Vol. 65.] THE HOWGILL FELLS AND THEIR TOPOGRAPHY. 597 



There is no doubt that in pre-Glacial times the Curling Gill 

 stream was almost ready to behead Little Ulgill Beck below the 

 site of what is now Black Force. The slopes on the south side of 

 Green Knott (a shoulder of Uldale Head) and on the opposite side 

 of Carling Gill indicate the existence of a curved valley-head (the 

 middle head above described), which cannot have been separated 

 from Little IJlgill Beck Valley by more than a few score yards, 

 and it was much more deeply cut than was the latter valley. The 

 valley above Black Force is well glaciated, U-shaped, and with 

 much drift which is now spilt over Carling Gill north-east of Black 

 Force, owing to the subsequent capture of Little Ulgill Beck by 

 Carling Gill. The evidence is, on the whole, in favour of the ice 

 in Little Ulgill widening that valley to a sufficient degree to cut 

 through the ridge between it and the middle head of Carling Gill, 

 at which time ice- and moraine-matter was spilt over into the 

 deeper Carling Gill. After this occurrence, and after the recession 

 of the ice, the waters of Little Ulgill Beck, following the ice-course, 

 have cut out the water- carved gorge of Black Force, which is 

 590 feet high from top to base, the old valley being one of the 

 most striking hanging valleys in the North of England, especially as 

 seen from Green Knott. 



After this capture, the further capture of the Great Ulgill Beck 

 discussed by Dr. Strahan was a small matter. The old beheaded 

 valley would be dry as far down as the point of incoming of the 

 next tributary, the waters of which would therefore tend to build 

 out a delta across the main valley. This delta would grow to a 

 height sufficient to direct the waters along the dry valley to a point 

 where they could get across to the Carling Gill draiuage. This has 

 been done, and, owing to the increased grade, a deep cut has been 

 made here also (at the Spout), though not with so marked a waterfall 

 as at Black Force. It must be noted that this cut is partly in the 

 old course of the curved middle head of Carling Gill, and that, 

 therefore, the amount of post-Glacial erosion is not so great as 

 Dr. Strahan suggested. The canon-like character of the gorge, 

 with its overlapping spurs and rocky precipices, indicates its post- 

 Glacial formation. Traces of an old shelf on the left bank of the 

 gorge mark the old east side of the valley-floor of Little Ulgill. 



The diversion by delta-growth described above is actually seen 

 in the process of diverting the next tributary down-stream into 

 Carling Gill at Blakethwaite Bottom, and in a few years will 

 probably be complete. At the time of our visit, the stream from 

 Docker Knott was flowing over the south side of the delta into 

 Carling Gill ; but a dry channel in the delta-material, northwards 

 into Uldale, may in time of flood take back the bulk of the waters 

 in that direction, although of course the growtb of the delta will 

 eventually send the stream always the other way and a further 

 stretch of Uldale will be permanently dry, and so prepare the way for 

 another growth of delta by a tributary farther down stream, and 

 yet other captures of the Uldale tributaries by Carling Gill. This 



