This paper is published essentially as prepared by Dr. John J. W. Rogers as a contribution to the basic geology and petrology of the western portion of Joshua Tree National Monument. As the study was not concerned with economic mineral deposits, no mention of these is made. The Division of Mines has, however, a report under preparation on the mines and mineral deposits of Riverside County which includes most of the area of this report and which will include discussion of possible mineralization in the district. The mineral deposits in the remaining and northern part of San Bernardino County already have been described in the California Journal of Mines and Geology, volume 49, numbers 1 and 2, January-April 1953.
CLIFFTON H. GRAY, JR.
Last Updated: 18-Jan-2007