Chap. VIII.] SILUEIAN KOCKS IN THE NORTH OP ENGLAND. 
147 
remains, it is clearly a representative of the Caradoc formation of the Lower 
Silurian rocks. For, among the fossils, the same species of simple -plaited 
Orthidse, of Trilobites, and Corals are again met with which characterize 
the limestones of Bala in North Wales and the shelly sandstones of Caer 
Caradoc in Shropshire. 
In proceeding to the south and south-east from the more mountainous 
and crystalline part of this north-western tract of England, the Lower 
Silurian rocks are seen to be succeeded by younger deposits, which, though 
of very different mineral characters, unquestionably represent by position 
and fossils the Wenlock and Ludlow formations. I cannot more tersely 
and clearly express these relations than in the language which Professor 
Sedgwick himself applied to this region in 1845. " Thus the fossiliferous 
slates," he says, " present, first, the Lower Silurian rocks in a very de- 
generate form, and secondly the Upper Silurians in a noble series " *. 
Nor can I convey a better idea of the succession of rocks in this district 
than by referring the reader to sections and descriptions by the same author 
published in 1846, to be studied in combination with his memoirs of 1851-2. 
It is enough for me, on this occasion, to state that these show a conformable 
succession of deposits, from the Skiddaw slates and a vast thickness of green 
slates and porphyry, to a thin band of limestone (Caradoc or Bala) and a 
considerable thickness of overlying flagstone with Lower Silurian fossils, 
followed by the 6 Coniston Grits,' which Professor Sedgwick believes to be 
the equivalent of the May Hill sandstone. They are surmounted by a 
copious Upper Silurian series, in which the Wenlock and Ludlow forma- 
tions are recognized by their position and fossils, though, as before said, 
their mineral aspect differs much from that of the original types. 
This Upper Silurian series, forming the ridges on both sides of "Winder- 
mere, and thence extending far to the south, consists in the lower masses of 
the Ireleth slates. These masses have a slaty cleavage oblique to the beds, 
are in parts calcareous, and have proved to be the equivalents of the Wen- 
lock formation, more particularly resembling certain schists in Denbigh- 
shire, which also assume a hard, arenaceous, and slaty character. Among 
other fossils the curious Graptolite, Betiolites Geinitzianus, Barr., found in 
the Upper Silurian (Etage E) of Bohemia occurs in these slates. The 
overlying strata are sandy and pebbly. Then follow other coarse slates, grits, 
and flagstones, called by Mr.D. Sharpe < Windermere rocks,' in which Lower 
Ludlow fossils occur, and a remarkable calcareous band, which is seen at 
Underbarrow, Docker Park, &e. This band, it is worthy of note, is charged 
with Starfishes similar to those which have been described as occurring in 
the Lower Ludlow rock of the Silurian region (p. 127). A very distinct 
representative of the Upper Ludlow succeeds, as proved both by position 
and fossils, but differs in being a siliceous flagstone much harder than 
its equivalent in Siluria — in short, akin to beds of this age in parts of 
* See Quart. Journ. Geol. Soc. Lond. vol. i. p. 443. 
i 2 
