Saturday, April 18, 2015

Geology of the Ustyurt


The Ustyurt is a low plateau in the north-westernmost part of the republic. It is located between the Mangyshlak and the Gulf of Kara-Bogaz-Gol on the Caspian Sea in the west, the Aral Sea and Amu Darya delta in the east.

The Ustyurt Plateau is a clay and stony desert with the total area of about 200 000 km². (77,000 square miles), with an average elevation of 150 meters (about 500 feet). It's highest point rises to a maximum of 1,200 feet (365 m) in the southwest. It consist of Sarmatian limestones (See below); its edges are separated from adjacent territories by steep scarps, sometimes by vertical slopes, while the surface is almost even, stony and gypsiferous.

At its edges it drops steeply to the Aral Sea and the surrounding plain. Its most characteristic features is the escarpment known as the Chink', a steep inaccessible slope with the height of about 190 m facing towards the Aral Sea (see picture above).

The dominant landscape is a desert plateau with little no vegetation or water. It once was the bottom of a dried-up sea (Tethys Sea), which existed here in the early and middle Cenozoic Era (some 21 million years ago). This is evidenced by shell traces in the limestone, as well as ferromanganese nodules scattered across the plateau which were formed on the bottom of the sea, and then, as more resistant to weathering, left on the surface while other limestone and dolomites were eroded. In places its flat desert terrain broken by chalk deposits in the form of rocks and random cracks looks like the Martian landscape.

The climate is continental and characterized by the coldest winters in Uzbekistan.(up to – 40 degrees C) , summers scorching (+50 degrees C) with heat searing the landscape with low rainfall. There are no permanent surface watercourses. The soils are brown-brown desert, composite soils. The vegetation consists of Anabasis salsa, Artemisia and Haloxylon. The zone is used as distant pastures. Oil and natural-gas deposits lie to the west of the plateau

The Ustyurt Plateau chalk rocks make an impressive sight at sunrise and sunset, when the white colour of the rocks are translated into shades of purple.

The varied flora and fauna of the Ustyurt. include colonies of gerbils, ground squirrels and jerboas and is home to a large number of birds of prey – eagles and vultures. The most interesting animals of the plateau is the endangered saiga and Ustyurt argali. The plateau’s semi nomadic population raises sheep, goats and camels. Also wild horses roam parts of the Ustyurt. Many plant and animal species living on the plateau are listed in the Red Book. Including the Central Asian tortoise. the sand cat as well as the cheetah, Ustyurt wolf, fox, corsac and jackal. The flora includes different types of polynyas, Anabasis salsa, sarsazan and other medicinal herbs.

NOTE: Sarmatian Stage, major division of Miocene rocks and time (23.7 to 5.3 million years ago). The Sarmatian Stage, which occurs between the Pontian and Tortonian stages, was named for Sarmatia, the ancient homeland of the Sarmatian tribes in what is presently southern European Russia, where important exposures are found. During the Miocene, a number of areas in western Europe became emergent, while sizable areas of eastern Europe were submerged by waters cut off from interchange with the oceans; these isolated, inland seas were freshened by the inflow of streams, resulting in the development of a very distinctive, lagoonal-type fossil fauna represented by peculiar species of clams, gastropods, and bryozoans. These animals were present in great abundance but exhibit little variety; almost no other kinds of animals occur. The bryozoans frequently occur in such local abundance that they form reef like masses. Sarmatian depositional basins fluctuated greatly from extremely salty to brackish.