THE JURA. 
25 
the main to the N.E., but at St. Ursanne it turns to 
the W.S.W., enclosing a high ridge (Fig. 74) known 
as the Clos du Doubs. 
The valley of the Rhine from Basle northwards 
IS of comparatively recent origin, being due to a sub- 
sidence which has separated the Black Forest from 
the Vosges. Just south of Basle the anhydrite beds 
which at Bettingen are 400 metres above the sea 
level, have sunk at Hiinningen to 600 metres below 
It, a drop of 1000 metres in about five miles. 
At St. Jacobs, near Basle, the section is as in 
79. Furthernorth the sinking is more profound, 
and the strata are fractured (Fig. 80). At Kandern 
the depression amounts to 1500 metres. 
The sinking of the Rhine valley near Basle was 
no doubt a slow process. It probably began before 
or early in the Glacial period, before which time the 
whole drainage of the country must (see ante, p. 225) 
have been entirely different from the present. 
The eastern boundary of the Rhine valley sub- 
sidence is apparently continued along the cross line 
of Mtimliswyl-Balstall. The downthrow of the fault 
IS here also to the west. Again, the western boundary 
of the Rhine valley, though this is more uncertain, 
niay perhaps be correlated with the cross valleys 
