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
Brazos Island Brazos Island Brazos Island, also known as Brazos Santiago Island, is a barrier island on the Gulf Coast of Texas in the United States, south of the town of South Padre Island. The island is located in Cameron County. The island is also known as Brazos Santiago Island, a reference to the port of Brazos Santiago, the first Spanish settlement on the island. Later it became the Port of Matamoros. With a draft of 31 feet, it was perhaps the best naturally occurring seaport in the Western Gulf of Mexico. No one knows who named this excellent seaport, but many