48 
SCENERY OF SWITZERLAND. 
The arrangement, both of the Marine and Fresh- 
water MoIIasse, makes it probable that the drainage 
of Switzerland was then eastwards by the Valley of 
the Danube to the Black Sea. The openings which 
now carry the waters of the Valais westwards to the 
Valley of the Saone and so to the Mediterranean, 
and of the Aar and the Rhine by Brugg and Basle 
to the North Sea, were not yet in existence. The 
Tertiary strata of France and Germany have no con- 
nection with those of Switzerland, and were evidently 
separated by dry land-by the Jurassic chains. The 
subsidence which has given rise to the Rhine Valley 
from Basle northwards, and the erosion of the Rhone 
Valley at Bellegarde, are therefore long posterior to 
the period of the MoIIasse. 
The Rhone was eventually shut off at Mormont, 
between the Lakes of Geneva and Neuchatel, the 
Aai at Baden, while the subsidence between the 
Vosges and the Black Forest opened a way for the 
Rhine to the north. The rivers Iheii adopted their 
present courses, the Rhone to the Mediterranean, the 
Aar and the Rhine to the North Sea, thus depriving 
the Danube of a very large part of its original terri- 
tory. It is evident that these changes must have 
taken a long time, though from a geological point of 
view they are very recent. The evidence of many 
