VOL. XIX. (2) THE SILURIAN INLII'.R OF IJSK 
L’iJ 
whole, of the Ludlow beds being attributed to upheaval and 
erosion in late Silurian and early Devonian time.' In the Usk 
B. 
area there are about 890 feet of Wenlock beds seen, and 1,300 
feet of Ludlow beds. There is no marked discordance in the 
dip of the strata of Old Red Sandstone and Ludlow ages. 
There is no occurrence of Aymestry Limestone nor of a 
fauna of Aymestry Lime.stone characteristics. The Ludlow 
beds cannot be separated into an upper and a lower division, 
and pass down conformably into Wenlock beds. The lower 
portion of the Ludlow beds contains Dayia navicula, which is 
not found in the highest beds seen. The Wenlock Limestone 
is possibly not at the summit of the Wenlock beds, and in 
consequence there is a difficulty in marking on a map the 
exact line along which these beds begin. 
The occurrence of the Wenlock Limestone in detached 
strips can be explained perfectly well as being due to the 
pressure to which the area has been subjected, this pressure 
having fractured the originally continuous limestone band and 
driven portions of it in on to the soft underlying shales to 
various extents. The Wenlock Shales are markedly of a 
sandy nature in their upper portion and more of the nature of 
a muddy deposit in their lower one. 
Considerable differences have been found from the pub- 
lished i-inch map. The Wenlock Shales have been proved by 
fossil evidence to cover much ground in the northern part of 
the area, which is represented in that map as consisting of 
Ludlow beds. The Wenlock Limestone shown in the map as 
running northwards from Trostrey is non-existent. A new 
outlier of Old Red Sandstone has been found to the North- 
West of the Pen-y-parc outlier. 
The identification of the fossils from the district has been 
carried out by Dr F. R. Cowper Reed, to whose kindness in 
undertaking this task the author is very much indebted. In 
conclusion mention must be made of the great kindness shown 
to the author by Mr Albert Williams, of Pen-y-parc, who 
allowed him access to his property. 
I “The Fossiliferous Rocks of the Tortworth Inlier,” by F. R. C. Reed and S. H. Reynolds 
Q.J.G.S., Ixiv. (1908), p. 535. See also Suminan.- of Progress of the Geological Survey for 1901 (1902), 
pp. 38-40. 
