222 Proceedings of the Boyal Physical Society. 



of imposing escarpment facing the mountains, and remind 

 the spectator of the white chalk-cliffs that girdle the southern 

 shores of Britain. 



The Zechstein is here divisible into three lithological groups : 



i Developed at Mansfeld, and along south, border of the Harz. 

 .0 \ Tj ) 8. Tough brown or blue clays, alternating with thin beds of 



\ •) Ppsr, \ yellowish limestone and dolomite. 



( 7. Gypsum without anhydrite (younger gypsum). 



{Developed all round the Harz. 

 6, Dolomite, foetid limestone, and shale. 

 5. Dolomite, granular and sandy (Asche), and porous and coarse 

 (Rauchwacke). 

 4. Anhydrite and gypsum, with rocksalt beds (older gypsum). 



[ 3. Zechstein. '\ 



(-, \ T 12. Kupferschiefer. f Always occur 



[l.) Liower, < ^ Zechstein conglomerate ("Weisslie- T together. 



( gendes) resting on Eothliegendes. ) 



The so-called " Weissliegendes " (white layer) or Zechstein 

 conglomerate occurs in the Mansfeld district conformably 

 on the top of the Eothliegendes; but at Ilfeld and other 

 places a discordance has been observed between the two 

 groups. It is a greyish conglomerate, with pebbles of decom- 

 posed greywacke, kieselschiefer, and quartz in a calcareous 

 matrix. Pebbles of the volcanic rocks of the Eothliegendes 

 do not occur in this bed. It occurs along the southern border 

 of the Harz and on the Kyffhauser, and has a thickness of 

 from 3 to 6 feet. In the Mansfeld district between Eisleben 

 and Hettstedt it is represented by a bed of coarse grey 

 round -grained sandstone, 1 inch to 6^ feet in thickness. 



The Kupferschiefer seam will be described under the 

 Metalliferous Deposits of the Harz. 



The Zechstein proper is a compact, yellowish or greyish 

 argillaceous limestone, with flat conchoidal fracture, and is 

 the most persistent of all the beds accompanying the seam. 

 It is usually in this district 15 to 35 feet thick, and is well 

 seen in the Mansfeld shale workings. In the lower portion 

 of the Zechstein, Produdus horridus (Sow.) and Spirifer 

 undulatus (Sow.) are the characteristic brachiopods. Higher 

 up come Fenestella retiformis (Schloth.), Schizodus obscurus 

 (Sow.), Gervillia ceratojphaga (Schl.), Avicula speluncaria 

 (Schl.), Pecten pusillus (Schl.), Terehratula elongata (Schl.), 



