HISTORICAL NOTICES. 13 



and meteorological objections might be urged against it, 

 and that it was not in accordance with the facts which I 

 had myself observed in Nova Scotia and in Canada. The 

 additional facts contained in the present report enable 

 me to assert with confidence, though with all humility, 

 that glaciers could scarcely have been the agents in the 

 striation of Canadian rocks, the transport of Canadian 

 boulders, or the excavation of Canadian lake -basins 

 [except in the great mountain ranges of the continent]. 



" The facts to be accounted for are the striation and 

 polishing of rock-surfaces, the deposit of a sheet of 

 unstratified clay and stones, the transport of boulders 

 from distant sites lying to the northward, and the deposit 

 on the boulder-clay of beds of stratified clay and sand, 

 containing marine shells. The rival theories in discussion 

 are -first, that which supposes a gradual subsidence and 

 re-elevatiori, with the action of the sea and its currents, 

 bearing ice at certain seasons of the year ; and, secondly, 

 that which supposes the North American plateau to have 

 been covered with a sheet of glacier several thousands of 

 feet thick. 



" The last of these theories, without attempting to 

 undervalue its application to such regions as those of the 

 Alps or of Spitzbergen or Greenland, has appeared to me 

 inapplicable to the drift-deposits of eastern America, for 

 the following among other reasons : 



" 1. It requires a series of suppositions unlikely in 

 themselves and not warranted by facts. The most impor- 

 tant of these is the coincidence of a wide-spread continent 

 and a universal covering of ice in a temperate latitude. 

 In the existing state of the world, it is well known that 

 the ordinary conditions required by glaciers in temperate 

 latitudes are elevated chains and peaks extending above 



