Uniformity in Geological Change 



interrupted series of changes in the animate and 

 inanimate world must give rise to such breaks in 

 the sequence, and such unconformability of 

 stratified rocks, as are usually thought to imply 

 convulsions and catastrophes. It is scarcely 

 necessary to state that the order of events thus 

 assumed to occur, for the sake of illustration, 

 should be in harmony with all the conclusions 

 legitimately drawn by geologists from the struc- 

 ture of the earth, and must be equally in accord- 

 ance with the changes observed by man to be 

 now going on in the living as well as in the in- 

 organic creation. It may be necessary in the 

 present state of science to supply some part of the 

 assumed course of nature hypothetically ; but if 

 so, this must be done without any violation of 

 probability, and always consistently with the 

 analogy of what is known both of the past and 

 present economy of our system. 



In pursuance, then, of the plan above pro- 

 posed, I will consider, first, the laws which regu- 

 late the denudation of strata and the deposition 

 of sediment; secondly, those which govern the 

 fluctuation in the animate world; and, thirdly, 

 the mode in which subterranean movements 

 affect the earth's crust. 



UNIFORMITY OF CHANGE CONSIDERED, FIRST, IN 

 REFERENCE TO DENUDATION AND SEDIMEN- 

 TARY DEPOSITION 



First, in regard to the laws governing the 

 deposition of new strata. If we survey the sur- 

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