Located in Central Asia, the Aral Sea is not a sea, but a huge closed lake. This conclusion was reached by a group of Russian and American scientists who have been researching the Aral Sea since 2008.
Research was carried out under the auspices of the Institute of Geology and Mineralogy named after V. S. Sobolev SB RAS and the University of Arizona since 2008. The interim results were published in 2014 in Gondwana Research, with the most recent publication in Quaternary Science Reviews.
In the course of the work, geologists drilled a number of wells in which the entire layer of lake sediments was exposed. The lithology (composition of the sediments) and microfauna (small and microscopic aquatic organisms with calcium carbonate shells - ostracods and foraminifera) were studied.
This made it possible to conclude that the Aral Sea - in size before the 1970s - appeared about 17.6 thousand years ago. Moreover, the very process of its appearance began earlier - about 18-23 thousand years ago, when the glaciers of the Pamirs and Tien Shan began to melt. The water went down the channels of the Amu-Darya and Syr-Darya rivers and began to gradually fill the basin, in which, as a result, the Aral Sea appeared.
The earliest phase of the development of the Aral Sea (17.6-15.3 thousand years ago) was characterized by a constant and abundant inflow of river waters into the lake basin. About 15.3-14 thousand years ago, the salinity of the water mass increased significantly due to a decrease in the amount of river waters; the peak of salinization falls on 14.5-14 thousand years ago. And about 14-13 thousand years ago, the waters of the lake again became slightly saline.
Since the 1970s, the Aral Sea began to shrink in size, and the process has become truly catastrophic. Research into the causes of what is happening has been going on for many years, but there is still no exact and unambiguous answer.