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.
Kashgar, which belongs to the Kashgar region of Xinjiang Uygur Autonomous region, is located in the southwest edge of Xinjiang, west of the Tarim Basin, east of the Taklimakan Desert, south of the Karakoram Mountains and Ali region of Tibet, and west of the Pamir Plateau. It is the westernmost border city in China and the resident of the administrative office of Kashgar region. Kashgar covers an area of 1056.8 square kilometers and has a population of 627900 (2016). It has jurisdiction over 6 streets, 2 towns and 9 townships. Kashgar is the political, economic, cultural and transportation center of southern Xinjiang, and the largest distribution center of agricultural and animal husbandry products. It is also an important commercial port on the ancient Silk Road, the throat hub of the transportation between the East and the West, and an important intersection of economy, culture and civilization between the East and the West. In December 1986, Kashgar was listed as a famous historical and cultural city in China. In May 2004, Kashgar was named Zhongzhong.