The up to 600 metres (2,000 ft) thick formation comprises sandstones, siltstones, mudstones and conglomerates with gypsum layers deposited in a fluvial to lacustrine environment.

The formation is known for its fossils of early dinosaurs, including the coelophysoid Zupaysaurus and the "prosauropods" Coloradisaurus, Lessemsaurus, and Riojasaurus.

[2] Los Colorados Formation is a unit with an approximate thickness of 600 metres (2,000 ft) of the Agua de la Peña Group in the Ischigualasto-Villa Unión Basin, where it is exposed in the Ischigualasto Provincial Park, a World Heritage Site in Argentina.

The formation comprises red-colored, fine- to medium-grain–size sandstones together with siltstones and ancillary floodplain mudstones with early calcisol development.

[2] Palaeochersis P. talampayensis Indeterminate theropod remains present in the Provincia de la Rioja.