陡坡或洞顶上的岩土体在重力作用下突然脱离母体崩落、滚动、堆积在坡脚沟谷或洞底形成结构松散、多孔隙的堆积体，经过沉积堆积，形成堆积地貌景观。

Under the force of gravity, the rock and soil on the steep slope or on the roof suddenly drop, move and accumulate at the bottom of the valley or cave, forming a deposit of loose structure. The accumulation landform is formed after deposition.