Chap. V.] UPPER LLANDOVERY ROCKS. 91 
parts almost a conglomerate, the beds rising at a low angle from beneath 
the Hollies or Pentamerus limestone and the overlying Wenlock shale, to 
both of which they are conformable. The chief fossil in this coarse grit 
and conglomerate is Rhynchonella decemplicata (PI. IX. f. 15). These 
rocks also range up to the sonth-eastern flank of the Wrekin, and dip 
with the Pentamerus limestone under the ' Die earth,' or Wenlock shale, 
of Buildwas and the gorge of the Severn. 
On the south flank of the Longmynd, this zone, whether in the form of 
a pebbly conglomerate or of an impure limestone, both charged with Pen- 
tamerus oblongus, reposes at a low angle of inclination on the ancient rock, 
as thus represented in my old work. 
At the spot to which this 
diagram refers, copper veins, 
v, are seen to penetrate both 
the subjacent Longmynd rock, (From giL Sygt> pl 32 f _ 4 ) 
a, and the overlapping Pen- 
tamerus rock, e, — the last being overlain by Wenlock shale, /. 
In another part of Shropshire the rock is seen to protrude along a line 
of fault as an isolated patch through the Wenlock shale of Brampton Bryan 
Park, and is again visible further to the S.W. at two points in Radnor- 
shire, — the one in a dome to the south of the town of Presteign, the other 
on the western slopes of the hill of Old Radnor. (See Map.) In these 
examples it is a quartzose, pebbly conglomerate, passing into a hard, coarse 
grit (Corton), in which casts of Pentamerus oblongus and other fossils 
occur, such as Atrypa hemispheric a, Petraia elongata, and P. bina. Along 
this line it is also obviously the lowest bed brought up in domes and arches 
by the line of igneous eruption, along which the hypersthenic and fels- 
pathic rocks of Stanner, Hanter, and Ousel have been evolved. These 
outbursts have so altered the contiguous sandstones, schists, and grits 
(just as around the Wrekin and Caer Caradoc), that in Old Radnor Hill 
and Yat Hill it is difficult to determine which parts of the masses are 
metamorphosed rocks resulting from the effect of volcanic eruption, and 
which have really been in a molten state. The diagrams illustrating this 
phenomenon, including the metamorphosis of the limestone of Nash Scar, 
will be given in the Sixth Chapter, which treats of the Wenlock formation. 
In that district of Radnorshire, the Upper Llandovery rock is a siliceous 
grit and conglomerate, and is at once conformably surmounted by shale 
and limestone, which, from their fossils, are grouped as the lower member 
of the Wenlock formation of the Upper Silurian rocks, or Woolhope lime- 
stone, as will be hereafter described. 
Again, on the western flank of the Malvern Hills we meet with sand- 
stone and conglomerate characterized by the above-mentioned Pentameri. 
As these rocks have there, according to Professor Phillips, a thickness of 
600 feet, and have peculiar relations to the rocks on which they repose, as 
