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.
Yanjin County is located in the north of the Yellow River and belongs to Xinxiang City, Henan Province. It is 31 kilometers away from Xinxiang city in the west, 70 kilometers away from Zhengzhou in the south, 80 kilometers away from Xinzheng International Airport, 50 kilometers east to Kaifeng and 130 kilometers north to Anyang. Yanjin County is 45.5 kilometers from north to south and 42.5 kilometers from east to west, with a total area of 886 square kilometers. The total population is 520000 (2016). Yanjin County is the national high-quality wheat production base and the main grain and cotton production base in China. The main scenic spots in the territory are the Forest Park of the Old Road of the Yellow River, the hanging place of Tang Wei Chi Jingde-Suanzao Pavilion, the tomb of King Chen Yucheng of the Taiping Heavenly Kingdom, the provincial cultural relics Wanshou Pagoda and so on. Local snacks include Yanjin fire and so on. Famous figures include Liu Zhenyun and so on. In March 2019, it was listed as the first batch of revolutionary cultural relics protection and utilization district and county list. The second batch of national farmers