208 HISTORICAL PALEONTOLOGY. 



(17) 'Ichnology of Annandale. ' Sir William Jardine. 



(18) 'Die Fossile Flora der Permischen Formation.' Gceppert 



(19) 'Genera et Species Plantarum Fossilium. ' Unger. 



(20) " On the Red Rocks of England of older Date than the 



Trias " ' Quart. Journ. Geol. Soc., ' vol. xxvii. Ramsay. 



CHAPTER XV. 



THE TRIASS1C PERIOD. 



We come now to the consideration of the great Mesozoic, or 

 Secondary series of formations, consisting, in ascending order, 

 of the Triassic, Jurassic, and Cretaceous systems. The Trias- 

 sic group forms the base of the Mesozoic series, and corre- 

 sponds with the higher portion of the New Red Sandstone of 

 the older geologists. Like the Permian rocks, and as implied 

 by its name, the Trias admits of a subdivision into three 

 groups a Lower, Middle, and Upper Trias. Of these sub- 

 divisions the middle one is wanting in Britain ; and all have 

 received German names, being more largely and typically de- 

 veloped in Germany than in any other country. Thus, the 

 Lower Trias is known as the Bunter Sandstein; the Middle 

 Trias is called the Muschelkalk; and the Upper Trias is known 

 as the Keuper. 



I. The lowest division of the Trias is known as the Bunter 

 Sandstein (the Gres bigarre of the French), from the generally 

 variegated colors of the beds which compose it (German, 

 bunt, variegated). The Bunter Sandstein of the continent of 

 Europe consists of red and white sandstones, with red clays, 

 and thin limestones, the whole attaining a thickness of about 

 1500 feet. The term "marl" is very generally employed to 

 designate the clays of the Lower and Upper Trias; but the 



