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.
Xundian Hui and Yi Autonomous County is under the jurisdiction of Kunming City, Yunnan Province. Located in the northeast of Yunnan Province, it is the focal point of northeast Yunnan. The Guizhou-Kunqu Railway, Kunqu and Songdai Expressway pass through the county, and the traffic is more convenient. The county has jurisdiction over 3 subdistrict offices, 9 towns and 4 townships, with a permanent population of 457000 (2010), inhabited by 16 ethnic groups such as Han, Hui, Yi and Miao, with a minority population of 110000, accounting for 21.8%. The county people's government is stationed in Rende Street. On September 29, 2018, Xundian Hui and Yi Autonomous County was approved to withdraw from the poverty-stricken county after being studied by the Yunnan provincial party committee and provincial government. (Overview of the source of the picture)