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 are known to contain marine invertebrate fauna because the Smoky Hollow and Drip Tank Member were deposited in terrestrial settings. The Tibbet Canyon Member was initially dated based a middle Turonian index fossil "Inoceramus howelli" which indicates the "Prionocyclus hyatti" ammonite zone. A variety of invertebrate fossils have been found in the John Henry Member including the ammonite "Baculites codyensis" and the bivalve "Endocostea baltica". Analysis of foraminifera and ostracods has helped refine depositional environment interpretations for a variety of shallow marine sub-environments such as lagoons, bays, and estuaries Vertebrate fossils have been found throughout the Straight Cliffs Formation. The