62 
HUGHES : IXGLEBOROUGH. 
Cyrtograptus murchisoni Carr. was found by Miss Elles in 
addition to the two species just mentioned. 
Tlie upper and more gritty part of this series plunges down 
under Whitestone Wood, and comes up again under Studrigg, 
holding the lower part of {a) the Horton Flags in a synclinal 
fold. The Horton Flags have yielded a few fossils in the 
line of the section, namel}^ Monograptus colonus Barr., M. roemeri 
Barr., M. hohemicus Barr., and Orthoceras primoevum Forbes. 
All the lower beds are inferred to occur in the line of the 
section below Hunterstye, but little is seen except some of 
the calcareous beds of the Bala series. They all roll over again, 
and plunge under the Mountain Limestone, but are here much 
obscured by moraine drift and talus. 
The section down the west side of Ribblesdale (Fig. 7) starts 
on the Green Slates and Porphyry near Bee Croft Hall Plantation, 
and is drawn a little way in front of the precipice of Mountain 
Limestone which is seen resting unconformably upon the folded 
Bala and Silurian rocks all the way to the south-east corner of 
Moughton Scar. The line of section is obscured by drift to near 
Gillet Brae, beyond which rock is seen almost continuously for 
all the rest of the section as far as Swarth Moor. At Garth 
House the Austwick Grits and Flags come on in a double S3mclinal 
with p. broken anticlinal between them, the second or more 
southerly synclinal being developed under Horton Wood. At 
Crag Hill we have the most interesting part of the whole section, 
where the base of the Silurian is folded over the Bala Limestone 
and shale as previously described. The Graptolitic Mudstone 
and Pale Slate are not clearly exposed, but the Austwick Flags 
with subordinate grit, and in the upper part grit with subordinate 
flags, are well seen near Crag Hill Barn. Here also we have the 
best development of the Horton Flags in the whole district. 
First we come to the great quarry at Arco Wood, where 
the flags have been cut back from the sloping flank of the valley 
until a clean face of rock is seen. The Mountain Limestone 
with a shghtly uneven pockety base rests unconformably upon 
the upturned flags. It was near the northern end of this quarry 
that I found the only specimen I have seen from this district 
