Douglass : A Geological Reconnaissance. 



271 



45 



II 



rermo-Carboniferous. 



Carboniferous. 



18. Conglomerate 



17. Gray sandstone , 



16. Gray sandstone stained brown 



15. Gray sandstone 



14. Conglomerate 6 



13. Gray and greenish shale ^ 



12. Thin-bedded sandstones with ripple marks and 



shells — Lingula, etc f 



Greenish sandstone — Liiigtila J 



10. Limestome shales and thin-bedded sandstones 



Fossil shells, Lingtda, etc 



). Brown thin-bedded limestones and shales. Lin- 

 gula, Aviculopecten, Myalina 



5. Shales with bands of limestone ...~] 



Soft shales or clay C 125 



Quartzite, massive 



Quartzite in layers with worm tracks 



Jaspery quartzite 



Cherty limestone impure 



Cherty limestone with carboniferous fossils 



Quartzite, massive but not in section 200 



85 



150 



7- 



6. 



5- 

 4- 



3- 

 2. 



100 



120 



There is nothing in this section very nearly like the thick-bedded 

 limestone of the Marine Jurassic of Jack Creek canon in the Madison 

 Range; yet the limestone No. 31 may represent the Marine phase of 

 this formation, though it seems quite high in the scale and overlies 

 what appears to be non-marine Jurassic. 



Other Localities. — On the west side of the North Boulder Valley, 

 near the road from Whitehall to Boulder, are red clays and sandstones 

 similar to a portion of those in the Big Hole section. In these some 

 bones of turtles were found. 



On the east side of the North Boulder opposite Cold Spring post- 

 ofifice these beds appear again ; and farther to the eastward on the east 

 side of the valley of Milligan Creek, near where the stream turns from 

 the eastward and flows to the southward, is an outcrop of red clays, 

 shales, and sandstones, which apparently belongs to the same forma- 

 tion. In the clays were found fragments of bones of large reptiles. 

 In the two latter localities the beds lie pretty close to the Carbonifer- 

 ous. As the fragmentary bones have not been specifically determined, 

 it is possible that the beds may be Triassic. 



On the top of the Tobacco Root Mountains, about twenty-five miles 

 south of Virginia City, are quite extensive outcrops of Jurassic shales, 



