CHAPTER XXXI. 



THE CARBONIFEROUS SYSTEM. 



A brief sketch of the various groups of strata which compose the great 

 Carboniferous system has been given in the first volume of this Report. 

 These will now be described somewhat more in detail, in order 'that our 

 citizens may have a more exact and comprehensive knowledge of the 

 composition and extent of this, the most important of the formations 

 represented in the geology of our State. 



It is known to most persons that the name Carboniferous, or coal-bear- 

 ing, was given to this group of rocks from the fact that they include in 

 Europe and America extensive deposits of mineral fuel, which not only 

 constitute a marked feature in the formation, but have great economi- 

 cal value, and have played a most important part in the development of 

 our modern civilization. The name Carboniferous is, therefore, not ill- 

 chosen, but it is liable to mislead, since the 'Devonian shales, in the Uni- 

 ted States, hold quite as large a quantity of cr„ -bonaceous matter as is 

 contained in our Coal Measures ; and in China, India, and Western Amer- 

 ica beds of coal occur in Mesozoic and Tertiary rocks which, in thickness 

 and lateral extent, are not surpassed by our Carboniferous coal strata, 

 while in these countries little or no coal occurs in rocks older than those 

 mentioned. Hence, if geology had been first studied in China, a Carbon- 

 iferous system would probably have been given a place in the geological 

 column, but it would have been put at a higher level than it holds in 

 our series. 



The Carboniferous system, known as such among our geologists, is 

 usually regarded as one of the most distinctly denned of all the great 

 groups of rocks, and yet in fact the lines which are now drawn to separate 

 it from the Devonian below and the Permian above are as shadowy as 

 any others that divide formations in the geological series. 



In England there has been much discussion as to where the lower 

 limits of the Carboniferous system should be fixed, and there is still 

 great difference of opinion as to how much of the Yellow sandstones of 

 Ireland and the Upper Old Red Sandstone of Scotland should belong to 

 the Devonian, and how much to the Carboniferous group. In our own 

 country a similar difficulty has been encountered. The relations of the 

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