Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/739

Rh the same strata have yielded similar forms elsewhere. With such good evidence before us we can have little hesitation in placing the "Slaty-band " beds on the horizon of Stage E.

As regards Stage C, perhaps the evidence is not so conclusive as in the former case. Nevertheless there are strong grounds for the course I have adopted. It will be recollected that as we proceed northwards from the borders of Lancashire a marine band of lime- stone makes its appearance, which ultimately assumes important proportions. In the Clitheroe and Pendle district the Yoredale series is of extraordinary thickness (from 3500 to 4000 feet) ; and it is really almost incredible that such a mass of strata should be unrepresented in Scotland, which is not (after all) so many miles distant. On the other hand, the Carboniferous Limestone of Derbyshire itself is represented in the North of England only by the " Scaur-limestone" series of Prof. Phillips, as Mr. Lebour has very clearly shown. On reading Mr. Lebour's paper, it occurred to me that the explanation of the Scottish series was to be found in an arrangement such as that given below ; and in consulting with my colleague, Prof. Geikie, and Mr. Lebour, I am glad to find that they regard my suggestion as not improbable, either on stratigraphical or palæontological grounds If we place the Scottish and the North-of-England series side by side we obtain the following results :— Supposed Representative Stages.

In corroboration of this view of the arrangement, Mr. Lebour states that "on comparing a list of 130 species of fossils from the 'Great Limestone' (the most marked Yoredale bed) with Scotch lists, I find that 32 species are not known in Scotland, that about 60 run through the three Scotch divisions, that 28 are found in the Scotch upper and middle series only, and 10 are only found in the lower series." Now, making allowance for the difference in geographical position, and recollecting that during the earlier Carboniferous periods the Scotch and English marine areas were to some extent separated by the barrier of Silurian land, it must be admitted