Barber Peak is a 5,778-foot volcanic plug on Navajo Nation land in northwestern New Mexico, rising about 300 feet above the surrounding plain and standing out as a local landmark in the high desert. It is one of the phreatomagmatic diatremes of the Four Corners region, formed in the Navajo Volcanic Field around 30 million years ago during the Oligocene. In Navajo it is called Tsé Naajin, meaning “black downward rock.” Runoff from the peak drains into the San Juan River basin, and the mountain remains a distinctive feature of the Navajo landscape within one of the Southwest’s most unusual volcanic terrains.