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 (160 km) N-S and 90 miles (140 km) E-W.
The San Juan structural basin is primarily in New Mexico and the southeast corner of the Colorado Plateau.
Depiction of the Cretaceous Western Interior Seaway.
Generalized cross section of the San Juan Basin.
The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.
The Four Corners region and the Colorado Plateau.
The Book Cliffs of Utah
The Green River runs north to south from Wyoming, briefly through Colorado, and converges with the Colorado River in southeastern Utah.
MODIS satellite image of Grand Canyon (lower left), Lake Powell (black, left of center) and the Colorado Plateau. White areas are snow-capped.
