Nacimiento Formation Nacimiento Formation The Nacimiento Formation is a sedimentary rock formation found in the San Juan Basin of western New Mexico (United States) and named for the Nacimiento Mountains. It is a heterogeneous nonmarine formation composed of shale, siltstone, and sandstone, deposited in floodplain, fluvial and lacustrine settings, and made up of sediment shed from the San Juan uplift to the north and the Brazos-Sangre de Cristo uplift to the east. It was deposited mostly between ~64.5 and ~61 million years ago, during the early and middle Paleocene. The climate was humid and warm to hot. This unit interbeds with the
Devil's Backbone (rock formation) Devil's Backbone (rock formation) Devil's Backbone is a rock formation and peninsula formed by the flow of Fourteen Mile Creek into the Ohio River, and is currently situated in Charlestown State Park near Charlestown, Indiana and across the Ohio River from Louisville, Kentucky. According to local legend, on this bedrock ridge once stood a stone fortress that was built by Welsh explorers led by Prince Madoc sometime in the 12th century. The Backbone is believed to have been formed by the processes of glaciation where a combination of ice sheet advances, meltwater flows and a diversion of the Ohio River