112 Gregory — Igneous Origin of the " Glacial Deposits " 



Feet 



6. Shales, argillaceous, calcareous, arenaceous, with 2-14 



inch beds and lenses of white and of light red sand- 

 stone ; shales various tones of red and brown, also 

 ash grey and green 35 



7. Conglomerate, olive-green in tone, compact, but not 



firmly cemented. The pebbles in sizes up to 16 inches 

 in long diameter are subangular with flattened and 

 in many cases polished surf aces, and include white 

 granite, granite porphyry, granite gneiss, diorite, 

 garnetiferous diorite gneiss, mica schist, chlorite 

 schist, serpentine, asbestos, quartzite, blue-grey marble, 

 grey and buff limestone, red sandstone, red shale ; 

 the matrix consists of tiny particles of rock types 

 present as pebbles, and also flakes of biotite and 

 muscovite, rare garnets and peridots. Materials of 

 the conglomerate identical except in size with those 

 forming the surface "drift" of this area. The 

 upper and lower contacts of the conglomerate some- 

 what wavy and shales enclosing it are slightly dis- 

 colored. Bed traced by excavation for 200 feet, 

 terminates abruptly at the west 4 



8. Sandstone, fine, even-grained, light red, lenticular ; 



replaced along the strike by white, sandy shales 1 



9. Shale, arenaceous ; banded white, green, ash gray, dark 



red, light red, chocolate ; colored bands in places 

 continuous for several hundred feet ; elsewhere 

 distributed as discontinuous stripes or as dots ; 

 beds paper-thin to \ inch in thickness ; uneven, 



wavy, and in places imbricated 42 



10. Sandstone, red-brown, fine ; well-rounded, quartz 



grains ; calcareous cement 5 



11. Shale, arenaceous ; dark red to light brown, with scat- 



tering patches of black, white and green ; irregularly 

 bedded ; where shale partings are not developed by 

 weathering, strata assume appearance of thick bed- 

 ded, variegated sandstone 28 



12. Sandstone, dark red with white patches ; many curved 



beds ; massive or irregularly bedded ; friable ; fine 

 quartz, even-grained ; weathers into knobs, hoodoos, 

 stone babies, bobbins. 30 ± 



13. Sandstone, light red, massive, cross-bedded ; Navajo 



sandstone, the upper member of the La Plata 227 

 Group. 

 The strata included in this section, Nos. 1-12, inclusive, 

 are tentatively assigned to the McElmo formation, 

 Jurassic (?) in age. 



A section of the southwest end of Garnet Ridge, measured 

 with the assistance of Mr. Heald, is substantially the equiva- 



