CHAPTER III. 



CARBONIFEROUS SYSTEM.— (Continued.) 



THE C0AL-MEASUKE GKOTTP. 



The name " coal-measures " is one that originated long 

 ago among the miners of England, and is now altogether 

 without significance, except as an arbitrary term used to 

 designate all that group of strata in which coal is found. 

 It was formerly supposed that all the coal of the world 

 was contained among the geological equivalents of the strata 

 which contained it in England. The study of the great coal- 

 fields of the United States and of Europe for a long time 

 confirmed this opinion, because they were found to corres- 

 pond as exactly in geological age with those in England 

 as we can ever hope to determine geological equivalency of 

 strata. It was afterwards found that certain varieties called 

 'lignite" or "brown coal" were contained in strata geologi- 

 cally, much more recent than those of the Carboniferous 

 System, but it was still supposed that true coal was found 

 alone in that System among the strata of which it was first 

 discovered. We now know that these views are erroneous, 

 and that all the coal of the earth was not formed simulta- 

 neously during any one particular period of its history, but 

 that much coal was formed in the ages subsequent to the 

 carboniferous, and some was probably previously formed. 



This question of the later formation of coal has been 

 very definitely settled by late researches in China, Mongolia 

 and Japan, by Prof. Raphael Pumpelly, and by others in 



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