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.
Zhaoan County (ancient Zhangzhou capital Zhaoan County) Zhangzhou County, Fujian Province, located at the southern end of Fujian Province, at the junction of Fujian and Guangdong. It is bordered by East China Sea and South China Sea to the south, Raoping County in Guangdong Province to the west, Pinghe County to the north, Yunxiao County and Dongshan County to the east, and Raoping County and Nanao County to the west. The land area is 1293.6 square kilometers, of which the planned area of the county and urban areas is 100 square kilometers, the built area is 17.5 square kilometers, the coastline is 88 kilometers long, and the sea area is 273 square kilometers. It has jurisdiction over 16 townships (districts), 7 state-owned agricultural and forestry farms, 1 provincial industrial park and 1 Jindu industrial concentration area (marine biological industrial park) under construction, with a population of 613000, of which agricultural population accounts for more than 80%. Zhaoan County is the "hometown of calligraphy and painting" and "Chinese folk".