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.
Pingyuan County is located in the northwest of Shandong Province, belonging to Dezhou City, bordering Linyi County and Yucheng City in the east and southeast, Wucheng and Xiajin in the west and southwest, Gaotang in the south and Decheng and Lingcheng in the north. Pingyuan County is located in the northwest plain of Shandong Province in the lower reaches of the Yellow River, with flat terrain and slow tilt from southwest to northeast. The climate belongs to the continental monsoon climate of the north temperate zone, with four distinct seasons and sufficient sunshine. The administrative area covers an area of 1047 square kilometers, with a total population of 470000. It has jurisdiction over 8 towns, 2 townships, 2 streets and 1 economic development zone. Pingyuan County is the hometown of "grain production base", "Beijing-Tianjin vegetable park", "strong county of animal husbandry", "big county of live pigs", "hometown of pigeons", Zhang Quanjing, an expert in the history of party building, Ren Jiyu, the late master of Sinology, Deng Youmei, a famous writer, and so on.