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.
Tongxiang City is located in the north of Zhejiang Province, the hinterland of Hangjiahu Plain, belonging to Jiaxing City. It was listed in the first batch of open counties (cities) in the country in 1985. 131 km east of Shanghai, 74 km north of Suzhou and 65 km west of Hangzhou, it is located in the triangle of Shanghai, Hangzhou and Sujin. It has jurisdiction over 3 streets, 9 towns and 2 new districts, with a total population of 820000 in 2010. Tongxiang City, located in the southeast coast, is a typical subtropical monsoon climate. Warm and humid, four distinct seasons, Rain Water abundant, plenty of sunshine. It has the climatic characteristics of wet spring, hot summer, dry autumn and cold winter. The annual average temperature is 16.5 ℃. It was the coldest in January, with a monthly average temperature of 4.0 ℃ and an extreme minimum temperature of-11.0 ℃. Tongxiang achieved a GDP of 69.37 billion yuan in 2016. The total annual financial revenue reaches 10.05 billion.