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.
Jinning District, which belongs to Kunming City, Yunnan Province, is located in the middle of Yunnan Province, southwest of Kunming City, surrounded by Dianchi Lake, Xishan District to the west, Chenggong District to the north, Hongta District and Jiangchuan District in Yuxi City to the south and east, respectively. It is an important part of the urban core area of Kunming. As of 2014, Jinning District has jurisdiction over 1 subdistrict office, 5 towns and 2 ethnic townships, with an administrative area of 1336.66 square kilometers. At the end of 2015, the total resident population of the region was 300000. Jinning, the ancient capital of Yunnan and the hometown of Zheng he, is one of the four largest phosphorus capitals in the world and ranks first among China's "Sanyang Phosphate Mine" (Kunyang, Kaiyang and Xiangyang). It has won "2014 most beautiful Chinese tourist destination city", "2016 top 100 deep breathing town", "2016 China's most beautiful county town", and two in a row.