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.
Shenxian is a county under the jurisdiction of Liaocheng City, Shandong Province, which is located in the west of Shandong Province, the southwest of Liaocheng City and the junction of Hebei, Shandong and Henan provinces. With an area of 1420 square kilometers and a population of 1.038 million (2014), Liaocheng is the largest and most populous county in Liaocheng. It has jurisdiction over 4 streets and 20 towns. No. 3, Government Street, County people's Government. Shenxian County is located in the flooded area of the alluvial plain in the lower reaches of the Yellow River, which is high in the southwest and low in the northeast. It belongs to the warm temperate semi-humid monsoon climate. The main rivers are Tuhai River, Majia River, Jindi River and so on. Mineral resources include oil, natural gas, rock salt and so on. Shenxian is the old revolutionary base area and the restoration area of Shandong Provincial Party Committee. During the Anti-Japanese War, it was the central area of Hebei-Shandong-Henan Anti-Japanese Base area. Revolutionaries such as Zhu de, Liu Shaoqi, Deng Xiaoping, Song Renqiong, Yang Dezhi and Yang Yong left work and war here.