Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/910

 picked up on the North-Cheshire beach, most of which are no doubt washed out of the main peat and the overlying Bithinia and Tellina sands. Amongst those preserved in the Liverpool Museum are some of Nero, Antoninus Pius (a.d. 138-160), Marcus Aurelius, others struck at Carthage, others struck by Canute and by various English kings from William I. to William III. Various antiquities have been described by Dr. Hume from this coast in his ' Ancient Meols ;' but the exact position from which they were derived is in almost every case extremely doubtful. But after carefully examining all the objects from the coast of Wirral in the Liverpool Museum, as well as the coast-section, the following correlation of historical periods with the geological formations appears to be warranted : —

Recent to Norman Conquest Sand dunes. Danes and Saxons B.-tentaculata sand. Saxons Peat and made earth. Saxons and Romans Tell.-balthica sand. Romans and Celts Main peat. Celts " lower portion. Palaeolithic-weapons race Lower blue silt. No trace of man Lowest peat.

Liverpool and the Country between the Rivers Alt and Douglas. — The form of the ground of this tract has already been mentioned as a great plain covered with peat-moss (fig. 3), mostly below high-water mark, with the exception of the few miles between Liverpool and Bootle, where some hard beds of the Trias, thrown up by faults, form one or two lines of escarpment, more or less covered with Boulder- drift. The peat and other postglacial deposits fringed this comparatively high ground, and connected the low grounds of the Alt plain with those of Wirral described above. The reexcavation of the valleys after the glacial period appears to have been nearly complete before the period when the peat and its underlying blue clays were formed and deposited ; for we find these deposits, not only at the bottom of the rivers Dee and Mersey and the old tributary of the latter, Wallasey Pool, but in the bottoms of all the little narrow brook-valleys on either side of the Ribble, as well as under the alluvium at the bottom of the great drift-cut gorge of that fine river. The deposition of freshwater silt, and the subsequent growth of peat, over so large a tract, embracing the whole of the north-west of England, must necessarily have been produced by some great cause tending to obstruct the natural drainage, causing the accumulation of vast freshwater lakes, afterwards land covered with dense forests, destined again to become swampy marshes, eventually choked with the growth of peat-moss.

An examination of the postglacial deposits between the rivers Mersey and Ribble tends in some measure to throw light upon the conditions which may have produced this obstruction of drainage. This peat-moss plain (shaded in fig. 3) is bounded to the east by a tract of country with an average elevation of 125 feet, separated from the lower plain by what may be called a double cliff, the first, of preglacial age (formed in the hard Keuper Sandstone rocks), being concealed