I9II.] STEVENSON— FORMATION OF COAL BEDS. 621 



Among the latter group, the most noteworthy example is the 

 Schieferkohle of Utznach, Diirnten and neighboring localities in 

 Switzerland, which is interesting from the economic as well as the 

 scientific point of view. Having been studied in great detail by 

 several geologists, it will suffice as type. Some have thought that 

 these deposits are post-glacial, in which case, they would possess the 

 greatest possible interest to students seeking to ascertain the mode 

 in which vegetable matter became converted into coal and gathered 

 into beds. But the age remains unsettled ; Heim^^*^ maintains that 

 the Schieferkohle lies between moraines. The section in detail at 

 Wetzikon and Utznach shows drumlines and erratic blocks of the 

 last glaciation resting on fluvio-glacial gravels. The lignite, under- 

 lying the latter, i to 3 meters thick, rests on bowlder clay of the 

 greatest glaciation. These lignites are autochthonous, full of Betula 

 alba, the stems at times vertical and with their roots in the under- 

 lying bowlder clay. 



Heer^^' in his earlier work discussed the Utznach and Diirnten 

 deposits, but dwelt more in detail on the latter as, at that time, it 

 was the better exposed. The lignite is 12 feet thick, rests on clay 

 and underlies about 30 feet of sand and gravel. It is not continuous 

 vertically, but is divided by 6 clay partings, in all about 2 feet. The 

 lowest bench contains much wood together \\ith cones oi Piiius abies, 

 which are not found in the upper benches. In each higher bench, 

 one finds at the bottom, whole layers of mosses, felted together and 

 pierced by reeds, while above are stems, lying in all directions, with 

 roots, barks and fragments of wood, all pressed flat. The annual 

 rings are distinct in many stems and in one Heer counted 100. Some 

 coaled stems were seen, which he thinks may have been charred by 

 lightning. The trunks are surrounded as in peat by a black-brown 

 mass, which undoubtedly originated from decay of herbaceous 

 plants, converting them into a pulp-like mass. This succession is 

 repeated in every branch, but, in the topmost, stems are compara- 

 tively rare, mosses and reeds predominating. 



'"^ A. Heim in letter of ^lay 23, 1911. 



'^' O. Heer. " Die Schieferkohlen von Utznach und Diirnten." Zurich, 

 1858, pp. 7-1 1 ; "The Primeval World of Switzerland," Eng. Trans., London, 

 1876, Vol. L, pp. 29, 30, 32; Vol. IL, pp. 149-155, 157, 161-163. 



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