Rio Brazos (New Mexico) abruptly west into the Brazos Box, one of the largest canyons in New Mexico with a maximum depth of more than . Here, it passes the Brazos Cliffs, receives Gavilan and Encinado Creeks, and picks up an unnamed tributary which feeds Brazos Falls, reputedly New Mexico's highest waterfall with a total drop of . Northeast of Tierra Amarilla, the river emits from the mountains, receiving Chavez Creek from the right. It passes the settlements of Ensenada, Brazos and Los Ojos before flowing into the Rio Chama about northwest of Santa Fe. The Brazos is a perennial stream, reaching its highest
Organ Rock Formation seymouriamorph found in the Organ Rock Formation. "Seymouria sanjuanensis" is a unique taxon because of its extensive geographic range. This particular animal was first described by Vaughn (1966) from the Organ Rock Formation. Since this initial find, a number of these individuals have been recovered from localities as distant as Germany. Four early synapsid taxa are present within the Organ Rock Formation. These include Ophiacodon, as well as three sphenacodontids: "Ctenospondylus", "Dimetrodon", and "Sphenacodon ferocior". Most taxa are known from fragmentary material. Early synapsids were dominant members of the terrestrial Permian ecosystem. Some early synapsids adapted an herbivorous diet, however,