Presented by the Glaciers of Switzerland. 351 



Alps — for example, those which surround the openings of the 

 lakes of Zurich, Greifensee, and Sempach, are connected 

 more or less intimately with the moraines of existing glaciers, 

 and that the mode of production in the one case is absolutely 

 the same as in the other. In general, it may be said, that the 

 more we study the erratic formation of the Alps the more we 

 find in it analogies with the deposits of glaciers, and the 

 more do the difficulties of the theory of currents multiply and 

 gather strength. 



With regard to the lapias^ of which M. Desnoyers has 

 spoken in discussing M. Durocher's Memoir (p, 85 of the Bui- 

 letin)^ I may be permitted to add, that this phenomenon ap- 

 pears to me to be completely independent of the action of 

 glaciers. The prevailing character of the latter is to make 

 all the natural asperities of the ground disappear, and to pro- 

 duce forms more or less rounded and flat. The characteris- 

 tic property of the lapias is, on the contrary, to increase the 

 inequalities of the ground, to have a surface excessively rough 

 and covered with projecting points, hollows between the pro- 

 minences, and even the smallest intervals bearing pointed 

 projections and plates as sharp as a knife, &c. In it the 

 furrows are, in general, in the direction of the steepest slope, 

 and frequently terminate below in funnels sensibly vertical, 

 very deep, often corresponding to the tributaries of the great 

 springs, spouting out on the slopes, and at the bottom of moun- 

 tains (Hundsloch in Wseggithal, sources at Engelberg, at Bi- 

 sithal, &;c.) The formation of lapias, in my opinion, depends 

 on the want of perfect uniformity of substance in the rock, 

 taken in connection with its being of a certain consistency, 

 a consistency which admits of the parts not destroyed to re- 

 main standing, and increase in size in proportion as the chan- 

 nels become deeper by the mechanical and chemical action of 

 what falls from the atmosphere. In fact, it is only, as far as 

 I know, calcareous rocks which exhibit lapias; they never ap- 

 pear in sandstone and crystalline rocks. Among the calcare- 

 ous rocks of the Swiss Alps, it is that at Caprotina^ and the 

 compact, bluish-black, brittle limestone (representing the 

 middle oolite), which are most favourable to the develop- 

 ment of this form of surface, principally in elevated regions, 



