砒砂岩, 泛指大面积出露于黄土高原北部鄂尔多斯高原以红色为主的中生代沉积岩。

Soft rock generally refers to large area Mesozoic sedimentary rock that mainly red being exposed in Ordos Plateau, north of Loess Plateau. 

砒砂岩分布区域, 面积约1.2万k㎡。主要分布在以内蒙古鄂尔多斯市准格尔旗为中心的蒙、晋、陕接壤区。砒砂岩区的水土流失强烈, 发源于此的多条黄河一级支流皇甫川、窟野河、十大孔兑(孔兑, 蒙古语, 指河谷)是黄河泥沙和粗沙的主要来源区。北京专业翻译公司

Distribution area of soft rock is about 12000 k㎡, is mainly distributed in contiguous area of Mongolia, Shanxi and Shaanxi that centered on Jungar Banner, Ordos City, Inner Mongolia. Water and soil erosion of soft rock regions is strong; many Yellow River first level branches (Huangfuchuan Watershed, Kuye River and ten major river valleys) originated in here are main source areas of Yellow River silt and coarse sand.        

该区域是石灰纪以前的古生代海洋。二迭纪海洋退出, 地壳上升, 公区由半封闭过渡为封闭的内陆盆地。气候炎热, 沉积了陆相红色泥岩、碎屑岩, 主要为蕨类植物生物群。深圳翻译

The region is Paleozoic ocean before Carboniferous period. In Permian period, the ocean exits and the crust rises up, public area is a transition from semi-closed to closed interior basin. Burning hot climate deposits continental red mudstone and clastic rocks; mainly is fern biota.     

三迭纪早、中期, 内陆盆地迅速下沉, 气候更趋干燥炎热, 继续沉积巨厚的陆相红色泥岩、碎屑岩。大量出现脊椎动物生物群。中三迭世末期, 受印支期构造运动影响, 盆地一度上升, 受短期风化侵蚀, 造成地层间(二马营组和延长组)的假整合和角度不整合接触。晚期地壳缓慢下降, 气候转向湿润温暖, 红色地层减少, 开始沉积灰绿色碎屑岩及煤层透镜体等有机物质。植物开始繁盛, 为河湖相沉积特征。末期受印支晚期构造运动影响, 盆地全面上升, 地层广泛遭受侵蚀剥蚀。

In early and middle Triassic period, interior basin rapidly sinks; the climate tends to be drier and more burning hot, continuously deposits extremely thick continental red mudstone and clastic rocks. Vertebrate biota is appeared in mass. At the end of Middle Triassic, affected by tectonic movement in Indo-Chinese epoch, the basin rises up for a time, is eroded by short-term weathering, and then causes the disconformity between stratums (Ermaying Formation and Yanchang Formation) and angular unconformable contact. In late Triassic period, the crust slowly declines, the climate turns to humid and warm, red stratum is reduced, begins to deposit grey green clastic rocks and coal seam lens and other organic matters. The plant begins to bloom and becomes fluvio-lacustrine facies sedimentary characteristics. At the end of Triassic period, it is affected by tectonic movement in late Indo-China epoch, the basin entirely rises up and the stratum is widely eroded.