232 MANUAL OF GEOLOGY. Representative Stages. 1 North of England. Stage E. Gannister beds. „ D. Millstone grit. p j “ Great limestone.” ” ' ( Flagstones and shales. „ B. Scaur-limestone series. „ A. Sometimes absent (Tuedian). Central Scotland, (E.) Slaty blackband series. (D.) Moorstone-rock series. Upper limestone series. Lower coal and ironstone series. (B.) Lower limestone series. (A.) Calciferous sandstone series. (C.) This view is corroborated by Mr. Lebour, who states that, on com paring a list of 130 species from the Great Limestone of Northumber land (the most marked Yoredale bed) with Scotch lists, he finds that 32 species are not known in Scotland, about 60 occur through the three Scottish divisions, 28 occur only in the Scotch upper and middle series, and 10 species only are found in the lower series. Allowing for the difference in geographical position, and recollecting that pro bably during the earlier Carboniferous periods the Scotch and English marine areas were to some extent separated by the barrier of old land (Silurian or Cambrian), this community of 28 species corroborates the views suggested :—“ We must remember that, over the north of Eng land and the borders of Scotland, land and shallow-sea conditions prevailed during the deposition of the earlier Carboniferous stages. This fully accounts for those changes in the thickness and condition of the limestone series, since such changes would necessarily, be accom panied by the disappearance of forms which flourished in the deeper seas of central England, and the appearance of others better adapted to shallow-water conditions.” 4. Coalhroolc Dale Coal-Field. On the east side of the Silurian ranges of the Wrekin and Wen- lock Edge, lies the coal-field of Coalbrook Dale. We are indebted to Professor Prestwich 2 for a complete survey of this remarkable coal-field, which on the north and east is entirely bounded by faults, and New Red and Permian rocks. On the west it rests on a representative of the Millstone Grit, or on Carboniferous Limestone, or on some of the several beds of the Silurian series. On these Silurian rocks it is unconformable, and for the most part this unconformity is proved on a large scale ; but, as in the Dudley field, to which this bears more than analogy, there is in many places very little difference of direction or angle of dip between the Silurian and Carboniferous strata. The coal-field is bounded on the west by Caradoc sandstone and its associated igneous rocks, and on the south-east by the Old Red Sandstone and Upper Ludlow. Between these extremes the Lower Ludlow and Wenlock series may be seen, the coal not so much abutting against as resting on them. 1 The stages B and C in Northumberland Mr. Lebour has included under the name “ Bernician beds.” See Note, ante. 2 Trans, of the Geol. Soc, vol. v. p. 18.