Geology of the Harz Mountains. 223 



Camarophoria Schlotheimi (Buch.), Strophalosia Goldfussi 

 (Miinst.), etc. 



It is the Gypsum of the Middle Zechstein (older gypsum) 

 that forms the white cliffs at Osterode. In the Mansfeld 

 district it occurs lenticularly, and has been passed through 

 in the various shafts sunk to the Kupferschiefer, but thins 

 out and does not make much appearance towards the edge 

 of the basin at the outcrop of the seam. Wherever the 

 gypsum occurs, subsidences of the surface take place, from 

 the falling in of subterranean cavities where the gypsum or 

 the local rocksalt beds it contains have been dissolved away 

 by percolating water. Many such cavities have been struck 

 in the Mansfeld shale workings. 



The so-called "Eauchwacke" is supposed to have been pro- 

 duced by the expansion accompanying the hydration of the 

 anhydrite. The increasing volume of the gypsum thus formed 

 would shatter the overlying dolomite, and convert it into the 

 brecciated, porous mass, called by the Mansfeld miners 

 " Eauh- " or " Eauchwacke," from its rough feeling to the 

 touch. The Eauchwacke has a thickness of from 6 to 65 

 feet, and contains the following fossils : Mytilus Hausmanni 

 (Goldf.), Gervillia ceratophaga (Schl.), Schizodus obscurtcs 

 (Sow.), etc. 



The great masses of Eocksalt, which occur along with the 

 anhydrite and gypsum, reach an enormous development at 

 Stassfurt and Schonebeck, and have recently been found to 

 exist in workable quantities at Aschersleben, near the eastern 

 end of the Harz, and at Vienenburg, a village opposite the 

 base of the mountains at Harzburg. The bottom of the 

 great salt bed at Stassfurt has not yet been reached, but 

 borings have proved it to have a thickness of at least 1600 

 feet (490m.).i 



/. Trias. 



It is not my intention to do more than give a general 

 glance over the Secondary rocks, as they are more interesting 

 to the palaeontologist than to the geologist, and do not differ 



1 See H. M. Cadell on ''Tlie Salt Deposits of Stassfurt" (Trans. Edinb. 

 Geol. Soc, vol. v., 1884). 



