Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/399

386 whettier they may be traced in formations syn-chronic with the glacial beds, is of no little interest and geological importance.

Whilst eocene, miocene, and older pliocene marine beds,—represented in our own country by the London clay, and the coralline and red crags,—are found in many parts of the north and middle of Europe and America, the "newer pliocene," such as is typified by the Sicilian tertiaries, those of Rhodes and other parts of the Mediterranean basin, is nowhere present within the area of the marine glacial beds, which, on the other hand, are nowhere to be met with within the area of the marine tertiaries of the Sicilian type. The latter, however (as we have already seen), includes a number of characteristic glacial forms which no longer exist in the same marine provinces, but are restricted to the northern or Celtic Seas. It is, therefore, extremely probable—I may say certain—that the glacial formations are "newer pliocene," and the SicUian tertiaries contemporaneous with the northern drift. As the sea in which those tertiaries were deposited communicated with the glacial seas, we might expect, à priori, to find among the relics of that ancient Mediterranean the still-surviving species which had lived in our seas previously to the glacial period, but had retired during its continuance.

The following table will shew that our search has not been in vain:—