-222 THE CANADIAN NATURALIST. [June, 



ily rejected this last doctrine ; being convinced that insuperable physi- 

 cal and meteorological objections might be urged agaiast 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. In 

 making this statement I know that I differ in some deg-ree from 

 many of my geological friends, but I know that they will be 

 rejoiced that I should freely and frankly state the reasons of my 

 belief. 



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 north- 

 ward, and the deposit on the boulder-clay of beds of stratified 

 clay and sand, containing marine shells. The rival theories in 

 discussion sue— first, that which supposes a gradual subsidence and 

 re-elevation, with the action of the sea and its currents, bearins; ice 

 at certain seasons of the year ; and, secondly, that which supposes 

 the American land 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 important of these is 

 the coincidence of a wide-spread continent and a universal cover- 

 ing 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 ex- 

 tending above the snow-line ; and that cases in which, in such 

 latitudes, glaciers extend nearly to the sea-level, occur only where 

 the mean temperature is reduced by cold ocean-currents approaching 

 to high land, as for instance in Terra del Fuego and the southern 

 extremity of South America. But the temperate regions of North 

 America could not be covered with a permanent mantle of ice 

 under the existing conditions of solar radiation ; for even if the 

 whole were elevated into a table-Iand,its breadth would secure a suffi- 



