GEOLOGY AND EVOLUTION. 375 



history of life- development, consists in the fact that only the hard 

 parts of animals and plants are, as a rule, capable of being preserved. 

 Bones, teeth, and scales, along with shells and corals, are the 

 structures which most commonly constitute the " fossils " found 

 in rock-formations. Although in a few instances the footprints of 

 animals, the tracks of sea-worms, and even the impress of a jelly- 

 fish have been discovered, the vast majority of fossils consist of the 

 remains of those animals and plants which possessed hard parts 

 and structures. If, therefore, we consider the enormous number of 

 soft-bodied organisms which, in this way, can have left no trace 

 whatever of their existence, one all-sufficient reason for the 

 imperfection of the geological record is not difficult to find. 

 Whilst this record is thus imperfect and at the best fragmentary, 

 such evidence as we do possess regarding its nature will be found 

 in no case to negative the conclusions to which evolution would 

 guide us. The whole of the evidence which geology has to submit 

 in reference to the life of the past, clearly points to the idea of 

 progression and modification of living beings as the only hypothesis 

 which can fully explain and connect the facts of cosmical history. He 

 who runs may literally read with pleasure and profit the story of life 

 which is written in the records of the rocks ; and that story is one 

 of evolution and modification. Of " special creation " the rocks tell 

 no tale ; and life at large has nothing whatever to say in support 

 of a tradition which belongs to the pre-scientific era of human 

 thought. 



It may lastly be pointed out how closely and intimately the 

 phases of geological history parallel those of biological growth. 

 Time was, when every phase of geological action was regarded as 

 the result of a sudden catastrophe. Sudden, physical revolution, 

 was but the counterpart of that special and independent " creation " 

 of living beings, in which the science of yesterday believed. To-day, 

 with wider and truer conceptions of both physical and biological 

 history, both theories have been consigned to oblivion. As the " uni- 

 formity " of geological action supersedes the catastrophes of the past, 

 so the evolution of life replaces the idea of its sudden creation. In 

 each case, the supernatural, unknowable action postulated by ancient 

 belief, is replaced by an efficient cause, the nature and direction of 

 which can be investigated by mankind. From a detached, abrupt, 

 and disconnected theory of nature, we have advanced towards a har- 

 monious explanation of this world's order, and towards a unity of 

 cause, outside which, as the growth of science tends to show, no 

 event of history, cosmical or human, can exist. 



