The Ustyurt natural-geographic district

Only the south-eastern part of the Ustyurt plateau belongs to Uzbekistan; it lies in the far north-west of the republic. The district borders Kazakhstan in the north and west, Turkmenistan in the south, and the Aral and Lower Amudarya districts in the east. Ustyurt is a plateau worn by a dry climate, 100–200 m high and edged by steep escarpments called chinks; on the Aral shore a chink reaches 190 m. The plateau lies on the Turan plate: the base is Paleozoic rock, covered by 3–4.5 km of Mesozoic and Cenozoic limestone, marl and clay. It became land from the sea bed at the end of the Neogene and the start of the Quaternary. The plateau consists of downwarps and uplifts running along latitude: the North Ustyurt downwarp (about 100 m), the Kassarma uplift (219 m), the Borsakelmas depression (lowest point 63 m), the Karabaur uplift (292 m) and the Asaka-Audan depression. Uplifts correspond to heights and downwarps to hollows. Saline soils lie in the hollows. Ustyurt has oil and gas, various salts and building materials.