MOOK, STUDY OF THE MORRISON FORMATION 



73 



Section of Rocks exposed in Gunnison Canyon at the 

 Mouth of Wells Gulch 



Feet 



1. Sandstone in thin flinty layers separated by 



dark colored shale 20 



2. Coal .3 



3. Shale, carbonaceous 8 



4. Conglomerate, quartzitic, gray to buff (Da- 



kota) 15 



[Base of Dakota and top of Morrison.] 



5. Sandstone, conglomeratic, with beds of varie- 



gated shale. The conglomerate contains 

 many pebbles of qartz and jasper 100 



6. Shale, variegated 175 



7. Sandstone, vs^hite, argillaceous 5 



8. Shale, soft, variegated ; contains pockets filled 



with pebbles of jasper, chert, argillite, etc. ; 

 also globular lenticular bodies of pink to 

 red calcite, having a maximum diameter of 

 5 feet 200 



9. Sandstone, gray, coarse-grained, cross-bedded. 50 



10. Sandstone, brown, massive 8 



11. Shale, pink 10 



12. Sandstone, brown, massive 15 



13. Shale, sandy 10 



14. Sandstone, flinty 4 



15. Shale, variegated 30 



16. Shale and limestone, evenly bedded 25 



17. Shale and sandstone in thin regularly bedded 



layers 50 



Unconformity by erosion. 



18. Sandstone (red beds) (?) 



728 



The Morrison (McElmo) formation is very well 

 exposed a few miles southwest of Mack, where the 

 Grand Eiver makes a sharp turn and where a trib- 

 utary cuts directly across the strata. The bend in 

 the river cuts directly across a large monoclinal 

 fold, exposing the underlying beds. Good expos- 

 ures occur for considerable distances, and it is pos- 

 sible to make a complete section of the formation 

 at a number of points. The chief characteristic of 

 the formation in this district is the presence of a 

 number of heavy, white, cross-bedded sandstones, 

 which stand out as prominent ledges. Sandstones 



Fig. 26. — Section of the 

 Morrison formation in 

 Gunnison Canyon at 

 the mouth of Wells 

 Gulch, Colorado. 



1. — Dakota ; 2. — Mor- 

 rison. Scale, 125 feet to 

 1 incli. (Lee.) 



