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
White Cliffs of Dover White Cliffs of Dover The White Cliffs of Dover, part of the North Downs formation, is the name given to the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint. The cliffs, on both sides of the town of Dover in Kent, stretch for eight miles (13 km). A section of coastline encompassing the cliffs was purchased by the National Trust in 2016. The cliffs are part of the Dover to Kingsdown Cliffs Site