the Earth's Contraction from Cooling. 47 



2. Have elevations been produced directly by lateral pressure ? 



The theory of Professor Hall denies that mountains are a 

 result of local elevations, or of any elevation apart from a general 

 continental. This hypothesis I have elsewhere discussed*. 



Professor LeConte makes the elevation of mountains real; 

 but after explaining that the crushing effects of lateral thrust 

 would necessarily cause a lengthening upward of the compressed 

 strata (as in the compression of slate rocks attending the pro- 

 duction of slaty cleavage), and thereby produce a large amount 

 of actual elevation, arrives at the view that there is no perma- 

 nent elevation beyond what results from crushing. With crush- 

 ing, in this action^ plication is associated; but it should have a 

 larger place than his words seem to give it (in all plication the 

 rocks over a region being pressed into a narrower space, which 

 could be done only by adding to the height), as it has performed 

 tenfold more work of this kind than crushing. 



But are plication and crushing the only methods of produ- 

 cing, under lateral pressure, the actual elevations of mountain- 

 regions ? Is there not real elevation besides ? 



In the later part of the Posttertiary or Quaternary era the 

 region about Montreal was raised nearly 500 feet, as shown by 

 the existence of sea-beaches at that height ; and similar evidence 

 proves that the region about Lake Champlain was raised at the 

 same time at least 300 feet, and the coast of Maine 150 to 200 

 feet. Hence the region raised was large. No crushing or pli- 

 cation of the upper rocks occurred ; and none in the under rocks 

 could well have taken place without exhibitions at the surface ; 

 and this cause, therefore, cannot account for the elevation. The 

 elevated sea-border deposits of the region are in general hori- 

 zontal. This example is to the point as much as if a mountain 

 had been made by the elevation. 



But we have another example on a mountain-scale, and one 

 of many. Fossiliferous beds over the higher regions of the 

 Rocky Mountains are unquestioned evidence that a large part 

 of this chain has been raised 8000 to 10,000 feet above the 

 ocean-level since the Cretaceous eraf. The Cretaceous rocks, 

 to which these fossiliferous beds belong, were upturned in the 

 course of the slowly progressing elevation ; and so also were part 

 of the Tertiary beds ; for the elevation went forward through the 



* Amer. Journ. Sci. 2nd ser. vol. xlii. pp. 205, 252 (1866), and 3rd sev. 

 vol. v. p. 347 (1873). 



t The height of the Cretaceous (stratum No. 2 of the Upper Missouri 

 Cretaceous) at Aspen, in Wyoming, is full 8000 feet above tide-level 

 (Meek). Beds occur also in South Park, Colorado, the height of which is 

 8500 feet ; and, according to Hayden, in the region of the Wind- River 

 Mountains the beds have a height of 10,000 to 11,000 feet above the sea. 



