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.
Kuerle City (Korla), the prefecture-level administrative capital of Bayingoleng Mongolia Autonomous Prefecture in Xinjiang, is located in central Xinjiang, the southern foot of Tianshan Mountain, the northeast edge of Tarim Basin, the Tianshan tributary in the north and the Taklimakan Desert, the second largest desert in the world in the south. It is the throat of the ancient Silk Road and one of the birthplaces of Western culture. It is not only an important transportation hub and material distribution center in southern and northern Xinjiang, but also an important political, economic and cultural center in the region. "Korla" means "overlooking" in Uyghur language, because it is rich in the world-famous "Korla fragrant pear", also known as "Pear City". Korla is the first "national civilized city" in the five northwestern provinces (evaluated on January 23, 2009). In February 2015, it was confirmed by the Central Commission of Civilization that the "National Civilization City" would continue to be retained.