A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Zhaosu County is located in the southwest of Yili Kazakh Autonomous Prefecture, between latitude 43 °15'N and longitude 80 °08 °81 °30'E. it is a high intermountain basin surrounded by mountains in the inland hinterland of Central Asia. It borders Tekes County in the east, Baicheng County and Wensu County in Aksu region in the south, Kazakhstan in the west and Chabuchal County in the north. The border is about 220 kilometers long, and there is a national first-class port-Muzart Port, which was listed as an open county by the State Council in 2001. The county is about 141km long from east to west and 132km wide from north to south, with a total area of 11200 square kilometers. The county seat, which is 2018 meters above sea level, is the only county with five types of difficult areas in Yili Prefecture. Zhaosu Town, a county town, is 879 kilometers away from Urumqi's highway.