Chap. VI.] LOWEE WENLOCK (WOOLHOPE) LIMESTONE. 
107 
agreeing with the pale slate before alluded to. Strictly speaking, there is 
no continuous band of limestone subordinate to the lower shale, d l , below 
the escarpment of Wenlock Edge in Shropshire, the rock to which atten- 
tion is first called being there merely represented, as also in some other 
tracts, by a few calcareous nodules and bands of sandstone, d 2 . 
In following these deposits from Shropshire into Herefordshire, the great 
limestone, <P, above the shale, d 2 , is already found, on the banks of the 
Lugg, west of Aymestry, and not more than ten miles from the Wenlock 
Edge, to be diminished to a thin irregular stratum, chiefly concretionary. 
Further to the south-west, and in Eadnorshire, the lime disappears entirely 
amid the mass of mudstones ; but to the south of Presteign an inferior 
course of limestone is interpolated in the lowest part of the Wenlock shale. 
This rock, d l of the diagram, and which has been alluded to in the last 
chapter, merits special attention. 
Lower Wenlock or Woolhope Limestone. — An examination of the old 
quarries at Corton, one mile south of Presteign, shows that this limestone 
is fairly subordinate to a black shale, which rests on the Llandovery grit 
and conglomerate before described. This superposition is delineated in the 
following diagram. 
Lower Wenlock Limestone at Corton, near Presteign. 
S. N. c. Coarse pebbly grit, known 
r ^ here as ' Corton grit,' with 
Pentamerus oblongus &c. 
d l . Wenlock shale with Wool- 
hope or Lower Wenlock 
limestone, q. Gravel of the 
Valley of Presteign. 
To the south of Corton lies the large and loftier rock of Nash Scar, 
formed of the same limestone, which, whether thick-bedded or nodular, 
has been fused into one subcrystalline mass, the stratified character 
having been destroyed, and the shale, once associated with the limestone, 
obliterated, as expressed in this diagram f. 
Presteign. 
s. 
Altered Limestone of Nash Scar. 
(From Sil. Syst. p. 313.) 
N. 
c. Arches of Woolhope limestone and shale, d\ followed by d*, amorphous or altered 
limestone, o. Caverns. 
*hl ™f r ° CkS ° f 7 r h S< f r a ^9} A Ea ? nor ar f the ? are of hi S h ™ lu e to the Welsh proprietors, 
^%^^^,^^ B ^^^^on;and the lime being transported to great distances 
as there are no other calcareous rocks worth burn- westward (see Map) 
mg to lime between this district and the sea-coast, 
