I91S.] SCHUCHERT— BLACK SHALE DEPOSITION. 267 



continental shelf seas, i. e., less than 600 feet. The freshwater 

 covering Pompeckj thinks was thin. 



Just as in the Black Sea the marginal fresh waters are deposit- 

 ing sands and other littoral sediments that are free of bitumen, so 

 in the Kupferschiefer sea there is some evidence of marginal sands, 

 sandy and clayey limestones, and regions free of metal sulphides. 



Later, the black sea of Permian time gradually changed, first 

 locally and finally everywhere, into the limestone-dolomite or Zech- 

 stein sea, still, however, an inland sea but devoid of muds and 

 bituminous materials. In the shallow regions nearer the shores 

 arose reefs of bryozoa, but at best the Zechstein sea, even when in 

 widest connection with the ocean, had a small and monotonous 

 fauna. 



In an earlier paper Pompeckj^ discusses a similar deposit, the 

 zone of Posidonomya bronni of the Upper Lias of Germany. It 

 seems desirable to cite also some of the details given in this paper, 

 because they are somewhat different from those concerning the 

 Permian. The deposits are fissile, calcareous, bituminous, dark 

 shales rich in iron pyrite. Locally there are also horizons of sand- 

 stone, barren of life, and layers of stinking limestone. These de- 

 posits are found in northwestern Germany (about 40 feet thick) 

 and France. 



In Germany (Swabia and Franconia) the fossils consist of 

 diatoms and coccoliths, horn sponges, very rarely a sea-urchin, 

 crinids (sometimes with stalks over 50 feet long), a few forms of 

 brachiopods, about 18 species of bivalves (of which the only com- 

 mon one is Posidonomya bronni, but this very thin-shelled form 

 is at times exceedingly abundant ; also Pseudomonotis substriata, Ino- 

 ceramiis dubius, Pecten contrarius), and rarely a gastropod or crus- 

 tacean (Eryon). Besides the common bivalves mentioned, there 

 are many ammonids, belemnids, sepias, fishes (selachians, many 

 ganoids, teleosts), ichthyosaurs, plesiosaurs, and crocodiles. With 

 the marine forms are associated drifted land plants (cycads, and 

 often a great abundance of conifer logs, now carbonized), beetles, 

 and dragons of the air (pterosaurs). 



5 " Die Jura-Ablagerungen zwischen Regensburg u. Regenstauf," Geog-- 

 nos. Jahresheften 1901, XIV. Jahrg., pp. 178-186. 



