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Show SECTIONS IN THE SEVIEE PLATEAU. 241 Section IV.â€"Monroe Amphitheater. Beginning near the central part of the upper verge of inner amphitheater; altitude, about 9,400 feet and descending west. Feet. 1. Granitoid trachyte............................................... ...... 80 2. Dolerite, brownish gray, much weathered on the surface, much shattered and splintered and falling apart in slabs and tiles, probably numerous layers, not distinctly separable....................................... 160 3. Granitoid trachyte, rather dork gray, slightly hornblendic, and somewhat fine grained.........................................................- 35 4. Granitoid trachyte, finer than above and rather lighter in color............ 30 5. Granitoid trachyte, like No. 3 ......................................... 50 6. Granitoid trachyte, a little darker and coarser than the preceding........ 65 7. Dolerite..... ,...................................................... 15 8. Argilloid trachyte, numerous sheets very massive and not distinctly sepa- rated.................................................. .......... 420 9. Dolerite............................................................... 50 10. Argilloid trachyte..............................................,...... 50 11. Argilloid trachyte..................................................... 60 12. Argilloid trachyte.................................................... 55 13. Trachytic conglomerate.............................................. 140 14. Granitoid trachyte, dark colored, coarse grain, very hard and compact, and in very massive layers........... ................................... 180 15. Dolerite or augitic andesite (?)......................................... 10^ 16. Hornblendic trachyte, dark and rather fine grained....................... 110 17. Hornblendic trachyte................................................. 40 18. Hornblendic trachyte.................................................. 50 19. Dark granitoid trachyte............................................... 50 20. Hornblendic trachyte..................................,............... 95 21. Granitoid trachyte, light brown........................................ 33 22. Hornblendic trachyte, dark, coarse grained. This and the preceding num- bers below 15 probably consist of several layers each, not well separated. 75 23. Augitic andesite in many layers, hard, compact, fine grained, and all very similar in appearance................................................ 260 24. Conglomerate, containing fragments of hornblendic trachyte and hornblen- dic andesite___................................................... 60 25. Hornblendic trachyte, numerous layers .»............................... (?)350 26. Hornblendic andesite, no good estimate possible, but not less than........ 200 16 H P |