San Juan Basin

The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah and Arizona. Specifically, the basin occupies space in the San Juan, Rio Arriba, Sandoval, and McKinley counties in New Mexico, and La Plata and Archuleta counties in Colorado. The basin extends roughly 100 miles N-S and 90 miles E-W.

The San Juan Basin is an asymmetric structural depression in the Colorado Plateau province, with varying elevation and nearly 3,000' in topographic relief. Its most striking features include Chaco Canyon (northwestern New Mexico, between Farmington and Santa Fe) and Chacra Mesa. The basin lies west of the Continental Divide, and its main drainage is the southwest- to west-flowing San Juan River, which eventually joins the Colorado River in Utah. Climate of the basin is arid to semiarid, with an annual precipitation of 15 inches and an average annual temperature of around 50 degrees Fahrenheit.

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