124 Mr Muvchihon on the Glacial Theory. 



ern banks of the lake* to Vevey or even to Lausanne, yet can- 

 not conceive that they could reach to the Jura ; and is there- 

 fore of opinion, that the blocks met with on the sides of 

 this chain of mountains have been brought thither by means 

 of a great sheet of ice, forming an inclined plane from the sum- 

 mit of the Alps. Ice, it is true, is thus the principal agent in 

 both hypotheses ; but the one supposes a very*considerablc 

 change in the temperature, and a state of things which no- 

 thing of our own times can enable us to form an idea of; while 

 the other is founded on the direct observation of actual facts, 

 and requires nothing more from the imagination of the reader 

 than to prolong, for a sufficient time, the exceptional circum- 

 stances, of which we yet witness occasional instances. This the- 

 ory of diluvial glaciers has already made much'progress among 

 geologists, and its application is by no means limited to the 

 erratic deposits of the Alps. At a great number of places, in 

 England, Scotland, and Norway, some have thought they re- 

 cognised facts analogous to those on which M. de Charpentier 

 has founded his hypothesis ; and now that the impulse is given, 

 it is perhaps more to be feared that we shall see a good many 

 geological phenomena ascribed to the influence of glaciers, 

 which the author of the theory would himself have excluded, 

 than that doubts will be thrown upon the facts which he has 

 so well described and so conscientiously observed."^ 



On the Glacial Theory. By Roderick Impey Murchisox, 

 Esq., President of the Geological Society, «foc.t 



From a study of the Alps, where Yenetz and Charpentier led the way 

 in shewing that a connection existed between the erratic blocks and the 

 advance of glaciers. Professor Agassiz has deduced a glacial theory, and 

 has endeavoured to generalize and apply it even to our own countries, 

 in which effort he has been supported by my predecessor in the Chair. 

 In the following observations, I will endeavour to point out what new 

 materials have been brought forward, abroad and at home, to enable us 

 to reason correctly on this difficult question, and I will then suggest some 

 essential modifications of the new hypothesis. 



As propounded by Agassiz, the glacial theory, even in its application 

 to the Alps, has met with an opponent in the person of Professor Necker 



* From Biblioth. Universelle do Geneve, No. 74, p. 390. 

 t From the address delivered ut the Anniversary Meeting of the Geologi- 

 cal Society of London, 1842. 



