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.
Gaotang County, which belongs to Liaocheng City, Shandong Province, is located in the northwest of Shandong Province, adjacent to Yucheng City and Qihe County in Texas in the east, Linqing City and Xiajin County in the west, Chiping County in the south and plain county boundary in the north, covering an area of 960 square kilometers and a population of 500000. Gaotang County is 70 kilometers east of Jinan International Airport, and Gaotang Railway Station is built through the border. It is more than 50 kilometers away from Liaocheng Station and Linqing Station of Beijing-Kowloon Railway, and 60 kilometers each from Dezhou Station of Beijing-Shanghai Railway. It is convenient to "get on the train in 20 minutes, board the plane in one hour and enter the capital to the port in four hours." Qingyin Expressway and Shandong West Outer Ring Highway pass through the county. The terrain in Gaotang is gentle and the land is fertile, and in the east there are