Sierra

Sierra, county, southwestern New Mexico, U.S. Sierra county is in the Mexican Highland section of the Basin and Range Province. Its irregular western border is the Black Range, including Hillsboro and Reeds peaks, both rising to more than 10,000 feet (3,000 metres). The Rio Grande, including large impoundments at Caballo and Elephant Butte reservoirs, flows southward through the centre of the county. Immediately east of the reservoirs are the Sierra Caballo and Fra Cristobal Range;...