Mark Wilson March 17th, 2011
ZZYZX, CALIFORNIA–After lunch we took a long drive south and east to the Hole-In-The-Wall visitor center and trail. Exposed here are diverse and colorful rocks called tuffs that were formed by pyroclastic eruptions from volcanoes roughly 18.5 million years ago. These eruptions of hot gases and ash swept the surrounding countryside depositing thick masses of complex rock. Plants and animals were incorporated in the ash flows, so we occasionally find charcoal in the tuffs as well as various other volcanic products.