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.
Wuzhong District, located in the southern city of Suzhou, Jiangsu Province, is the birthplace of Wu culture, the birthplace of Sun Tzu's Art of War, and the hometown of Xiao Xiang, the founder of the Xiangshan Gang and the designer of the Forbidden City. Wuzhong District has a land area of 742 square kilometers. As of 2011, Wuzhong District has jurisdiction over Suzhou Taihu National tourist Resort, Wuzhong Economic Development Zone, Dome Mountain Scenic Management area, 7 towns, 8 streets and 6 national 4A-level scenic spots, with a registered population of 600000. Wuzhong District occupies 1459 square kilometers of Taihu Lake, about 3000,000 square kilometers of 5 blue waves of water, more than 180km of hydrophilic coastline, Suzhou nearly 80% of the hills and mountains. The area is rich in Dongting Mountain Biluochun tea, Taihu hairy crab, loquat, bayberry and "Taihu Sanbai" and other famous agricultural and sideline products. twenty