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.
Nanfen District, which belongs to Benxi City, Liaoning Province, is located 25 kilometers south of Benxi City, bordering Benxi County in the southeast, Liaoyang City in the west and Pingshan and Mingshan districts in the north. The region covers an area of 619 square kilometers and has a population of 100000. Nanfen District has jurisdiction over 3 streets, 1 town and 1 ethnic township: Nanfen Street, Tieshan Street, Guojia Street, Xiamatang Town, Sishanling Manchu Township. The district government is located in Nanfen Street. In 2014, the regional GDP was 5.85 billion yuan, a comparable growth of 8%; the public budget revenue was 738 million yuan, an increase of 5%; the added value of large-scale industry was 4.3 billion yuan, a comparable increase of 15%; the fixed assets investment of the whole society was 6.6 billion yuan, the same as that in 2013; the total retail sales of consumer goods was 430 million yuan, an increase of 10%, and introduced into other provinces