FORMATIONS AND PHYSICAL HISTORY 507 



Juraic tinu- in sonu- other regions. On the other hand, the Upper 

 Jurassic and the Lower Cretaceous beds are in places so closely 

 iated as to show that no change of continental dimensions 

 brought the Jurassic period to a close. 



Other continents. The Upper Jurassic is widespread in Arctic 

 lands. This 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 in western America. The Lower Jura is want- 

 ing in these latitudes, so far as known, and the Middle Jura is limited. 

 The Lower Jura occurs in southwestern Asia and Japan. The 

 Middle Jura, largely clastic and of terrestrial origin, is widespread 

 in Northern Asia, and marine 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, Australia, 

 and South America (Peru, the Bolivian Andes, Chile, and Argentina). 



Coal. Coal is somewhat widely distributed, occurring in Hun- 

 gary, the Caucasian region, Persia, Turkestan, southern Siberia, 

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

 of A>ia, in Australia and New Zealand. Most of the coal is in the 

 lower part of the system (Lias). Outside of North America, it is 

 probable that no other system except the Pennsylvanian contains 

 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 probably were defined. The detailed 

 study of the 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 

 Mu rope and lands farther south. 



LIFE 



The Jvrassic was a period of sea extension, and the marine life 

 again assi mes a place of leading importance in the fossil record. 

 At the same time the land life, though suffering somewhat by the 

 smaller area available for it, was favored by genial climate. 



Marine life. The faunal progress of the period is less well 

 revealed in North America than in Europe and Asia. The great 



