Volcanic Rocks of the Colorado Plateau

Volcanic Deposits: Volcanic eruptions have occurred on the Colorado Plateau in Quaternary times. Most notable are the volcanic fields in the vicinity of Flagstaff, Arizona (the San Francisco Peaks), the Uikaret Volcanic Field along the northwest end of the Grand Canyon, and throughout the southeastern side of the plateau in New Mexico. Older Tertiary-age volcanic deposits form the core of the high mountain uplands throughout the Colorado Plateau (including the Abajo Mountains, Henry Mountains, La Sal Mountains, Boulder Mountain, and Navajo Mountain). Volcanic rock from these areas can be seen in colluvial and alluvial deposits throughout the Colorado Plateau.

References

Billingsley, George H.. Hamblin, W. Kenneth, Wellmeyer, Jessica L., and Dudash, Stephanie L., 2001, Geologic Map of Part of the Uinkaret Volcanic Field, Mohave County, Northwestern Arizona: U.S. Geological Survey Miscellaneous Field Studies 2368. [Geologic map scale: 1:31,680 and text (39 p.)] - <http://geopubs.wr.usgs.gov/map-mf/mf2368/>.