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.
Zizhong County, which belongs to Neijiang City, Sichuan Province, is located in the middle of Sichuan Basin, the middle reaches of Tuojiang River, with latitude 29 °34'~ 30 °24 'north and longitude 104 °27' ~ 105 °07 'east. It is adjacent to Anyue County of Ziyang City and Dongxing District of Neijiang City to the east, to the south of Neijiang City and Weiyuan County, Renshou County and Weiyuan County of Meishan City to the west, and Yanjiang District of Ziyang City to the north. 143 kilometers away from Chengdu and 197 kilometers away from Chongqing, it is one of the first 27 powerful counties in Sichuan. Zizhong County covers an area of 1733.96 square kilometers and has jurisdiction over 22 towns. at the end of 2016, the county's total registered population was 1.2791 million. In 2016, the county's gross domestic product (GDP) reached 25.594 billion yuan, an increase of 8.1 percent over 2015. The territory is affected by rock strata and the topography is in the west.