ON THE CONDITIONS UNDER WHICH THE VEGETABLE 



MATTER OF THE ILLINOIS COAL 



BEDS ACCUMULATED 



T. E. SAVAGE 

 University of Illinois, Urbana 



All students of the subject agree that coal was derived from 

 vegetable material which has undergone imperfect decomposition 

 without free access of air. The complete explanation of the coal 

 beds involves, among other things, an explanation of (i) the 

 method and conditions under which the plant material accumulated; 

 (2) the kinds and proportions of the different plants that con- 

 tributed the vegetable material; and (3) the chemical changes 

 by which the plant tissues were transformed into coal. The first 

 part of the problem, with regard to the method and the conditions 

 under which the vegetable matter of the coal beds accumulated, 

 can be studied somewhat independently of the other two, and the 

 solution should be found in the structural features of the coal beds 

 and associated strata. 



Two important theories have been proposed to explain the mode 

 of accumulation of the vegetable matter of coal beds. The older 

 of these, known as the "transport or driftage theory," assumes that 

 the vegetable materials grew on land areas, whence they were car- 

 ried by streams and deposited in the bodies of water where they 

 accumulated. The other, known as the " swamp or growth-in-place 

 theory," was suggested in 1778, and assumes that the vegetable 

 matter of coal beds accumulated in swamps practically in the 

 places where the plants grew. 



The following facts presented in the principal coal beds of Illinois 

 make impossible the application of any form of the transport 

 theory of accumulation of the vegetable material: (i) the great 

 extent of the coals — ^the Herrin (No. 6) and Springfield (No. 5) 

 beds extend in practical continuity over at least 7,000 square miles, 

 and probably over a considerably greater area in the state; (2) the 



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