17 
east of Malham ; and Flasby Fell, near Skipton. The out- 
line of the latter, as seen from the south-east, presents a 
striking, but I need scarcely say, purely superficial resem- 
blance to that of a volcano with ancient crater and modem 
cone. 
At Skipton commences the third area, composed of Mill- 
stone Grit and Lower Coal Measures. The country thence to 
beyond Leeds presents the characteristic scenery of these 
formations, with rugged scarps where the coarse grits occur, 
bold, wooded banks for the finer-grained, but still massive 
sandstones, gentler undulations for the softer flagstones, and 
irregular hummocks of shale. 
The lower part of Airedale is occupied by Permian and 
Triassic rocks and tidal warps : not having seen these, I can 
say nothing about them. 
I will now briefly describe the lithological characters of 
the rocks of the district, and indicate the most instructive 
sections in each. 
The oldest rocks occurring in the basin of the Aire are the 
Silurian slates already mentioned as present at the source of 
the river, where however they are completely hidden by the 
drift. On the north, their denuded edges are covered by the 
Carboniferous rocks, and on the south they are bounded by 
the great North Craven fault. The strip of land thus 
enclosed varies in width from a few dozen yards on the 
western watershed to nearly a mile at the Tarn, eastwards 
from which the base of the Carboniferous series rapidly 
approaches the fault, reaching it just beyond the Gordale 
Beck, in which it and the subjacent slates are seen in section. 
In Eibblesdale this series is largely exposed, and, besides 
running far up the vr^leys to the bases of Ingleboro' and 
Penyghent, it extends quite across Pibblesdale to Clapham, 
a distance of eleven miles from Gordale. The exact position 
of these beds in the typical Silurian series is, I believe, not 
2 
