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.
Fangcheng District, located on the Beibu Gulf in southern Xinjiang of China, is located in the center of Fangchenggang, connecting Nanning to the north, Fangchenggang to the south, Qinzhou to the east and Dongxing to the southwest to the border between China and Vietnam, with a coastline of more than 130 kilometers and a border of more than 200 kilometers. Dongzhong and other four townships are bordered by Vietnam. Nanfang Railway and Qinfang Expressway run through the territory. In 2012, Fangcheng District has a total population of 414500, inhabited by 19 ethnic groups, including Han, Zhuang, Yao and Beijing, of which ethnic minorities account for 35.7% of the total population. There are more than 260000 overseas Chinese and compatriots from Hong Kong and Macao, making it the second largest hometown of overseas Chinese in Guangxi. Fangcheng District is the hometown of Chinese golden scented tea, star anise and cinnamon. It is one of the top ten counties for scientific development in Guangxi in 2008, and the pilot county for the development of county industry in Guangxi.