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.
Henan Province, referred to as "Yu", is the provincial administrative region of the people's Republic of China. Zhengzhou, the provincial capital, is located in central China. Henan is bounded by 31 °23 & # 39 in north latitude, 36 °22 & # 39 in north latitude, 110 °21 & # 39 in east longitude, 116 °39 & # 39 in east longitude, Anhui and Shandong in the east, Hebei and Shanxi in the north, Shaanxi in the west, Hubei in the south and Henan Province with a total area of 167000 square kilometers. The topography of Henan Province is from north to south, from the east to the west, high in the west and low in the east, composed of plains and basins, mountains, hills and water surfaces, and across the four major river systems of the Haihe River, the Yellow River, the Huaihe River and the Yangtze River. Most of Henan Province is located in the warm temperate zone, the south is across the subtropics, and belongs to the continental monsoon climate from the north subtropical zone to the warm temperate zone; Henan is located in the coastal open areas and the central and western regions.