THE JURASSIC PERIOD 79 



the great expanse of land in the tropical latitudes, and the great expanse 

 of sea in the Arctic regions. According to Neumayr's conjecture, the 

 late Jurassic expansion of the sea was one of the greatest known in 

 geological history, and the distribution of the land at the time of 

 the maximum extension of the sea was very different from that which 

 existed in the Lias, when there was a great expanse of land in the 

 Arctic latitudes. 



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 3000 miles north of their present limit, 

 and saurians and ammonites flourished within the Arctic circle. Never- 

 theless, climatic zones were probably defined at that time. 1 Corals 

 are unknown in the deposits of the great Arctic belt of Upper Jura, 

 and the detailed study of the faunas has led to the belief that three 

 more or less well defined zones were in existence. One is recorded 

 in the Jurassic beds of the Arctic belt; a second in the deposits of the 

 central European belt; and a third in the southern province of Europe, 

 and in the lands farther south. 



There can be no doubt of the great 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. 



It should perhaps be noted that there are conglomerates in the 

 Lias of Scotland which have been conjectured to be glacial, 2 but there 

 is no proof that this was their origin. 



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

 to have been marked by a somewhat widespread emergence. In the 

 central province, this disturbance appears to have begun before the 

 close of the Jurassic, for the latest beds (Purbeck) referred to that 

 period in England are unconformable on beds lower in the series. 

 Similar changes are known to have occurred in late Jurassic time in 

 some other regions; but the L^pper Jurassic and the Lower Cretaceous 

 beds are in many regions so closely associated as to show that no change 

 of continental dimensions intervened between them. Great deformative 

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

 the period. 



1 Neumayr, loc. cit., p. 331. 



8 J. Geikie, Outlines of Geology. 



