• Mesa
  • Jiayuguan

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.

Jiayuguan, known as "the first male pass in the world", is located in the middle of the narrowest valley 5 kilometers west of Jiayuguan City, Gansu Province. the city walls on both sides of the pass cross the Gobi Desert, the suspended Great Wall of Montenegro in the north and the first pier in the south. it is the westernmost pass of the Ming Great Wall. it was once known as Hexi throat in history, because of its dangerous topography and majestic architecture, it is known as the chain key of the border. Jiayuguan is the traffic fortress of the ancient "Silk Road" and one of the three wonders of the Great Wall of China (Shanhaiguan in the east, Zhenbeitai in the middle and Jiayuguan in the west). Jiayuguan was built in the fifth year of Hongwu of the Ming Dynasty (1372). It is composed of inner city, outer city, Luocheng, Wengcheng, trench and the north and south wings of the Great Wall, with a total length of about 60 kilometers. The platform, pier and fortress of the Great Wall are dotted with three lines of defense, namely, the inner city, the outer city and the moat.
Travel Sights In Jiayuguan
Travel Notes In Jiayuguan