XXXIV PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



eompanies the * Geology of Russia.' Independently of its zigzag 

 irregularities, it may be considered approximately as the circumference 

 of a circle having its centre near the northern extremity of the Gulf 

 of Bothnia. A very large majority of the blocks dispersed over this 

 immense area can be distinctly referred to their Scandinavian origin, 

 thus showing in a remarkable manner the centrifugal or radiating 

 action already mentioned of the forces by v;hich this dispersion has 

 been effected. 



The granite-boulders seem to have been in this, as in so many 

 other cases, the best travellers. They constitute the greater part of 

 the blocks in the external zone of the drift. But it is of more im- 

 portance to remark, that whatever may be the nature of the blocks, 

 they become almost universally smaller and more rounded as we ap- 

 proach the external boundary above indicated. This seems to me 

 conclusive as to the nature of the transporting agencyin this outer zone. 

 I can conceive water alone to be capable of giving these characters 

 to the transported materials. On the contrary, as we approach the cen- 

 tral portion of this region of drift, we find the blocks of enormous size, 

 perfectly angular, and not unfrequently imbedded in masses of fine 

 drift, indicative of the absence, at the time of its deposition, of any 

 violent currents capable of moving the blocks imbedded in it. In this 

 we recognize the transport by floating ice. And again, on the central 

 land, we recognize glaciers as the source of the floating ice, and the 

 means of transporting large angular blocks from their original sites 

 on the mountains to the level of the ocean. 



You will not suppose. Gentlemen, that in stating these conclusions 

 I regard myself as opening new views to you. My object is merely 

 to present the subject to you in a general but compendious form, in 

 the hope that I may thus lead you to contemplate its various points 

 collectively, and to see how much they are brought into harmony 

 with each other by a distinct recognition of the three causes above 

 mentioned, and a due allotment of the varied phsenomena of the drift 

 to their respective modes of transport. 



The authors of the * Geology of Russia ' consider the present 

 boundary of the region of the drift in north-eastern Russia, as indi- 

 cating the approximate boundary of the glacial sea in that region 

 during the drift-period, and this conclusion appears to me perfectly 

 legitimate. They also consider the low, flat lands of northern Asia 

 to have been, about the same period, under the sea. In favour of 

 this view, there appears to be the unequivocal, though not perhaps 

 abundant, evidence of marine remains. There seems to be no evidence, 

 however, of a submergence of this region approximating in depth to 

 that of many parts of the European continent ; the present low lands 

 were probably covered only with shallow water. And hence we may 

 conclude that northern Asia was in a state of comparative repose 

 during the period of much greater oscillation, and probably of more 

 frequent and comparatively violent disturbance of the European area. 

 Again, no traces of former glaciers have been detected on the Ural 

 •Mountains, or on the projecting headlands which run out to the 

 laorthward from the high lands of northern and central Asia. This 



