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
Starved Rock State Park the National Register it had been determined that there were three "village and mound" sites within the park. Besides Corbin Farm and Little Beaver, the Simonson site, an open-air occupation site, is also considered a village and mound site. Simonson Site has faced significant alterations over the years Approximately 150 different types of plants grow at Starved Rock State Park. On the sandstone cliffs of Starved Rock State Park white pine, Canada yew and northern white cedar are found; these plants are more commonly found further north. On the surfaces of the canyons and cliffs, where it is cooler, other