32 THE CANADIAN NATURALIST. [Feb. 



Rhinoceros tichorhinus. Well may we then ask, how is it that the 

 ancient and larger glaciers, which were supposed to have had such 

 enormous excavating power as to have scooped out deep valleys in 

 hard rocks, should not have entirely destroyed the loose accumula- 

 tion of gravel over which they have been spread ? Or, if glaciers 

 excavated the Lago di Garda and Lago Maggoire, why did they 

 not produce any such effect at Ivrea, in the Valley of Aosta, down 

 which we know that enormous masses of ice travelled ; or at Rivoli, 

 in their march from Mount Cenis towards Turin ? 



Leaving it to physical philosophers, such as Forbes, Faraday, 

 Hopkins, and Tyndall, to show what is the real measure of the 

 abrading power of masses of moving ice, I simply form my opinion 

 from what glaciers are accomplishing, or have accomplished. Judg- 

 ing from positive data, I infer that if, as agents, they have been 

 wholly incapable of removing even the old and loose alluvial drift 

 which encumbered the valleys, infinitely less had they the power 

 of excavating hard rocks. At the same time I know that, in every 

 mountain tract which I have examined, there have been quite a 

 sufficient number of rents and denudations to account for all ine- 

 qualities. These openings have doubtless been greatly increased 

 by the atmospheric agencies of ages, and particularly in all those 

 situations where water has acted with great power, during the 

 melting of glaciers. **********•*# 



Whilst I was reading this Address to the Geographers in Lon- 

 don, that sound practical geologist, Principal Dawson, was perform- 

 ing a similar duty at the Annual Meeting of the Natural History 

 Society of Montreal. Having received a copy of his Address in 

 time for insertion of a Postcript, I am glad to have the opportu- 

 nity of stating that he also is a vigorous opponent of the theory 

 which refers the striation of the North American rocks, and the 

 excavation of the great lake-basins of that country, to the action 

 of terrestrial glaciers. He shows indeed that the great striation of 

 a large portion of the continent from N. e. to s. w. was from the 

 ocean to the interior, against the slope of the St. Lawrence valley 

 thus disposing at once of the glacier theory ; for it is impossible 

 to imagine that a glacier travelled from the Atlantic up into the 

 interior. Admitting that in limited tracts of Eastern America 

 there may have been local glaciers, Mr. Dawson believes, as I do, 

 that the rocks of the chief countries in question were striated when 

 the land lay beneath the sea. — From his address as President at 

 the Anniversary of the Royal Geographical Society, London, 1864. 



