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.
Qingshen County, which belongs to Meishan City, Sichuan Province, is located in the southwest of Chengdu Plain, bordering Dongpo District in the north, Leshan in the south and Emei in the west. Now it has jurisdiction over Qingcheng Town, Nancheng Town, Heilongjiang Town, Xilong Town and other seven towns and three townships. Qingshen County has a total area of 386square kilometers and a resident population of 197029. The county government office is located in Qingcheng town. In 2017, Qingshen County achieved a GDP of 7.46 billion yuan. Qingshen is the hometown of Silkworm Cong, the first king of Shu, and is known as "Southern Silk Road", "Little Emei of Minjiang Ancient Waterway", "Su Shi's second hometown", "hometown of Ponkan in China" and "hometown of Chinese Bamboo Weaving Art".