Page:Early Man in Britain and His Place in the Tertiary Period.djvu/99

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The Pleiocene strata of Britain, known as the Crags of Norfolk and Suffolk, extend over the eastern parts of those counties and over north-eastern Essex, and consist of sands and gravels more or less impregnated with iron, containing numerous shells, most of which are still living in our seas. They contain also singular accumulations of fossil bones, derived from the break-up of several different formations. In the phosphatic or coprolitic deposit, for example, of the Red Crag, there are fossil sharks, rays, and crabs from the London Clay, and fragments of land mammalia, such as the Hyænarctos, which have been derived from the destruction of Meiocene strata, in the area now occupied by the North Sea. There are also water-worn fragments of teeth, and bones of the Pleiocene mammalia, derived from the destruction of old land surfaces, in the Coralline and Red Crags, as well as in that of Norwich. These strata, therefore, are the marine equivalents of the accumulations on the borders of ancient lakes, and in the ancient river valleys, which have afforded so rich and varied a Pleiocene fauna and flora in France and Italy, although in point of time they may be referred to the later, rather than the earlier, stage of the Pleiocene, because the mammalia which they contain have been washed out of the strata in which they were originally buried. The mammalia, however, of the Norwich Crag are considered by Professor Prestwich to be in part undisturbed. The lower portion of the mammaliferous deposit at Thorpe, near Norwich, seems to me to be an isolated fragment, which happens to have been spared