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.
Wangcang County, which belongs to Guangyuan City, Sichuan Province, is located on the northern edge of Sichuan Basin, at the southern foot of Micang Mountain, Nanjiang County, Bazhong City in the east, Chaotian District, Lizhou District and Zhaohua District in the west, Cangxi County in the south, and Nanzheng County and Ningqiang County in Shaanxi Province in the north. The county covers an area of 2987 square kilometers and has jurisdiction over 18 towns, 17 townships and 3 street offices. In 2012, the total population was 458200, living in Han, Qiang, Yi, Tibetan, Hui, Miao, Dong and other ethnic groups. The topography of the territory is high in the north and low in the south, and the abdomen is low and flat. The landform is dominated by northern peaks, towering Chongshan in the south, hills and dams in the abdomen, and streams and rivers crisscross. Belongs to the subtropical humid monsoon climate. The average annual temperature is 16.5 ℃ and the annual precipitation is 920.9 mm. Guangwang Railway and National Highway 542 run from east to west. The venue of the wooden door meeting of the fourth Red Front Army,