238 ^ IA ^ T AND THE GLACIAL PERIOD. 



that extended across the mouths of the Dwina, the A'istula, 

 the Oder, the Elbe, the Weser, and the IJhine. The 

 drainage of the obstructed rivers in Russia was perhaps 

 turned southward into the Caspian and Black Seas, and 

 then assisted in forming the fertile soil of the plains in the 

 southern part of that empire. 



The obstructed drainage of the German rivers was 

 probably turned westward in front of the ice through the 

 Straits of Dover or across the southern part of England. 

 This was during the climax of the Glacial period ; but later, 

 according to Dawkins, during a period in which the land 

 of the British Isles stood about 600 feet above its present 

 level, the streams of the eastern coast — namely, " the 

 Thames, Medway, Humber, Tvne, and others, joined the 

 Ehine, the Weser, and the Elbe, to form a river flowing 

 through the valley of the ocean. In like manner, the 

 rivers of the south of England and of the north of France 

 formed a great river flowing past the Channel Islands due 

 west into the Atlantic, and the Severn united with the rivers 

 of the south of Ireland ; while those to the east of Ireland 

 joined the Dee, Mersey Eibble, and Lune, as well as those of 

 western Scotland, ultimately reaching the Atlantic to the 

 west of the Hebrides. The water-shed between the valleys 

 of the British Channel and the North Sea is represented by 

 a ridge passing due south from Folkestone to Dieppe, and 

 that between the drainage area and the Severn and its 

 tributaries on the one hand, and of the Irish Channel on 

 the other, by a ridge from Holyhead westward to Dublin. 



" This tract of low, undulating land which surrounded 

 Britain and Ireland on every side consisted not merely of 

 rich hill, valley, and plain, but also of marsh-land studded 

 with lakes, like the meres of Norfolk, now indicated by 

 the deeper soundings. These lakes were very numerous 

 to the south of the Isle of Wight and off the coast of Nor- 

 folk and Suffolk."* 



* Earl) T Man in Britain, p. 151. 



