Page:Early Man in Britain and His Place in the Tertiary Period.djvu/159

] The sands and red marls forming of No. 5 owe their singular contortions and foldings probably to the grounding of large masses of ice, as well as to the subsequent melting of ice on which some parts of them had been originally deposited. The Forest-bed of this section is to be seen along the coast of Norfolk and Suffolk from Cromer as far as Pakefield, where it has been protected by the thick covering of sands and clays seen in the section, from the denuding forces, by which the traces of both forest and animals have been removed from other parts of Britain. Close on the destruction of the forest followed the depression of temperature marked in the lignites. No. 3, which arrived at its maximum in the period of the boulder drift, No. 4, when the area was invaded by icebergs. This was accompanied by a considerable geographical change. The North Sea rolled over both forests and lignites, and had become sufficiently deep, in Norfolk and Suffolk, to allow of icebergs depositing their burden to form the covering of boulder clay resting on the lignites and fluvio-marine strata.

The forests of France, according to the recent investigations of the Count de Saporta, present a regular series of changes in the Meiocene, Pleiocene, and Pleistocene ages, the tropical species gradually and successively retreating farther to the south. Under the present climatal conditions the species of fig-tree, known as Ficus carica, essentially a southern form, is not found farther north than 45° in central France, except under