I9II.] STEVEXSOX— FORMATIOX OF COAL BEDS. 9 



Darwin^'' adhered to the doctrine of formation in situ but with 

 modifications. " In other circumstances, probably where less mois- 

 ture has prevailed, morasses seem to have undergone a fermenta- 

 tion, as other vegetable matter; new hay is liable to do so from the 

 great quantity of sugar it contains. From the great heat thus 

 produced in the lower part of the morass, the phlogistic part, or 

 oil or asphaltum. becomes distilled and. rising into higher strata, 

 condensed, forming coal beds of greater or less purity, according to 

 their greater or less quantity of inflammable matter; at the same 

 time the clay beds become poorer or less so as the phlogistic part is 

 more or less completely exhaled from them." 



Patrin,^^ cited by Parkinson, thought coal and the interposed 

 beds of rock due to alternating ejection of bituminous and earthy 

 materials by submarine volcanoes. In another work cited by 

 Pinkerton he describes the characteristics of coal beds, that they 

 have a boat-like form and that they are never single, there being 

 many in each coal field. He thinks the deposit must have been 

 made in still water. The occurrence of plant impressions in the 

 roof shales has led several naturalists to think that coal is composed 

 of vegetable remains. But Patrin thinks that this opinion presents 

 great difficulties. The naturalist le Blond found beds of coal near 

 Bogota at 13,200 feet above the sea. When the ocean reached that 

 height there would be islands ; and it cannot be seen how the small 

 quantity of vegetables, which had been brought accidentally from 

 those mountains, could have formed the thinnest bed of coal or 

 even of peat. 



Hutton's^- opinions appeared in final form in 1795. They are 

 not always stated clearly but the confusion may not be that of the 

 author's mind : it may be only apparent and due to the somewhat 

 involved method of presenting the case. The carbon of coal is evi- 

 dently of organic origin. Bituminous coal and anthracite are parts 



^° E. Darwin, " Botanical Garden,"' Add. X'otes. XVIL, 1791. Cited by 

 J. Parkinson ; not seen by the writer. 



"Patrin, Art. Houille. "Diet, d'hist. Xaturelle," cited by Parkinson; 

 " Mineralogie, V., p. 317. Cited by J. Pinkerton in " Petrology," pp. 567, 568. 



'^J. Hutton, "Theory of the Earth With Proofs and Illustrations," 

 Edinburg, 1795, Vol. I., pp. 565, 566, 570, 575-581, 586. 



9 



