The Glacial Theory. 591 



monstrate what he now seems to believe, that the great mass of the 

 continent of North America was formerly covered with ice, he must 

 first prove that it was not at that period below the level of the sea ; 

 but as yet no facts are before us to lead us to doubt that the great 

 accumulation of detritus and the transport of blocks did take place 

 beneath the waters in that country. In justice, however, to this 

 author, it must be said, that in expounding the glacial theory he 

 ingenuously acknowledges the great difficulty of believing that solid 

 masses of ice 3000 to 4000 feet thick, covered the whole region ; 

 that no action of a glacier will explain the persistent striation of the 

 surface of an entire continent from N. to S., and that the direction 

 of the boulders and the striae is to a great extent up-hill. When 

 these and many other difficulties shall have been carefully weighed, 

 our transatlantic fi'iends may be disposed to modify their views, par- 

 ticularly when they find that the existence of glaciers in Scotland 

 and England (I mean in the Alpine sense) are not yet, at all events, 

 established to the satisfaction of what I believe to be by far the 

 greater number of British geologists. 



The presence of Mr. Lyell at this time in North America, is m- 

 deed, most opportune, for whatever changes his mind may have 

 recently undergone, no geologist has more strenuously laboured to 

 make himself master of all its bearings, or more systematically en- 

 larged our knowledge of this disputed subject. Possessing as he now 

 does the advantage of observation on a vast scale, I have little doubt 

 that he will account for the wide dispersion of blocks in America 

 from N. to S. by referring to a cause quite as general and quite as 

 aqueous as that by which he originally sought to explain the phaeno- 

 menon in Europe*. 



Although the consideration of this subject has already carried me 

 beyond the limits I had prescribed to myself, yet I cannot quit it 

 without reminding you, that the greatest geological authorities on 

 the continent, led on by Von Buch who has so long studied these 

 phaenomena in his native land, are opponents to the views of Agassiz. 

 Even whilst I write, I find that M. de Beaumont has just communi- 

 cated to tlie Institute of France, a report on the results of a journey 

 through Lapland, Finland, and the north of Europe, by his country- 

 man M. Durocher, in which grouping the facts with great perspi- 

 cuity, he handles the whole subject with his usual master's hand, 

 and points out the value of the previous observations of Von Buch, 

 Brongniart, and otlier writers. M. Durocher conceives that the 

 phaenomenon of the transport of erratic matters has proceeded from 

 two successive and distinct operations : the first a great current from 

 the pole, to which the striae and polisii of rocks, and the deposits 



views, when he places my name among those who had espoused the Alpine 

 glacial theory. My efforts have been invariably directed towards its limi- 

 tation, nay, to its entire rejection as applicable to by lar tlie largest por- 

 tions of the surface of the globe. 



• Sec Principles of Geology, 2nd ed. vol. i. p. 342 ; and Elements of 

 Geology, 1st ed. p. 136. 



