ILLUSTRATIONS. 



Page. 



PLATE I. Geological Map of Ruby Hill 115 



II. Geological Cross-sections 174 



III. Minerals in section 396 



IV. Quartz grains in section 398 



V. Feldspars in section 400 



VI. Micropegmatite and andesite 402 



VII. Andesite and basalt 404 



VIII . Rhyolite 406 



FIG. 1. Silurian quartzite west of Castle Mountain 56 



2. Section across Lone Mountain 62 



3. Nevada limestone, Modoc Section 66 



4. Section across Pifion Range 201 



5. Granite porphyry dikes 223 



6. Vertical Cross-section Phoenix mine 306 



7. Carlsbad twinn of labradorite 351 



8. Diagram exhibiting extinction angles of a Carlsbad twin of Inbradorite 351 



9. Carlsbad twin of plagioclase 353 



VII 



