132 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



as are observed in recent forests. These belong mostly to Taxodium 

 distichum, the bald cypress of American swamps. Many of the stems 

 are hollow and, especially those near the bottom of the mass, con- 

 tain Schwelkohle. The presence of an ancient Torfmoor, resting on 

 the clay cover of the brown coal, indicates that peat-making condi- 

 tions recurred here until diluvial accumulations began. The sand 

 overlying this old bog contains erect stems belonging to either Pinus 

 syhestris or Picea excelsis and stumps have been found in the peat 

 itself. One great uncompressed fragment of a trunk was found by 

 Potonie, but usually the prostrate stems are flattened. The presence 

 of Schwelkohle in the hollow stumps led the author to suggest that 

 it was formed by the flow of resins, which, he thinks, must have 

 been great in the injured trees. Schwelkohle is, for him, essentially 

 a fossil resin ; it burns with brilliant flame when pure. 



The forest of the roof is well shown in a photograph reproduced 

 on a postal card, for which the writer is indebted to W. Gothan of 

 Berlin. It shows ten or more erect stumps, 4 and more feet high, 

 distinctly rooted in the coal and associated with some prostrate stems. 

 These were overwhelmed by the detritus which brought peat-growth 

 to an end. Kukuk^®-^ has reproduced a noteworthy photograph of 

 the Victoria stripping in Niederlausitz. The brown coal has been 

 removed and the floor is exposed with the very numerous great 

 rooted stumps of Taxodium distichum. 



Russwurm^^'^ has given a section of the brown coal bed at Oreb- 

 kau, about 50 miles south-southwest from Frankfurt a.O. and some- 

 what more than 10 miles northeast from Senftenberg. The bed is 

 9 meters thick, is divided by a thin parting and underlies 10 meters 

 of mostly black clay, containing comminuted fragments of plants. 

 The upper bench, free from wood, is lump coal (Knorpelkohle) and 

 bears shipping, so that briquetting is unnecessary ; but the lower 

 bench is fine coal (Formkohle) and tender, but it is rich in wood, 

 the quantity increasing downward until at the bottom the stems pre- 

 dominate. Russwurm found no erect stems. A second bed, at times 

 3 meters thick, is here at half a meter to 4 meters below the main 



182a p Kukuk, " Unsere Kohlen," Leipzig, 1913, p. 25. 

 is^ P. Russwurm, " Braunkohlen Formation, etc., bei Orebkau," Zcitsch. 

 f. pr. GeoL, Jahrg. 17, 1909, pp. 87 ff. 



