Triassic-Jurassic stratigraphy, San Ysidro area, Sandoval County, New Mexico
— Spencer G. Lucas, [ed.]

Abstract—Triassic and Jurassic strata are prominently exposed by faults and folds in the nexus of the San Ysidro area in Sandoval County, New Mexico. The Triassic strata are assigned to the Middle Triassic Moenkopi Formation overlain by the Upper Triassic Chinle Group, a section of mostly siliciclastic red beds about 582 m thick. The Jurassic strata are assigned to the (ascending) Middle Jurassic Entrada and Todilto, Middle-Upper Jurassic Summerville, and Upper Jurassic Morrison Formations—a section about 416 m that that records eolian, lacustrine, evaporitic, coastal plain, and fluvial deposition. The Triassic-Jurassic strata of the nexus are a characteristic section of these strata on and along the edge of the southern Colorado Plateau.