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.
Huanning County, a subordinate county of Yuxi City, Yunnan Province, is located on the southern edge of the lake basin area of the central Yunnan plateau and belongs to the Zhongshan type landform. It is bordered by Maile County in the east, Jianshui County in the south, Tonghai County and Jiangchuan County in the west, Chengjiang County and Yiliang County in the north. The territory is 34 km wide from east to west, 59 km from north to south, with a total area of 1313 square kilometers, with a mountain area of 89%. It is located between 23 °59'N and 24 °34 °N and 102 °49'E to 103 °09'E. the terrain is high in the northwest, low in the southeast, narrow in east and west, long in the north and south, undulating mountains and mountains, hills, basins and valleys interlaced with "two ridges and two grooves". The larger basins are Ningzhou Dam and Panxi Dam. The main rivers are Nanpan River, Qinglong River, Haikou River, Longdong River and Huaxi River, all of which belong to the Pearl River system.