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.
Midong District belongs to Urumqi City, Xinjiang Autonomous region. Approved by the State Council in August 2007, the former Miquan City of Changji Hui Autonomous Prefecture and Dongshan District of the former Urumqi City were merged and established. The district has a total area of 3407.42 square kilometers and has jurisdiction over 5 towns and 2 townships, 6 streets, 81 administrative villages and 48 communities, with a resident population of 333676 (2010). In 2013, the regional GDP for the whole year reached 26.06 billion yuan, an increase of 15.8 percent over 2011, and the general budget revenue of local governments reached 3.04 billion yuan, an increase of 21 percent over 2011. The per capita disposable income of urban residents reached 20780 yuan, an increase of 13 percent over 2011, and the per capita net income of farmers and herdsmen reached 12300 yuan, an increase of 16 percent over 2011.