The Los Esteros Member is interpreted as a lacustrine deposit in lakes that formed due to local subsidence from dissolution of underlying Permian salt beds.

[3] The Los Esteros Member has yielded fossils of the fern Cynepteria lasiophora, the cycad Zamites powelli, the conifer Pelourdea pleoensis, the gymnosperm Dinophyton spinusos, and seeds (Samaropsis).

[4] This member also includes a microvertebrate site in Santa Fe County, New Mexico that has yielded a diverse fossil assemblage.

Reptiles include Trilophosaurus, indeterminate phytosaurs, Desmatosuchus haplocerus, Stagonolepis wellesii, several new aetosaurs, Chatterjeea elegans, Hesperosuchus, and Parrishia mcreai.

[7] The formation was first named as the Santa Rosa Sandstone by N.H. Darton in July 1919 but the report was not published until 1922.