Uniformity in Geological Change 



mass above the waters, because nearly three- 

 fourths of the globe are covered by the ocean. 

 But if it be upheaved and made to constitute 

 part of the dry land, it must also, before it can 

 be available for our instruction, become part of 

 that area already surveyed by geologists. In 

 this small fraction of land already explored, and 

 still very imperfectly known, we are required to 

 find a set of strata deposited under peculiar con- 

 ditions, and which, having been originally of 

 limited extent, would have been probably much 

 lessened by subsequent denudation. 



Yet it is precisely because we do not encounter 

 at every step the evidence of such gradations 

 from one state of the organic world to another, 

 that so many geologists have embraced the doc- 

 trine of great and sudden revolutions in the 

 history of the animate world. Not content with 

 simply availing themselves, for the convenience 

 of classification, of those gaps and chasms which 

 here and there interrupt the continuity of the 

 chronological scries, as at present known, they 

 deduce, from the frequency of these breaks in 

 the chain of records, an irregular mode of succes- 

 sion in the events themselves, both in the organic 

 and inorganic world. But, besides that some 

 links of the chain which once existed are now 

 entirely lost and others concealed from view we 

 have good reason to suspect that it was never 

 complete originally. It may undoubtedly be 

 said that strata have been always forming some- 

 where, and therefore at every moment of past 

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