VOL. XIX. (2) 
THE SILURIAN INLIER OE USK 
135 
the railway. In the lane leading down to Upper Wern-hir 
from the road which runs past High Cross Inn, there is a very 
fossiliferous sandstone band. 
In the railway cuttings near Bryn, sandy shales are seen, 
and similar beds occur near Frescoed farm, in Pentrewaun 
Wood and in Pentrewaun minor wood, to the East of Pentre- 
waiin farm. They are well exposed by the roadside near 
Tyn- y-caeau farm, and are found dipping below the limestone 
exposures of Cil-feigan, Cefn-Ila and Rhadyr. 
Lower down in the succession, thin calcareous bands and 
layers of calcareous nodules are found in the sandy shales, 
and, finally, beneath these come soft grey mudstones, which 
often show a concretionary structure. These are well seen by 
the roadside to the West of Little Ccfn-Ila. 
The Usk Inlier is cut through from West to East by the 
Berthin Brook, which flows past Little Mill and runs to the 
South of Monkswood to join the Usk close to Rhadyr, about a 
mile above the town of Usk. This stream has deposited a 
certain amount of Alluvium, which lies chiefly to the South of 
its present course, whilst the country to the North of it as far 
as Kemeys Commander is covered by a deposit of drift. This 
paper is not concerned with the origin or nature of this drift, 
but only with its extent, as it prevents one from telling any- 
thing about the nature and arrangement of the underlying 
Silurian beds. Fortunately, the river Usk has cut its way 
through the drift capping, and exposed Wenlock Shales at 
three places. These are (i) the hill-side opposite Kemeys 
Commander on the West side of the river, (2) the steep face 
of the river bank on the East side, near Trostrey, and (3) the 
Western bank near Craig-y-Garcyd, not far from Rhadyr. 
Opposite Kemeys Commander the hill-side rises steeply 
from the alluvial plain near the Chain Bridge for a couple of 
hundred feet, and the first hundred and fifty feet are in beds 
of Wenlock age, while the upper part of the liill-side is covered 
by drift which stretches Westwards up to and beyond tlie 
Abergavenny railway. 
The hill-side sloping down to the Usk is largely covered 
with wood, but continual small exposures sliow that tlie rock 
