I9II.] STEVEXSOX— FORMATIOX OF COAL BEDS. 57 



But most of the material forming the beds was transported ; 

 yet all coals resemble that found almost in place and the parts, cer- 

 tainly transported, are identical with similar parts of the rooted 

 stems. The materials were derived from marshy forests on borders 

 of the basin, which doubtless succeeded those temporarily installed 

 in the basin of the deposit which afterwards became a lake. At the 

 foot of this forest was elaborated, as in peat bogs, the humus or 

 fundamental material of the coal. The basin of deposit was much 

 like the bottom of a morass, for the mud of coal beds often resem- 

 bles the clay underlying peat bogs. The debris of plants falling 

 into water on the borders of the marsh became stratified in its 

 depths. Grand' Eury was convinced that by this hypothesis he had 

 reconciled the opposing theories, for he has shown that certain coal 

 beds were formed by concurrence of both processes, as in the sub- 

 aquatic parts of some swamps. 



The permanent swamps, where primitive peat was elaborated, 

 were not exposed to deposit of mineral sediments, they remained 

 uncovered and disappeared ; so that very little of the coal formed 

 in place remains. The researches of Renault and C. E. Bertrand 

 on cannel and the fundamental matter of coal show that coal was 

 not always deposited on lake bottoms under moving waters, but that 

 it may have been formed in stagnant or quiet waters of swamps. 



The coal was deposited slowly, not continuously and there may 

 have been long periods of arrested growth. The concentration of 

 fossil forests and soils of vegetation in and near coal beds proves 

 for the thick beds a very long period. Additional evidence in this 

 direction is found in the advanced decomposition of the rocks form- 

 ing the roof, their new chemical combinations, their impregnation 

 with carbon, showing that they had been long in contact with the 

 swamp before being transported and deposited on the coal bed. 



The basin of the Loire was subjected to orogenic movements. 

 The fossil forests have irregular distribution both vertically and 

 horizontally ; great sterile deposits break up the continuity. The 

 basin was deepening throughout the period of formation, but each 

 important coal bed corresponds to an interval of stability. That 

 the mineral materials were brought in by streams is shown by their 



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