The Glacial Theory. 593 



Buckland abandons, to a great extent, the theory of Agassiz, and 

 admits fuUr the effects of water as well as of ice, to account for 

 many of the long-disputed phsenomena. Whilst this admission in- 

 volves the concession for which we have been contending, viz. that 

 the great surfaces of our continents were immersed, and not above 

 the waters when by far the greater number of the phaenomena on 

 the surface of rocks was produced, I reject for those who entertain 

 the same opinions as myself, the simple division into "glacialists" 

 and " diluvialists," into which Dr. Buckland has divided the com- 

 batants on this question ; for to whatever extent the former title 

 has been won by Agassiz and himself, we who have contended for 

 the submarine action of ice in former times, analogous to that which 

 we believe is going on at present, can never be merged with those 

 who, under the name of diluvialists, have contended for the rush of 

 mighty waves and waters over continents. Besides glacialists and 

 diluvialists, my friend must therefore permit me to call for a third 

 class, the designation of which I leave to him, in which some of us 

 desire to be enrolled who have advocated that modified view to 

 which the general opinion is now tending. 



The other point to which I allude, and bearing at once on this 

 view, is a discovery Avhich our Librarian has just made without 

 quitting the apartments which he so truly adorns. In the Ameri- 

 can Journal of Science for the year 1826, Mr. Lonsdale has de- 

 tected a short, clear, and modest statement, entitled " Remarks on 

 Boulders, by Peter Dobson," which, though little more than one 

 page in length, contains the essence of the modified glacial theory 

 at which we have arrived after so much debate. First describing 

 in a few lines the manner in which large boulders, weighing from 

 ten cwt. to fifteen tons, were dug out in clay and gravel, when 

 making the foundations for his own cotton factory at Vernon, and 

 seeing that it was not uncommon to find them worn, abraded, and 

 scratched on the lower side, "as if done (to use his own expression) 

 by their having been dragged over rocks and gravelly earth in one 

 steady position" he adds this most remarkable sentence: — " I think 

 vie cannot account for these appearances, unless we call in the aid of 

 ice as well as icater, and that they have been worn by being suspended 

 and carried in ice over rocks and earth under water." To show 

 also that he had read much and thought deeply on this subject, 

 Mr. Dobson quotes British authorities to prove, that as ice-floes 

 constantly carry huge masses of stone, and deposit them at great 

 distances from their original situation, so may tliey explain the trans- 

 portation of foreign boulders to our continents. 



Apologising therefore for having detained you long, and for 

 having previously too much extended a similar mode of reasoning, 

 I take leave of the glacial theory in congratulating American science 

 in having possessed the original author of tlie best glacial theory, 

 tliough his name had escaped notice ; and in rcconnnending to you 

 the terse argument of Peter Dobson, a previous acquaintance with 

 which might have saved volumes of disputation on both sides of 

 the Atlantic. 



In the mean time, however wc may attempt to account for tlic 



