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.
Heyuan, also known as "Croucher City", is a prefecture-level city in Guangdong Province, located in the northeast of Guangdong Province, the middle and upper reaches of Dongjiang River, Meizhou City and Shanwei City in the east, Huizhou City in the south, Shaoguan City in the west, and Ganzhou City in Jiangxi Province in the north, with a total area of 15642 square kilometers. It has jurisdiction over five counties in one district, namely, Longchuan County, Dongyuan County, Heping County, Zijin County and Lianping County. By the end of 2018, there are 3.0939 million permanent residents. Heyuan City has Wanlu Lake, the largest lake in South China, and the highest fountain in Asia. It is one of the top 10 green economy cities in China, the most potential financial ecological city, and the top ten characteristics of China.