Sliv I'ROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Cambrian rocks nowhere exhibit fossils, and hence no living being 

 could have existed in their epoch. 



To this there are two repHes: the first, that the observational 

 basis of the assertion that the lowest rocks are nowhere fossihferons 

 is an amazingly small one, seeing how very small an area, in com- 

 parison to that of the whole world, has yet been fully searched : the 

 second, that the argument is good for nothing unless the unfossiU- 

 ferous rocks in question were not only contemporaneous in the geo- 

 logical sense, but synchronous in the chronological sense. To use 

 the alihi illustration again. If a man wishes to prove he was 

 in neither of two places, A and B, on a given day, his witnesses 

 for each place must be prepared to answer for the whole day. If 

 they can only prove that he was not at A in the morning, and not at 

 B in the afternoon, the evidence of his absence from both is m7, 

 because he might have been at B in the morning and at A in the 

 afternoon. 



Thus everything depends upon the validity of the second assump- 

 tion. And we must proceed to inquire what is the real meaning 

 of the word " contemporaneous " as employed by geologists. To 

 this end a concrete example may be taken. 



The Lias of England and the Lias of Germany, the Cretaceous 

 rocks of Britain and the Cretaceous rocks of Southern India, are 

 termed by geologists '^ contemporaneous" formations; but when- 

 ever any thoughtful geologist is asked whether he means to say that 

 they were deposited synchronously, he says " No, — only within the 

 same great epoch." And if, in pursuing the inquiry, he is asked 

 what may be the approximate value in time of a "great epoch" — 

 whether it means! a hundred years, or a thousand, or a miUion, or 

 ten million years — his reply is, " I cannot tell." 



If the further question be put, whether physical geology is in 

 possession of any method by which the actual synchrony (or the 

 reverse) of any two distant deposits can be ascertained, no such 

 method can be heard of; it being admitted by all the best autho- 

 rities that neither similarity of mineral composition, nor of physical 

 character, nor even direct continuity of stratum, are absolute proofs 

 of the synchronism of even approximated sedimentary strata : while, 

 for distant deposits, there seems to be no kind of physical evidence 

 attainable of a nature competent to decide whether such deposits 

 were formed simultaneously, or whether they possess any given differ- 

 ence of antiquity. To return to an example already given. AH 

 competent authorities "will probably assent to the proposition that 

 physical geology does not enable us in any way to reply to this 

 question — Were the British Cretaceous rocks deposited at the same 

 time as those of India, or are they a million of years younger or a 

 million of years older ? 



Is pala3ontology able to succeed where physical geology fails? 

 Standard writers on palaeontology, as has been seen, assume that she 

 can. They take it for granted, that deposits containing similar organic 

 remains are synchronous — at any rate in a broad sense ; and yet, 

 those who will study the eleventh and twelfth chapters of Sir Henry 



