THE GLACIAL HYPOTHESIS 313 



After exhibiting to their own satisfaction the inadequacy of either 

 the iceberg or the glacial hypothesis to account for their production, 

 the authors attempted to show how all the phenomena might be ex- 

 plained by the theory of a sudden discharge of a portion of the Arctic 

 Ocean southward across the land. They discussed the important func- 

 tions of the ' wave of translation/ showing its surpassing velocity and 

 great propulsive power, and traced the influence of vehement earth- 

 quakes near the pole in dislodging the northern waters and ice and 

 maintaining in the rushing flood these vast and potent waves. They 

 then suggested that, at a certain stage of the inundation, the ice, pre- 

 viously floating free, might impinge with irresistible violence against 

 the tops of submerged hills, and that the Canaan Mountain stood pre- 

 cisely in the position to take the brunt of the ice-driving flood as it 

 swept down the long, high slope of the distant Adirondacks and across 

 the low, broad valley of the Hudson. 



They then proceeded to show that, at the instant when some enor- 

 mous ice island struck the crest of the mountain and scooped the trench 

 which we there behold, a great vortex was produced by the obstruction 

 thus suddenly thrown in the path of the current, which, endowed with 

 an excessive gyratory or spiral velocity, was capable of sustaining and 

 carrying forward the greater part of the fragments. As in the instance 

 of the waterspout and the whirlwind, the whirlpool would gather into 

 the rotating column the projected blocks and strew them in a narrow 

 path in the line along which its pendent apex would drag the ground. 



Truly there were catastrophists in those days ! 



Agassiz, it will be remembered, came to America in 1846, and in 

 1847 was appointed to the professorship of geology and zoology in 

 Harvard. Naturally, an attempt was made to apply his views on 

 glaciation to the phenomena of the drift in America. In the summer 

 of 1848, in company with Jules Marcou and a party of students, he 

 undertook the exploration of the Lake Superior region, the results of 

 which were published in 1850. The views set forth relating to the 

 glacial phenomena of the region are of paramount interest. 



He argued that the drift of all northeast America and northwest 

 Europe was contemporaneous and due to a general ice sheet. Through 

 a repetition of many of his former arguments, he showed that a current 

 of water sufficiently powerful to transport the large blocks found would 

 have swept practically over the entire globe and not have stopped 

 abruptly, as did the drift, after reaching latitude 39° north. This 

 limit of distribution of the boulders to the northern latitudes also indi- 

 cated to his mind that the matter of climate was an important factor. 

 Water-transported material, he argued, would not cause straight fur- 

 rows and scratches, and the theory that such might be due to drifting 

 icebergs was rejected on the ground that existing bergs were insufn- 



