252 



GENERALIZATIONS. 



The following Table exhibits the various periods of elevation 

 and depression of the ground in Switzerland : 



UPHEAVAL OF THE GROUND. 



DEPRESSION OF THE GROUND. 



1. From the Trias to the Lower Lias. 



2. From the White Jura to the close 

 of the Wealden (Lower Creta- 

 ceous formation). 



3. From the Upper Cretaceous to 

 the Aquitanian stage of the 

 Miocene. A partial upheaval 

 along the Alps at the close of 

 the Eocene period. 



4. From the Helvetian stage (Middle 



Miocene) to the close of the 

 (Eningian stage (Upper Mio- 

 cene). 



5. Upheaval of the Alps and Jura in 



Pliocene times. 



1. At the close of the Carboniferous 



period. 



2. From the Lias to the Brown Jura. 



3. From the Valangian stage (Lower 

 Cretaceous) to the Middle Cre- 

 taceous). 



At the Tongrian epoch (Lower Miocene) 

 in North-western Switzerland. 



4. From the Grey Miocene to the 

 Helvetian stage (Middle Mio- 

 cene) . 



These changes of level did not occur suddenly, but in all 

 probability very gradually. But when people assert that the 

 last Pliocene upheaval of the Alps also took place so gradually 

 and imperceptibly that, if the district had been inhabited by men, 

 they would not have suspected what was going on, it must be 

 borne in mind that the dislocations were colossal, that the 

 tilting-over piled rock-masses several thousand feet in height one 

 upon another, that deep fissures tore asunder whole mountains, 

 and that enormous masses of debris accumulated which were 

 thrown into valleys, and formed there complete mountains. 



