THE GEOLOGY OF SWITZERLAND. 
43 
Eocene period, so far as Switzerland is concerned. 
In other strata numerous fossils have been found, in- 
cluding many Mammalia, and even a Monkey. 
Miocene. 
During this period the main elevation of the 
Alps took place. We should naturally expect that 
rapid rivers would rush down from the heights bring- 
ing masses of gravel with them, and in fact we find 
enormous deposits of coarse gravel, often cemented 
into a hard rock, and containing blocks six inches, 
a foot, and even sometimes as much as a yard in 
diameter. This conglomerate is known as the Nagel- 
flue, and the materials of which it is composed be- 
come gradually finer as we recede from the Alps, 
forming a more or less marly deposit known as the 
Mollasse. It attains a great thickness; indeed the 
whole of the Rigi from the Lake of Lucerne to the 
summit consists of Nagelflue. The Mollasse is com- 
posed of several deposits, some fresh-water and some 
marine; it is probable that the conditions may have 
been different in different parts of what are now the 
Swiss lowlands. The pleasant scenery of Central 
Switzerland is greatly due to the Mollasse. The 
Freshwater Mollasse is generally soft, but the Marine 
beds afford excellent building materials. Large 
