1845.] 625 



immediately after the completion of the Lower Silurian group, 

 these two continents were elevated and placed beyond the reach of 

 the depositary influence of the sea in which the isles were formed, 

 and therefore that in ancient times, as at the present day, a great 

 trough existed between these opposite continental masses of land. 

 This early elevation was probably unaccompanied by any great 

 fractures ; for the lower Silurian rocks of both lands have still pre- 

 served a general horizontality, which is the more remarkable in the 

 case of Russia, as it has been shown that the sediments, after 

 having been raised, must again have been depressed to permit of 

 copious marine accumulations of Devonian age upon their surface. 

 In like manner, we must believe from the evidences of conformable 

 apposition of the Devonian and carboniferous deposits of Russia, 

 that no sort of disturbing influence could have existed in these re- 

 gions when the one formation succeeded to the other. The uppermost 

 beds of the Devonian, loaded with Holoptychius and Onchus, Coc- 

 costeiis, Placosteus, and De7idrodus, are at once conformably sur- 

 mounted by strata containing the most universally diffused car- 

 boniferous types. In short, fishes identical with those of the Old 

 Red Sandstone of Scotland are invariably surmounted by the 

 Stigmaria ficoides and the large Producti of our British moun- 

 tain limestone ; and thus the examination of Russia has taught 

 us, not only in this instance, but also in the overlying Permian 

 succession, that the great changes in animal life have not been de- 

 pendent on physical revolutions of the surface, but are distinct 

 creations, independent of any such pi'oximate local causes ; though 

 I .would by no means deny that the grand operations of change 

 which have affected the conterminous regions of Russia did not 

 tend to produce these results. 



The first elevation and depression of the Lower Silurian strata 

 having been moderate, and probably not extensive, and those strata 

 having, during the long succeeding Devonian and carboniferous 

 periods, remained beneath the sea, in which these sediments were 

 accumulated, we next reach that period of disturbance which is so 

 strongly marked in nearly every part of Europe, or that which 

 followed the close of the carboniferous epoch. Then it was that the 

 whole of the older palaeozoic series of Northern Russia was raised 

 up in lines extending from S. W. to N. E. And, although even 

 then their elevation must have been infinitely more equable than 

 any of those upheavals which have determined the strike and 

 escarpments of rocks of the same age in Western Europe, we 

 cannot injagine the upward movement of such enormous masses 

 from beneath the sea to some height above it, without the ac- 

 companiment of some of those transverse fissures and breaks, 

 which, though feeble in the slightly elevated tracts, increase in 

 intensity with the amount of upheaval. 



