104 J. D. Dana— Flood of the Connecticut River Valley. 



changes of land-level and not simply a change of oc< 

 connected with the coming on and disappearance of the ice of 

 the Glacial era; and that the level during the Glacial era was 

 not below the present, like that of the era following, but at 

 least as high as the present, and probably, in many portions of 

 the colder latitudes, somewhat higher than now. 



It thus follows that a change of level of very wide continen- 

 tal range introduced the era of depression or 01 

 period — a change so great and so marked in its effects that it is 

 reasonably recognized as a time-boundary in Quaternary his- 

 tory; and as the Champlain period was one of ameliorated cli- 

 mate, it may have begun with the beginning of the melting. 

 As I have shown in the earlier part of this memoir, the depres- 

 sion was certainly a fact during the great flood, and began before 

 the melting had far advanced. The fact of a warmer climate in 

 the Champlain period is manifested in the distribution of the 

 quadrupeds and forest trees of America, Europe and Siberia, 

 as now generally admitted. It is monstrated 



among the lands of the Arctic seas, where, on Banks's Land 

 (74° 48'), Prince Patrick's Island (76° 12' N.), and elsewhere, 

 unaltered trunks of modern fir trees, single and in forest-like 



But the facts as to amount of change of level are not so well 

 known that we can mark off the limits of the areas of elevation 

 and depression over the higher latitudes. They do not enable 

 us to decide whether there were not, extending northward, a 

 series of upward and downward flexures, with only a greater 

 general emergence than now in the Glacial era and a greater 

 general submergence in the era following. The heights of ter- 

 races on the coast of Greenland seem to be an indication as to 

 one in this series of flexures. In any case the facts do not 

 sustain the ordinary assumption that the amount of depression 

 in the Arctic regions was approximately alike in all parts, and 

 they leave it to be proved that all portions participated in the 

 subsidence. 



The cause of the depression of the land, or of the previous 

 elevation, this is not the place to consider. 



