DEARBORN RIVER SECTION V 



Feet Feet 



1). Light gray and greenish, siliceous beds in layers and 

 shaly bands. Alternating bands of arenaceous, shaly, 

 and thin bedded sandstones and compact, siliceous, 

 banded layers, flint-like in appearance, occur through- 

 out this part of the series. At 455 feet from the top a 

 sill of dark, eruptive rock, 35 feet thick, outcrops, and 

 17 feet above, 3 feet of dark, siliceous, hard shale. 

 Mud cracks occur at many horizons 1 ,21 5 



c. Purple, arenaceous shales with occasional thin bands of 



greenish shale. In the upper part the greenish shales 

 predominate, with occasional bands of purple shales. . . 2,430 

 Dip 45 degrees southwest. 



d. Fine, quartz conglomerate 2 



e. Shaly and thin bedded, siliceous and arenaceous shales. 



They are purple colored in the upper 245 feet and with 

 occasional purple bands in greenish shales below. 



At 300 feet from the top a bed of eruptive rock 25 

 feet thick occurs and another 5 feet thick 435 feet 

 below. 



Dip 30 degrees near base and 40 degrees near top 

 of 3e. 

 4. Bluish gray limestone in thin layers 15 



Resume 



la-cl. Gray and greenish gray, siliceous and arenaceous beds. . 510 



2. Gray, siliceous limestone 435 



Sa-e. Greenish and purple, siliceous and arenaceous beds 5,757 



4. Gray limestone 15 



0,717 



The upper portion of this section, la-d and 2, appears to belong to the 

 Blackfoot Limestone series, and the beds below to the Eavalli series of the 

 Camp Creek, Mission Bange section. 



The Cambrian beds are cut oif by a fault just above the Flathead sand- 

 stones, which brings up gray, arenaceous shales and sandstones of the 

 Algonkian, and above these, brownish red beds corresponding to the 

 Spokane shales of the Lewis and Clark Pass section. The latter are 

 capped by the coarse sandstone of the Cambrian Flathead formation. 



LEWIS AND CLARK PASS SECTION 



Location of the section. — This section is about 10 miles south of that 

 south of the north fork of the Dearborn river. 



Cambrian, Flathead sandstones. — The divide at the Lewis and Clark 

 pass trends northeast and southwest. The massive bedded, coarse sand- 



II — Bull. Geol. Soc. Am., Vol. 17. 1905 



