The Brazos Mountains is a range in far northern

Rio Arriba County Rio Arriba County () is a List of counties in New Mexico, county in the U.S. state of New Mexico. As of the 2020 United States census, 2020 census, the population was 40,363. Its county seat is Tierra Amarilla, New Mexico, Tierra Amarilla. Its ...

, in northern

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

in the southwestern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. The range is part of the

Tusas Mountains The Tusas Mountains are a mountain range in northern New Mexico, extending slightly into southern Colorado. They are considered the southeasternmost part of the San Juan Mountains. Grouse Mesa, , is the highest peak in the range. The mountains a ...

(the southern portion of the

San Juan Mountains The San Juan Mountains is a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry ...

), which extended slightly into Colorado. A high crest runs from the border with

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

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 the southeast is the more distinctive Brazos Peak, at 11,288 feet (3440 m). The range is mostly located in the privately held Tierra Amarilla Land Grant (the

Carson National Forest Carson National Forest is a United States National Forest, national forest in northern New Mexico, United States. It encompasses 6,070 square kilometers (1.5 million acres) and is administered by the United States Forest Service. The Forest Serv ...

is to the east and south). It is a distinctive part of the view from the west, including from Heron Lake.

U.S. Route 64 U.S. Route 64 (US 64) is an east–west United States highway that runs for 2,281 miles (3,672 km) from Nags Head in eastern North Carolina to just southwest of the Four Corners in northeast Arizona. The western terminus is at U.S. Route ...

crosses the southern end of the range at a 10,481 foot (3194 m) pass. This is the highest paved through road pass in New Mexico. Nearby are the photogenic Brazos Cliffs, headwaters of the Rio Brazos and part of the

Rio Chama The Rio Chama, a major tributary river of the Rio Grande, is located in the U.S. states of Colorado and New Mexico. The river is about long altogether. From its source to El Vado Dam its length is about , from El Vado Dam to Abiquiu Dam is abo ...

river system. These mountains overlook the Chama River, the largest tributary of the Rio Grande which lies to the east. In essence, these mountains are the southern extension of the South San Juan Range that lies in southern Colorado and northern New Mexico. Brazos Mountains New Mexico

Geology

The Brazos Mountains are the southwestern remnants of a Laramide

peneplain In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or ...

resulting from the erosion of mountains formed 80 to 55 million years ago during the

Laramide orogeny The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 80 to 70 million years ago, and ended 55 to 35 million years ago. The exact duration and ages of beginning and end of the o ...

. To the east and northeast lie the

Sangre de Cristo Mountains The Sangre de Cristo Mountains (Spanish language, Spanish for "Blood of Christ") are the southernmost mountain range, subrange of the Rocky Mountains. They are located in southern Colorado and northern New Mexico in the United States. The mountai ...

which share a similar geological history. The Brazos Cliffs, which form a dramatic backdrop to Tierra Amarilla, are formed of Precambrian quartzite.

References

External links

* * {{Mountains of New Mexico Landforms of Rio Arriba County, New Mexico Mountain ranges of New Mexico