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
Raven Rocks (rock formation) Gap. The formation is often referred to as "the rollercoaster" by Appalachian Trail hikers as the trail undulates between these spurs and hollows along the western face of the mountain along this stretch of the ridge. The peak is notable for the Crescent Rock cliffs. The Appalachian Trail crosses the saddle of the ridge. Raven Rocks (rock formation) Raven Rocks is spur of Blue Ridge Mountain in Jefferson County, West Virginia. The peak is located just north of Jefferson County's border with Clarke County, Virginia and west of its border with Loudoun County, Virginia. Raven Rocks is formed by the