SEVENTH ANNUAL MEETING 101 



cumulated 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 : 

 (1) the great extent of the coal beds — the Herrin (No. 6), 

 and Springfield (No. 5) beds were deposited in practical con- 

 tinuity over at least 7000 square miles, and probably over a 

 considerably greater area in the state; (2) the regularity of 

 thickness of the coals — the Herrin (No. 6) bed ranges from 7 

 to 9 feet over a known area of at least 5,000 square miles. A 

 thin band of shale or shaly coal (blue band) one-half to two 

 inches thick, is present 18 to 24 inches above the floor of this 

 coal over practically the entire area of its distribution, and the 

 thickness of the benches above and below the "blue band" is re- 

 markably uniform. The Springfield (No. 5) bed, also scarcely 

 varies one foot in thickness over more than 5,000 square miles. 

 (3) The small percentage of mineral matter or ash in the coal 

 shows that very little mud and sand sediments were mixed with 

 the plant remains as they accumulated. 



In time of flood the amount of mud and sand carried by 

 streams is so great compared with the amount of vegetable mat- 

 ter, and the latter is deposited so irregularly, that it can scarce- 

 ly be imagined how the plant material of these coal beds could 

 have been carried by streams into the Illinois basin, and have 

 accumulated in practical continuity over such extensive areas, 

 in anything like such uniform thickness, and with so little 

 mingling of mineral sediments. Extensive areas of relatively 

 pure vegetable matter are known to be accumulating in 

 swamps at the present time, but there is no known place where 

 plant remains transported by streams during floods are ac- 

 cumulating as a continuous bed over any considerable area, in 

 anything approaching uniformity of thickness, and without 

 a very large mixture of sand and mud ; nor does it seem prob- 

 able that pure transported vegetable deposits have ever accu- 

 mulated over any considerable area in the past. 



From a study of small coal basins of France in recent years 

 Fayol, supported by DeLapparent and other French geologists, 

 has revived the transport theory of accumulation of the veget- 

 able matter of coal beds. However, practically every geologist 

 who has studied extensive coal beds, especially those of the 

 Appalachian region of the United States with which the coal 

 beds of Illinois are comparable, has rejected the transport 

 theory of accumulation as applied to those beds. Rogers 



