SWAN RANGE SECTION 11 



Algonkian. — The red and gray arenaceous beds of the Camp Creek 

 series form the top of the Algonkian section in the Swan range, and 

 overlie the limestones of the Blackfoot series. 



Blackfoot series — Upper division 



Feet Feet 

 la. Banded, siliceous or cherty layers predominate at the 

 top, with a few thin layers of gray limestone and shaly, 



arenaceous layers 6 to 15 inches thick 410 



&. Gray, thin bedded limestones, with intercalated cherty 



layers 585 



995 



2a. Gray, banded chert, with a dark bluish black layer 2 feet 



thick near the top 23 



h. Gray, thin bedded limestone, weathering buff, somewhat 

 shaly in the upper 600 feet and more distinctly bedded 

 below 845 



c. Alternating cherty beds and grayish limestone, with the 



cherty beds predominating in the upper portion 195 



Near the base there is a layer three feet in thickness 

 almost entirely made up of massive specimens of 

 Cryptozoan. 



d. Gray, thin bedded cherty beds 52 



e. Gray, rough, siliceous, and arenaceous limestone in thick 



layers 109 



f. Dark, bluish black cherty bed 4 



g. Gray, rough, siliceous, and arenaceous limestone layers 2 



to 16 inches thick 105 



About 50 feet from the summit numerous specimens 

 of Cryptozoan occur in a bed about 6 inches in thickness. 



Total of Upper division 2,328 



Blackfoot series — Lower division 



la. Banded cherts, dark and gray 70 



b. Gray, compact, more or less siliceous limestone, with 



cherty layers and irregular nodules that correspond in 



form to the calcareous nodules in If 80 



c. Dark and gray banded cherts 65 



d. Gray, compact, more or less siliceous limestone, with thin 



cherty layers and irregular nodules similar to the 



cherty matter in If 175 



e. Banded, cherty beds, with small amount of calcareous 



matter in the form of nodules and irregular thin layers 210 



f. Siliceous and calcareous layers, from one-half to 2 inches 



in thickness. The calcareous matter is in the form of 



