A reversed profile of Archaean metamorphic grades is exposed in Guyang Wuchuan area of central nei Mongol, which was caused and preserved by early Proterozoic napping from north west to south east during continental collision.

• 由早元古代造山运动早期自北西向南东推覆作用引起并使之得以保存的太古代变质作用强度逆转的剖面出露在内蒙古中部的固阳－武川地区。