328 HUGHES : INOLEBOROUGH. 
The Green Slate Series is seen in several sections, or on 
glaciated surfaces near Horton in Ribblesdale, but, except in the 
railway cutting south of the station, there is no continuous exposure 
for more than a few yards, so that it is difficult to correlate the 
horizons with those seen in Chapel-le-dale. It is, however, probable 
that it is the upper part of the series that is here represented 
from the occurrence of the Coniston Limestone Series so close 
to it on the south, and from the transitional character of the 
upper part of the series, which here contains much calcareous 
matter and even beds of limestone. The main mass, which succeeds 
in apparently descending section, consists of green slates, grits, 
and conglomerates not very unlike those which appear to underlie 
the passage beds in the gorge at the foot of Chapel-le-dale. The 
beds are generally inclined from 45° to 75° in a south-westerly 
direction, but they vary to such an extent and in such a manner 
in the direction and amount of dip, and are in places so crushed 
and veined, as to suggest that they are much folded and perhaps 
repeated, a supposition which is strengthened by the fact that all 
the pre-Carboniferous rocks are more and more intensely plicated 
as we follow them up Ribblesdale from south to north. 
The Green Slate Series of Ingleborough is probably the 
"geological equivalent""^ of the Green Slates and Porphyry of the 
Lake District and of the Bala Volcanic Series of North Wales. But 
there is a difference between the results of volcanic activity in these 
three areas. In North Wales there are lavas and volcanic breccias 
and ashes associated with fossiliferous marine deposits. It is clear 
that the volcanic masses were here built up on a sea floor, but that 
most of the lavas and ashes of successive great eruptions remain 
where they were first thrown out, and are not merely the 
volcanic material distributed far and wide over the bottom of 
the sea. 
In the Lake District, on the other hand, there are lavas and 
agglomerates, and ashes, but no traces of fossiliferous sediments 
associated with the great masses of volcanic ejectamenta, nor is 
* Whewell, History of the Inductive Sciences, Vol. III., p. 5.32 
