224 THE, JOURNAL OF GEOLOGY. 



the time the ice began to accumulate, and higher than the corre- 

 sponding point of the surface of the ice at every earlier stage. 

 When 3,000 feet of ice had accumulated, and when this body of 

 ice had caused its full measure of depression, the temperature 

 over it must have been reduced at each point by an amount cor- 

 responding to the actual increase of elevation of the snow surface 

 over the pre-existent land surface at that point. The force of 

 the point here made is in no way lessened if the depression 

 caused by the accumulation of the ice l.ags behind the accurtiula- 

 tion itself. In so far as the sinking lags behind the loading, the 

 temperature of the surface is reduced beyond the limits indicated. 

 The principles here referred to will neither be reversed in their 

 operation, nor rendered nugatory, by further accumulation of ice. 

 So long as the ice thickens, it will remain true at all times that 

 each point of the surface of the ice-field must be higher than the 

 corresponding point at any earlier stage in the process of accumu- 

 lation, isostasy alone being considered. The elevation of the ice 

 surface (and this is the surface which determines the climate), 

 will overbalance any depression of the land surface which the ice 

 can cause by the disturbance of isostatic equilibrium. There 

 is, therefore, not only no tendency to the amelioration of climate 

 as the result of excessive snow accumulation, but there is a con- 

 stant reduction of temperature. Whatever may have caused the 

 dissolution of the Pleistocene ice-sheet, it was not the ameliora- 

 tion of climate resulting from the depression caused by the weight 

 of the ice itself, under conditions of isostasy. R. D. S. 



* 

 With this number. The Journal of Geology begins the pub- 

 lication of a series of articles on the geological surveys of the 

 various states of the Union. These articles will be prepared, so 

 far as practicable, by the ofificial geologists of the several states. 

 Their purpose is to publish to the geological world the present 

 condition of geological work in the various regions with which 

 they deal. They will indicate what has been done, and by 

 whom. They will make known the various plans on which sur- 

 vey work has been prosecuted in the several states. They will 



