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.
Zhongjiang County, which belongs to Deyang City, Sichuan Province, is a major agricultural county in the western part of the hilly area of central Sichuan. Named after ancient Zhongshui (present-day Luojiang). Zhongjiang is located in the northwest of Sichuan Basin, facing Chengdu to the west, Mianyang to the north and Suining to the south. The main highways passing through the territory are CICC Express, Luogui Highway, Tangba Highway, Chengda Railway, Chengnan (Chong) Expressway, Chengba (Bazhong) Expressway and so on. Zhongjiang is the hometown of Huang Jiguang, a national "two hundred people" and super hero. National intellectual property rights strong county project pilot county (district). The county covers an area of 2200 square kilometers and has jurisdiction over 45 townships and 837 villages (communities) with a registered population of 1.399 million (2017). Zhongjiang famous specialty products are hand-made noodles, Babao oil cake, Zhongjiang pomelo and so on. Famous scenic spots include China Shaoyao Valley, Zhongjiang North Pagoda and Huang.