52 
SCENERY OF SWITZERLAND. 
They are as a rule more folded and contorted 
than the Jura, but less so than the central chains. 
The arches, however, though less compressed, are 
more often fractured at the summit,* pointing to a 
difference of conditions. Possibly the explanation 
may be that the compression was more rapid or 
nearer to the surface. 
The Eocene strata often lie in troughs between 
Jurassic and Cretaceous mountains, and it has been 
supposed by some geologists that they were deposited 
m bays or fiords. It seems, however, now to be 
established that the Eocene strata were formerly 
continuous, that the elevation of the Jurassic and 
Cretaceous mountain ranges is of more recent date, 
and that where the Eocene strata are absent this is 
due to denudation. The presence of fragments of 
Eocene, as for instance on the summit of the Ganterisch 
near Bovatez, between the Jaun and the Montelon 
(though too small to be marked on the map), seems 
conclusive on this point. 
hi many places the Secondary strata have been 
considerably reduced in thickness by the tremendous 
pressure to which they were subjected during the 
process of folding. This is the case for instance on 
Favre and Schardt, Beitr. z. Geol. A', d. Schiv., L. xxii. 
