I 435 



112 GEOLOGICAL SURVEY OF THE TERRITORIES. 



Thickness 

 in feet. 



14. Compact quartzite / 4 



15. CoDglomerate 2 



16. Yellow limestoae - 3 



17. Cherty limestone 15 



18. Quartzite 5 



19. Limestone 20 



20. Calcareous sandstone 4 



21. Limestone 4 



22. Sandstone 15 



23. Quartzite 15 



24. Yellow calcareous sandstone 5 



25. Red sandstone 5 



26. Purple and greenish sandstone 2 



27. Spotted purple sandstone 4 



28. Brick-red sandstone ^ 4 



29. Purple sandstone 3 



30. Greenisb-wlaite quartzite 2 



31. Purple sandstone 5 



32. Arenaceous limestone , 



33. Limestone , 



Outside of the quartzite bed, with which I have headed the above sec- 

 tiou, there is a succession of beds of hard quartzites aud couglomerates 

 followed by soft sandstones of steel-gray colors. Just below these sand- 

 stones, which are Cretaceous, there is a layer of hard, green shale con- 

 taining fossils. Outside of them there occurs a bed of limestone. All 

 these beds curve around the Spring-Caiion layers, to which they seem 

 to be conformable. Above the Cretaceous beds there is an immense 

 thickness of brown aud dark-gray Tertiary sandstones, (EocCne,) contain- 

 ing beds of coal. They also follow the curve of the Cretaceous beds and 

 are seemingly conformable to them. They extend for four or five miles. 



About five miles north of Spring CaQon there is a range, the Bridger 

 Eange, the trend of which is north and south. I shall here refer only 

 to the southern end and western side of this range, reserving any 

 further consideration of it to a subsequent chapter. Near the south- 

 ern end of the range there is quite a high peak known as Bridger's 

 Peak, which is 9,000 feet above the sea. The crest of the raage is made 

 up of Carboniferous limestone, dipping southeast, containing Hemi- 

 pronites crenesfria, Froduehis longispiniis. Then follows a succession 

 of beds as we found them in Spring Caiion. Following these, and still 

 dipping southeast, are the Cretaceous beds that we noticed outside of 

 Spring Canon. In a layer of hard, green shales I found Gryphwa, Avi- 

 cilia, Pinna, Inoceramus, Turritella, Crassatella, &c., proving their un- 

 doubted Cretaceous age. Next we find the Tertiary sandstones, which 

 are unconformable to the Bridger layers. There is therefore between 

 Spring Caiion aud the Bridger Eange a synclinal valley the floor of which 

 is Cretaceous, filled in with the Tertiary sandstones, dipping northwest, 

 north, and northeast at an average angle of 40°. Many of these sand- 

 stones are calcareous and contain veins of calcite. The thickuess of these 

 beds must exceed 1,000 feet, and from the specimens of fossil-plants 

 found in them they are for the most part Eocene. Some of the upiper 

 layers may be of Miocene age. 



Opposite Fort Ellis, between our camp and Bridger Peak, there are 

 bluffs composed of Pliocene sandstones, marls, and conglomerates. The 

 strata are for the most ijart horizontal, although inclining sometimes at 

 a very small angle, which is never more than 5°. The height of these 

 bluffs above the level of the creek is 175 feet. They are the remnants 

 of Pliocene formations that once spread over the entire valley of the 

 Gallatin, and formed the bottom of a vast lake that spread over what 



