The Lower Amudarya natural-geographic district

The Lower Amudarya district includes the ancient and the present deltas of the Amudarya. It borders Ustyurt in the west, Turkmenistan in the south-west, Kyzylkum in the east and the Aral district in the north; its area is about 50 thousand km². It stretches about 400 km from the Tuyamuyun gorge in the south-east to the Aral, widening and falling from south-east to north-west. After the Tuyamuyun gorge its width is 10–12 km at about 150 m; then the ancient delta begins and widens to 75–80 km, and beyond Takhiatash the present delta widens to 140–150 km and falls to 60–95 m. Because the surface is flat, the Amudarya meandered, split into branches and left many channels: on the right bank towards the Aral the Kara Uzak, Shertanbay and Kindiksay; on the left bank towards Sarykamysh the Kuhnadarya, Daryalyk and Davdan. Between the channels stand hills and residual mountains 60–80 m high, such as Kuyonchik, Karatau, Jumirtau and Barlitau. The base is Cretaceous rock covered by Paleogene, Neogene and Quaternary alluvium (clay, loam, sand). Minerals: various salts, building materials, and marble and iron in the Sultan Uvais mountain. As the Aral Sea shrank, a salty-sandy Aralkum desert formed near the delta, from which wind carries salt and dust.