ZION A Geologic and Geographic Sketch of Zion National Park

A GEOLOGIC AND GEOGRAPHIC SKETCH OF ZION NATIONAL PARK

VOLCANIC ROCKS

LAVA.—The lava flows at Coalpits Wash, and along North Creek are outliers of more extensive sheets on Kolob Terrace and the Markagunt Plateau. Most of them may be traced to their feeding craters. All of them are composed of basalt in the form of dense rock, porous clinkers, bombs, and coarse-grained miscellaneous fragments. All the volcanic eruptions that produced the lavas are of recent geologic dates. The craters retain much of their original shape and the flows pass over the cliffs, across lands, and follow canyons that had their present forms before the eruptions took place.

East Patriarch—R. K. Grater Photo.