840 GEOLOGY 



California, 1 belong to this time, and probably some of those of 

 nearly or quite every other state west of the Rocky Mountains. 

 Many of the prominent volcanic peaks of the west date from this 

 time, or later, and represent the later phases of the prolonged period 

 of volcanic activity, just as the great lava flows and intrusions 

 represent the earlier. Many lesser cones belong to the same period. 



Foreign 



From considerable areas of Europe covered by water during the 

 Miocene, the waters retreated late in the period or at its close; but 

 the sea covered southern and southeastern England, Belgium, and 

 parts of France during at least some portion of the Pliocene, and 

 still more extensive areas of the present continent about the Medi- 

 terranean. Beyond the inland margins of the marine Pliocene, 

 there are contemporaneous beds of terrestrial origin. In south- 

 eastern Europe, brackish and salt lakes came into existence, as 

 shown by the fossils and the local deposits of salt and gypsum. 

 In some places, as in the Vienna basin, brackish water beds below 

 grade up into fluviatile beds above. 



In Italy only do Pliocene beds attain massive development. 

 Along the Apennines, their thickness has been variously estimated 

 at from 1,600 to 3,000 feet, and in Sicily 2,000 feet. Limestone as 

 well as clastic beds enter into the system, and occur up to heL 

 of 3,000 feet. 



Marine Pliocene is known in Egypt, where the sea is thought to 

 have extended up the Nile to Assuan. The formation of the b;i- 

 (rifts) of the Red Sea and the Gulf of Suez, has been assigned to 

 this period, though the rift origin of these depressions has not 1 

 accepted universally. 



THE LJFE OF THE PLIOCENE 



The land plants. During the Pliocene there was n further 

 ing out of the mixed flora of previous periods, and the south* 

 migration of what are now tropical and subtropical plant.- contin- 

 ued. In southern France there were species identical with ti 



1 Hershey, Jour. Geol., Vol. X, pp. 377-392. 



