sketch of the Thuringerwafd. Q^ 



ttie chain on the west, rising rapidly from beneath the newer 

 secondary formations ; it soon forms entire branches of 

 mountains in the environs of Eisenach. It stretches along 

 the chain, on the Thuringian side, for a considerable dis- 

 tance. It also occurs in many situations on the Franconian 

 side; it especially fills the valleys descending from the 

 primitive chain, and, in two places, even covers, in very thick 

 beds, the summit of this chain. It contains near Tabarr 

 veins of fluor spar, heavy spar, and iron ore. Important iron 

 mines are worked in it near Friederichsrode. The rocks 

 constituting this formation are of very various natures ; 

 sometimes formed of rolled fragments of the size of the head, 

 sometimes their grain is that of the finest sandstone, some- 

 times they altogether resemble sandy or argillaceous schists. 

 The intermediate varieties between these extremes are in- 

 numerable. When the rock does not contain any visible 

 fragments, it is most frequently formed of red or green 

 schistose clay ; this same substance forms the paste else- 

 where enveloping fragments, the nature of which is that of 

 the surrounding primitive rocks. Sometimes it contains, 

 calcareous parts ; it is often a fine sandstone, with parcels of 

 mica, and containing nests or nodules of clay. 



The coal formation of the Thuringerwald appears to be- 

 long, as a subordinate member, to the preceding, to which, 

 according to the author, must be referred the sandstones 

 and schistose clays accompanying the coal, and with which 

 relations always exist, but in a manner difficult to determine. 

 The coal formation occurs only in scattered patches, situated 

 generally at the upper extremity or commencement of narrow 

 valleys, filled by the red sandstone rock. The roof and 

 floor of the coal are commonly of schists and sandstones, 

 with impressions of ferns. At Tenneberg, near Tabarz, the 

 coal is covered by Zechstein, or alpine limestone, a rock 

 between which and the coal formation relations often also 

 exist. 



The alpine limestone occurs in the Thuringerwald, of 

 very variable thickness, and of very different nature. M. 

 de Hoff describes under this name : 1. marno-bituminous 



