Karakum Desert
The Karakum Desert, also spelled Kara-Kum and Gara-Gum (, ; ), is a desert in Central Asia. Its name in Turkic languages means "black sand": "kum" means sand; "kara" is a contraction of : "dark" or may pre-date that (be a derivation from a likely broader meaning which the word for black bore: ) in this language family. This refers to the shale-rich sand generally beneath the sand of much of the desert. It occupies about 70 percent, 350,000 km, of Turkmenistan. The population is sparse, with an average of one person per 6.5 km (2.5 square miles). Rainfall  is also rare, ranging from 70 to 150 mm per year. Geography. The desert covers roughly seventy percent of Turkmenistan, a long east–west swath. It sits east of the Caspian Sea which has a steep east bank. It adjoins, to north, the long delta feeding the South Aral Sea further north, another endorheic lake, about 58 metres higher than the Caspian Sea. The delta is that of the Amu Dar'ya river to the northeast demarcating the long border with the Kyzyl Kum desert, of Uzbekistan. The desert is divided into three regions, the eleveated northern Trans-Unguz Karakum, the  low-lying Central Karakum, and the southeastern Karakum, home to a chain of salt marshes. In decades since the early 1980s, the relatively small desert extension the "Aral Karakum" occupies most of the former seabed of the Aral Sea, about 15,440 sq mi/40,000 km. The sea has fluctuated over millennia. Its majority loss during Soviet Union existence coinciding with great irrigation projects. The North Aral Sea was restoring to a status in 2009 but the South Aral Sea ebbed to a small-size stasis at its river mouth. Within the north-west edge of the desert used to be a  river. In the late Pleistocene, the Amu Dar'ya used to flow beyond the Aral Basin to Sarykamysh Lake then to the Caspian Sea. Sedimentation and floods during a pluvial period led to overflow to the Zeravshan River valley to the east. The two flows merged and formed or expanded Horezm Lake, which had been formed by the earlier Khvalinian period, and as it overflowed northwards it carved its link with the Aral Sea along the Akcha Dar'ya population corridor of that low, gentle valley (a remote community of Western Uzbekistan and north-east Turkmenistan). Environment. The sands of the Aral  Karakum are made of finely-dispersed evaporites and remnants of alkaline mineral deposits, washed into the basin from irrigated fields. Wildlife. Wildlife in this area is not very diverse and includes insects such as ants, termites, ticks, spiders, dung beetles, and darkling beetles. Lizards, turtles, and snakes also live in the Karakum. Bird species include alauda, desert sparrows, and other species, while rodents include jerboas and gophers. The tolai hare, goitered gazelle, corsac fox are examples of mammal species in the Karakum Desert. Geology. The Karakum Desert is home to the Darvaza Gas Crater. Also called the "Door to Hell  or the Gates of Hell" by locals, it is a crater of natural gas that has been burning since 1971. The crater is a major tourist attraction, with hundreds of visitors arriving each year. The area has significant oil and natural gas deposits. Hydrography. To the south the Murghab and Tejen rivers flow out of the Hindu Kush Mountains, flow west, and empty into the desert, providing water for irrigation. The desert is crossed by the second largest irrigation canal in the world, the Karakum Canal, which brings water from the Amu Darya to southern regions of the desert. Construction  on the canal was started in 1954 and completed in 1958. It is 1,375 km in length, and carries 13-20 km³ of water annually. Archaeology. Within the Karakum are the Uly Balkan, a mountain range in which archaeologists have found human remains dating back to the Stone Age. Economy and resources. The oases of Mary and Tejen are noted for cotton growing. Transport. The desert is crossed by the Trans-Caspian Railway.