Investigations / Epoch of Extremal Inundations

EPOCH of EXTREMAL INUNDATIONS

During the Last Pleistocene Glacial Ponto-Caspian basins lost the connection with ocean and transformed into isolated brackish and demifreshwater basins. In time of Last Glacial deglatiation (17-10 Ka BP) territory of NW Eurasia effected by events of Epoch of Extremal Inundations (EEI) peak of which (17-15 Ka), supposed to be as the Great Flood or biblical Noah’s Flood (Chepalyga 2002, 2003).

Events of EEI held place within four landscapes: marine lowlands (marine transgressions), river valleys (superfloods), watersheds (thermocarst lakes) and slopes (solifluction flows). The space of these events cover of Eurasia territory between Atlantic and Enissey river, Subarctic and Himalayan mountain belt on more 10 mln km².

Cascade of Eurasians basins Landscapes of EEI

This territory was effected by permafrost that time. Marine transgressions of Ponto-Caspian basins forms Cascade of Eurasians basins (CEB) with set of sea-lakes: Aral Sea, Caspian, Black Sea, Sea of Marmara connected by spillways-straits: Uzboy, Manych-Kerch, Bosphorus, Dardanelles.

During Great Flood stage of EEI (17-15 Ka BP) the Khvalynean basin appeared to be an epicenter of Flood events. Its sea level raised on just 200 m., aquatorium space increased 6 times and reach to 1 mln km². Water volume increased two times (up to 130 000 km³), salinity was 10-12‰. It is waters overflow Caspian depression and flew along the Manych-Kerch spillway (900 km long, 10-50 km wide) to the Black Sea depression. Water discharge of this spillway reached 10-50 000 m³/sec.

Cascade of Eurasians Basins. General characteristics of marine-lake basins of CEB are: total aquatorium space — 1 mln 500 000 km², including flooded space — more 1 mln km² , water volume – up to 700 000 km³ , water system of CEB covered the space 3000 km from East to West and 2500 from North to South.

Catastrophic character of events of EEI are: in the peak of Khvalynean transgression sea level raised just 200 m during 100-200 years with rate 1-2 m/year. It is 10 times more then recent catastrophic rising Caspian Sea level at the end of XX c. (2,5 m per 25 years). Coastline migration rate reached 10-20 km/year or 50 m per day. Flooded space increased reach 1mln km², so each year population in Ponto-Caspian basin loosed 10 000 km² the most fertile land (deltas, coastal plains, flood-plains and lower river terraces). It was real catastrophe and stress for population.

Influence of CEB waters on Black-Sea Mediterranean Corridor.

Early Khvalynean basin reconstruction on SRTM by Lavrentiev (2006)

It was quick rising of Black Sea level (New-Euxinean) in time range 17-15 Ka BP on 50-60 m from 100-110 m to level –50-60 m. New-Euxinean sea (present Black Sea) level depends from Khvalynean basin oscillations. Previous Karangation marine basin (present Black Sea) were refreshed by Khvalynean waters and transformed into demifreshwater basin. It is interesting Khvalynean brackish waters with 10-12‰, which spilled in the Black Sea depression appeared to be lower salinity (to 6-8‰) less then Khvalynean basin. The reason of refreshing is influence of river flow of Danube, Dnepr etc. The Azov Sea as a marine basin disappeared that time, its depression transected by Manych-Kerch spillway, filled by Khvalynean waters. Bottom of this spillway was incised into previous sediments up to level –10-20 m asl in Taganrog bay and to –50-60 in Kerch strait.

Human adaptation to Flood events. Marine basins and spillways of EEI especially CEB (Ponto-Caspian) influenced on Early Man migrations. For example: in Kamennaya Balka Late Paleolithic site within 3 cultural layers lower one and upper one contain microlitique tools of Near-East origin. This indicates cultural connections from southern regions (Caucasus, Iraq). But middle culture layer represents by autochthon Kamennaya Balka culture without microlites. Its age (17-15 ka BP) coincides with Manych-Kerch spillway activity and seams to be a barrier for culture connections with Near East this time.

Manych-Kerch spillway was barrier for culture connections

Events of EEI in general strongly effected on Late Paleolithic people, but not in sense of destroying of civilizations. Contrary, under waives of Great Flood events the first elements of productive economy as a base of Earliest civilizations appeared. Flood events of EEI effected inundation of the most productive land and primitive model of feeding (hinter-gathering) become useless. This was multiplied by many refuges from flooded regions (1-2 mln km²). As a result it was increasing of density population and stress on the edge of surviving. The only way to survive was fundamental change of food production strategy: appearance of productive economy (cattle breading, crops and transport). The oldest last one (horse domestication, marine navigation) discovered in Caspian basin (Matyshin 1976, Dzhafar-Zade 1973.)