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 River nutrient loads, high bacterial and salinity levels and low dissolved oxygen. These water quality issues can be attributed to livestock, fertilizer and chemical run off. Sources of run off are croplands, pastures, and industrial sites among others. Fracking is also cause for concern regarding water quality within the Brazos Watershed. The Barnett Shale lies partially within the watershed which is the second largest source of natural gas in the US. Studies have shown that the watershed receiving the most toxic pollution is the lower Brazos river which received 33.4 million pounds of toxic waste in 2012. Canoeing is a very