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
Raven Rocks (rock formation) Gap. The formation is often referred to as "the rollercoaster" by Appalachian Trail hikers as the trail undulates between these spurs and hollows along the western face of the mountain along this stretch of the ridge. The peak is notable for the Crescent Rock cliffs. The Appalachian Trail crosses the saddle of the ridge. Raven Rocks (rock formation) Raven Rocks is spur of Blue Ridge Mountain in Jefferson County, West Virginia. The peak is located just north of Jefferson County's border with Clarke County, Virginia and west of its border with Loudoun County, Virginia. Raven Rocks is formed by the