2O0 NEW YORK STATE MUSEUM 



ance with the observations recently made on the constitution of the waters, 

 the sedimentation and the bionomic conditions in a somewhat similarly 

 inclosed marine body, the Black sea. The important results therefrom 

 obtained by Andrussow ' have been employed by Pompeckj 2 in the interpre- 

 tation of the black deposits and depauperated fossils of the Posidonomya 

 bronni shales (Jurassic) of the vicinity of Regensburg, Bavaria; and it 

 is well that, for the sake of their bearing on the correct significance of the 

 similar bituminous deposits of Portage time, an abbreviated selection from 

 these observations be here given. 



The Black sea has a superficial water layer of about 125 fathoms, of 

 less salinity and density than the water of the depths. The yearly 

 increment of surface water is due in great part to the ingress of fresh water. 

 The heavier deep water is derived from a lower current coming from the 

 Mediterranean by way of the richly saline Marmora and Aegean seas and 

 requires about 1 700 years for its renewal. In consequence of the greater 

 salinity and density of the deep water, the Black sea shows only slight 

 evidence of vertical currents. It is apparent only to a depth of 125 

 fathoms, and only to this depth therefore, is there sufficient O for the 

 support of animal life. The deep water, fed only by the undercurrent, 

 which, on account of the high specific gravity due to its salinity, does not 

 mix with the surface water, has insufficient O for animal life. At a depth 

 of about 100 fathoms the separation of H,S is observable; 33 ccm from 100 

 liters of water. With greater depth the amount of H 2 S rapidly grows ; 

 570 ccm at 500 fathoms ; but farther down the increase is less rapid. The 

 separation of H 2 S is regarded as due to microbes (Sulfobacteria) specially 

 to Bacterium hydrosulfuricum p o n t i c u m, derived from animal 

 remains of the necton and plankton ; and in part also from sulfates. Hand 

 in hand with the separation of and enrichment in H,S is the diminution of 

 sulfates in the sea water, the separation of carbonates and of FeS. . . 



The constant, specifically lighter surface layer over the heavier, richly 

 saline deep water, the lack of O and the separation of H 2 S in the depths, 

 thus condition in the Black sea its peculiar bionomic character, the absence 

 of benthonic animals below the 100 fathom line. In the littoral and shallow 

 water zone benthonic life is present ; in the depths from 35-100 fathoms, 

 the zone of the " Modiola muds," there is, with M o d i o 1 a p h a s e o 1 i n a , 

 a large number of clams and snails. . . 



1 La mer noire : Guide des excursions du 7 Congres geolog. intermit. 1897. no. 29. 



2 Die Jura-Ablagerungen zvv. Regensburg und Regenstauf (Separate from Geognost. 

 Jahresheft. 1901. 14 Jahrgang, p. 43 et set/.) 



