HUGHES : IXGLEBOROUGH. 
367 
abundance of these in the basement bed of the Carboniferous 
also, which is well seen on the other side of the stream, nearer 
the mouth of the keld. it is clear that the Green Slate Series can- 
not be far off. The matrix of this basement bed of the Silurian 
is here also rather calcareous, especially in the white band at 
its base, but ps it is composed almost entirely of the soft sand- 
stone beds of the older series, the general appearance of the 
rock is very different from tliat seen near Wharfe Mill Dam, 
where the predominance of hard rocks in the conglomerate 
makes it stand out, and the number of pebbles of grit and con- 
glomerate, bright with pink orthoclase felspar mixed with various 
shades of green and grey, give the whole a rich and pleasing 
colour. But in the section at Austwick Beck Head it is dull 
coloured and inconspicuous. 
The basement bed of the Silurian is again seen in the next 
valley to the east at Crag Hill, near Horton-in-Ribblesdale. 
The plan and sections (Figs. 6, 7 and 8)* show the relation 
of this bed, the grey crystalhne limestone (e), to those above 
and below ; (e) is the band which, starting from the " H " of 
Crag Hill, is shown lapping round the Bala Beds on the ridge 
above the farm. It consists of a very tough, coarsely crystalline 
Umestone, very like that which forms the matrix of the thicker 
part of the conglomerate near Wharfe, and it contains the same 
two corals, F. alveolaris and F. fibrosa. It has a mottled darker 
and lighter grey appearance, both on weathered and newly- 
fractured surfaces, such as might be due to brecciation in place 
and subsequent alteration, or to incipient concretionary 
action. It is quite different from the Bala Limestone which is 
seen close by, and is a close-textured dark blue grey rock, ^Wth 
abundant fossils, as explained in the previous part. Soft beds 
probably succeeded it, but they have been cut back by denuda- 
tion, and their outcrop must be sought in the deep hollow on 
the north of the ridge. On the top of the anticlinal, at the higher 
end of the ridge near the foot of the Carboniferous scar, the 
overlying beds much resemble those which form the base of the 
Austwick Flags near Wharfe. 
* Reprinted from Proc. Yorks. Geol. and Polytcc. Soc, Vol. xiv., p. 340. 
B 
