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.
Yunfu City is located in the central and western part of Guangdong Province, south of the middle reaches of the Xijiang River, adjacent to the Pearl River Delta, bordering Zhaoqing, Foshan, Jiangmen, Yangjiang, Maoming and Wuzhou, Guangxi. The urban area is more than 140 kilometers away from the provincial capital Guangzhou and 177 nautical miles away from Hong Kong by waterway. In April 1994, a prefecture-level city was established, under the jurisdiction of Yuncheng District, Yunan District, Xinxing County and Yunan County, in charge of Luoding City. Yunfu is one of the cities in the Pearl River Delta urban agglomeration and an important node city in the Pearl River-Xijiang Economic Belt. Yunfu is rich in mineral resources. Yunfu is one of the important polymetallic mineralization concentration areas in China, in which the reserves and grade of pyrite rank first in the world and are known as the "sulfur capital". It is the largest production base of sulfur chemical industry in China and the largest production base of stainless steel tableware in Guangdong Province. Stone processing has a long history and is known as the "stone capital". Yunfu is the center of China's stone base.