Uniformity in Geological Change 



tions in animal or vegetable life may have been 

 completed in the interval. 



As to the want of completeness in the fossil- 

 iferous series, which may be said to be almost 

 universal, we have only to reflect on what has 

 been already said of the laws governing sedimen- 

 tary deposition, and those which give rise to 

 fluctuations in the animate world, to be con- 

 vinced that a very rare combination of circum- 

 stances can alone give rise to such a superposi- 

 tion and preservation of strata as will bear testi- 

 mony to the gradual passage from one state of 

 organic life to another. To produce such strata 

 nothing less will be requisite than the fortunate 

 coincidence of the following conditions: first, a 

 never-failing supply of sediment in the same 

 region throughout a period of vast duration; 

 secondly, the fitness of the deposit in every part 

 for the permanent preservation of embedded 

 fossils; and, thirdly, a gradual subsidence to 

 prevent the sea or lake from being filled up and 

 converted into land. 



In certain parts of the Pacific and Indian 

 Oceans, most of these conditions, if not all, are 

 complied with, and the constant growth of coral, 

 keeping pace with the sinking of the bottom of 

 the sea, seems to have gone on so slowly, for such 

 indefinite periods, that the signs of a gradual 

 change in organic life might probably be detected 

 in that quarter of the globe if we could explore 

 its -submarine geology. Instead of the growth 

 of coralline limestone, let us suppose, in some 

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