98 M. DE Hoff's Geologicat 



deposited, were much more elevated than those which after- 

 wards formed the limestone beds. The author draws dif- 

 ferent conclusions from it on the successive formations of 

 valleys ; but confesses that many facts appear to him ine:5- 

 plicable. 



M. de Hoff says that the disposition of the gypsum, sand- 

 stone, and shelly limestone, more recent than alpine lime- 

 stone, and surrounding the Thuringerwald, is known from 

 the writings of M. Voigt. We shall only notice the super- 

 positions made known by a gallery, named Herzog-Ernts- 

 Stollen, pierced into the northern slope of the chain, near 

 Friederichroda, in order to discover the disposition of the 

 beds, and to give occupation to poor miners. 



This gallery is pierced, i, in variegated sandstone (hunter 

 sandstein) very thick beds of which it at first traverses, they 

 contain subordinate beds of clay, which are often six or 

 twelve feet thick. Afterwards occur, 2, four fathoms of a 

 fine grained limestone, disposed iu beds from a few inches 

 to a foot in thickness, with a regular direction towards 

 about NW. by "W. (9 or lOheures), and inclining towards the 

 east. This limestone is of a clear grey, or of a yellowish 

 grey, granular, or almost spathose, often full of small salient 

 points of a darker colour, which appear with a microscope 

 to be spalhose grains, and give the rock the appearance of a 

 fine grained oolite. No fossils are seen in it, and it gives 

 out no smell. It is cut by a nearly horizontal vein of red 

 clay, a foot thick, without the beds being at all shifted ; but 

 on the wall of this vein, the calcareous beds have a spongy 

 exterior, about an inch thick, containing large spathose spots. 

 Beneath this limestone, the gallery traverses; 3dly, a bed of 

 clay ; 4thly, a soft marly limestone of a whitish grey colour; 

 5thly, another clay bed ; 6thly, another bed of grey lime- 

 stone, compact, and a little cellular ; 7thly, clay ; 8thly, a 

 thick gypsum bed, containing cavities, in which superb 

 crystals of selenite have been found half a foot in length. 

 It is only in this place, and near Kittelsthal, that ancient 

 secondary gypsum has been recognised on the north of the 

 Thuringerwald. 9thly, grey clay is aftervvards met with ; 



