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.
Panji District is the municipal district of Huainan City, Anhui Province. Formerly known as Gugou District, it was changed to Panji District in 1980. Panji District is located at the southern end of the Huang-Huai Plain, bordered by the Huaihe River to the south, Cihuaixin River to the north, Huaiyuan County to the east and Fengtai County to the west. By the end of 2017, Panji District covers an area of 600square kilometers and has jurisdiction over one street, nine towns and one ethnic township, with a registered population of 454000. In 2017, Panji District completed a GDP of 17.46 billion yuan, an increase of 7.0%, the added value of the primary industry was 1.78 billion yuan, the added value of the secondary industry was 12.3 billion yuan, the added value of the tertiary industry was 3.38 billion yuan, and the tertiary industrial structure was 10.2%. The famous and special products of Panji District are mainly Panji crisp melon, Luji mung bean circle and so on.