Sketch of the Thuringerwald. 97 



marine fossils in the same bed is rather a remarkable fact. 

 The remains of fish do not exist every where in the marno- 

 bituminous schist. They occur near Ilmenau in a species of 

 flattened nodules, situated in the middle of the bed; upon 

 clearing the nodules, the two impressions are seen, which 

 are sometimes entirely filled by calcareous spar. 



The well characterised zechstein, of a smoke grey colour, 

 slightly slaty, with a splintery and almost uneven fracture, 

 is generally but few fathoms thick. When It encreases 

 much in mass, it changes its nature, and its upper parts 

 appear as stinkstein, or raulikalk. As soon as it acquires 

 the porous and cavernous texture of (he last variety, it be- 

 comes of enormous thickness, and forms rocks and entire 

 mountains of six hundred feet (English) and upwards in 

 height. It is difficult to assign the constant relations be- 

 tween stinkstein and rauhkalk, which often pass into each 

 other. Yet the latter most frequently covers the stinksteinj 

 the smell of which, sometimes scarcely perceptible, appears 

 owing to sulphuretted hydrogen gas, and not to bitumen. 

 Both the one and the other do not appear (o contain fossils. 

 Many considerable caverns are known in it, among others 

 one situated near Altenstein, from which flows a consider- 

 able stream, not far from Gliicksbruim. 



The red sandstone is sometimes w anting on the south of 

 the Thuringerwald, and the alpine limestone rests imme- 

 diately on granite ; on the north, the superposition of the 

 limestone on the red sandstone, forms altogether a straight 

 line, prolonged without deviation, for many leagues across 

 mountains and valleys. It probably results from this : 

 1. that when the sea deposited this limestone, the shore, 

 formed of red sandstone, was thus cut, it may be said, in a 

 straight line; 2. that at this epoch the present valleys were 

 not formed, or did not descend below the surface of the sea, 

 since the waters would have entered into these valleys, and 

 would have deposited the limestone, in the same manner as 

 the red sandstone and coal formation have been deposited in 

 the first valleys of the primitive rocks ; 3. that the waters 

 under which the red sandstone and coal formations were 



