3IO HISTORY OF THE EUROPEAN FAUNA. 



of the state of Europe when they were deposited, as 

 in Switzerland. Rising into massive mountains, as 

 in the well-known Rigi and Rossberg, they attain a 

 thickness of more than 6000 feet." "By far the larger 

 portion of these strata is of lacustrine origin. They 

 must have been formed in a large lake, the area of 

 which probably underwent gradual subsidence during 

 the period of deposition, until in Miocene times the 

 sea once more overflowed the area." 



From these remarks by our most eminent British 

 geologist, we gather that in early Tertiary times 

 much of the present area of Switzerland was either a 

 sea or a large freshwater lake. The Alps were then 

 appearing in this sea, probably as a chain of islands, 

 and in the beginning of the Miocene Epoch one large 

 elongated island had made its appearance the future 

 European Alps. I have already mentioned that the 

 Miocene Sea skirted the Alps from the Mediterranean 

 up the valley of the Rhone and along its northern and 

 eastern margin. Miocene marine deposits are also 

 known from the Southern Alps and the east side of 

 the Apennines, from Corsica, Sardinia, and Malta. 

 No trace, however, of them has been noticed any- 

 where along the ^Egean Sea or on the Balkan 

 peninsula. The Alps were therefore connected to the 

 east with the outliers of the Balkan Mountains, and 

 in this way with Asia, from which they received so 

 large a proportion of their fauna and flora. In 

 pliocene times the sea still washed the southern shore 

 of the Alps, but to the north dry land gradually 



