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 County, Texas Brazos County, Texas Brazos County ( ) is a county located in the U.S. state of Texas. As of the 2010 census, its population was 194,851. The county seat is Bryan. Along with Brazoria County, the county is named for the Brazos River, which forms its western border. The county was formed in 1841 and organized in 1843. Brazos County is part of the Bryan-College Station, Texas Metropolitan Statistical Area, which consists of Bryan, College Station, and smaller cities and towns in Brazos, Burleson, and Robertson counties. In 1837 most of the area of present-day Brazos County was included in