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.
Raohe County, which belongs to Shuangyashan City, Heilongjiang Province, is located in the northeast border of Heilongjiang Province, the middle and lower reaches of the Wusuli River, across the river from Russia, the border is 128 kilometers long. The geographical coordinates are 46 °30 °44 "~ 47 °34 °26" N and 133 °07 "26" ~ 134 °20 "16" E respectively. The south is surrounded by the Wanda Mountains and the north is supported by the Sanjiang Plain. The county covers an area of 6765 square kilometers. In 2017, Raohe County has a population of 150000 and has jurisdiction over 4 towns and 5 townships, including 5 state-owned farms and 11 forest industrial forest farms. There are 27 ethnic groups in the county, including 1 Hezhe Township and 3 Korean villages. The county government is stationed in Raohe Town. In the first year of Xuantong of the Qing Dynasty (1909), Shixian County was founded, in 1949 (1925).