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.
Aheqi, Kirgiz language, meaning Bletilla splendens, used to have a large area of Achnatherum splendens beach, hence the name. Aheqi County is a border county located in the hinterland of the southern Tianshan Mountains in the west of Xinjiang Uygur Autonomous region. it is located in alpine mountains. it is 198km long from east to west, 132km wide from north to south, and covers an area of 16800 square kilometers. it borders Wushi County in the east, Keping County in the southeast, Bachu County in the south and Atushi City in the southwest, and the Kyrgyz Republic in the north and west. The border is 305.3 km long. It has 46 Tongwai mountain passes. The elevation of the county is between 1730 and 5958 meters, and the topography shows the overall characteristics of "two mountains sandwiched with one valley". It is known as "nine mountains, half water and half land". In 2013, the total population of Aheqi County was 34000, including Han.