152 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



as well as land shells, along with remains of plants. The peculiar 

 features of the deposit led him to recognize a condition analogous 

 to that of cedar swamps on the low border of a bay. Treated with 

 Schultze's reagent, the coal shows under the microscope that the 

 bright layers are composed of leaves, epidermis and plant-parts with 

 parenchymatous structure. The dull layers are more intricate. 

 Faserkohle is quite abundant. 



Haidinger,"^- 20 years earlier, had described a characteristic frag- 

 ment of mineral charcoal obtained at Haring. He thought it prob- 

 ably an inclusion in the peat from which the brown coal was formed. 

 This Faserkohle passes so gradually into the enclosing glance coal 

 that Haidinger was inclined to believe it a case of external con- 

 version into coal. At the same time, the Faserkohle is interwoven 

 with vein-like lines of bright coal, which in his opinion could have 

 been introduced only in a gelatinous condition like that of dopplerite. 



Heer-^^ notes that, near the Diirnten Schieferkohle area, a deposit 

 of lignite occurs in soft sandstone of the Molasse. It often con- 

 tains tree trunks but other parts of plants have become indistinguish- 

 able. Yet one finds marsh plants in the marls overlying the lignite, 

 while the underlying limestone contains Unio and Planorhis. 



The Bovey Tracey deposits in Devonshire, England, were de- 

 scribed in great detail by Pengelly.-^* They had been subject of 

 discussion during many years and the associated clays had been uti- 

 lized on an extensive scale. The excavation, at the time of Pen- 

 gelly's examination, was more than 100 feet deep, 350 feet wide and 

 almost 1,000 feet long. His section, greatly condensed, is: Clays, 

 sandy clays, thin sands and 4 beds of lignite, 7 to 15 inches thick; 

 this lignite is poor, loose, brittle, woody ; the clays are dark to gray, 

 with streaks and fragments of lignite, 37 feet 7 inches; lignite with 

 partings, 14 feet of lignite in 5 benches with about 7 feet of clay in 

 the partings ; the uppermost bench is more or less wood-like and at 

 the bottom is a mass of dicotyledonous leaves ; two of the clay part- 



212 w. Haidinger, Vcrhandl. k. k. Gcol. Rcichsant., Bd. XIV., 1864, p. 241. 



213 O. Heer, "The Primaeval World of Switzerland," Eng. Trans., London, 

 1876, Vol. I., p. 32. 



214 W. Pengelly, " Lignite and Clays of Bovey Tracey, Devonshire," Phil. 

 Trans. Roy. Soc, Vol. 152, 1863, pp. 1019-1038. 



