This volume covers Leg 42B of the cruises of the Drilling Vessel Glomar Challenger. The Glomar Challenger left its anchorage off Istanbul, Turkey to begin Leg 42B on 21 May 1975 on course for Site 379; she returned on 11 June for a total cruise length just over 20 days, covering a distance of 793 nautical miles. Six holes were drilled at three sites, in water depths ranging from 1750 to 2171 meters. In general the main objectives of the drilling program in the Black Sea were: 1) To obtain as complete as possible a Quaternary lithostratigraphic and biostratigraphic section. 2) To detail the interactions between the Black Sea and the Mediterranean, especially glacio-eustatic sea level changes, periods of lacustrine sedimentation, and periods of stagnation, and to establish a paleoclimatic record. 3) To attempt to reach Neogene deposits. 4) To obtain information on the nature and history of the Black Sea depression. 5) To determine the age, composition, and significance of several strong acoustic reflectors. 6) To study organic diagenetic changes, including the formation of hydrocarbons and the degradation of amino acids, carbohydrates, and porphyrins, and to attempt to observe the beginning of catagenesis in the intermediate depth zone below 500 meters.