402 H. Wood — Cretaceous of Northwestern Montana. 



proper in Montana. Exposures of this inter- mountain series 

 are found as far south as the 48th parallel along the banks of 

 the south fork of the Flathead River, also in the vicinity of 

 Marias Pass through the Rockies. Still farther south, a hun- 

 dred miles or more from the 49th parallel, a younger series of 



i»€k^;SI2f1 



ijMs* ?|tf^ 





represent the limit of Gravel Deposits. 



— represent the Coal Exposures examined. 



the Cretaceous has been observed in the vicinity of Missoula 

 extending 18 miles east and west and dipping into the moun- 

 tains at 30° northwest. It consists of clays, shales and 

 sandstones, with small seams of impure lignite, and capped 

 with a heavy conglomerate, the series resting unconformably 

 on the greatly denuded upturned beds of the Cambrian or 

 Pre-Cambrian rocks which dip south 25°. The valley is a 

 plateau valley from fifteen to twenty-five miles in width and 

 thirty to forty in length, with heavy beds of bowlder and 

 gravel detritus, the grooved and polished rocks (gray quartz- 

 ites of the Cambrian), on the flanks of the southern range 



