300 
DAKYNS : GLACIAL PHENOMENA OF WHARFEDALE. 
scratches I got in this district were on Millstone Grit, on the 
southern part of Hebden Moor ; there I found scratches trending 
N.W. and S.E., and close by some doubtful ones pointing E.N.E. 
The valley of the Wharfe is crossed at Grasswood, a mile above 
Grassington, by a barrier of limestone, through which the river runs 
in a narrow channel. Above the barrier stratified sand and gravel is 
found. There is all the appearance of this rock barrier being the 
lower tip of a rock basin filled in with drift and alluvium. It is 
difficult to say how much of the sand and gravel is of the glacial 
period and how much is ordinary river gravel. The river gravels 
probably run back to glacial times. A similar barrier, of coarse 
gritsone, crosses the valley at the elbow in the stream near Drebley. 
The hills on either side of the river formed by this rock are called 
Herd's Hill and Heugh. Herd's Hill has a distinctly glaciated look 
as seen from a distance, but I could find no scratches for the reten- 
tion of which the rock is in fact too coarse. I found, however, some- 
thing like grooves running N.N.E. and S.S.W. This hill, along with 
the Heugh on the opposite side of the river, forms a prominent bank 
of grit, stretching across the valley, which it would dam up but for 
the narrow passage which the river has cut for itself. The drift is 
piled up against the high side of this dam. Gravel mounds enclose 
the Heugh on the north-west. These mounds gave no section ; 
externally they have an Esker-like look, as they are moundy and 
enclose hollows. They reach an altitude of 600 feet above the sea 
level. 
In constructing the puddle trench of the Barden Reservoir for 
the Bradford Corporation Waterworks, a total thickness of 65 feet of 
drift was met with. The section, as kindly communicated to me by 
the resident engineer, was as follows : — 
Ft. 
Yellow Clay ... .. ... ... 10 
Blue Clay, sandy and strong . . ... ... ^ 
Sand and Gravel ... . . ... . . . / 
Blue Clay, containing limestone boulders and great 
blocks of grit ; hard and water-tight ... ... 42 
