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.
Shangri-La (Shangri-la), which means "Sun and Moon in the Heart" in Tibetan, is the prefecture-level administrative capital of Diqing Tibetan Autonomous Prefecture in Yunnan Province. It is located in the northwest of Yunnan Province and the hinterland of Hengduan Mountain area on the Qinghai-Tibet Plateau. It is also the junction of Yunnan, Sichuan and Tibet provinces and regions. It is also the site of the World Natural Heritage site of "three parallel Rivers". As of 2014, Shangri-La has a total area of 11613 square kilometers and has jurisdiction over 4 towns, 7 townships, 6 communities and 58 administrative villages. At the end of 2011, the total population of Shangri-La was 174585. In addition to the main Tibetan nationality, there are more than a dozen ethnic groups such as Han, Naxi, Yi and Bai, with a population density of 10 people per square kilometer. it is one of the cities with the largest area and the lowest population density in Yunnan Province. In 2011, Shangri-La