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.
Altay was the pastoral land of Chinese ethnic minorities in ancient times. According to historical records, the tribes who lived here in the Qin Dynasty were Sai people who moved from the Hexi Corridor in Gansu Province. Since the Western Han Dynasty, successive central governments have set up administrative organs here. "Altay" is Turkic, meaning "Jinshan". It gets its name because of the gold in the mountains. It is said that there are 72 ditches in the Altai Mountains. The Ertix River in Altay is the only river in China that flows into the Arctic Ocean. The Brento Sea, which is located in Fuhai County, covers an area of 100000 hectares and is rich in more than 10 kinds of fish, known as the "fishing hometown of the North". Altay mountains and rivers are magnificent and colorful, with unique natural scenery, the main scenic spots are Kanas Lake Nature Reserve, Burgen River Beaver Nature Reserve, Butterfly ditch and so on.