166 EVOLUTION AND DOGMA. 



subsidence will tend to submerge the area whence 

 the sediment is derived, and thus diminish the sup- 

 ply whilst the downward movement continues. In 

 fact, this nearly exact balancing between the supply 

 of sediment and the amount of subsidence is prob- 

 ably a rare contingency ; for, it has been observed 

 by more than one paleontologist, that very thick de- 

 posits are generally barren of organic remains, except 

 near their upper or lower limits." ' 



The foregoing are but a few of the reasons that 

 might be assigned for the paucity of intermediate 

 forms which characterizes the earth's fossil-bearing 

 strata. When we come to reflect on the matter, 

 however, the wonder is not that there is such a small 

 number of gradational forms, but rather that there 

 are any fossils at all. For everything has tended to 

 render their formation impossible ; and in the com- 

 paratively few instances in which circumstances have 

 been favorable to the fossilization of animal or vege- 

 table forms, a variety of circumstances has intervened 

 to compass their destruction. Such being the case, 

 therefore, we should be surprised, not at the exist- 

 ence of such extensive tracts that are utterly devoid 

 of any traces of organic life, but rather at the fact 

 that there are so many formations in different parts 

 of the world which contain such a wealth of fossil 

 remains. 



For let us consider for a moment under what ad- 

 verse conditions the slight vestiges of the fauna and 

 flora of the ancient world have been preserved ; 

 what are a few of the agents of destruction, how 



1 Op. cit., vol. II. pp. 68 and 69, 



