100 
SILURTA. 
[Chap. V. 
As above said, we see that between this Pentamerus rock and all the 
inferior strata there is a greater hiatus even than on the west flank 
of the Malverns. Infinitely less, in short, does the May Hill Sandstone 
exhibit any feature of that close relationship with the lower deposits 
which is evident in the environs of Llandovery and Llandeilo. 
Tortwortli, the Lickey, Sfc. — The same north and south anticlinal which is 
apparent in May Hill and Huntley Hill, is continued southwards with a 
bend to the east at Pyrton Passage ; and, crossing the Severn, it passes into 
the remarkable tract of Tortworth, where the Silurian rocks, emerging from 
beneath the Old Red and Carboniferous formations, have been long known 
to geologists. There, the elevation of the axial line being less considerable 
than in the Malverns or at May Hill, the oldest rock visible is the Upper 
Llandovery sandstone with much trap-rock ; and, occupying a large area, it 
is seen to be immediately surmounted by the Wenlock formation with two 
courses of limestone and feeble representatives of the Ludlow rocks*. 
(For details see Sil. Syst. chap. 34.) 
The most eastern tracts in England where the Upper Llandovery rock 
has been raised to the surface are the Lower Lickey Hills in Worcester- 
shire, and near Barr in Staffordshire, at both of which localities that rock 
supports the base of the Upper Silurian deposits of the adjacent tracts of 
Dudley and Walsall. At the Lickey, low heathy hills are chiefly com- 
posed of quartz-rocks, lithologically identical with those masses on the 
flanks of the Caradoc and Wrekin which have been formed by the fusion 
of sandstone. The Lickey quartz most probably owes its character to a 
similar cause, though in this case the igneous agency has not found issue 
at the surface in the form of trap-rock, as at Dudley further north, or in 
Shropshire, where such igneous rocks are rife upon a similar axial line. 
In other words, the Lickey quartz lies upon a line of former eruption. 
On its flank this rock graduates into an ordinary grit or sandstone, in 
which Pentamerus lens occurs, and thus all doubt of its age is removed ; 
whilst, just as in the other tracts above mentioned, this hard, siliceous 
sandstone, particularly on its eastern and southern parts (Colmers and 
Kendal End), is conformably surmounted by a calcareous shale with a thin 
course of limestone, which, as at Woolhope, Corton near Presteign, and 
Old Radnor, contains Upper Silurian (Lower Wenlock) fossils. 
Evidences have now been given to show how certain portions of the 
Silurian strata are omitted in variable quantities in different districts. 
At May Hill all the Lower Silurian rocks, including the Lingula-flags, 
the Llandeilo and Caradoc formations, and even the Lower Llandovery 
rocks, are absent, the Pentamerus (Upper Llandovery) sandstone being 
there seen to repose at once on hard, unfossiliferous, slaty Cambrian rock. 
* Earl Ducie, who has made himself completely our acquaintance with it, by collecting several 
master of the structure and range of the rocks of species of fossils unknown to me when I published 
this complicated district, so large a portion of the ' Silurian System.' 
which belong to him, has also added much to 
