The Stillwater Deep Well— Meeds, 275 



No. THICKNESS, DEPTH. 



11. Grayish sand with some green grains. Effervesces 



slightly with hydrochloric acid 27 ft. 349 ft. 



12. Gray shale or limestone with some rounded grains 



of quartz. Effervesces strongly. Resembles No. 



2, but more shaly 31 ft. 380 ft. 



13. Impure sandstone made up of rounded with some 



angular grains of quartz, with much broken up 

 dark material, some red and yellow grains which 

 effervesce with acid 70 ft. 450 ft. 



14. Fine grained quartz sand with some impurities 



from No. 13 10 ft. 460 ft. 



15. Pinkish shale with streaks of white and green, some 



quartz grains. Effervesces strongly with acid. . . .80 ft. 540 ft. 



16. Coarse quartz sand, some grains of a yellowish 



color. Some grains very large and mostly 



rounded 90 ft. 630 ft. 



17. Same as last but more yellowish 58 ft. 688 ft. 



18» Dark red shale with grains of sand. Effervesces 



with acid 13 ft. 701 ft. 



19. Coarse quartz sand, mostly rounded grains, with 



some red shale from No. 18 5 ft. 706 ft. 



20. Fine dark red shale. Effervesces. lift. 717 ft. 



21 . Fine grained dark red sandstone. Effervesces .... 79 ft. 796 ft. 



22. Same as last 96 ft. 892 ft. 



23. Same as last, very fine grained. In thin sec- 



tion* this is shown to be undoubtedly a clastic 

 rock, made up of grains of quartz, feldspar 

 and metallic grains probably magnetite, with a 

 cement highly stained by ferric oxide and contain- 

 ing masses of calcite. Many of the clastic grains 

 as well as the cementing material are heavily 

 charged with ferric oxide 31 ft. 923 ft. 



24. Same as last in general appearance. A small amount 



of salt water was struck at a depth of 1,950 ft. In 

 thin section, however, this rock is shown to con- 

 sist of an altered diabase porphyrite. The pyrox- 

 enic mineral is almost completely changed to 

 chlorite and hornblende, and the feldspar is badly 

 kaolinized. This latter mineral lies in long, lath- 

 like individuals extinguishing very nearly to 

 labradorite. With these non-metallic minerals 

 there occurs quite a large quantity of some metal- 

 lic mineral, probably magnetite, which is beginning 

 to change slightly to hematite as can be seen on 

 the borders of irregular and interstitial matters. 

 The texture of this rock is medium 1327 ft. 2250 ft. 



*In identification o! minerals in thin sections the writerwas assisted by Prof. C. W. Hall. 



