﻿478 



Correspondence — Mr. A. J. Jukes Broivne. 



this, and, wishing to gain a better view of the country, I dismounted, 

 and ascended the steep slope which formed its northern side ; I then 

 found myself on a flat-topped ridge looking down into three valleys 

 at once (as shown in diagram at A). 



The watercourse I had been following (B) was cut off by a 

 wider and deeper valley, here making a magnificent curve : and on 

 my left was a deep, broad, and short hollow (C), only separated 

 from the same valley by a narrow ridge or knife-edge. Its sides 

 presented a succession of irregular steps, resulting from the weather- 

 ing of the hard and soft beds of the limestone ; but these were 

 interrupted by numerous small channels and gulleys, and the heaps 

 of debris which choked up the bottom testified clearly to the mode 

 of its formation. Although evidently a rain-gorge, its cirque-like 

 form struck me at first sight, and the reason of its taking this shape 

 was easily perceived ; having been cut backwards till a mere knife- 

 edge remained between it and the valley beyond, elongate extension 

 had become impossible, but the runlets which drained the flat-topped 

 heights on each side had so extended it laterally that its width was 

 already more than half its length. 



Now is not this very suggestive of the origin of other cirques? 

 Mr. Helland finds a difiiculty in the fact that the part of the crest 

 surrounding the cirque, and sloping to it, is so narrow that it cannot 

 feed even a small stream. Mr. Bonney has shown that he should 

 have said, " can only feed very small streams," and with this cor- 

 rection the sentence would fairly indicate the very conditions which 

 I conceive to be essential to the formation of a cirque, viz. the con- 

 centration of small streams falling off a narrow mountain crest. 



Mr. Helland himself says (p. 165) : " The cirques which occur 

 isolated in the mountains are not essentially different from the 



valleys which end in a cirque They both occur in the same 



waj', except that the valleys are longer, their area being as much as 

 25 times as great as that of the cirques." Surely he would not have 

 us believe that these valleys are likewise the result of glacial action ; 

 and if not the valleys, then why the cirques ? 



