Ill] TRIASSIC PERIOD. 47 



SYSTEM, includes the sediments of more than one geological 

 period, some of the older members being regarded as Permo- 

 Carboniferous in age. These Indian beds, with others in 

 Australia, South Africa, and South America, are of special 

 interest on account of the characteristic southern hemisphere 

 plants which they have afforded, and from the association with 

 the fossiliferous strata of extensive boulder beds pointing to 

 widespread glacial conditions. 



VIII. Trias. 



As we ascend the geologic series, and pass up to the rocks 

 overlying the Permian deposits, there are found many indica- 

 tions of a marked change in the records of animal and plant 

 life. Many of the characteristic Palaeozoic fossils are no longer 

 represented, and in their place we meet with fresh and in 

 many cases more highly differentiated organisms. The threefold 

 division of the rocks of this period which suggested the term 

 Trias to those who first worked out the succession of the strata, 

 is typically illustrated over a wide area in Germany, in which 

 the lowest or Bunter series is followed by the calcareous 

 Muschelkalk, and this again by the clays, rock-salt, and sand- 

 stones of the Keuper series. In the Cheshire plain and in the 

 low ground of the Midlands, we have a succession of red sand- 

 stones, conglomerates, and layers of rock-salt which correspond 

 to the Bunter and Keuper beds of German geologists. These 

 Triassic rocks were obviously formed in salt-water lakes, in 

 which from time to time long continued evaporation gave rise 

 to extensive deposit of rock-salt and other minerals. From the 

 fact that it is this type of Triassic sediments which was first 

 made known, it is often forgotten that the British and German 

 rocks are not the typical representatives of this geological 

 period. The 'Alpine' Trias of the Mediterranean region, in 

 Asia, North America, and other countries, has a totally differ- 

 ent facies, and includes limestones and dolomites of deep-sea 

 origin. "The widespread Alpine Trias is the pelagic facies of the 



