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.
Burjin County, which belongs to Altay, is located in the north of Xinjiang Uygur Autonomous region, at the southwest foot of Altai Mountains, along the northern edge of Junggar Basin, bordering Kazakhstan, Russia and Mongolia in the north and northeast. It is one of the two counties bordering Russia in western China (the other is Habahe County). The national boundary is 218 kilometers long and there are many rivers in the country. it is a necessary place for import and export of the two border trade ports in northwest Xinjiang. An ideal port on the border with Russia is of great development value. it is the only nearest channel to open economic and trade exchanges between Northwest China and Russia, and the largest tributary of the Ertix River, the only Arctic water system in China. It is adjacent to Mongolia in the northeast, Altay to the east, Habahe County to the west, Jimunai County and Fuhai County to the south. At the end of 2011, the total population of Burjin County