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.
Huayuan County, which belongs to Xiangxi Tujia and Miao Autonomous Prefecture of Hunan Province, is located in the west of Hunan Province, in the middle of Wuling Mountains, at the junction of Hunan, Guizhou and Chongqing. In 2016, Huayuan County had jurisdiction over 3 townships and 9 towns. Huayuan County has a total population of 312700, with a total area of 1109.35 square kilometers. The proven reserves of Huayuan Manganese Mine ranks the second in Hunan Province, the second in China, and the second in Hunan Province and the third in China, with the reputation of "Oriental Manganese Capital" and "hometown of Nonferrous Metals". Huayuan is an old revolutionary base county and a key county in national poverty alleviation and development work. There are the sites of ancient human activities 100000 years ago, the ancient battlefield sites of Qianjia Miao uprising, Shen Congwen's border town tea cave and other cultural landscapes; there are also large and small Longdong waterfalls, border town tea cave scenic spots, ancient Miao River ruins