Page:Early Man in Britain and His Place in the Tertiary Period.djvu/53

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Since the higher grounds in Great Britain in the Eocene time were in their present positions, it will follow that the watersheds of the principal rivers were then very much as they are now, so far as relates to their upper courses. On the western side of the Pennine mountain axis the Ribble, Mersey, Dee, and Severn fell then, as now, into the Atlantic, after traversing the broad valleys reaching to the line of cliffs off the west of Ireland. Those on the east fell into the south-eastern sea (see Map, Fig. 3), probably joining some of those of Norway, and contributing to form the great river which was the chosen haunt of the alligator and the crocodile, and which flowed through the dense forests of palms and banksias, then covering the Eocene continent in these latitudes. The lower course, however, of the Trent was determined by movements of level, which took place in Post-meiocene times, and the river Thames, as Professor Ramsay has pointed out, came into being also after the close of the Meiocene age.

The lower Eocene vegetation in Britain preserved in the London Clay was, as Professor Heer observes, of a tropical and Indo-Australian character. The forests were composed of palms of various sorts (Palmacites,