VOL. XIX. (2) THE SILURIAN INLIER OF USK 137 
The total thickness of the Wenlock Shales seen is about 
850 feet. 
In the northern part of the Inlier the relation of the 
Wenlock Shales to the rocks to the West of them is obscured 
by Alluvium, but Ludlow beds are seen in the roadside to 
the West of the Chain Bridge and again in the river bank 
above the bridge, where they are bent into shallow folds, 
whose axes run South-eastwards straight towards the Wenlock 
Shales, which are exposed not far off. Hence it seems clear 
that a fault separates the beds of the two ages in this region. 
Further to the North there is much drift, but Ludlow 
beds which dip to the North are seen near Clytha. It is possible 
of course that Wenlock Limestone occurs beneath this drift, 
but it certainly is not found stretching in a great curve from 
Tump Farm on the Usk to the West of Bettws-Newydd to the 
Usk near Trostrey as represented on the i-iiich map, although 
it is seen at Tump Farm, as will be recorded later. 
It is to be noticed that to the North of the Usk the anti- 
clinal arrangement of the Wenlock Shales, which was so obvious 
to the South, no longer obtains. The dip of the beds is 
generally to the East or South-East, though near Bettws- 
Newydd it becomes North-North-East. East of Trostrey 
drift covers the country up to about the 300 ft. contour line, 
but above this are frequent exposures in Wenlock sandy 
shales, with occasional thin limestone layers. These beds 
form the crest of the hill, where they dip i5°E., and are also 
seen near the bottom of the valley beyond, but the far side 
of this valley is in Ludlow beds, which dip to the North-East, 
and there seems little doubt that the line of separation between 
the two sets of beds is a fault, and dislocations are seen in an 
old quarry in a field a few yards below where the road from 
Hill Farm crosses the stream. 
The South-Eastern edge of these Wenlock Shales lies along 
the continuation of the big fault dividing the two anticlines 
in the South, which runs along the base of Llancayo Hill, 
Wenlock Shales with calcareous nodules being seen in the 
stream here and Upper Ludlow beds a short way up the hill- 
side to the East. 
