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.
Changji City, which belongs to Changji Hui Autonomous Prefecture of Xinjiang Uygur Autonomous region, is located at the northern foot of Tianshan Mountain, the southern edge of Junggar Basin, the center of Eurasian continent and the location of the state capital. The total area is 8215 square kilometers. By 2018, Changji had jurisdiction over 5 streets, 8 towns, 2 townships, 2 functional areas, 2 farms and 1 management station. By the end of 2017, Changji City had a total population of 547481, with a regional gross domestic product (GDP) of 40.041 billion yuan, of which the added value of the primary industry was 3.513 billion yuan, that of the secondary industry was 19.843 billion yuan, that of the tertiary industry was 16.685 billion yuan, and that of the tertiary industrial structure was 8.8%, 49.5%, 41.7. Reconfirm the national health city (district) in 2018. 2019