Frijoles Canyon is carved into a thick layer of volcanic ash that over time compacted into a soft rock known as tuff. This ash was deposited over 1 million years ago in two separate eruptions of the Jemez Volcano, each spewing over 600 times more ash than Mt St Helens in 1980. Tuff is a malleable rock overall and one component within the tuff, pumice, is especially susceptible to erosion by wind and water. Using this quality of the tuff, Ancestral Pueblo people used harder rock, such as basalt found further down this canyon and under the tuff, to enlarge natural erosional cavities into human excavated openings called cavates (CAVE-eights). You will be able to climb ladders into several of these further down the trail.If you are interested in learning more about this fantastic volcanic geology, visit the Valles Caldera National Preserve located about 40 minutes away on Highway 4. The Preserve protects the collapsed top (caldera) of the Jemez Volcano.
Last updated: May 2, 2022