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.
Shangqiu, referred to as "Shang", is a prefecture-level city in Henan Province. Shangqiu lies between 114 °49 & # 39 in east longitude and 116 °39 & # 39 in latitude, and 33 °43 & # 39 in north latitude. It spans 168 kilometers from east to west, 128 kilometers from north to south, east to Huaibei of Anhui and Xuzhou of Jiangsu, west to Kaifeng of Henan, Zhoukou of Henan and Bozhou of Anhui, and Heze and Jining of Shandong to the north. Shangqiu City area accounts for about 6.4% of the total area of Henan Province, with an area of 10704 square kilometers. According to the characteristics of its genesis and morphological types, the geomorphology of Shangqiu City can be divided into three types: the Yellow River alluvial plain, the Huaihe alluvial plain and the denuded residual hills. Shangqiu City has a warm temperate continental monsoon climate. Shangqiu City belongs to the Huaihe River Basin and belongs to flood.