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
Straight Cliffs Formation fossils from the Straight Cliffs Formation document a diverse assemblage of therian mammals. The Tibbet Canyon Member contains sharks’ teeth from marine deposits rare mammal fossils from deltaic deposits. Recovered fossils include sharks, rays, lepisosteid fishes, crocodyliforms, and fragmentary marsupial mammal teeth. The Smoky Hollow Member also contains a variety of sharks, amphibians, reptiles, snakes, crocodyliforms, and dinosaurs. The member also contains multituberculate and marsupial mammals. The John Henry Member contains more brackish and marine fauna, as well as mammals and other terrestrial species which are less common. The Drip Tank Member is primarily fluvial and consequently only water worn