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.
Zhengyang County, which belongs to Zhumadian City, Henan Province, is located in the southeast of Zhumadian City, Henan Province, on the coast of Huaihe River, facing Luoshan and Xinyang in the south, Xincai and Xixian in the east, Runan and Pingyu in the north, and Queshan in the west. Beijing-Hong Kong-Macao Expressway, Daguang Expressway, Shanghai-Shaanxi Expressway and Xinyang Expressway look around. The county covers a total area of 1903 square kilometers, with 19 townships, 294 administrative villages (neighborhood committees) and 1421 villagers with a total population of 800000, including 2.3 million mu of arable land and more than 3 mu of arable land per capita. Zhengyang history, known as "plaster sorghum plentiful land", known as "half a meter and a half, it is difficult to buy Zhengyang County" reputation, with peanuts, pigs, wheat three national "top 100 agricultural county business cards", is the country's largest peanut planting county, pigs transferred out of the largest county