142 STEVENSON— FORMATION OF COAL BEDS. [April i8, 



nite conditions to the explanation of another set of phenomena, 

 which are impossible under those conditions. It is in constant con- 

 flict with what seem to be the established laws in nature. The true 

 explanation of the formation of coal beds may be still unknown, and 

 it may be the lot of chemists, geologists and palaeontologists to follow 

 many paths of investigation for many years before discovering the 

 truth ; but, to the writer, it appears certain that the path marked by 

 allochthony ends in a cul dc sac, walled with contradictions ; and 

 that farther investigation along that path will be fruitless ; for 

 allochthony magnifies the exceptional into the normal and endeavors 

 so to explain away the normal that it may appear to be the ex- 

 ceptional. 



AUTOCHTHONY. 



According to the doctrine of autochthony, the plants, yielding 

 material for the coal, grew where the coal is now found ; this is not 

 to deny that some deposits were made of transported materials ; that 

 would be to deny the evidence of one's senses ; but such deposits are 

 of limited extent and have definite features, which distinguish them 

 sharply from deposits made in the normal \vay. 



Cannel and Boghead. 



The peculiar structure of cannel compelled geologists to recog- 

 nize that in origin it differed from the ordinary coals. Newberry in 

 1857 asserted that it is merely vegetable mud, composed of macerated 

 cells, deposited in poiifls within swamps ; Dawson in 1866, J. Geikie 

 in 1872, E. B. Andrews in 1873 and Davis in 1880 enforced this 

 explanation by their observations. In 1880, J. P. Lesley, ^^^ correct- 

 ing an erroneous reference to his opinions, enlarged the conception 

 and anticipated much of what has been announced in later years. 

 His -words are 



"*J. P. Lesley, Sec. Geo!. Surv. Penn., Preface to Rep. H5, 1880, p. xxii. 

 " Cannel coal I regard as vegetable matter macerated in water, mixed 

 with gelatinous water-plants and with the fine sedimentary clay which even 

 the purest current-water always holds in suspension ; and I ascribe the origin 

 of petroleum in cannel, as I do the origin of the well-oil, to such water plants 

 and to gelatinous water-animals." 



