New Mexico Geology

Hogbacks of the upper Oligocene to middle Miocene Hayner Ranch Formation, located adjacent to San Diego Mountain and along the southern flank of the Tonuco uplift in northern Doña Ana County, New Mexico. As much as 1.1 km in total thickness, only 150–200 m in the middle part of the formation is exposed here. At this location, the formation consists of interbedded mid and distal alluvial fan deposits, derived from a nascent Caballo uplift and deposited in the "early rift" Hayner Ranch half graben. Ridge on left skyline is approximately 35–40 m high; Sierra de las Uvas on the far skyline. View looks southwest.