Diluvium
Encyclopedia
Diluvium is a term in geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 for superficial deposits formed by flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...

-like operations of water, and so contrasted with alluvium
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...

 or alluvial deposits formed by slow and steady aqueous agencies. The term was formerly given to the boulder clay
Boulder clay
Boulder clay, in geology, is a deposit of clay, often full of boulders, which is formed in and beneath glaciers and ice-sheets wherever they are found, but is in a special sense the typical deposit of the Glacial Period in northern Europe and North America...

 deposits, supposed to have been caused by the Noachian
Noah
Noah was, according to the Hebrew Bible, the tenth and last of the antediluvian Patriarchs. The biblical story of Noah is contained in chapters 6–9 of the book of Genesis, where he saves his family and representatives of all animals from the flood by constructing an ark...

 deluge.

In the late 20th century Russian geologist Alexei Rudoy proposed the term "diluvium" for description of deposits created as a result of catastrophic outbursts
Glacial lake outburst flood
A glacial lake outburst flood is a type of outburst flood that occurs when the dam containing a glacial lake fails. The dam can consist of glacier ice or a terminal moraine...

 of Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 giant glacier-dammed lakes in intermontane basins of the Altai. The largest of these lakes - Chuya and Kuray, had a volume of water in hundreds of cubic kilometers, and their discharge in peak hydrograph flow rate exceeded the maximum rates of the well-known Pleistocene Lake Missoula in 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...

. The term "diluvium" in the meaning of A. N. Rudoy has become accepted, and the process of diluvial morpholithogenesis can be found in modern textbooks.

Flood deposits of the Altai region

Nearly all intermountain depressions in southern Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

 and northern Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

 hosted glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

-dammed lakes during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 ice ages. Climatic changes and hydrostatic alterations of the ice dams were followed by repeated fillings and releases of the basin lakes. The lake outbursts
Glacial lake outburst flood
A glacial lake outburst flood is a type of outburst flood that occurs when the dam containing a glacial lake fails. The dam can consist of glacier ice or a terminal moraine...

had a cataclysmic character. In accordance with climatic conditions, the glaciers would protrude again into the main drainage valleys immediately after dam deformations and lake outbursts and would again dam the basins.

The greatest of the lakes (Lakes Chuya, Kuray, Uymon, Darkhat and others)
achieved volumes up to hundreds of cubic kilometres, while the discharges of the outburst
floods reached millions of cubic metres per second. These floods transformed the
drainage valleys, repeatedly building new sediment deposits. The dating of the latter proves
the occurrence of large-scale floods in the Chuya and the Katun River valleys in the interval
between 23 and 7 thousand years ago. During that period there were at least five
large-scale flooding events. Enormous water masses were drained simultaneously and repeatedly
towards the south of West Siberia. The total water volume out of the Altai basins
only used to reach 10 thousand cubic kilometres. With some periodicity, all of the
basins of South Siberia were able to deliver northwards about 60 thousand cubic kilometres
of flood waters.
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