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.
Shayibak District, one of the downtown areas of Urumqi, is an important window and land transportation hub for Urumqi to open to the outside world. Located to the west of Hetan Road in the urban area, it is located in the middle of Urumqi. Dongjiehetan Highway is adjacent to Tianshan District and Shuimogou District, facing 104th regiment to the west and Toutun River District, bordering Urumqi County from Wulapo and Daxigou in the south, and Xinyi Road to the north adjacent to the new urban area. Shaibak District has 10 subdistrict offices, 114 community neighborhood committees and 1 village. The total area is 378 square kilometers and the population is 528000 (2010). In 2009, Shayibak District achieved a GDP of 15.797 billion yuan, an increase of 7% over the same period last year.