19".] STEVENSON— FORMATION OF COAL BEDS. 109 



then sink to give the appearance of growth in si tit. If the storm 

 continue long enough, it would wash ofif the soil itself, which would 

 become an intercalation in the bed. If the flood return, attaining 

 a higher stage than before, another area of forest region would be 

 torn ofif to form a new bench of coal, possibly directly on the other. 

 When the flood subsides, the superficial currents would find only 

 inorganic materials on which to act, and the first deposit would be 

 mud to form the roof of the coal bed, after which would follow 

 some sandstone and conglomerate. Between floods the vegetation 

 is restored and the area is increased by encroachment on the lake. 

 During this long interval, the flora might be changed. 



Lemiere is convinced that, by his hypothesis, he has succeeded 

 in explaining converging beds, parallel formations and floating islets. 

 All are allochthonous ; aerial plants have formed no autochthonous 

 beds, for no erect stem has been found in the coal ; in fact, the 

 plants could not thrive in a humus not nitrefied. Peat cannot become 

 coal, as its tannic acid checks the process of conversion. He applies 

 his doctrine with great ingenuity to several basins in France and 

 finds it confirmed in all. 



Lemiere^'^" has published several papers in more recent years and 

 he presented a resume of his opinions in 19 lO. In that he expresses 

 surprise that in recent congresses the dominant opinion was that 

 coal beds are ancient wooded-bogs buried by successive subsidences, 

 because this opinion involves the supposition that the coal beds were 

 not formed in the same way as the sterile beds which enclose and, 

 at times, penetrate them. This opinion is based upon palaeobotan- 

 ical evidence, which is often untrustworthy, providing two-edged 

 weapons, available equally for defenders of each theory. It is nec- 

 essary to discover some criterion which will be conclusive. In an 

 earlier paper, he had demonstrated finally in geometric form that the 

 peat bog theory leads to arrangement of beds unknown in nature. 

 In this he proposes to restudy the conditions after the same method, 

 avoiding palseontological discoveries, and availing himself of dis- 

 coveries which have the character of certitude. He describes three 

 types of structure observed in areas of the coal formation. 



^"^ L. Lemiere, "Resume des theories sur la formation de la houillc,"' 

 Bull. C. R. mensitels. Soc. Ind. Min., Sept., 1910. separate, 19 pp. 



109 



