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.
Yangjiang, a prefecture-level city under the jurisdiction of Guangdong Province, is located on the southwest coast of Guangdong Province, with Jiangmen Enping and Taishan to the east, Maoming to the west, the South China Sea to the south and Yunfu to the north. It is the direct hinterland of the Pearl River Delta and the frontier of western Guangdong facing the Pearl River Delta; the topography is mainly low mountain and hilly landforms, which belongs to the subtropical monsoon climate area with obvious marine climate; it has jurisdiction over two districts, one city and one county. The total area is 7955.9 square kilometers and the total registered population is 2.9606 million. Yangjiang Shenhai Expressway, Western Guangdong Coastal Expressway, Shanzhan Expressway, Zhongyang Expressway, National Highway 325, Sanmao Railway, Yangyang Railway and Shenzhan Railway run through the whole territory. There are many talents in Yangjiang, including Ruan Tuizhi, a southern poet and calligrapher who is one of the eight sons of Lingnan in modern times, Guan Shanyue, a master of traditional Chinese painting, and the New fourth Army.