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.
Yihuang County, which belongs to Fuzhou City, Jiangxi Province, is located in the east-central part of Jiangxi Province and the south of Fuzhou City. Yihuang County was founded in Wu Taiping of the three Kingdoms for 2 years (257 AD). It has a history of 1759 years and gets its name because the county administration is located at the confluence of Yishui and Huangshui. Yihuang, known as the "opera town", is the birthplace of Erhuang Opera. Caoshan Temple in Yihuang is the ancestral court of the Zen Cao Dong sect. With a total area of 1944 square kilometers, the county has jurisdiction over 12 townships, 2 reclamation farms and 1 provincial industrial park, 139 administrative villages and 8 neighborhood committees with a total population of 240000, including she, Hui and Yao ethnic minorities, and most of the rest are Han nationality, belonging to the Jiangyou people. The topography and geomorphology of Yihuang County are mainly mountains and hills, and the general situation is "eight mountains and half water, one sub-field, half-divided roads and manors". Yihuang County has successively