A little known fact is that the United States Geological Survey (USGS) considers New Mexico to be a “volcano state”, as it has examples of every known type of volcanic activity. Numerous volcanic formations can be found throughout the state such as famous Shiprock in the northwest and the seldom traveled Cornudas in the southeastern region. Driving through the state, volcanic activity is visible in just about every part of the landscape.
The USGS defines New Mexico as follows; “New Mexico is the Volcano state. New Mexico has one of the greatest concentrations of young, well-exposed, and uneroded volcanoes on the continent. And as a bonus, it is also the Rift Valley state; it has one of only five big continental rifts in the world, East Africa being one of the other ones. The fact is, New Mexico is one of the best places to study the natural history of volcanoes. Twenty percent of the U.S. National Parks and Monuments based on volcanic themes are in New Mexico. There are more here than Arizona, Idaho, Oregon, and Washington combined.”
Capulin Volcano in the northeastern region of the state and Bandera Volcano south of Grants in the central west region are examples of dormant cinder cones. Throughout the state, there are numerous old and younger lava flows, volcanic domes, volcanic craters, layers of volcanic ash, and landscape that was transformed by volcanic activity.
The Aden-Afton Lava Flow, within the Potrillo Volcanic Field of the Santa Teresa Desert, can be found southwest of Las Cruces. Kilbourne Hole and Hunt’s Hole are located within the lava flow. Both are examples of collapsed steam craters (maar volcanic crater). Kilbourne Hole is 1.25 miles/2 km wide and in places 300’/91 m deep. This crater is thought to be about 80,000 years old. The second maar crater, Hunt’s Hole, is 2 miles/3 km south of Kilbourne. Astronauts for the Apollo flights trained here in 1969. On the western edge of the lava flow, just north of the Kilbourne Hole, Aden Crater is an example of a well preserved crater that is often said to be one of the best preserved volcanic features of the southwest. A fossilized giant ground sloth was found in its crater fumerole (volcanic vent) in 1928, and was dated to 11,000 BCE. The sloth is now at the Smithsonian.
The Valles Caldera (Caldron Valley, formerly El Valle Grande) exemplifies a giant volcanic caldron. German geologist Leopold von Buch introduced the term “caldera” after an 1815 visit to the Canary Islands. He theorized that calderas are formed when a magma chamber underground triggers a volcanic eruption. If enough magma is ejected to the surface, the ground is unable to support the weight and collapses, thus forming a giant pot-like structure on the earth’s surface. The Valles Caldera in the Jemez is an example of just such an eruption.
Another large volcanic field is found in the northeastern part of the state near Raton. The Raton-Clayton Volcanic Field covers approximately 8,000 square miles/12,875 km north and south of the Colorado border. There are nearly one hundred volcanic features in the field, the most famous of which is the cinder cone Capulin Volcano.
Volcanic lava flows of the Mt. Taylor Volcanic Field are prominent along Interstate 40 east and west of Grants. This volcanic field begins north of Grants at Mesa Chivato and continues many miles/km south of the interstate.