418 blackwelder: new formations in Wyoming 



narrower limits. The term Flathead has now been reserved for 

 the basal sandstone or quartzite. The use of the term Gallatin 

 has been established in Hague's modified sense; but the present 

 writer does not concur, because he believes Peale's original usage 

 should have been pi'eserved. The intervening greenish and gray 

 calcareous shales, with gray, striped, conglomeratic and oolitic 

 limestones, is here called the Gros Ventre formation. Its fossils 

 indicate Middle Cambrian age. A typical section of the forma- 

 tion, exposed in the west slope of Doubletop Peak in the Gros 

 Ventre Range, is as follows : 



Gallatin limestone (base) 



Feet. 

 Limestone; gray and ocher colored in alternate bands, contains 

 black oolitic granules; rock massive and forms a promi- 

 nent cliff in association with overlying members of the 

 formation. Rests disconformably on underlying beds.. 27-|- 



Gros Ventre formation 



15. Limestone; very massive, dense and gray, top eroded 4+ 



14. Limestone; thin-bedded, gray laminated with olive drab. ... 13 

 13. Shale; green shale and flakes of brown-gray limestone, with 

 a few beds of flat-pebble conglomerate and oolite. Much 



of this part of the section is concealed by talus 350 



12. Limestone; thin-bedded, dense, hard blackish-gray rock 

 mottled with drab and ocher, and containing some shale 

 partings. Fragments of trilobites are rather common ... 24 

 11. Shale; largely green shale with thin layers of limestone like 



the last ; largely concealed 26 



10. Limestone; like " 12." Surfaces of beds are rough, and some 

 of them rather massive. This forms a distinct cliff in the 



slope , 115 



9. Shale; greenish clay-shale with thin plates of limestone. 



Largely concealed by talus 36 



8. Limestone; gray, with irregular laminae and pockets con- 

 taining siderite (?), and therefore weathering ocher color. . 10 

 7. Limestone; somewhat pisolitic, dark drab limestone weather- 

 ing blue gray 2| 



6. Shale; gray calcareous shale and shaly limestone; largely con- 

 cealed 4 



5. Limestone; dark drab to bluish limestone, hard but flaggy.. 5 

 4. Shale; graj' calcareous shale and shaly limestone; largely con- 

 cealed 6^ 



3. Limestone; hard but flaggy, dark gray-bluish, mottled with 

 light ocher. Contains traces of trilobites, and forms a 

 prominent cliff 52 



