Did you know that the volcanic fields in northern New Mexico, including El Malpais' field, Zuni-Bandera, form a line across the state? This line is called the Jemez Lineament, and it marks an area of weakness in the Earth’s crust.
Why is the crust weak here? It all boils down to the power of plate tectonics. The current line of the Jemez Lineament follows an ancient subduction zone between oceanic crust and what was then the edge of North America. The hydrous, or water-containing, minerals within the rocks of the oceanic plate remnants cause them to melt at a lower temperature.
Magma repeatedly took advantage of this former subduction zone, erupting in many different locations over millions of years. That’s why volcanic fields like Raton-Clayton, Valles Caldera, Mount Taylor, and Zuni-Bandera all line up. Volcanoes didn’t just pop up wherever they felt like it — they followed a geologic boundary. Not only is this region rich with volcanoes, but nearly all types of volcanic formations are found here, from small cinder cones to stratovolcanoes, fissures to calderas, northern New Mexico has it all!
Learn about other volcanoes on the Jemez Lineament at Petroglyph National Monument, Valles Caldera National Preserve, Bandelier National Monument, Fort Union National Monument, and Capulin Volcano National Monument.