THE AGE OF REPTILES 



are 10,000 feet thick. There must also have been con- 

 siderable volcanic or earthquake action as we know, 

 because in Germany, near the Hartz Mountains and else- 

 where, there are many igneous rocks thrust into the 

 strata, and also because in Belgium and in France the 

 coal strata are very much twisted and contorted. The 

 same or similar beds are found in Siberia, in Japan, and 

 in China, where the coal beds are said to be thicker 

 than anywhere else in the world. The Carboniferous 

 system is also found in Africa, in the north, south-east, 

 and south of the continent ; and in Australia and New 

 Zealand Carboniferous strata to the thickness of 10,000 

 feet are indicated. 



At the close of this period the changes ever taking 

 place transformed the conditions of life in a way the 

 reverse of that which we have hitherto been examining. 

 So far each age has shown an increase of life on the age 

 preceding it. But when the great outburst of carboni- 

 ferous activity began to wane it was followed by a 

 lessening of the wave of life. As we said in the last 

 chapter, there lie on the top of the coal-bearing strata 

 beds to which the older geologists gave the name of New 

 Red Sandstone. But in 1841 the New Red Sandstone 

 was divided into two distinct geological formations. To 

 the lower and older part Murchison gave in 1841 the 

 name of PERMIAN (from Perm or Permia, an ancient 

 kingdom in Russia, where red sandy rocks of this age 

 form nearly all the surface), but in Germany it is more 

 frequently called the DYAS (from Lat. duo, two), because 

 in that country it is composed of two well-marked 



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