70 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



Diirnten, where he found about 12 feet of coal resting on marly 

 clay, with freshwater mollusks, and underlying about 30 feet of sand 

 and gravel. The bed is divided by six partings of dark earthy ma- 

 terial unfit for fuel and, in all, about 2 feet thick. The benches of 

 coal are not alike. The lowest contains much wood and cones of 

 Pinus abies, which are wanting in higher parts of the bed. In each 

 of the upper benches, one finds, first, layers of moss felted into dense 

 masses and pierced by reeds, which are followed by trunks lying 

 in all directions, associated with roots, barks and pieces of wood, 

 seldom very thick and always pressed flat. The annual rings are 

 distinct though, at times, they have been distorted by the pressure. 

 Some stems are wholly coaled as if by lightning. The tree trunks, 

 as in peat, are embedded in a brown-black substance, derived un- 

 questionably from herbaceous plants and originally forming a pulpy 

 mass. This succession appears in every bench except the highest, 

 in which reeds and mosses predominate, while stems of trees are 

 comparatively rare. At Unterwetzikon, the lignite rests on marl 

 with freshwater shells. At Utznach, there are two beds of lignite, 

 5 and 3 feet thick, separated by 16 to 20 feet of marly deposits. At 

 Morschwyl, the Schieferkohle, variable in thickness, overlies and 

 underlies marl and has a cover of 26 to 70 feet. It contains vertical 

 stems, which in many cases extend into the overlying marl. 



Heer's study of the plants proved that the resemblance of Schie- 

 ferkohle to peat is complete. The trees are Pimis abies, P. sylvestris 

 and P. montana, which are prostrate — they must have been over- 

 turned and been sunken in the bog. The wood is soft when first 

 removed, but it hardens quickly on exposure ; the bark is commonly 

 present and twigs and branches, retaining the leaves, occur fre- 

 quently. Other trees are yew, larch, white birch and sycamore. The 

 last is represented by a few leaves in the lignitiferous clays. Corylus 

 is not rare ; Menyantlins is represented by abundant seeds and PJi rag- 

 mites abounds in the clay partings with Scirpus; Sphagiinni and 

 three species of Hypnwn were obtained at Diirnten. The Schiefer- 

 kohle and its partings contain abundance of mussels and swamp in- 



pp. 7-1 1 ; "The Primseval World of Switzerland," London, 1876, Vol. I., pp. 

 29, 30; Vol. II., 155, 157, 160-163. 



