Los Colorados Formation is a unit with an approximate thickness of 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 gradually overlies the
Ischigualasto Formation and is unconformably overlain by the
Cretaceous Cerro Rajado Formation. The formation comprises red-colored, fine- to medium-grain–size
sandstones together with
siltstones and ancillary
floodplain mudstones with early
calcisol development. The formation was deposited in a
fluvial to
lacustrine environment. ==Fossil content==