Or. XV. | 



ACTION OK RIVERS. 



signs of the lateral valleys having been first filled up with 

 drift to a certain height above their present streams, and 

 then hollowed out again, it is probable that such denuding 

 action has not been wanting. In favour of such an opinion, 

 I may refer to two isolated stone-capped columns of hardened 

 mud and gravel, which, are to be seen in a pine forest near 

 the village of Viesch, in a picturesque glen at the bottom of 

 which flows a stream bearing the appropriate name of the 

 Lawine Bach or ' Avalanche Brook. 5 The column which is 



18), occurs on the left side of the glen 





here figured (fi 



about 500 feet above the brook on a steep slope, the angle of 



which is about 4J 

 schist. 



k° 



The height 



greatest diameter about 10 feet, 

 is capped by 



The fundamental rock consists of mica- 

 of the column is about 40 feet, its 



and its irregular summit 



angular 



blocks of 



gneiss. 



Fragments 



of 



the same and of micaceous and talcose schist and pebbles 

 of white quartz enter largely into the composition of ' the 

 tower/ and many rocky fragments which may once have 

 formed the capping-stones of other columns are everywhere 

 strewed over the ground. There is a second similar pillar 

 within 80 or 100 yards of the largest one, which is about half 



diameter 



60 feet than the 



smaller tower is at \ 

 summit of the larg 



I could detect 



no scratches or signs of glacial polishing on any of the stones 

 which enter into the composition of these ' towers ;' but this 

 may perhaps be owing to the absence of limestone, serpen- 

 tine, and greenstone rocks, which are much more favourable 

 than gneiss for acquiring and retaining glacial markings. 

 Avalanches of snow descend annually the steep slopes of this 

 len, with such force as frequently to uproot the largest pine- 

 trees ; and when we consider the destructive power of this 

 cause and the earthquakes which have occurred again and 

 again in the neighbourhood, we cannot but wonder that even 



former 



seems 



up the lower part of this narrow valley to a height of 500 



am 



Action of 



The pillars above described, especially 



