A large granitic pegmatite near Campo, in southern San Diego County was found to contain several radioactive biotite-rich inclusions. The pegmatite is irregularly zoned, and in general comprises a well defined graphic granite border zone, an irregular wall zone of intergrown quartz and perthite, a discontinuous intermediate zone of blocky pert...

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The Manix Beds were deposited in a Pleistocene lake basin that occupied 200 to 300 square miles of the Mojave Desert, near the center of San Bernardino County, California. Three stages of lake deposition are recognized. Arenace...

A magnetic survey was made in Sand Canyon, which is in the northwestern part of the San Gabriel Mountains, the object being to locate possible placer deposits. The bedrock in this area is an iron rich igneous rock which has been intruded by numerous dikes. The stream gravels consist of large boulders interspersed with highly magnetic sands....

Within recent years there has been a renewed interest among geologists in the field of sedimentary petrography. This interest has been rewarded by the accumulation of much new and interesting data. Careful studies of the textures and mineral compositions of formations have yielded important clues regarding climatic and geographic conditions duri...

Situated in the San Gabriel Mountains of Southern California is a large body of anorthosite which is associated a number of bodies of ilmenitic magnetite. During the summer of 1937, the E. I. duPont de Nemours Corporation obtained options on a group of properties thought to contain several such deposits. In connection with the exploration of the...

An erosion surface of low relief was developed on the granitic complex of the Rosamond Hills area during the early part of the Tertiary period. Sometime during the Miocene epoch, faulting and volcanic activity formed a series of shallow lakes in which pyroclastic debris accumulated to a maximum depth of 900 feet to form the lower part of the...

The Paradox No. 3 mine, Atolia, California, was mapped and thin sections of the vein minerals and wall rock were examined. Veins containing quartz, scheelite and carbonate occur along faults and fractures in Atolia quartz monzonite (Upper Jurassic ?), which is an orthoclase-biotite tonalite in the mine area. The mineralization occurs along thre...

The Paradox No. 3 mine, Atolia, California, was mapped and thin sections of the vein minerals and wall rock were examined. Veins containing quartz, scheelite and carbonate occur along faults and fractures in Atolia quartz monzonite (Upper Jurassic ?), which is an orthoclase-biotite tonalite in the mine area. The mineralization occurs along thre...

The Paradox No. 3 mine, Atolia, California, was mapped and thin sections of the vein minerals and wall rock were examined. Veins containing quartz, scheelite and carbonate occur along faults and fractures in Atolia quartz monzonite (Upper Jurassic ?), which is an orthoclase-biotite tonalite in the mine area. The mineralization occurs along thre...

The Paradox No. 3 mine, Atolia, California, was mapped and thin sections of the vein minerals and wall rock were examined. Veins containing quartz, scheelite and carbonate occur along faults and fractures in Atolia quartz monzonite (Upper Jurassic ?), which is an orthoclase-biotite tonalite in the mine area. The mineralization occurs along thre...