Rev. T. G. Bonney — Cirque in the Hills of Shye. 539 



of sodden peat ; but the upper half is bare and bald, a stony desert ; 

 for the rain brings down fresh streams of screes from above faster 

 than even the mountain grass can grow in a Hebridean summer. 



Indeed, so rapid is this destructive agency, that in not a few 

 corries and cirques, here as elsewhere, the transporting power can 

 hardly keep pace with the excavatory. The water- saw and the ice- 

 wedge can quarry the rock faster than the stream can carry away 

 the spoil; and so, to some extent, they are counteracting themselves, 

 and the excavation is being filled up faster than it is being enlarged. 



f^urther, these Cirques, though not made by glaciers, have been 

 occupied by them. The ice-worn slopes at the very foot of the cliffs 

 show that comparatively little change has taken place since the 

 time when the last snow melted away from the head of the glen ; 



Fig. 3. — Cirque in Process of Formation. Pass near Engelberg. 



A. Limestone cliffs. B. Shaly bank, witTi some trees, etc., out of whieli the streams break. 

 D. Cirque. The arrows mark Cascades. 



they, therefore, were prior to the glacier, and far more tlie cause 

 of it than it of them. They must have been Cirques when the 

 approach of a polar climate first enabled the winter snow to remain 

 in these sheltered nooks all through the summer. Some modification 

 there would doubtless be then. The cliffs would still be cut back 

 by water in summer, by frost in winter ; the talus borne away, or 

 crushed by the glacier ; the rocks below somewhat worn and 

 rounded ; but still the completeness of the Cirque as a whole 

 forbids us — unless we assign it entirely to glacial action — to suppose 

 that it was more than slightly altered by this. It therefore, like 

 those which I examined in the Alps, shows that in crystalline, as in 

 sedimentary, districts the action of glaciers was little more than 



