“ The Pennine system is hardly a range, but the hills are in effect broken up into numerous short ranges by valleys cut back into them in every direction, for the Pennines form a north and south watershed which determines the course of all the larger rivers in the north of England. ”

“ The English system is comprised within the following physical boundaries. On the N. a well-marked depression, falling below 500 ft. in height, between the upper valleys of the Irthing and the south Tyne, from which it is known as the Tyne Gap, separates the Pennines from the system of the Cheviots. On the N.E., in Northumberland, the foothills extend to the North Sea. On the N.W. the Eden valley forms part of the boundary between the Pennines and the hills of the Lake District, and the division is continued by the upper valley of the Lune. ”

“ Malham Tarn, near the head of the Aire, is drained by a stream which quickly disappears below ground, and the Aire itself is fed by a brook gushing forth in full stream at the foot of the cliffs of Malham Cove. ”