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.
Tiemenguan is a county-level city directly under the jurisdiction of Xinjiang Uygur Autonomous region. It implements the integrated management system with the second Division of Xinjiang production and Construction Corps and is managed by Xinjiang production and Construction Corps. Located at the southern foot of the Tianshan Mountains and in the eastern part of the Tarim Basin, it is the traffic hub at the intersection of the southern foot of the Tianshan Mountains and the northern slope of the Kunlun Mountains, and a necessary place in the middle of the ancient Silk Road. Tiemenguan City is composed of "one district and two towns", covering an area of 590.27 square kilometers, about 50 kilometers away from Korla, the capital of Bazhou. The name of the city comes from "Tiemenguan", one of the 26 passes in ancient China. No. 1 Xingjiang Road, Tiemenguan City, Municipal people's Government. Tiemenguan City was established on December 29, 2012. On December 29, 2018, the sixth national unity and progress demonstration zone (unit) was named by the State Civil Affairs Commission.