post- Cretaceous Mountain-making along its course. 185 



Paleozoic series are here shoved up so as to bring the Cam- 

 brian, C, into view. The Cambrian extends eastward in a broad 

 anticline with the Devonian above, and is so continued 

 to and over the Cretaceous of the foot-hills, as is seen in the 

 following section, ligure 4, taken a little to the south, on the 



Section across the Cascade Valley Cretaceous. 



South Fork of Grhost River. The actually observed overlap in 

 this section made by the older beds amounts to nearly two 

 miles. " The vertical displacement is over 15,000 feet, and the 

 estimated horizontal displacement of the Cambrian beds is 

 about seven miles in an easterly direction." The sinuous out- 

 crop of the plane of junction, says Mr. McConnell, is exactly 

 like the line of contact of two nearly horizontal formations. 

 The overlying Cambrian stratum is bleached and cracked from 

 the friction and " some enclosed argillaceous beds are con- 

 verted into schists " — a fact not surprising since more than 

 15,000 feet of strata had a long move eastward in the over- 

 thrust. At one point, fossils of the Benton Cretaceous were 

 found in the beds under the Cambrian limestone, while two 

 miles north the latter limestone yielded Cambrian fossils, so 

 that the demonstration of the overthrust was complete. 



Mr. McConnell observes, in explanation, that in the Appala- 

 chian region, " the valley of East Tennessee presents an almost 

 identical structure, and Professor J. M. Safford's interesting 

 section across this valley might almost be taken for an illus- 

 tration of the structure of this part of the Pocky Mountains." 

 As in his section of fifty-two miles, with "eight great faults," 

 and " no great flexures " crowded together, " the incipient 

 folds split open longitudinally and the southeastern side of 

 each heaved up, and over the northwestern," so it is essentially 

 in the Pocky Mountain region described, except that the direc- 

 tion of up-thrust is reversed ; and yet it is the same, since in 

 each it is landward. West of the Sawback Pange, between it 

 and the valley of the Columbia, the facts are different in that 

 " ordinary and overturned folds play the most important role. 

 The greater part of the district has also been subjected to 

 regional metamorphism, and all the beds except the purer 

 limestones are in a more or less altered condition." The only 

 fault indicated in the section is a down-throw fault. 



These concordances, or rather identities, with Appalachian 

 mountain structure are of the highest geological interest. 



