J. D. Dana on American Geological History. 327 



we know how the ice, while a glacier, or along a shore of cliffs, 

 (for all bergs are believed to have once been glaciers,) may re- 

 ceive upon them or gather up heavy blocks of stone, even a 

 thousand tons in weight, and bear them off to distant regions, as 

 now happens in the Northern Atlantic. But we have no reason 

 to believe that the massy foot of a berg could pick up such blocks 

 and carry them twenty miles, to drop them again : and hence 

 the short distance of travel would prove that the bergs were 

 made that short distance to the north, and this implies the exist- 

 ence there of glacier valleys and requires a glacier theory. 



But without considering other difficulties, I pass to the inquiry, 

 Whether the lands, if not submerged, were at any higher level 

 than now ? 



There is evidence of striking character, that the regions or 

 coasts over the higher latitudes, in both the northern and south- 

 ern hemispheres, were once much elevated above their present 

 condition. The fiords, or deep coast channels, scores of miles 

 long, that cut up the coast of Norway and Britain, of Maine, 

 Nova Scotia and Greenland, of Western America from Puget's 

 Sound north, of Southern South America from Chiloe south, of 

 Van Diemen's Land and other southern islands, are all valleys 

 that could not have been scooped out when filled with the 

 ocean's waters as now ; that could have been formed only when 

 the land in those high latitudes, north and south, was elevated till 

 their profound depths were nearly or quite dry. Whether this 

 elevation was in the period of the Post-tertiary has not been pre- 

 cisely ascertained. But as they are proof of a north-and-south 

 system of oscillations, the same that was in action in the Drift 

 epoch, and as the cold that such a change would occasion is not 

 very distinctly apparent in the Tertiary period, and much less in 

 the earlier, we have reason for referring the greater part of the 

 elevation to that Drift era, and for believing that the excavation 

 of these fiord valleys was then in progress. Both fiords and drift 

 are alike high-latitude phenomena on all the continents north 

 and south. The change of climate between the Cretaceous and 

 Tertiary, and the absence of Tertiary beds north of Cape Cod, 

 may have been connected with an incipent stage in this high- 

 latitude movement. 



However this be, there is other evidence in the cold of the 

 Drift period, of some extraordinary cause of cold. The drift in 

 Europe and Britain is generally attributed to glaciers and ice- 

 bergs during a period of greater cold than now ; and the fact of 

 this greater cold is so generally admitted, that it is common to 

 speak of it as the glacial period. Professor Agassiz, moreover, 

 has urged for this continent the glacial theory. 



In a memoir of great research by Mr. Hopkins of Cambridge, 

 England, the able author maintains that this glacial cold might 



