THE GEOLOGY OF' SWITZERLAND. 
47 
Granite. If we draw a line across Switzerland, say 
from Basle to Como, we find from Basle to Olten, 
say to the line of the Aar, Jurassic formations thrown 
into comparatively gentle undulations, and stretching 
from south-west to north-east. From Olten to Lucerne, 
the great plain of Switzerland is made up of upper 
Tertiary strata, known as Mollasse, and Nagelflue, 
consisting of sand and gravel washed down from the 
rising mountains and deposited partly in a shallow 
sea, partly in lakes. Near Lucerne we come upon 
Eocene strata, also of marine origin, which have been 
raised to a height of as much as 2000 metres. 
Continuing in the same direction, and soon after 
passing Vitznau, we come upon Cretaceous rocks, 
which occupy most of the canton of Nid Dem Wald. 
In Ob Dem Wald we find ourselves on Jurassic. In 
other parts of Switzerland a considerable thickness of 
Triassic strata appears beneath the Jurassic, and rests 
on Verrucano, one of the Carboniferous series, but 
along our line the Jurassic region is immediately fol- 
lowed by Crystalline rocks, and Gneiss, forming the 
great Central ridge of Switzerland, and reaching as 
far as the Lake of Como. On the south of the 
mountain range, as on the north, the Gneiss is 
followed in succession by Carboniferous, Triassic, 
Jurassic, Cretaceous, and Tertiary strata, but they 
