452 ARTHUR BEVAN 



(or the roughly equivalent Cleverly) formations, both in the main 

 of Comanchean age, the Colorado shale, and the divisions of the 

 Montana group, are exposed in several places. The Morrison and 

 Cloverly formations crop out only in the southeastern part of the 

 district, where they consist of varicolored elastics and thin lime- 

 stones of non-marine origin. The Kootenai formation is present 



Fig. 7. — Massive Madison limestone that forms a conspicuous ridge west of 

 Red Lodge. The beds are overturned slightly to the east (right). Gravel-capped 

 Fort Union strata beyond east base of the ridge. 



along the base of the range east of Livingston, where it corresponds 

 approximately to the Dakota formation, as delineated on the 

 Livingston areal map (FoHo No. i). The Colorado shale is the 

 typical thick deposit of marine shale, but with more interbedded 

 sandstone than is common farther north in Montana. A succession 

 of non-marine sandstones and marine shales similar to that of the 

 Lake Basin district"" to the northeast, constitutes the Montana 



' E. T. Hancock, "Geology and Oil and Gas Prospects of the Lake Basin Field, 

 Montana," U.S. Geol. Survey Bull. 691-D, 1918, pp. 114-24. 



