Theories of the Formation of Mountains, 417 



certain line of the earth's crust, from the accumulation of sedi- 

 ments, without producing the phenomena which we observed in 

 the Appalachian and other mountain ranges." — Introduction to 

 Pal. N. Y. Vol. 3. 



Remarhs on the above several Theories. 



The theory of Professor Rogers depends upon the action of 

 two forces, an upward pulsating force, and a lateral compressing 

 force. But it appears to us that he does not show how either of 

 these forces was generated. The cause of these forces yet re- 

 mains unknown, and is it not true that to explain natural 

 phenomena without tracing them to some known cause, is sim- 

 ply not to explain them at all ! If this deficiency were supplied 

 the theory might be good enough. The contraction of the mass 

 of the earth would undoubtedly produce plications of the surface 

 and although most physicists do believe in the former fluid con- 

 dition of the planet, and its contraction during the process of 

 consolidation, yet it remains to be demonstrated that any such 

 contraction has taken place during that period within which the 

 existing mountain chains were elevated. Sir Charles LyelPs the- 

 ory supposes the plications to have been formed by the subsidence 

 of the disturbed country. He thus refers the phenomena to a known 

 cause, for it is unquestionable that there has been subsidence in 

 the region of the Appalachians. But on the other hand, Rogers 

 contends that the cause assigned could not have produced a pli- 

 cation of any important dimensions, and we have been long since 

 convinced by his reasoning. We shall offer some mathematical 

 proofs on this point in connection with Professor Hall's views. 



Sir John Herschel refers the phenomenon of subsidence 

 to a known cause, for we know that matter is constantly being 

 transferred from the land to the sea bottom, or in other words 

 that a force tending to depress the floor of the ocean is con- 

 stantly accumulating there. If the crust of the earth is only a 

 few miles in thickness, then if we could imao-ine the continent of 

 America to be taken up bodily to the depth of two miles, and 

 laid down upon Europe it is almost impossible that subsidence 

 should not immediately take place. The molten matter beneath 

 would be forced out and caused to flow under and elevate the 

 ocean's bottom, and perhaps form a ring of volcanic mountains all 

 round the margin of the depressed area. Although no such sud- 

 den transfer of matter has ever taken place, yet it can be proved 

 that sheets of matter now converted into solid rock equal in su- 



