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
Fossil Beach (Sedbury Cliffs) examples in the bulk of the mudstone: the cliffs are easily weathered, with parts subject to notable expansion and contraction, Sedbury Cliffs and the foreshore contain similar geological layering to the more famous and visible Aust Cliff the on the opposite site of the River Severn. However, at Sedbury the cliffs are wooded at the top and overgrown with bushes and trees at the base, with fallen blocks and old trunks amongst them. Farther along the beach from the grass, sandstone blocks become more common. The highest rock layer is the brown rocks of the Blue Lias formation, which was