Topic summary
Bearhead Rhyolite
Extracted from the Wikipedia article Keres Group.
Formations
The Bearhead Rhyolite is a thick stack of rhyolite tuffs, flows, domes, and associated shallow intrusions exposed from the northeastern Valles caldera rim to north of Cochiti Pueblo. It is named for exposures on Bearhead Peak (35°43′30″N106°28′59″W / 35.725°N 106.483°W), one of the major source vents of the formation. The formation ranges in age from 7.1 to 6.5 million years. High-silica volcanism shifted to the north around 7.5 million years ago, producing the separation between the Canovas Canyon Rhyolite and the Bearhead Rhyolite.