed of sandstone, siltstone, and conglomerate eroded from a late Cenozoic uplift of the Rocky Mountains, it is separated from the lower Trujillo Formation by a disconformity, and a very long hiatus. The coarse, porous sedimentary units of the Ogallala Formation comprise the Ogallala Aquifer, which has historically functioned as a major source of drinking water for much of the High Plains . Fossils of saber - toothed cats (Smilodon), bone - crushing dogs (Borophagines), mastodons, horses, long - necked camels (Aepycamelus), rhinoceroses, and tortoises are present in the Ogallala . </Li>

What county is palo duro canyon state park in