Excerpt from Geology and Mineral Resources of Santa Ysabel Quadrangle, San Diego County, California The Santa Ysabel quadrangle lies along the east edge of the composite Peninsular Ranges batholith of Creta ecoas age. The oldest rocks are Triassic schists which occur as small roof pendants and as one large body in the vicinity of Julian. Jurassic gneissose quartz dio rite is intimately mixed with much of the schist, the two making a complex into which were intruded various members of the Cretaceous batholith. These intrusions are limited to gabbro and several tonalites. Structural features of the igneous rocks suggest that emplacement may have been accomplished by stoping in some places and by forceful injection in others. Pleistocene continental gravels occur as remnants of a once continuous extensive blanket in the northern portion of the quadrangle. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.