The work has been aimed at the search for events which are not unlike in dimensions and age to the Noahs Deluge retained in human memory.Long-term field investigations and laboratory works in the Black Sea — Caspian region and its drainage basin within Eastern Europe provided a factual basis for the work.That conflicts with the existing climatic hypothesis of the Khvalynean transgression, attributing the latter to wetter climate.Recently, the Khvalynyan sediments (and the chocolate clays in particular) are considered as "cryo-suspensites" resulting from rapid melting of permafrost and activation of solifluction processes at warmer phases during the Valdai deglaciation (Chystyakova and Lavrushin, 2004).Finally, on the basis of archeological data, an influence of those events on the ancient human life has been studied, and on the old civilizations in particular.
In case the Flood was a real fact of the history, then besides tales and myths, it had to leave certain traces in bottom sediments of the sea, in fossils, landforms, old coastlines, etc.
The level of the latter was 110—120 m below the present-day Caspian level, that is -140 to -150 m.
(Lokhin and Maev, 1990; Maev, 1994; Maev and Chepalyga, 2002).
Thickness of the chocolate clays and related Khvalynean sediments does not usually exceed a few meters (3—5 m), occasionally reaching 20—25 m and more.
They are mostly confined to the Caspian Lowland, from the modern Caspian coast to the feet of bordering elevations (Ergeni, Obshchiy Syrt, Privolzhskaya, Stavropol); they are also found in the Volga and Ural estuaries.