THE TRIASSIC PERIOD 443 



In the Mesozoic era no less than twelve reptilian orders flourished, 

 and nearly all of them had gigantic members. Some were the 

 largest land animals that ever existed, and the sea-dragons rivalled 

 the whales in size. Nothing so clearly shows that the Mesozoic era 

 is a great historical fact, as the dominance of its reptiles. 



The Mesozoic climates offer some difficult problems. In general, 

 the climate was mild, as is shown by the plants found in the Meso- 

 zoic rocks of Arctic lands, for in Greenland, Alaska, and Spitsbergen 

 was a luxuriant vegetation of warm temperate type. On the other 

 hand, certain geologists have maintained the existence of distinct 

 climatic belts in the Mesozoic, indicating equatorial, northern, and 

 southern zones, but by others this interpretation is denied. 



The Mesozoic era comprises three periods, — the Triassic, 

 Jurassic, and Cretaceous. 



THE TRIASSIC PERIOD 



The Triassic period is so named from the very conspicuous 

 threefold subdivisions of this system of strata in Germany, where 

 its rocks were first studied in detail, and where they occupy a 

 greater area than in any other European country. The German 

 Trias is, however, not the usual and normal facies of the system, 

 but a very peculiar one, and cannot be taken as the standard of 

 comparison for most other countries. 



The Trias of North America is displayed under three very 

 different facies, — that of the Pacific coast, which is marine; that 

 of the interior, which is lacustrine ; and that of the Atlantic border, 

 which is estuarine. Owing to the absence of fossils common to 

 all it is not yet possible accurately to correlate the three facies, 

 but the divisions of the Pacific and Atlantic borders are given in 

 the following table : — 



Pacific Border Atlantic Border 



Xewark Series. 



( Bajuvaric Series. 

 Triassic J Tirolic Series. 

 System. | Dinaric Series. 



I Scythic Series. 



