Canon Bonney — Moraines and Mud-streams in the Alps. 11 



weighed many tons ; the largest were about ten-foot cubes. The 

 stuff that followed them filled the nala to a width of about forty 

 and a depth of about fifteen feet. The thing moved down at a rate 



of perhajos seven miles an hour Looking up the nala, 



we saw the sides of it constantly falling in and their ruins carried 

 down." Finally, the material spread out as a fan on the bed of the 

 valley below.^ Earth pillars, he observes, are frequently seen to be 

 carved from the older masses. 



Thus it is evident that under certain circumstances deposits, which 

 may be termed mud avalanches, do not a little towards filling up the 

 valleys in mountain countries. Such deposits are, I believe, more 

 common in the Alps than is sometimes supposed. In my diary for 

 1893 I made this note on the valley between Hinterrhein and 

 Splugen : — " A marked feature is the quantity of debris brought 

 down by the lateral torrents, forming alluvial fans cut through 

 by the main river. The stuff is often like moraine, but the stones 

 (ranging from sub-rotund to angular) are more rounded, and there is 

 a considerable quantity of earthy matter, often more than the stones. 

 The deposit exhibits a slight stratification, and reminded me at 

 times of the esker material which I had seen near Parsonstown."^ 

 It is clear that under certain circumstances this method of accumu- 

 lation of debris in valleys is most important, and, where not closely 

 studied, might be mistaken for till. Below Andeer, where the valley 

 again opens out, great fans of debris are seen on the left bank, 

 similar to those described above, exhibiting in places fairly marked 

 stratification. The river has exposed a fine section of one on that 

 bank, the cliff being perhaps fifty feet high, and on the opposite 

 side, where the valley is contracting, is another. As the drift can 

 be traced down to the level of the river, the valley must have been 

 excavated to its present level before these fans were deposited. 

 But it is often extremely difficult, when only an isolated section 

 can be obtained, to say whether this is in a mud avalanche or 

 a true moraine.^ 



From these I pass to deposits which have been often claimed 

 as moraines, such as that from which the earth pillars at Useigne, 

 in the Eringerthal, have been sculptured. Very near to these the 

 main valley is joined by the Val d'Heremence. The deposit, 

 a kind of till in which large boulders are not very numerous, 

 extends some distance into the latter and for more than two miles 

 up the former, occurring first mainly on the left bank, then on the 

 right.* Good sections may be frequently seen. In one case, on 



1 See also " The Making of a Frontier," by Colonel A. Durand, pp. 33, 34. (As 

 I have explained in a paper now in the hands of the Geological Society, I think 

 Sir M. ConAvay's description includes with the mud avalanches a breccia which has 

 a rather different history.) 



^ I had examined this dm'ing the previous Summer (1892). 



^ In my diary I have given the facts which make for the one or the other 

 conclusion, but as there is no impossibility that both may occur in this valley I deem 

 it needless to enter into particulars. 



* It is shown clearly on the Geological Map, where it is marked as "Terrain 

 Glaciaire." The material, from which the actual pillars are carved, is perhaps 

 more directly in the line of the Val d'Heremence. 



