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.
Huzhu Tu Autonomous County is a county under the jurisdiction of Haidong City, Qinghai Province. it is located in the east of Qinghai Province and north of Haidong City, relying on the Daban Mountains of Qilian Mountains in the north, adjacent to Menyuan Hui Autonomous County of Haibei Prefecture in the northeast, adjacent to Tianzhu Tibetan Autonomous County and Yongdeng County in Gansu Province in the northeast, Ledu District of the municipal government in the southeast, bounded by Huangshui in the south, facing Pingan District in the south, Datong County in Xining City in the west, and the provincial capital Xining City in the southwest. The county is about 64 kilometers from north to south and 86 kilometers from east to west, with a total area of 3423.9 square kilometers. There are no lakes in the county, there are 8 large and small natural rivers, all of which belong to the Yellow River basin and Huangshui water system, with a total length of 2895 kilometers. The bluestone of the Daban Mountains runs through the whole territory from northwest to southeast, dividing the whole county into two major topographic units. Huzhu Tu Autonomous County has jurisdiction over 8 towns and 9 townships.