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CHAPTER VIII. 



ON THE LOWER OR GREAT COAL FORMATION. 



The Geological Position and Structure of Coal Districts, called Coal-Fields. — 

 Dislocation and Disturbances of Coal Strata by Faults and Dykes. — Mineral 

 Coal, Anthracite, Plumbago, Wood-Coal or Lignite. — Iron-Stone accompany- 

 ing Coal Strata. — On Carbon as an original Constituent Part of the Globe.— 

 On the Origin of Coal Strata, and their Deposition in Fresh-Water Lakes or 

 Marshes. — Numerous Repetitions of the same Series of Beds in the same Coal- 

 Field. — Precautions necessary in the Establishment of Iron Furnaces. — On the 

 Mode of searching for Coal. — Hints to landed Proprietors on the Probability of 

 finding Coal in Districts where it has not yet been discovered. — On the Forma- 

 tion of Coal-Beds in Fresh- Water Lakes. — On the Conversion of Vegetable 

 Matter into Coal. — Imperfect Coal Formations. — Salt Springs in Coal Strata. — 

 Coal Mines in France and North America. — Observations on the Consumption 

 of Coal in England, and the Period when the Coal-Beds will be exhausted. 



In the transition rocks covering the primary, described in the pre- 

 ceding chapter, we very rarely, indeed, discover any remains of ve- 

 getables, either terrestrial or marine. Carbon, which is the principal 

 constituent element of all plants, is seldom found as a mineral sub- 

 stance in these rocks ; for, with a very few exceptions, all the ves- 

 tiges of organic forms which they contain, are of marine animals. 

 Hence we are led to infer, that there were but few islands, or tracts 

 of dry land, rising above the ancient ocean, in which these marine 

 calcareous beds were formed or deposited. The attention of the 

 geological student is now required to contemplate a most important 

 and extensive change in the condition of the globe, — at least, of that 

 part of it which forms the subject of the present chapter. Over the 

 marine rock formations before described, we find a series of strata, 

 two thousand feet or more in aggregate depth, in which remains of 

 marine animals are extremely rare, but which contain, almost exclu- 

 sively, the remains of terrestrial plants, or such as have grown either 

 on dry land or in marshes. Carbon, in the form of coal, constitutes 

 also numerous beds in the series, varying in thickness from a few in- 

 ches to thirty feet or more, and alternating with beds of sandstone, 

 indurated clay, and shale or schistose clay. The remains of vegeta- 

 bles are distributed in greater or less abundance throughout the 

 whole series, which, taken together, are called by miners, in the 

 north, coal-measures. The coal strata were, doubtless, deposited in 

 the vicinity of extensive tracts of dry land, containing rivers, marsh- 

 es, fresh-water lakes, and mountains ; the marine beds which are 

 the foundation of the series of coal strata, and also surround them, 

 must, therefore, have been raised from the bottom of the ancient 

 deep, before the vast accumulation of vegetable matter could be 

 formed. To whatever cause we attribute this change in the condi- 

 tion of the globe, it appears to have been attended with another re- 



