CHAPTER XXVI 

 THE CARBONIFEROUS PERIOD 



The name Carboniferous was given in the early part of the 

 present century, when it was supposed that every geological sys- 

 tem was characterized by the presence of some peculiar kind of 

 rock. We now know that this conception is erroneous and that 

 workable coal seams have been formed in all the periods since the 

 Carboniferous. It still remains true, however, that the latter con- 

 tains much the most important share of the world's supply of 

 mineral fuel, upon which the whole fabric of modern industrial 

 civilization is founded. The great economic importance of the 

 coal measures has caused them to be most carefully surveyed in 

 all civilized lands, a process greatly assisted by the innumerable 

 shafts and borings which penetrate these rocks. One result of 

 this. gigantic work is, that the history and life of the Carbonif- 

 erous are better known than those of any other Palaeozoic period, 

 though our knowledge is still very far from complete. 



The Carboniferous rocks are displayed in very different aspects 

 or facies in the various parts of the continent and even in contigu- 

 ous regions. New York no longer gives the standard scale, for 

 that state has very little that is newer than the Devonian. For 

 the eastern part of the country the sequence of strata in Pennsyl- 

 vania serves as the scale of reference, while a very different one is 

 needed for the Mississippi valley. In the Rocky Mountain region, 

 again, the character of deposition deviated markedly from what oc- 

 curred in the East, and all over the far West the Carboniferous is 

 entirely marine, without coal. Even in this region, however, the dis- 

 tinction between the Lower and Upper Carboniferous may be drawn. 

 The following table, modified from Dana's, gives the succession in 

 Pennsylvania and the middle West, Illinois, Missouri, Iowa, etc. 



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