b C. D. WALCOTT ALGONKIAN FOKMATIONS OF MONTANA 



river, below Dry fork. The section was measured on the high ridge east 

 of the river, and passes over Mineral hill. 



Above the Blackf oot limestones the red and gray arenaceous beds of 

 the Camp Creek series extend northward and pass beneath the Cambrian 

 strata of Scapegoat mountain. 



Feet Feet 



1. Passage bends; sandy layers, pinkish to dull red, with 



coarser grains of sand than below, followed by grayish, 

 buff weathering, slightly calcareous, fine grained sand- 

 stones. The upper half has more buff and yellowish 

 beds and the lower half more of the reddish beds 155 



2. Shaly limestones, alternating with thin layers of gray lime- 



stone. Near the top a few oolitic layers occur, and 

 throughout are occasional layers with Cryptozoan. 

 About 730 feet down the shaly beds give way to bedded, 

 gray limestone, alternating with impure, dark gray, 

 buff weathering limestone. About 160 feet from the 

 base the shaly limestone again predominates, with 



frequent layers of oolitic and siliceous limestone 1,310 



Cryptozoan is abundant in the lower 100 feet. 



3. Calcareous shales with bands of green arenaceous shale. . . 155 



4. Thin bedded and shaly, gray limestone, with occasional 



layers of gray limestone 2 to 10 inches thick. In the 

 lower 70 feet, oolitic layers and semi-cherty layers 

 occur. The siliceous portions of the latter weather buff 

 and the irregular nodules and stringers of gray lime- 

 stone a bluish gray 815 



Cryptozoan occurs abundantly in. the upper 60 feet 

 on the high point north-northeast of Mineral hill. Fine 

 specimens of Cryptozoan two feet and more in diameter 

 occur in beds 3 feet thick at horizons 360 and 373 feet 

 below the top. 



5. Thin bedded, more or less shaly, compact, gray limestone, 



weathering buff and gray 520 



6. Gray limestone in layers 8 to 20 inches thick, with irregular 



nodules and stringers of cherty matter, weathering buff. 

 This extends down about 330 feet, where there is a 

 gradual change into banded calcareous and siliceous 

 beds, with layers of gray limestone. These give way 

 1,040 feet down to gray, compact, siliceous, buff 

 weathering limestone in shaly bands and thin layers. 

 Siliceous matter becomes more prominent, until the 

 only evidence of calcareous matter is the buff weather- 

 ing beds. A bed 28 feet thick of purplish colored, 

 siliceous rock, in hard, compact, smooth layers, occurs 



285 feet above the base 1,850 



Cryptozoan of large size, 15 inches and more in 

 diameter, occur 165 feet from the top. 



