306 THE BEAUTIES OF NATURE CHAP. 



Lake of Constance into the Danube, and so to 

 the Black Sea. Then, after the present valley 

 was opened between Waldshut and Basle, 

 they flowed by Basle and the present Rhine, 

 and after joining the Thames, over the plain 

 which now forms the German Sea into the 

 Arctic Ocean between Scotland and Norway. 

 Finally, after the opening of the passage at 

 Fort de 1'Ecluse, by Geneva, Lyons, and the 

 Valley of the Saone, to the Mediterranean. 



It must not, however, be supposed that 

 these changes in river courses are confined to 

 the lower districts. Mountain streams have 

 also their adventures and vicissitudes, their 

 wars and invasions. Take for instance the 

 Upper Rhine, of which we have a very inter- 

 esting account by Heim. It is formed of 

 three main branches, the Vorder Rhine, Hinter 

 Rhine, and the Albula. The two latter, after 

 meeting near Thusis, unite with the Vorder 

 Rhine at Reichenau, and run by Chur, May- 

 enfeld, and Sargans into the Lake of Con- 

 stance at Rheineck. At some former period, 

 however, the drainage of this district was 

 very different, as is shown in Fig. 43, 



