31G CUTTRISS : NOTES ON THE CAVES OF YORKSHIRE. 
action of water is seen where a stream, descending from higher 
ground, reaches the limestone, into which it rapidly cuts a channel. 
The gorges thus formed are often 30 ft. or 40 ft. deep, and occa- 
sionally so narrow at the top they may be jumped across with 
ease. Sometimes a natural bridge of rock is left, which usually 
receives the appellation of God's Bridge. When the gorges have 
been enlarged by atmospheric denudation, they become clothed with 
vegetation and trees, forming picturesque retreats. Howstein in 
Upper Nidderdale, Ling Gill in Ribblesdale, and Yordas Gill in 
Kingsdale, may be cited as good examples. 
I. — Caves of the Yoredales. 
Turning to a consideration of the caves themselves, and follow- 
ing the classification already defined, the first to claim attention are 
those found in the rocks of the Yoredale formation. Towards the 
west the beds of limestones are of varying thickness, from a few feet 
upwards, being intercalated with beds of shale and sandstone, which, 
being unaffected by water, prevent the formation of high passages or 
caverns of large area. Being small and encumbered with accumula- 
tions of fallen rock and dirt, they do not offer much sport to the 
cave-hunter, nor do they materially affect the general drainage of 
the ground. For these reasons I have turned my attention more 
particularly to those in the other two divisions. 
The Fox-Holes on Cam Fell, at an elevation of about 1,600 ft., 
may be taken as fairly typical of this class. They are in the form 
of narrow fissures roofed over with sandstone, ver}' dirty, rotten, 
and choked with earth, through which the trickling water sinks. 
The rocks consist of alternate beds of dark and light limestones, 
highly fossiliferous (Encrinites), the dark beds being a few inches 
thick and the lighter coloured ones from inches to feet in thickness. 
Above these are soft sandstones, while underneath shale appears. 
The most interesting feature is the curious appearance of the 
limestone, the water having dissolved out the fossils on the surface, 
leaving a honeycombed mass of rotten rock having very much the 
appearance of pumice stone. The fissures will be from 25 ft. to 
30 ft. in depth. 
