443 



the gravel and other transported materials of the basin of Geneva? 

 being a second part of his former essay on the same subject. He in- 

 dicates the localities in which the fragments of different rocks have 

 originated, showing that although some have been drifted from the 

 east, and others from the west, many of them are probably rem- 

 nants of those calcareous mountains which were shattered on the 

 spot, at that period of dislocation, when by the expulsion of their 

 debris, that great cavity was formed, which is now occupied by the 

 lake. The superficial sediments of the basin are said to vary much 

 in their composition ; whilst their beds are inclined in all directions, 

 thereby indicating the effects of numerous and conflicting currents 

 of water, which in some cases have hurled down large boulders of 

 primary rock from the higher Alps, and in others have heaped up the 

 finer alluvia derived from the adjacent secondary formations. All 

 these phenomena are supposed by the author to have been caused 

 by debacles incident to lengthened periods in which the surrounding 

 mountains were forcibly and violently elevated. 



From these and other writings of the present day, we perceive 

 that correct observations have now established, that the diluvial and 

 transported detritus of each great geographical division of Europe, 

 when viewed on a great scale, can for the most part, be traced to 

 an axis of elevation within that region ; so that as each great mountain- 

 chain has been the source of the detritus covering the adjacent low 

 country, we can no longer attribute such drifts of sedimentary 

 matter to one particular diluvial current, which has acted in any given 

 direction. 



However indisposed, therefore, the diluvialists may be to adopt as 

 a full and satisfactory explanation of these appearances the modi- 

 fied view of the theory of diurnal action of Hutton, as put forth by 

 Mr. Lyell, the dispassionate reasoner must admit, that the question 

 between the diluvialist and the advocate of existing causes is fast 

 resolving itself into one of amount or intensity of forces. Each party 

 has now recourse to modern analogies in referring changes between 

 the levels of sea and land to eruptions from beneath; and he who is 

 unwilling to quit a path of induction pointed out, as he believes, by 

 nature, invokes only repeated shocks of earthquakes, elevations, and 

 depressions, in preference to a limited number of stupendous cata- 

 strophes insisted upon by his antagonist. 



Tertiary Deposits. — In the illustration of tertiary geology, I may 

 announce to you, that the last pages of the Third Volume of the Prin- 

 ciples of Geology, by Professor Lyell, are in the press. In this volume, 

 which I have perused, the author successfully applies to the tertiary 

 formations the principles laid down in the two first volumes. He 

 subdivides these younger deposits into four natural epochs, founded 

 upon a mass of zoological evidence infinitely more comprehensive, and 

 yet more precise than any which has ever been brought before us. In 

 treating chronologically of alluvial, fresh-water, marine, and volcanic 

 phenomena, a wide range is afforded for the development of his exten- 

 sive knowledge and observation ; enabling him to ground his rea- 



