26 



GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



Crowfoot 

 section. 



Num- 

 ber. 



30 15 



29 



r 11 



13 



12 



2<*< 



§ 



- 





28 < 





27 



. 



. 



11 



10 



9c 



96 



9o 



8 



7 



6 



£ 1 



H 



Q J 



o 



w 



20 



19 



Bighorn Pass section — Continued. 



Clierty limestone. The lower 30 feet is a brown fossiliferous limestone, over- 

 lain by 70 feet of a moderately coarsely crystalline gray rock, weathering 

 brownish. One bed is a compact brown limestone, full of criuoid stems 

 and fossil fragments, which appear as crystalline masses of calcite on fresh 

 fracture, but on weathered surface show their true nature. The upper 

 portion of No 15 is cherty and massive 



Limestone; the lower portion light brown, shading to gray; massive, with 

 cherty band near center. The upper part is rich in coral. This limestone 

 varies in crystallization, being both fine and coarse 



Limestone, gray, weathering brown, finely crystalline and compact 



Limestone, finely crystalline, white, cherty. Chert is light gray, weathering 

 rusty or black 



Limestone, blue, finely crystalline, very splintery 



Cherty limestone, white, finely granular 



Limestone, coarsely crystalline, light drab, with few fossils; runs down to 



Feet. 



saddle 



Limestone, finely crystalline, compact, massively bedded, light drab, vertically 

 jointed. Dip 18°, N. 20° W 



Limestone, very light gray, coarsely crystalline, containing crinoid stems and 

 other fossils 



Limestone, somewhat coarsely crystalline, compact, white; the base concealed 

 by talus of No. 9 of this section 



Limestone, fine grained, fissile, dark gray, weathering blue; certain layers 

 are quite fossiliferous 



Limestone, dark gray, often brownish gray ; cherty and siliceous near base. 

 The upper 50 feet more friable and soft; contains numerous fossils, shells, 

 crinoid stems, and corals 



Limestone; finely crystalline, with quartzose band near top; gray, weather- 

 iu"' creamy. The top is concealed by the talus of No. 6, and the thickness 

 should be increased about 40 feet 



Limestone, dense, massive, dark blue-gray, impure (argillaceous) 



Limestone, alternating beds of massive, steely gray, arenaceous limestone, 

 weathering brown and containing corals, and fissile, light-gray, and dense 

 limestone 



225 



30 

 12 



5 



6 



30 



25 



20 



50 



30 



90 



250 



40 

 20 



2 Limestone, at the base dark blue-gray and very compact, changing to a 

 bro wu-gray arenaceous limestone. Dip 15°, N. 10° W 



1 Limestone, light drab, finely crystalline and dense, somewhat cherty. Chert 

 light and dark gray; thickly bedded. 



40 



10 



The dip of the lower beds of the section is 15°. Five hundred feet 

 above the pass it is 18°, and near the summit of Bannock Peak it is 10°. 

 The direction of the dip also changes from N. 11° W. to NW., becoming 

 N. 41° W. on the summit. The beds appeared to be perfectly conformable 



throughout. 



