262 SCHUCHERT— BLACK SHALE DEPOSITION. [May 7, 



by the land-derived fishes, while the coaly substance has resulted 

 from the land plants. Along the shores, in the oxygenated waters, 

 there probably also was an abundance of sea- weeds and among them 

 doubtless lived most of the invertebrates preserved in the Kupfer- 

 schiefer. The marine plants are broken up by the storms, and the 

 water currents plus the undertow generated by the waves and tides 

 drag this material into deeper waters, where it is slowly rotted and 

 further altered by the sulphur bacteria. There results a foul bot- 

 tom, free of oxygen, and reeking with carbonic acid and sulphuretted 

 hydrogen gas. The chemical reactions set up here (diagenesis) 

 result in the deposition of the metal sulphides (copper, zinc, silver) 

 and the bituminous alteration products. 



The paleogeography, as stated above, indicates an inland and 

 almost land-locked sea. Into such a basin the currents generated 

 in the oceanic areas can at best enter but little, and that such did 

 not enter in any marked degree is seen in the almost complete ab- 

 sence of floating and swimming invertebrates. As for the general 

 physical conditions, Walther thinks of stagnant waters, with marine 

 swamp's ; Kayser of quiet bays of inland seas with foul bottoms ; and 

 Dosz of stagnant places like the present bays around the island of 

 Oesel, where the bottoms are rich in iron sulphide deposits, the 

 healing or medicinal muds. Pompeckj, however, finds more or less 

 valid objections to all of these suggestions, and thinks the best 

 present analogue to be the Black Sea, whose physical and organic 

 conditions are now well understood through the work of Andrus- 

 sow and Lebedintzew. In other words, the Kupferschiefer sea is 

 " a fossil Black Sea " in nearly all its characteristics except depth. 



With regard to the conditions of the Black Sea, it is an inland, 

 relic sea, which was once a part of the Tethyian mediterranean. 

 Its greatest length is about 715 miles and its maximum width 380 

 miles (making its area 170,000 square miles), and it attains 7,360 

 feet in depth. Flowing into it are many rivers, among the largest 

 of which are the Danube, the Dnieper, and the Don. Its only outlet 

 of surface water is through the strait and over the barrier of the 

 Bosporus into the Sea of Marmora and thence through the strait 

 of Dardanelles into the ^gean Sea and the Mediterranean. A 

 compensating but smaller inflow of salt water (salinity 3 per cent.) 



