PALAEONTOLOGY AND GEOLOGY 



throughout, containing the same organic remains, and 

 having similar beds above and below it, may yet dif- 

 fer to any conceivable extent in age. . . , All that 

 geology can prove is local order of succession. It is 

 mathematically certain that, in any given vertical 

 linear section of an undisturbed series of sedimentary 

 deposits, the bed which lies lowest is the oldest. . . . 

 For anything that geology and palaeontology is able 

 to show to the contrary, a Devonian fauna and flora 

 in the British Islands may have been contemporane- 

 ous with Silurian life in North America, and with a 

 Carboniferous fauna and flora in Africa." We can 

 then be certain that geology cannot^ and never will be 

 able to^ translate the thickness of any one stratum 

 into an equivalent length of time and that it cannot^ 

 and never will be able to^ establish real conte?npora- 

 neousness of time in different parts of the world. 



Let us now turn to the positive evidence of palae- 

 ontology, giving first the opinion of Huxley, at the 

 time when he was advancing the doctrine of evolu- 

 tion with such assurance, and then a brief summary 

 of the science at the present time. In the same essay 

 just quoted, Huxley sums up as follows : "We are all 

 accustomed to speak of the number and the exterit of 

 the changes in the living population of the globe dur- 

 ing geologic time as something enormous ; and indeed 

 they are so, if we regard only the negative differences 

 which separate the older rocks from the more mod- 

 ern, and if we look upon specific and generic changes 



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