52 [March 27, 



ture of Yakutsk were raised to that of our own climate, this line of 

 53 would undergo a vertical displacement of 1550 feet. The time 

 required for its uniform re-adjustment over a large area would depend 

 upon various conditions, the chief one being the conductivity of the 

 different strata. The question, therefore, arises, whether traces of 

 perturbation in the temperature of the outer part of the earth's crust 

 in these latitudes, resulting from the action of the extreme cold of the 

 glacial period, may not yet exist, and, if so, whether they may not 

 admit of exact determination with reference to the time elapsed since 

 the removal of the disturbing cause. 



In conclusion, the author thinks that in the present state of the 

 inquiry it would be premature to attempt to fix even approximately 

 the lapse of time attaching to the flint-implements. It is obvious, 

 however, that our present chronology with respect to the first appear- 

 ance of Man must be very greatly extended ; but, like a mountain- 

 chain in the distance, its vast magnitude is felt before an exact 

 measurement of its height and size can be taken. 



Attention is then directed to the remarkable uninterrupted succes- 

 sion of life from the pleistocene period under review to the present 

 time a succession so large- and important, that it is not possible to 

 imagine the occurrence of any intervening catastrophe of such a 

 nature as to destroy the life of the period over this part of Europe at 

 any recent geological period. There are difficulties in the problem, 

 especially the disappearance of the larger animals ; but the remark- 

 able and convincing feature in the case is the transmission to our 

 time of so large a proportion of the small and delicate land and 

 freshwater shells, which even now follow almost precisely the same 

 law in their distribution as they did at these latest geological periods. 



Looking at the special nature of the glacial period, and seeing its 

 exceptional character, the author feels strongly impressed with the 

 belief that its effect has possibly been" to give increased rigidity and 

 immobility to the flexible crust of the earth, and to produce a state 

 of equilibrium which might otherwise have been of long and slow 

 attainment, whereby it has been rendered fit and suitable for the 

 habitation and pursuits of civilized man*. 



* In this and his former paper the author has used the terra " pleistocene" 

 in the sense of post-pleiocene, including also some beds placed in the newer 

 pleiocene. 



