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.
Hetang District was established in August 1997 by the merger of three offices in the original East District of Zhuzhou City and three townships in the former suburbs. The total area is 159 square kilometers. It borders with Liuyang City, Zhuzhou County, Lusong District and Shifeng District. Located in the "north-south thoroughfare" three key points, convenient transportation. The terrain is high in the northeast, low in the south, high in the middle and low in the west, belonging to the hilly area. Is a subtropical monsoon warm climate, rich in heat, Rain Water is abundant. In 2012, the GDP was 16.879 billion yuan, the added value of the primary industry was 280 million yuan, the added value of the secondary industry was 11.024 billion yuan, and the added value of the tertiary industry was 5.575 billion yuan, up 3.8%, 14.4% and 10.1% respectively. The main mineral resources are limestone. In January 2013, the State Taxation Bureau of Hetang District obtained