Vol. 65.] THE HOWGILL FELLS AND THEIE TOPOGRAPHS'. 



603 



truncated spur immediately south of the latter gill. A snow- slope 

 ' moraine ' crosses this gill high up. 



We are now in the drainage oi Cautley Beck, which Pickering 

 Gill joins just hefore the former beck flows into the Rawthey. 

 Cautley Beck occupies a wide U-shaped valley, the lower part of 

 which is graded to the Rawthey. This beck presents an admirable 

 example of a series of captures which, beginning in pre-Glacial time, 



Fig. 5. — The Cautley-Bowderdcde diversions. 



[The broken lines indicate the former course of the drainage.] 



have continued through Glacial time to the present day. The 

 phenomena displayed are only explicable on the supposition that 

 Bowderdale Beck (which flows northwards in a valley to be described 

 later) once arose in two tributaries on each side of the plateau 

 known as Great Dummacks, over 2150 feet high. The drainage 



