Cenozoic Volcanic Rocks of the Devils Postpile Quadrangle, Eastern Sierra Nevada, California

Cenozoic volcanic rocks of the Devils Postpile quadrangle are of late Pliocene to Recent age and are divided into 11 map units. The suite is alkalic-calcic and ranges in composition from basalt to rhyolite. It includes a rhyolitic welded ash-flow tuff which is probably correlative with the Bishop Tuff, although the two units are geographically isolated by the Sierra Nevada drainage divide. The Devils Postpile itself is a classic example of columnar jointing in the lower part of a lava flow.