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.
Heping County is located in the northeast of Guangdong Province, the upper reaches of Dongjiang River and the Jiulian Mountains on the border between Guangdong and Jiangxi, and is under the jurisdiction of Heyuan City. Heping County is connected to Longchuan County to the east, Dongyuan County to the south, Lianping County to the west, and Dingnan County and Longnan County in Jiangxi Province to the north. It was said in ancient times that she was "the key place to contact Fujian and Guangzhou, take control of Longnan and Anyuan". It is the first county in Guangdong under the Beijing-Kowloon Railway and Beijing-Kowloon High-speed Railway, and it is also a window for Guangdong-Hong Kong-Macau Greater Bay Area to radiate to the mainland. By the end of 2017, there were 245 villages in 17 towns of Heping County, including Yangming, Dam, Changtang, Xiaxia, Shangling, Yousheng, Beidun, Guzhai, Pengzhai, Heshui, Gongbai, Qingzhou, Liyuan, Hot Water, Dongshui, Lishi, Linzhai, and one municipal state-run Liming Forest Farm, with a total area of 2286 square kilometers and a total population of 557900. 2018