88 T. BELT ON THE DRIFT OF DEVON AND CORNWALL. 



the older forest-beds and the immigration of the great mammalia, 

 indicating that the sea had retired from the British Channel and the 

 German Ocean. A great river appears to have run to the south- 

 west through this now submerged area, on the banks of which and 

 of its tributaries palaeolithic man and the great mammalia lived, the 

 latter frequenting low marshy tracks near to the streams, the former 

 higher grounds more distant from them. That this river flowed 

 southward, and not to the north, as supposed by Mr. Godwin-Austen, 

 is indicated by the fact that the fauna is the same on the Somme and 

 the Thames, which would scarcely have been the case if the Straits 

 of Dover then formed the division between watersheds draining to 

 the north and the south. This applies with particular force to the dis- 

 tribution of the hippopotamus. Its remains are found not only in all 

 the southern parts of the area, but as far north as Yorkshire. There 

 is evidence that the winters were more severe then than now; and it 

 would have had no refuge from them to the north of Dover if the 

 rivers there ran northwards ; but if they drained into a great stream 

 running southward as far the Bay of Biscay, it might easily have 

 retreated down this in the autumn and reascended in the spring. 



The presence of southern shells, such as Cyrena jiuminalis, Unio 

 littoralis, and Paludina marginata, in the old mammalian gravels 

 both to the north and to the south of the Straits of Dover, is evidence 

 nearly as strong that the streams in which they lived all belonged 

 to the same watershed, and that the course of the main river was 

 southward. For this great stream I propose the name of the Ger- 

 manic River, as its principal drainage-area was the bed of the 

 present German Ocean and the waters discharging into it. 



The second stage of the Glacial Period is marked by the continued 

 advance of the ice from the north, and, possibly, by the retreat of the 

 southern fauna and the arrival of the Arctic mammals, whilst the 

 woolly rhinoceros and the mammoth still roamed in summer over the 

 area that had formerly been their winter retreat. 



In the third stage the Atlantic Glacier reached the coast of Europe, 

 and blocked up the English Channel and with it the drainage of the 

 whole of Northern Europe, forming a great continental lake, over 

 which floated icebergs carrying boulders from the Scandinavian 

 of mountains. 



In the fourth stage the barrier of ice blocking up the English 

 Channel was suddenly broken away, causing the tumultuous discharge 

 of the waters of the great lake and the consequent outspread of the 

 Lowland deposits, including the Middle Glacial sands and gravels 

 Norfolk and Suffolk. 



In the fifth stage the Atlantic glacier again advanced, and the 

 great lake was reformed ; but its discharge this time was more gra- 

 dual. To this period belongs the formation of the Upper Boulder- 

 clay of Norfolk and Suffolk, which I have not been able to satisfy 

 myself is represented south of the Thames except by the "Trail" of 

 Mr. Fisher ; but some of the Upland deposits may belong to this and 

 not to the third stage. 



In the sixth and last stage, I consider that the Atlantic ice had 



