GLACIO-AQUEOUS ACTION IN NORTH AMERICA. 217 



aqueous action. Can either of these effects have been the result 

 of the elevation of the bed of the northern ocean by volcanic 

 agency ? Have we any example on record that wUl justify us in 

 assigning such effects as we witness to so apparently inadequate 

 a cause ? 



The glacier theory of Agassiz supposes an immense accumu- 

 lation of ice and snow around the poles dm-ing the glacial period, 

 which sent out enormous glaciers, southerly of course, by which 

 a part of the phenomena of drift was produced, and as the ice 

 melted away, upon the return of a warmer period, the oceans 

 of water thence resulting, produced southerly currents, which 

 ti-ansported icebergs and detritus in the same direction, and thus 

 finished the work begun by the glaciers. This theory, equally 

 with the last, fm-nishes an ocean, icebergs, and cold. It happily 

 explains, also, and so does the last theory, two facts with difficulty 

 reconciled to the first theory, namely, the transportation of detritus 

 from lower to higher levels, and the smoothing and furrowing of 

 the northern slopes of mountains. That these would be natural 

 effects of icebergs, urged southerly in an ocean which was grad- 

 ually rising over the land, so as to lift those icebergs to higher 

 and higher levels, is obvious : but how they could be produced 

 when the land was rising out of the ocean, and the water conse- 

 quently retreating, I am unable to conceive. 



If the glacial theory undertook to explain all the phenomena of 

 drift by the action of common glaciers, it would not need a mo- 

 ment's argument to show its entire inadequacy to account for 

 those phenomena in this country. But when it admits, as a 

 legitimate part of it, that accumulations of ice to an unlimited 

 extent may have existed around the poles, and that the return of 

 heat, by melting that ice, must produce southerly cm-rents, and 

 even vast deluges, for a long period, a new aspect is put upon it, 

 and we listen mth attention to its advocates. I confess, how^ever, 

 that as usually advanced by its able originators, it does not seem 

 to me to furnish a cause adequate to the effects. To account for 

 all the phenomena in this country, we want currenjs of water to 

 flow over a large part of the surface, loaded with ice and detritus, 

 for centuries at least. Now it is usual to speak of the accumula- 

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