270 Canadian Record of Science. 



permanent ice would take place, along the American coast 

 at first, but probably at length even on the European side. 

 This would still further chill the atmosphere, glaciers would 

 be established on all the mountains of temperate Europe 

 and America, 1 the summer would be kept cool by melting 

 ice and snow, and, at length, all Eastern America and Europe 

 might become uninhabitable, except by arctic animals and 

 plants, as far south as perhaps 40° of north latitude. This 

 would be simply a return of the Glacial age. I have 

 assumed only one geographical change; but other and more 

 complete changes of subsidence and elevation might take 

 place, with effects on climate still more decisive; more 

 especially would this be the case if there were a considera- 

 ble submergence of the land in temperate latitudes. 



"We may suppose an opposite case. The high plateau of 

 Greenland might subside or be reduced in height, and the 

 North Atlantic might be closed. At the same time, the 

 interior plain of America might be depressed, so that, as we 

 know to have been the case in the Cretaceous period, the 

 warm waters of the Mexican Gulf would circulate as far 

 north as the basins of the present great American lakes. In 

 these circumstances there would be an immense diminution 

 of the sources of floating ice, and a correspondingly vast 

 increase in the surface of warm water. The effects would 

 be to enable a temperate flora to subsist in Greenland, and 

 to bring all the present temperate regions of Europe and 

 America into a condition of sub-tropical verdure. 



It is only necessary to add that we know that vicissitudes 

 not dissimilar from those above sketched, have actually 

 occurred in comparatively recent geological times, to enable 

 us to perceive that we can dispense with all other causes of 

 change of climate, though admitting that some of them may 

 have occupied a secondary place. 2 This will give us, in dealing 



1 According to Bonney, the west coast of Wales is about 12° above 

 the average for its latitude, and if reduced to 12° below the average, 

 its mountains would have large glaciers. 



2 More especially, the ingenious and elaborate arguments of Croll 

 deserve consideration; and, though I cannot agree with him in this 

 main thesis, I gladly acknowledge the great utility of the work he 

 has done. 



