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.
Xichou County, a county under the jurisdiction of Wenshan Zhuang and Miao Autonomous Prefecture in Yunnan Province, is located in the southeast of Yunnan Province, south-central of Wenshan Zhuang and Miao Autonomous Prefecture; the terrain rises from the middle to the west and is lower in the southeast; it belongs to the subtropical low-latitude mountain monsoon climate zone; the total area is 1506 square kilometers and has jurisdiction over 2 towns and 7 townships; in 2017, the resident population is 263000, including 5 ethnic minorities. Xichou County has the Mausoleum of Martyrs in Southern Xinjiang, as well as Xiaoqiaogou Provincial Nature Reserve, Xiangping Mountain rare Botanical Garden, Lion Rock Cliff painting, and Xisa Immortal Cave Paleolithic sites. On September 25, 2018, he won the honorary title of "2018 e-commerce into rural comprehensive demonstration county" of the Ministry of Commerce. On April 30, 2019, the people's Government of Yunnan Province decided that Xichou County would withdraw from the sequence of poor counties. 2017