DAKVN's: (;lacial puknomexa of wiiarfkdale. 
Tlie valley of the Wliarfe is crossed at Grasswood, a mile 
above Grassiiigton. 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 every appearance of this 
rock barrier being the lower lip of a rock basin filled 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 more modern 
river gravel. The river gravels probably run back to glacial 
times. 
A similar barrier of coarse grit stone crosses the valley at 
the elbow in the stream below Dribley. The hills on either 
side of the river, formed by this rock, are called Herds Hill and 
Heugh. Herds Hill has a distinctly glaciated look, as seen 
from a distance ; but I could not find any scratches, for the 
retention of which the rock is. in fact, too coarse. I found, 
howevei'. something like grooves running X.X.E. and S.S.W. 
This hill, with the Heugh on the op])osite side of the river, forms 
a prominent l)ank of grit stretching across the valley, which 
it would dam u]) but for the narrow passage which the river has 
cut for itself. The drift is piled up against the high side of 
tliis dam. Gravel mounds enclose the Heugh on the north- 
west. These mounds gave no section ; but externally they look 
like Eskers. as they are moundy and enclose hollows. They 
attain an altitude of 600 feet above 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 communi- 
cated to me by the residing engineer, was as follows : — 
Yellow clay, 10 feet. 
Blue clay, sandy and stony 1 ^ ^ 
Sand and gravel / 
Blue clay, 42 feet thick, hard and watertight ; con- 
taining limestone boulders and great blocks of grit. 
The yellow clay at the surface is doubtless merely the 
weathered part of the blue clay. 
