800 



GEOLOGY 



The oldest Oligocene deposits of cent nil and western Europe 

 are largely of terrestrial, fresh- and brackish-water origin. Local 

 deposits of salt, gypsum, and coal arc suggestive of the physical 



conditions at various times and 

 places. The Oligocene of southern 

 Europe is chiefly marine, hut in 

 the upper part of the series, lake 

 and marsh deposits are not rare. 

 In Italy it has been estimated to 

 have the extraordinary thickiu-s 

 of nearly 12,000 feet. 



In Europe, as in North America, 

 there were considerable igneous 

 eruption, during the Tertiary, and 

 especially during the Oligocene 

 The results are to be seen in I Bo- 

 hemia, where there is much igne- 

 ous rock; in northern Ireland and 

 western Scotland, where outpour- 

 ings of lava probably made great 

 plateaus, of which some of the 

 adjacent islands are remnants; in 

 Iceland, and in the Vienna basin. 

 Between eruptions, vegetation 

 grew in the marshes and shallow 

 lakes and over the surface of the 

 lava. The substance of this \ < 

 tation is locally (Faroes, and 

 land) preserved in the form of coal 

 between the lava beds. Someoi 

 lakes of France seem to have i 

 obliterated by volcanic action. 

 Amber. One of the peculiar accessories in the Lower Oliu 

 is the amber of northern Germany, principally in the vicinity < 

 Konigsberg. While amber in small quantities is found in Sicily 

 and a few other places, that of the Baltic region is more abundant 

 than that of any other part of the earth, so far as now known. 



Fig. 538. Map showing supposed 

 distribution of land and water on 

 the Pacific coast of the United 

 States during the Oligocene 

 epoch. (Ralph Arnold.) 



