Brazos Mountains to 55 million years ago during the Laramide orogeny. To the east and northeast lie the Sangre de Cristo Mountains which share a similar geological history. The Brazos Cliffs, which form a dramatic backdrop to Tierra Amarilla, are formed of Precambrian quartzite. Brazos Mountains The Brazos Mountains is a range in far northern Rio Arriba County, in northern New Mexico in the southwestern United States. A high crest runs from the border with Colorado for over in a south-southeasterly direction. The high point of the range at is on Grouse Mesa, at the Brazos Benchmark. Two miles (3 km) to
Roan Cliffs Roan Cliffs The Roan Cliffs are a series of desert mountains and cliffs in eastern Utah and western Colorado, in the western United States that are distinct from (but closely associated with) the Book Cliffs. While Roan Cliffs are "remote and inaccessible", the Book Cliffs run along the edge of the Castle, Gunnison, and Grand valleys and are therefore readily visible from populated areas (i.e., Price and Green River in Utah and Grand Junction in Colorado) and well traveled transportation corridors (i.e., I‑70, US‑6, US‑50, and US‑191). As such the Book Cliffs are much better known than the Roan Cliffs.