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.
Runzhou District, located in the southwest of Zhenjiang City, Jiangsu Province, is the main city and administrative center of Zhenjiang, a famous historical and cultural city in China. Runzhou District is located at the confluence of the Yangtze River and the Beijing-Hangzhou Grand Canal, the core of the Yangtze River Delta where China's economy is most active, and is the southern "bridgehead" of the Runyang Yangtze River Bridge. Beijing-Shanghai Railway, Beijing-Shanghai High-speed Railway, Shanghai-Nanjing Railway Zhenjiang Station and Zhenjiang entrance and exit of Shanghai-Nanjing Expressway and Yangzhou-Yangzhou Expressway are all in the area. Runzhou is the epitome of "Landscape Zhenjiang", "Ecological Zhenjiang" and "Humanistic Zhenjiang". There are 4A scenic spots-Jinshan, and Xijindu, a historical and cultural district awarded as the quality Award for Cultural Heritage Protection by the United Nations Scientific, Educational and Cultural Organization. Runzhou District has won the title of "Ping'an District of Jiangsu Province" for five years in a row.