268 
DAVIS I ERRATIC BOULDERS. 
escarpments overlooking Clapdale, and on the opposite one 
precipitous ridges extend for nearly two miles in a northerly 
direction towards the head of the dale, overlooking the Crum- 
mack valley. The escarpments of the limestone extend across the 
upper part of the dale, and on its eastern side constitute the 
rugged scars of Monghton Fell. Except on the Norber side, 
where a plateau of the limstone, considerably below the summit 
of the hill, and near the base of the limestone, extends across 
the valley to about J its width ; the whole of the surface of the 
valley lower than the limestone escarpments is composed of Silurian 
grits and slates. The latter form two or three anticlinals extend- 
ing across the valley ; the whole of the limestone which form- 
erly overlaid them having been denuded and removed, probably 
long before the period when glaciers descended the valley of 
which we are now speaking. Referring to the plan (plate XIV,) 
the whole of the surface of the upper part of the valley to the 
base of the Limestones is composed of Silurian rocks. At A, 
which is the primary source from whence the boulders strewn 
over the surface southwards have been derived, the rock is a 
massive thick-bedded grit forming the summit of an anticlinal, 
extending to, and exposed at Al. Near this point is the lime kiln 
marked on the survey map. Westwards the ground rises very 
rapidly in the direction of B, and the Silurian rocks dip at a 
very sharp angle to the N.E. By tracing these beds towards 
the upper part of the valley, it will be seen that they form a 
synclinal, and in about 150 yards again double over, forming an 
anticlinal. 
On the opposite side of the valley under the precipitous scars 
of Monghton Fell, the whole of the limestone has been denuded, 
and there are several exposures of the Silurian rocks, approach- 
ing more or less to the vertical, as at C and D on the plan, near 
Southwaite and as far south as the village of Wharfe ; beyond 
this point the Silurian rocks appear to be cut off by the northern 
branch of the Craven Fault. From A southwards the surface of 
the ground gradually rises, forming a plateau which extends to 
