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
Madder Cliffs colony of about 22,000 pairs of Adélie penguins which nest on exposed knolls and ridges above the beach. Other birds nesting at the site in smaller numbers include gentoo penguins, kelp gulls and snowy sheathbills. Madder Cliffs The Madder Cliffs are reddish rock cliffs which form the north side of the entrance to Suspiros Bay, at the west end of Joinville Island, Antarctica. They rise steeply from the sea to about . The cliffs were surveyed by the Falkland Islands Dependencies Survey in 1953–54. The name, given in 1956 by the UK Antarctic Place-Names Committee, is descriptive of the red