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 water snake Brazos water snake The Brazos water snake ("Nerodia harteri" ), also called commonly Harter's water snake, is a species of mostly aquatic, nonvenomous snake in the family Colubridae. The species is endemic to Texas in the United States. "N. harteri" is found only in central Texas in the Brazos River system. The preferred habitat of "N. harteri" is rocky areas along the Brazos River. Due to its limited range, "N. harteri" is considered to be a threatened species in the State of Texas. The specific name or epithet, "harteri", is in honor of American amateur herpetologist Philip Harter, who collected