I9II.] STEVEXSOX— FORMATION OF COAL BEDS. 585 



surfaces. This is clearly the younger stage of dopplerite referred 

 to by Friih. 



The Schieferkohle, studied in detail by both v. Giimbel and Friih, 

 is a Quaternary deposit observed at several places in Switzerland. 

 It will be described on a succeeding page. v. Giimbel's"^ type speci- 

 mens come from Alorschwyl, but he studiefl also specimens from 

 other localities. The mass is partly loose, like peat, partly dense, 

 like pitch coal, containing remains of conifers, birches, etc. It is 

 undeniably peat-like in the less dense portions, where one can recog- 

 nize mosses and grasses as the predominating constituents. The 

 denser portions are changed by caustic potash into an opaque mass. 

 The microscope shows great quantity of deep brown shell-like 

 splinters of an amorphous textureless substance, which acts as dop- 

 plerite. In many parts of plants, the same dark brown material fills 

 the cell spaces. He thinks it not doubtful that the denser condition 

 of this portion of the coal comes from richer accunuilatif)n of the 

 amorphous filling material, which he terms Carbohumin. This 

 Schieferkohle contains vast numbers of pine cones, not deformed, 

 and of flattened pieces of wood. In many of the latter, he found an 

 inner woody zone, composed of a soft yellow substance, like rotten 

 wood, while the bark zone had been changed into a shining pitch coal. 



Friih, ^- after studying Schieferkohle from many localities, con- 

 firmed the view of Heer, Kaufmann and others that the deposits 

 agree with peat in microscopic character. They are peats more 

 strongly ulminified. He often found the interior of rootlets appar- 

 ently little changed, but after a few minutes exposure, they began 

 to change and at length became brown like the Marmortorf. With 

 regard to the wood fragments, he thinks that the outer portion was 

 ulminified early, perhaps before the bog was covered with drift, 

 whereas the inner portion was merely peated. At the same time he 

 does not recognize dopplerite in the Schieferkohle. 



It is sufficiently evident that the dift'erence between Friih and 

 the other observers is merely respecting nomenclature. There is 

 agreement on all matters which concern the questions at issue here. 



"' V. Gi'tnihel, op. cit.. pp. 136, 137. 



■'^J. J. Friili, flp. cit.. pp. 83, 84. . . 



183 



