THE JURASSIC PERIOD 709 



England (4,000-5,000 feet) Germany (2,000-3,000 feet) 



Upper (Portland) Oolite Upper (White) Jura or Malm 



Middle (Oxford) Oolite Middle (Brown) Jura or Dogger 



Lower (Bath) Oolite 

 Lias Lower (Black) Jura or Lias 



Among the more distinctive features of the system in Europe 

 are the following: 



(1) A considerable content of coal in some places, notably 

 Hungary. (2) The abundance of oolitic limestone, both in Eng- 

 land and on the continent. (3) The presence of lithographic stone 

 (Solenhof en limestone of southern Germany) . This stone is so fine 

 and so even-grained, and at the same time so workable and so 

 strong, that it has come into use the world over for lithographic 

 purposes. The stone is also remarkable for the perfection of its 

 fossils, including such delicate parts as the gauzy wings of insects. 

 (4) The considerable development of non-marine beds in the lower 

 part of the system, and again at its very top, especially outside 

 of southern Europe. 



Close of the Jurassic in Europe. The close of the Jurassic 

 appears to have been marked by a somew r hat wide-spread emergence 

 of land. In central Europe, the emergence appears to have begun 

 before the close of the Jurassic, for the latest beds (Purbeck) of 

 the system in England are unconformable on beds lower in the 

 system. Similar changes are known to have occurred in late 

 Jurassic time in some other regions. On the other hand, the Upper 

 Jurassic and the Lower Cretaceous beds are in places so closely 

 associated as to show that no change of continental dimensions 

 brought the Jurassic period to a close. Great deformative move- 

 ments seem to have affected no part of Europe at the close of the 

 period. 



Extra-European Jurassic 



The Upper Jurassic is wide-spread in Arctic lands. This distri- 

 bution points to a great Arctic sea in the later part of the period, 

 with two considerable dependencies to the south, the one in 

 Russia, the other, as we have seen, in western America. The 

 Lower Jura is wanting in these latitudes, so far as known, and the 

 Middle Jura is present but rarely. 



