What is the Rio Grande Rift?
A rift is a surface feature characterized by an elongated valley. Rifts are created when Earth’s crust stretches and thins. The Rio Grande Rift began forming between 35 and 29 million years ago when Earth’s crust began to spread apart, triggering volcanism (volcanic activity) in the region. It stretches from the state of Chihuahua, Mexico, to at least Leadville, Colorado, and probably even further north. Rifts like the Rio Grande form basins (topographic depressions) that fill with sediments over millions of years. In Albuquerque, New Mexico, the basin sediments are three miles thick. The Rio Grande Rift continues today to widen very slowly. Back to the Rio Grande Rift main page.
