246 GENERALIZATIONS. 



Here, in the valley of the Sernf, are seen the Flysch rocks, 

 which have been already described (vol. i. p. 255), rising from 

 the bottom of the valley to a height of several thousand feet. 

 Upon these rocks there lies (as at Gantstock and Karpf ) a band 

 of limestome belonging to the Jurassic series; and over the 

 limestone are vast masses of sernifite, which forms nearly all the 

 summits of the Freiberg. At the Lake ofWallenstadt, and also 

 on the Glarnisch, the sernifite lies below the oldest limestone 

 strata. Although it may be imagined that the sernifite had 

 forced its way up from below, had penetrated the covering formed 

 by the Flysch and calcareous deposits, and had pushed them aside 

 and covered them up, still the occurrence of Jurassic limestone 

 beds above the Flysch remains .unexplained, and can only be 

 accounted for by assuming that a large portion of the older 

 masses slid over the newer rocks. A similar explanation is 

 needed for the stratification of the Glarnisch, the foot of which 

 consists of Nummulite limestone, over which are Jurassic and 

 Cretaceous formations in a regular and partly in a horizontal 

 position. 



These upheavals and depressions have exerted the greatest 

 influence not only upon the prominent features of Switzerland, 

 but also upon the distribution of the Swiss waters. This is so 

 much the case that even the direction of the flow of water and 

 its collection in lakes is due to upheavals and depressions ; and 

 on these causes depends the distribution of Swiss land and 

 water. As soon as the land becomes raised above the level of 

 the sea, the water must run off; and it returns again when the 

 land has sunk below its level. Prof. Heer has already repeatedly 

 discussed this distribution of sea and land in various geological 

 periods, and has endeavoured to illustrate it pictorially for the 

 Middle Jurassic period (vol. i. p. 168, fig. 97), for the Cretaceous 

 period (vol. i. p. 175, fig. 98), and for the middle stage of the 

 Miocene period (vol. i. p. 296, fig. 154). A comparison of what 

 has been said will give us an idea how these changes have gra- 

 dually been brought about, and how Switzerland has slowly 

 risen from the sea. In connexion with this subject Prof. Heer 

 mentions that, probably at a very early period, a decided de- 

 pression of the country took place between the island of the 



