348 STEATIGRAPHICAL GEOLOGY 



tites with the Ammonites which are so characteristic of the 

 Mesozoic periods. 



A similar dying out of old forms and a rapid spread of newer 

 types took place in the vegetable world. The Palaeozoic Lyco- 

 podiales Lepidodendron, Bothrodendron, and Stigmaria have now 

 all disappeared, while the Cycads which appeared in Permian time 

 now become much more numerous, and are associated with the 

 coniferous Voltzia. Among ferns, though some of them have been 

 referred to Pecopteris and Neuropteris, it is very doubtful whether 

 any belong to these Palaeozoic genera ; most of them are rather 

 referable to the more recently established genera Chladophlebis and 

 Todites. Many other new genera make their appearance. 



Here, therefore, at the base of the Trias is drawn the line between 

 the Palaeozoic and Neozoic eras, and here begins that division of 

 Neozoic time which is often called the Mesozoic. It must not be 

 supposed, however, that there is any great break between the two 

 series of formations, for though there is a partial break in Britain, 

 there is complete conformity between the Permian and the Trias, 

 with a passage from one to the other in the Alpine region, and 

 in most parts of Germany. 



THE TRIASSIC SYSTEM 



A. NOMENCLATURE AND CLASSIFICATION 



The Triassic System resembles the Devonian System in that it 

 presents us with two very different facies, (1) a terrestrial and 

 lacustrine facies formed within the limits of a large continent, and 

 (2) a marine facies of the usual kind. The first forms the upper 

 part of what used to be known as the New Red Sandstone (see p. 6), 

 but was called the Trias by von Alberti in 1834 on account of its 

 obvious tripartite arrangement in Germany. In England, however, 

 it has only two parts, and these are both of terrestrial or lacustrine 

 origin ; in Germany these persist, but the middle beds are lime- 

 stones containing marine fossils, and consequently there are three 

 series, which have received the following names : 



3. The Keuper (red marls and sandstones). 



2. The Muschelkalk (marine limestones). 



1. The Bunter (variegated marls and sandstones). 



For the normal marine facies of the Trias we must go to the 

 Alps, and the student cannot tinderstand the true relations of the 

 Triassic System to those which precede and follow it until he has 

 learnt something about the important marine facies of the forma- 



