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.
Cuiping District, which belongs to Yibin City, Sichuan Province, is the seat of the Yibin Municipal CPC Committee and the Yibin Municipal people's Government, and is the political, economic, cultural center and transportation hub of Yibin City. It is a municipal district reestablished by Yibin City at the county level in January 1997. Located in the southern edge of Sichuan Basin, located in the junction of Sichuan, Yunnan and Guizhou provinces, where the Jinsha River and Minjiang River converge into the mighty Yangtze River, the golden waterway of the Yangtze River begins, so it is known as "the first city of the Yangtze River". Cuiping District covers an area of 1502 square kilometers with a total population of 890000 in 2018. In 2018, the region's GDP broke through the 70 billion yuan mark (the tenth place in the province's counties and districts), an increase of 10% over the same period last year. In 2017, it was awarded as one of the top 100 industrial districts in China. In October 2018, it was selected as one of the top 100 green development areas in 2018. twenty