ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxiii 



considered to have been formed by the waves beating against the 

 mountains during their elevation. 



Finally, with reference to the question of the angular erratic 

 blocks on the sides of the Jura and in other districts, the author 

 observes that, by showing that the levels at which these blocks are 

 found were below the sea for a long period at the epoch of their 

 removal, he gets rid of the only serious difficulty opposed to the 

 views of those who have supposed them to have been transported by 

 floating ice. 



Objections have been raised against some of Mr. Sharpe's views 

 on the ground of no marine remains having been found in the nu- 

 merous terraces which represent the ancient beaches or sea-bottoms. 

 Much of the force of this objection disappears when we consider the 

 nature of the deposit or detritus which forms these terraces. They 

 consist almost invariably of coarse sand, gravel, and rounded boulders, 

 the movement of which would have prevented the preservation of the 

 deUcate shells which the marine waters may have contained. More- 

 over, the objection is merely a negative one, and when we consider 

 the remarkable fact of the terraces of alluvium occurring at the 

 same height on the opposite sides of the alpine chain, as described by 

 Mr. Sharpe, it appears impossible to doubt their having been occa- 

 sioned by the agency of water which enveloped both sides of the moun- 

 tains at the same time and at the same level, and it appears equally 

 certain that this body of water must have been an oceanic body. At 

 all events the existence of such a sea filUng up the great Swiss valleys 

 affords a more simple mode of accounting for the occurrence of the 

 angular erratic blocks on the Jura, by supposing them to have been 

 floated across from the central chain on icebergs, than the theory by 

 which they are supposed to have been carried across on glaciers fill- 

 ing up the whole intervening space. It is a similar fact to that of the 

 occurrence of enormous fragments of granite on the island of Chiloe, 

 which Mr. Darwin supposes may have been carried from the main 

 land across the intervening arm of the sea by the same agency. 



Views of a nature somewhat different from those of Mr. Sharpe 

 have been advocated by M. A. Morlot in a paper published in the 

 Edinburgh New Philosophical Journal*, " On the past Tertiary and 

 Quaternary Formations of Switzerland." The author of this paper 

 alludes to the numerous terraces that occur at different heights in all 

 the valleys of Switzerland, but he attributes the origin of the diluvial 

 formation or drift of which they consist to the action of the existing 

 system of rivers, when their beds were at a higher level, in conse- 

 quence of the continent standing lower by several hundred feet. 

 But he adds, if the continent were to be uniformly upheaved once 

 more, the rivers would scoop out a deeper channel in their modern 

 deposits which would then project in the shape of terraces, as is the 

 case with the diluvial drift. Without stopping to examine this 

 apparent contradiction of rivers forming the diluvial deposit and 

 then scooping it out, I will mention that the main object of the 

 author's paper is to point out the existence of two glacial periods- 



* Vol. ii. 1855, p. 14. 



