the bajada colorada formation, first defined by roll in 1939, pertains to the mendoza group. it overlies the quintuco and picún leufú formations and is overlain by the agrio formation. the contact with the agrio formation is discordant and the unconformity has been dated to 134 ma. the formation is laterally equivalent with the mulichinco formation. the formation comprises red and greenish-brown, fine to coarse grained conglomerates and thick-bedded sandstones with well developed bands of light brown siltstones and reddish, pinkish grey and purple-reddish claystones. the formation was deposited in a fluvial environment, and the paleoenviroment resembled a braided river system with well-preserved channels and paleosols.