710 GEOLOGY 



The lower Jura occurs in southwestern Asia and Japan. The 

 Middle Jura, largely clastic and of terrestrial origin, is \vide-spre:id 

 in Northern Asia, and marine in Middle Jura is known in northern 

 India. The Upper Jura is much more extended, especially in the 

 north. The system is known in New Zealand, Borneo, and Aus- 

 tralia, and is well developed in Mexico, Peru, the Bolivian Andes, 

 Chile, and Argentina. 



Coal. Coal of considerable value is somewhat widely distributed 

 in the Jurassic system. Besides that in the Lias of Hungary, coal 

 occurs in the Caucasian region, Persia, Turkestan, southern Siberia, 

 China, Japan, and Farther India, in many of the islands southeast 

 of Asia, and in Australia and New Zealand. In the last-named 

 island, the coal-bearing formations are interbedded with marine 

 strata, suggesting considerable oscillations of level. In most of 

 these countries, the coal is Liassic. Outside of North America, 

 it is probably that no other system except the Pennsylvanian con- 

 tains so much coal. 



Climate 



The testimony of fossils gathered in various parts of the world 

 is to the effect that the climate of the Jurassic period was genial. 

 In Europe, corals lived 3,000 miles north of their present limit, 

 and saurians and ammonites flourished within the Arctic circle. 

 Nevertheless, climatic zones were probably denned. Corals are 

 unknown in the deposits of the great Arctic belt of Upper Juia, 

 and the detailed study of the Jurassic faunas has led to the belief 

 that one climatic zone is recorded in the Jurassic beds of the Arctic 

 belt, a second in the deposits of central Europe, and a third in the 

 southern province of Europe and the lands farther south. There 

 can be no doubt of the differences in the faunas of these different 

 provinces, but it is not certain that the differences were due wholly 

 or even mainly, to climatic influences. 



THE LIFE OF THE PERIOD 



As the Jurassic was a period of sea extension, the marine life 

 again assumes a place of leading importance. At the same time 

 the land life, though suffering somewhat by the limitation of its 



