Karakum

(Turkmenskie Karakumyi; in Turkmen, Qara Qum, “black sand”), a sandy desert in the south of Soviet Middle Asia occupying much of the Turkmen SSR. On the north and northeast the desert is bounded by the Sarykamysh Depression and the Amu Darya River valley, on the southeast by the Karabil’ and Badkhyz uplands, on the south by the piedmont plain of the Kopetdag, and on the west by the old riverbed called the Zapadnyi Uzboi. Area, around 350, 000 sq km.

The Karakum consists of the northern, elevated Transunguz Karakum, the southern Lowland or central Karakum, and the southeastern Karakum. In its topography the Karakum Desert is a hilly, strongly dissected plain with a general slope from east to west. The Karakum Desert was basically formed by sandy deposits of the ancient course of the Amu Darya, which flowed across this territory into the Caspian Sea. In the south the Karakum is composed of sediments of the Murgab and Tedzhen rivers; their ancient and modern deltas extend through this area. The Karakum is characterized by compacted areas known as takyrs, which have been formed from the clay deposits of ancient rivers and from alluvial floods, and by the solonchak basins known as shory. Around 5 percent of the Karakum is occupied by loose barchan sands virtually devoid of vegetation. They form large areas around the takyrs (alkany), narrow strips along the crests of ridges, and uneven sandy areas around oases. The basic area of the Karakum is semiovergrown sands with a broken-up, predominantly alveolate-ridgy and hummocky zoning. In the west the ridges extend to the southwest along the course of the winds; in the center they extend to the south, and in the east they extend to the southeast. In places there are asymmetrical barchan and semiovergrown chains that are perpendicular to the winds. In the southeastern and central Karakum, which are composed of the ancient alluvium of the Amu Darya, Murgab, and Tedzhen, the height of the sand ridges is from 3–5 to 30 m and the distance between them is 150–200 m. In the Transunguz Karakum, which is basically composed of clay-sand deposits of the Miocene and Pliocene paleo–Amu Darya, the ridges are up to 40–60 m high with an average distance of 0.5 km between them. Along the boundary of the Lowland and Transunguz Karakum runs the Unguz, a chain of isolated solonchak basins of various levels. In the west some of these were flooded by Pliocene seas, and others at times were filled with sandy debris of the paleo’Amu Darya.

The Transunguz Karakum is an Epihercynian platform with a Mesocenozoic mantle made up of a series of branching anticlinal structures, downwarped in the north (the Khorezm Depression in the lower courses of the Amu Darya) and subsiding along the flexure of the Unguz to the south. The topography has not retained its previous alluvial features and as a whole has been formed by neotectonics and aeolian processes.

The Lowland Karakum is a foredeep-type formation with an Epipaleozoic cover up to 12 km thick. The overlying Anthropogenic river deposits have basically maintained the topographic features of the delta fans of the Murgab and Tedzhen and of the plain of the paleo-Amu Darya, which extends transversely to the deltas. The thickness of the Anthropogenic alluvium varies from 500 m in the southeastern Karakum to 5, 000 m and more in the west. The Amu Darya left the Lowland Karakum at the end of the Anthropogenic period (approximately 20, 000–30, 000 years ago). When the Khvalys’ Sea (around 15, 000–20, 000 years ago) formed a vast bay in the Lowland Karakum with a level of + 50 m absolute elevation, its waters were salty, since the Amu Darya was diverted into the Khorezm Depression. Here it formed a lake from which it began to flow initially to the north (the Akchadar’ia Channel) and later to the west into the Saryka-mysh Depression. Having filled it, the Amu Darya in the fifth to the second millennia B.C. again began to flow into the Caspian, having formed the Zapadnyi Uzboi River.

The climate of the Karakum is sharply continental, with a very hot, cloudless, and protracted summer, a mild spring with rains, a warm dry autumn, and a winter that is frosty but with frequent thaws. The mean January temperature in the north is around −5°C and, in the south, about 3°C; the mean July temperatures are 28° and 34°C, respectively. There are very high daily temperature variations (up to 50°C for the air and up to 80°C for the soil). Precipitation is from 60 to 150 mm per year (more in the south). Up to 70 percent of the precipitation falls from November to April. The growing season is 200–270 days. The Amu Darya flows along the northeastern edge of the Karakum; the Tedzhen and Murgab run out in the sands without reaching a lake or sea. The Karakum is rich in groundwater, which lies at varying depths: from 3–6 m near the Amu Darya (the basic source of all the Karakum underground water) to 300 m on the Karabil’ Uplands. The groundwater is recovered by wells. In those areas where river waters seep through to it, the groundwater is slightly saline, but in the central portions of the Karakum it is highly mineralized.

The Karakum soils on the overgrown sands are of the gray-brown type and are shallow; in the depressions are solonchaks and takyrs. In the spring, the entire territory of the Karakum, with the exception of the barchan sands, is covered with a green carpet of ephemerals and ephemeroids that die out in late April and early May. Typical is sand sedge (ilak, the basic feed for sheep) and brush, including the black and white saxauls, kandym [Calligonium ], the sand acacia, ephedra, and Astragalus. Those barchan sands that are overgrown are characterized by Aristida grass, sand acacia, one or two species of Calligonium, and the arboreal saltwort, or cherkez [Salsola richteri]. The typical animals are the Persian gazelle, the corsac, the wolf, the sand cat, and the steppe cat; rodents are particularly numerous. Of the birds, there are the saxaul jay, numerous larks, the desert raven, and sparrows. The characteristic reptiles are snakes (including the carpet viper, Taphrometoron lineolatum, the sand snake, and the cobra), lizards (the agama, geckos, and the monitor, which can be up to 1.5 m long), and the Horsfield’s terrapin. Tarantulas and scorpions are common. Much of the desert is used as year-round pasture for sheep and camels. Minerals include sulfur, oil, and gas.

Human habitation is concentrated predominantly in the oases formed by the Amu Darya, Tedzhen, and Murgab rivers and by the small rivers flowing off the northern slopes of the Kopetdag. During the years of Soviet power, large livestock sovkhozes have been created in the Karakum, more than 6, 000 wells have been reconstructed or dug, dirt roads have been built, the Chardzhou-Kungrad railroad has been constructed along the northeastern edge of the desert, and motor transport has come into wide use. Air connections have also been developed. In the southern part of the Karakum, the Karakum Canal has been built, contributing to both irrigation and navigation. The Middle Asia-Center Gas Pipeline passes across the Karakum.

The development prospects of the Karakum are linked with a rapid growth in the exploitation of the very rich oil and gas deposits and with the further development of mechanized irrigation and cotton growing, particularly in the zone of the Karakum Canal; a further rise in livestock raising is also envisioned. Extensive work is being done on reforestation, on stabilization of the drifting sands, and on plant improvement of the pastures. In the southeastern Karakum lies the world’s oldest center for the study of sand, the Repetek Sand Research Station of the Academy of Sciences of the Turkmen SSR.