Epoch of Extremal Inundations
Encyclopedia
The Epoch of Extremal Inundations is the unique nature event in the past. This theory is about wide inundations in the Ponto-Caspian basins which have been associated not only with well-known marine transgression
s but also with four landscapes: marine lowlands (marine transgressions), river valleys (superfloods), transgression
s (thermocarst lakes) and slopes (solifluction
flows). Events of Epoch of Extremal Inundations had catastrophic character and influenced on the ancient human life.
) was formulated the theory of Epoch of Extremal Inundations (EEI) - the unique nature events in the past. Long-term field investigations and laboratory works provided a factual basis for the theory. On the basis of archaeological data was studied the influence of this event on the ancient human life.
At the first stage, was searched for extreme hydro-climatic events through the last 18-20 thousand years, first of all, for most striking ones, such as marine Pontian in the endemic and Caspian basins
; the attention was focussed on possible sources of water for events, such as overfloods in river valleys and relict permafrost thawing on watersheds.
The second stage included chronocorrelation of the events using stratigraphic and geomorphologic facts, and available radiocarbon dates. That was followed by paleohydrological reconstructions of the basins, including their level, areas, water mass volumes and water exchange between the basins.
Finally, on the basis of archeological data, an influence of those events on the ancient human life has been studied. The final aim of the investigation was to develop a comprehensive concept of the Epoch of Extremal Inundations.
deglatiation (17-10 Ka BP) the territory of North-West Eurasia
effected by wide inundations. The space of these flooded area cover of Eurasia
territory between Atlantic
and Enisei river, Subarctic and Himalayan mountain belt on more 10 mln km². Inundations held place within four landscape
s: marine lowlands, river valleys, watersheds and slopes. The peak of inundations was 17-15 Ka BP.
, bottom sediments attributable to this event are dated to the Khvalynean basin (recent Caspian Sea
). They differ from under- and overlying layers in many characteristics. Typically, they are so called "chocolate clays" (because of their specific reddish brown color). 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.
the Khvalynean layers occur above the Late Khazarian ones (dated to the last interglacial) and below the New Caspian (Holocene) deposits. They are separated from the Lower Khazarian series by continental Atelian layers synchronous to marine sediments of the Atelian regressive basin. The level of the latter was 110–120 m below the present-day Caspian level, that is -140 to -150 m. On the Caspian Lowland the Khvalynean sediments occur mostly close to the surface. Younger (and higher in the sequence) are only the Holocene
floodplain lacustrine and marine (New Caspian) sediments.
The EEI deposits in the Black Sea
basin occur within the New Euxinian series. On the continental slope and within the deep-sea basin they are light reddish-brown and pale yellow mud about 0.5—1.0 m thick. In color they are not unlike the chocolate clays of the Caspian basin, their age is also close to the latter (15 ka). They had been identified (by the A. Chepalyga, together with W. Ryan
) in the core 1 (section 3) of the DSDP hole 380 (drilled north of the Bosphorus Strait) within 384–450 cm depth interval.
Gastropods are usually represented by Caspian endemic genera Caspia and Micromelania. Shells of the Early Khvalynean complex are distinct for small size (2—3 times smaller than those of today) and thin walls. The complex is usually considered as a product of cold climate and low salinity. New Euxinian sediments contain mollusk fauna of the Caspian type.
, Caspian
, Black Sea
, Sea of Marmara connected by spillways-straits: Uzboy
, Manych-Kerch, Bosphorus, Dardanelles
. Parameters of this superbasin were as follows: area — about 1.5 million km²; water volume — up to 700 thousand km³; salt resource —5000 km³, or 10 billion tons; water discharge — more than 60 thousand m³ per second; extension of the system from west to east — 3000 km (from the Mediterranean to Central Asia
), extension of the system from north to south — 2500 km (from 57 to 35°N); drainage basin area — more than 3 million km³.
The Eurasian cascade system of seas and lakes is unparalleled in water area. The largest intracontinental lake system of today — the Great Lakes
of North America
— ranks below it in all the parameters: its area is 6 times smaller (245,000 km²), water volume — 30 times smaller (22,700 km³), discharge — more than 4 times less (14 thousand m³/s), and drainage basin area — about 3 times less.
During the peak of inundations the Khvalynean basin (recent Caspian Sea
) appeared to be an epicenter of inundations. 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.
The water for all the processes could be supplied from various sources, namely:
The superflood phenomenon has been first inferred from studies of macromeanders in river valleys. The macromeanders dated to the Flood epoch exceeded considerably the modern ones in dimensions; their width tends to increase from north to south: they are similar to the modern meanders in tundra zone, 2 or 3 times greater in forest-tundra, 3 to 5 times in taiga, 5 to 8 times in mixed forests zone, 10 times in broadleaf zone, and 13 times in the forest-steppe and steppe. No superflood effect has been noted within the recent permafrost area. Accordingly, annual runoff values calculated from the macromeander dimensions is also above the modern runoff (twice the modern value for the Volga R., thrice for the Kama R., and almost 4 times for the Don R.
As for the recent rise of the Caspian Sea, it amounted to 2,5 m since 1978, the rate thus being as high as 10 cm per year. Yet it had a considerable adverse effect on the human activities. Therefore, the Khvalynean transgression was all the more catastrophic, especially when considering the rate of the coastline shifts over the plains of the North Caspian region. The coastline migrated from the Atelian coast (near the Mangyshlak sill) northwards by 1000 km, that is about 5 to 10 km yearly. That would be quite appreciable for the coast dwellers. Even greater was the rate of the northward migration of the Volga River
mouth. It shifted upstream by more than 2000 km within 150–200 years, that is at a rate more than 10 km per year (about 30 m per day).
Later was confirmed this conclusion. In Kamennaya Balka Late Paleolithic
site in Russia
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.
Events of Epoch of Extremal Inundations in general strongly effected on ancient people, but not in sense of destroying of civilizations.
Transgression (geology)
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the land sinking or the ocean basins filling with water...
s but also with four landscapes: marine lowlands (marine transgressions), river valleys (superfloods), transgression
Transgression (geology)
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the land sinking or the ocean basins filling with water...
s (thermocarst lakes) and slopes (solifluction
Solifluction
In geology, solifluction, also known as soil fluction, is a type of mass wasting where waterlogged sediment moves slowly downslope, over impermeable material. It occurs in periglacial environments where melting during the warm season leads to water saturation in the thawed surface material ,...
flows). Events of Epoch of Extremal Inundations had catastrophic character and influenced on the ancient human life.
History of investigation
In 2002 by Russian geographer Andrey L. Chepalyga (Institute of Geography RASRussian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....
) was formulated the theory of Epoch of Extremal Inundations (EEI) - the unique nature events in the past. Long-term field investigations and laboratory works provided a factual basis for the theory. On the basis of archaeological data was studied the influence of this event on the ancient human life.
At the first stage, was searched for extreme hydro-climatic events through the last 18-20 thousand years, first of all, for most striking ones, such as marine Pontian in the endemic and Caspian basins
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
; the attention was focussed on possible sources of water for events, such as overfloods in river valleys and relict permafrost thawing on watersheds.
The second stage included chronocorrelation of the events using stratigraphic and geomorphologic facts, and available radiocarbon dates. That was followed by paleohydrological reconstructions of the basins, including their level, areas, water mass volumes and water exchange between the basins.
Finally, on the basis of archeological data, an influence of those events on the ancient human life has been studied. The final aim of the investigation was to develop a comprehensive concept of the Epoch of Extremal Inundations.
Time and place
In time of Last GlacialLast Glacial Maximum
The Last Glacial Maximum refers to a period in the Earth's climate history when ice sheets were at their maximum extension, between 26,500 and 19,000–20,000 years ago, marking the peak of the last glacial period. During this time, vast ice sheets covered much of North America, northern Europe and...
deglatiation (17-10 Ka BP) the territory of North-West Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
effected by wide inundations. The space of these flooded area cover of Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
territory between Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and Enisei river, Subarctic and Himalayan mountain belt on more 10 mln km². Inundations held place within four landscape
Landscape
Landscape comprises the visible features of an area of land, including the physical elements of landforms such as mountains, hills, water bodies such as rivers, lakes, ponds and the sea, living elements of land cover including indigenous vegetation, human elements including different forms of...
s: marine lowlands, river valleys, watersheds and slopes. The peak of inundations was 17-15 Ka BP.
Geology
Bottom and littoral sediments of the basins, together with fossils they contain, may be considered as geological evidence of the EEI. In the epicenter of the EEI, that is within the Caspian basinCaspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
, bottom sediments attributable to this event are dated to the Khvalynean basin (recent Caspian Sea
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
). They differ from under- and overlying layers in many characteristics. Typically, they are so called "chocolate clays" (because of their specific reddish brown color). 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.
Stratigraphy
In the marine sequence of the Caspian basinCaspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
the Khvalynean layers occur above the Late Khazarian ones (dated to the last interglacial) and below the New Caspian (Holocene) deposits. They are separated from the Lower Khazarian series by continental Atelian layers synchronous to marine sediments of the Atelian regressive basin. The level of the latter was 110–120 m below the present-day Caspian level, that is -140 to -150 m. On the Caspian Lowland the Khvalynean sediments occur mostly close to the surface. Younger (and higher in the sequence) are only the Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
floodplain lacustrine and marine (New Caspian) sediments.
The EEI deposits in the Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
basin occur within the New Euxinian series. On the continental slope and within the deep-sea basin they are light reddish-brown and pale yellow mud about 0.5—1.0 m thick. In color they are not unlike the chocolate clays of the Caspian basin, their age is also close to the latter (15 ka). They had been identified (by the A. Chepalyga, together with W. Ryan
Black Sea deluge theory
The Black Sea deluge is a hypothesized catastrophic rise in the level of the Black Sea circa 5600 BC due to waters from the Mediterranean Sea breaching a sill in the Bosporus Strait. The hypothesis made headlines when The New York Times published it in December 1996, shortly before it was published...
) in the core 1 (section 3) of the DSDP hole 380 (drilled north of the Bosphorus Strait) within 384–450 cm depth interval.
Fossils
The main indicators of the EEI are specific brackish-water mollusk species close to modern North Caspian ones. Among those, there are Caspian endemic species belonging to Limnocardiidae family, such as Didacna Eichwald genus. The latter is not found at present anywhere outside the Caspian Sea, while it occurred widely in the Azov—Black Sea basin during the Pleistocene, up to the Karangatian time.Gastropods are usually represented by Caspian endemic genera Caspia and Micromelania. Shells of the Early Khvalynean complex are distinct for small size (2—3 times smaller than those of today) and thin walls. The complex is usually considered as a product of cold climate and low salinity. New Euxinian sediments contain mollusk fauna of the Caspian type.
Marine basins and spillways
Thenadays marine transgressions of Black-Caspian basins formed Cascade of Eurasians basins with set of sea-lakes: Aral SeaAral Sea
The Aral Sea was a lake that lay between Kazakhstan in the north and Karakalpakstan, an autonomous region of Uzbekistan, in the south...
, Caspian
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
, Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
, Sea of Marmara connected by spillways-straits: Uzboy
Uzboi Vallis
Uzboi Vallis is a valley on Mars. It is named after a dry river valley in USSR, now in Turkmenistan.The valley begins on the northern rim of the Argyre basin, and cuts through several craters, before ending at Holden crater....
, Manych-Kerch, Bosphorus, Dardanelles
Dardanelles
The Dardanelles , formerly known as the Hellespont, is a narrow strait in northwestern Turkey connecting the Aegean Sea to the Sea of Marmara. It is one of the Turkish Straits, along with its counterpart the Bosphorus. It is located at approximately...
. Parameters of this superbasin were as follows: area — about 1.5 million km²; water volume — up to 700 thousand km³; salt resource —5000 km³, or 10 billion tons; water discharge — more than 60 thousand m³ per second; extension of the system from west to east — 3000 km (from the Mediterranean to Central Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
), extension of the system from north to south — 2500 km (from 57 to 35°N); drainage basin area — more than 3 million km³.
The Eurasian cascade system of seas and lakes is unparalleled in water area. The largest intracontinental lake system of today — the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
— ranks below it in all the parameters: its area is 6 times smaller (245,000 km²), water volume — 30 times smaller (22,700 km³), discharge — more than 4 times less (14 thousand m³/s), and drainage basin area — about 3 times less.
During the peak of inundations the Khvalynean basin (recent Caspian Sea
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
) appeared to be an epicenter of inundations. 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
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
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.
Sources of water
To provide water for the EEI events, there must have been some additional sources. To fill the Caspian basin to a level of +50 m, it would take as much as 70,000 km³ of water, that is equal to 200 year river discharge to the Caspian. Besides, some water flowed through the Manych Spillway 250 to 1000 km³ per year, and some was lost through evaporation from the water surface (>100 km³ per year).The water for all the processes could be supplied from various sources, namely:
- superfloods in river valleys;
- permafrost melting;
- higher runoff coefficient under conditions of permafrost;
- increased catchment area (including Central Asia area, closed at present);
- lower evaporation from the water surface (due to ice cover in winter).
The superflood phenomenon has been first inferred from studies of macromeanders in river valleys. The macromeanders dated to the Flood epoch exceeded considerably the modern ones in dimensions; their width tends to increase from north to south: they are similar to the modern meanders in tundra zone, 2 or 3 times greater in forest-tundra, 3 to 5 times in taiga, 5 to 8 times in mixed forests zone, 10 times in broadleaf zone, and 13 times in the forest-steppe and steppe. No superflood effect has been noted within the recent permafrost area. Accordingly, annual runoff values calculated from the macromeander dimensions is also above the modern runoff (twice the modern value for the Volga R., thrice for the Kama R., and almost 4 times for the Don R.
Catastrophe
Catastrophic character of events of EEI. The rate of water level rise may be inferred from duration of the whole cycle estimated at 500–600 years. Assuming an equal duration of the phases of rising, high stand and lowering to be of (about 150–200 years each), the sea level would rise by 180–190 m at a rate of at least 1 m per year.As for the recent rise of the Caspian Sea, it amounted to 2,5 m since 1978, the rate thus being as high as 10 cm per year. Yet it had a considerable adverse effect on the human activities. Therefore, the Khvalynean transgression was all the more catastrophic, especially when considering the rate of the coastline shifts over the plains of the North Caspian region. The coastline migrated from the Atelian coast (near the Mangyshlak sill) northwards by 1000 km, that is about 5 to 10 km yearly. That would be quite appreciable for the coast dwellers. Even greater was the rate of the northward migration of the Volga River
Volga River
The Volga is the largest river in Europe in terms of length, discharge, and watershed. It flows through central Russia, and is widely viewed as the national river of Russia. Out of the twenty largest cities of Russia, eleven, including the capital Moscow, are situated in the Volga's drainage...
mouth. It shifted upstream by more than 2000 km within 150–200 years, that is at a rate more than 10 km per year (about 30 m per day).
Influence on the early man
Marine basins and spillways of the event influenced on Early Man migrations. P.M. Dolukhanov from School of Historical Studies, Newcastle University, UK concluded that Caspian-Black Sea spillway across the Kumo-Manych Valley, effectively isolated the Caucasian-Central-Asian area. The spread of Upper Palaeolithic technology in that area became possible only after the maximum of the Upper Khvalynian transgression, 12.5-12 ka BP.Later was confirmed this conclusion. In Kamennaya Balka Late Paleolithic
Paleolithic
The Paleolithic Age, Era or Period, is a prehistoric period of human history distinguished by the development of the most primitive stone tools discovered , and covers roughly 99% of human technological prehistory...
site in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
within 3 cultural layers lower one and upper one contain microlitique tools of Near-East origin. This indicates cultural connections from southern regions (Caucasus
Caucasus
The Caucasus, also Caucas or Caucasia , is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea...
, Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....
). 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.
Events of Epoch of Extremal Inundations in general strongly effected on ancient people, but not in sense of destroying of civilizations.