184: J. D. Dana — Rocky Mowitain Protaxis and the 



The rocks comprise, approximately, 10,000 feet of Lower Cam- 

 brian shales and quartzytes, in which have been found species of 

 Olenelhis, 7700 feet of dolomites, the lower part affording Para- 

 doxides and the upper Lower Silurian fossils, 1500 feet of Lower- 

 Silurian graptolitic schists, 1300 feet of Upper Silurian limestone 

 with Haly sites, 1500 feet of Devonian limestone, 5100 feet of 

 Carboniferous limestones and shales, probably Devonian below, 

 and 5000 feet of Cretaceous beds anterior to the Laramie. 



Figure 1 represents a portion of Mr. McCoimell's section east 

 of the Sawback Range crossing Cascade Trough. It represents 



Case. Mt. l. 



Cb 3 Cb- Cb 1 D Cr Cr Cr Cb 1 Cb 2 D C 



Section across the Cascade Yalley Cretaceous, with the Cascade Mountains on 

 the west; Cb, Carboniferous; D, Devonian; C, Cambrian. 



the Carboniferous formation and Devonian shoved up, along a 

 fault, over the Cretaceous of the Cascade Trough ; while, to 

 the eastward the Cretaceous rests conformably on the Devo- 

 nian and Carboniferous ; and then another great upthrust fault 

 puts the Devonian above the Cambrian. 



Figure 2 represents an overthrust synclinal in the Cretaceous 

 beds of the Cascade Trough, 25 miles south of Mr. McCon- 



nell's main line of section, the whole breadth of which is about 

 two miles. On the west side of the flexures, the Devonian and 

 Carboniferous rise at a very steep angle ; and they appear to 

 have once stood as a great inclined anticlinal bending over the 

 Cretaceous. 



Cb, Cb 2 Cb, Cb, D C 



Section of mountains along Devil's Lake Yalley, east of section in fig. 1. 



In figure 3 a section is shown of the beds east of those of 

 figure 1, along Devil's Lake Yalley. The rocks of the whole 



