Xlvi PKOCEEDINGS OF THE GEOLOGICAL SOCIETT. 



gical time sufficient to allow of some of the greatest physical changes 

 the world has seen, what becomes of that sort of contemporaneity the 

 sole evidence of which is a similarity of facies, or the identity of half 

 a dozen species, or of a good many genera ? 



And yet there is no better evidence for the contemporaneity as- 

 sumed by all who adopt the hypotheses of univer&::il faunae and florae, 

 of a imiversally uniform climate, and of a sensible cooling of the 

 globe during geological time. 



There seems, then, no escape from the admission that neither 

 physical geology nor palaeontology possesses any method by which the 

 absolute synchi'onism of two strata can be demonstrated. 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. 

 In any other vertical linear section of the same series, of course, 

 corresponding beds will occur in a similar order ; but, however great 

 may be the probability, no man can say v^ith absolute certainty 

 that the beds in the two sections were synchronously deposited. 

 For areas of moderate extent, it is doubtless true that no practical 

 evil is likely to result from assuming the corresponding beds to be 

 synchronous or strictly contemporaneous ; and there are multitudes 

 of accessory circumstances which may fully justify the assumption 

 of such synchrony. But the moment the geologist has to deal with 

 large areas or with completely separated deposits, then the mischief 

 of confounding that " homotaxis " or *' similarity of arrangement," 

 which can be demonstrated, with "synchrony" or 'identity of 

 date," for which there is not a shadow of proof, under the one com- 

 mon term of " contemporaneity " becomes incalculable, and proves 

 the constant source of gratuitous speculations. 



For anything that geology or palaeontology are able to show to 

 the contrary, a Devonian fauna and flora in the British Islands may 

 have been contemporaneous with Silurian life in North America, and 

 with a Carboniferous fauna and flora in Africa. Geographical pro- 

 vinces and zones may have been as distinctly marked in the Palaeozoic 

 epoch as at present, and those seemingly sudden appearances of new 

 genera and species, which we ascribe to new creation, may be simple 

 results of migration. 



It may be so ; it may be otherwise. In the present condition of 

 our knowledge and of our methods, one verdict — " not proven, and 

 not proveable" — must be recorded against all the grand hypotheses 

 of the palaeontologist respecting the general succession of life on 

 the globe. The order and nature of terrestrial hfe as a whole are 

 open questions. Geology at present provides us with most valuable 

 topographical records, but she has not the means of working them 

 up into a universal history. Is such a universal history, then, to be 

 regarded as unattainable ? Are all the grandest and most interest- 

 ing problems which oflbr themselves to the geological student essen- 

 tially insoluble? Is he in the position of a scientific Tantalus — 

 doomed always to thirst for a knowledge which he cannot obtain ? 



