[2][3] The formation was deposited by high-energy streams on a muddy floodplain that was the last preserved sedimentation episode in the San Juan Basin.

[4] The basal Cuba Mesa Member is found throughout the depositional basin and is a coarse-grained sheet sandstone.

[4] The mudstone beds of the San Jose Formation are locally rich in fossils.

Instead, he headed south to explore the area north of the San Pedro Mountains, where fossils had been reported.

Simpson visited the same area and assigned the fossil beds to the San Jose Formation.