| OCR Text |
Show 242 GEOLOGY OP THE HIGH PLATEAUS. Section V.â€"Moneoe Amphitheater. In the middle gorge of the amphitheater, beginning at 7,750 feet altitude and descending to the west. Feet. 1. Granitoid trachyte................................................... 110 2. Augitic andesite, in layers varying muck in thickness along the exposure.. 200 3. Hornblendic trachyte, very rough and coarse in texture, probably four or five layers.......................................................... 330 4. Augitic andesite...................................... .....-.....----- 80 5. Hornblendic trachyte................................................ 40 6. Hornblendic trachyte......'............................â- .,............ 40 7. Hornblendic trachyte............................... ................. 70 8. Conglomerate, with fragments of hornblendic andesite and trachyte and au- gitic andesite....................................................... 55 9. Hornblendic andesite of unknown thickness in numerous layers, with very uneven divisional lines. 10. Modern alluvial or torrential deposits of unknown thickness. 11. Tufas, water laid, of unknown thickness. 12. Hornblendic andesite, possibly forming a part of the same mass as No. 9, lying upon the eroded and highly-inclined surface of propylite; thickness unknown. 13. Hornblendic propylite, rising in a precipitous Avail or barrier far above the last-named mass, but also extending beneath it and unquestionably of greater antiquity.................................................... 775 Section VI.â€"Sevier Plateau. In a large ravine about 3^ miles south of Marysvale Peak, beginning on the south side of the ravine and descending westward; altitude, 7,700 feet. Feet. 1. Hyaline trachyte, Avith a few porphyritic crystals, somewhat resembling a liparite, but no free quartz........................................ 35 2. Granitoid trachyte, rather dark gray.................................... 22 3. Granitoid trachyte, dark gray and coarser than preceding................ 20 4. Granitoid trachyte................................................... 32 5. Granitoid trachyte................................................... 28 6. Dolerite, with large crystals of plagioclase in a very fine base............. 15 7. Hyaline trachyte, similar to No. 1...................................... 25 8. Hyaline trachyte, bright reddish color................................. 37 9. Argilloid trachyte, in several layers, varying slightly in character......... 90 10. Dolerite in seA^eral layers, similar to No. 6, with smaller crystals of plagio- clase ............................................................. 75 11. Argilloid trachyte, in numerous layers.................................. 160 12. Tufas of unknown thickness, but a visible exposure of.................... 220 |
