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
Hole in the Rock (rock formation) Hole in the Rock (rock formation) Hole in the Rock is a narrow and steep crevice in the western rim of Glen Canyon, in southern Utah in the western United States. Together with another canyon on the eastern side of the Colorado River, it provided a route through what would otherwise be a large area of impassable terrain. In the fall of 1879, the Mormon San Juan Expedition was seeking a route from south-central Utah to their proposed colony in the far southeastern corner of the state. Rejecting two longer routes, they chose a more direct path that initially took