The impact of raindrops on the loose soil tends to transfer fine clay particles into the tiniest soil spaces, sealing them and producing a surface that allows very little water penetration.

降水往往会把细小的粘土颗粒转移到土壤的最微小的空隙中，使这些空隙变得封闭，从而形成了一种几乎不允许任何水分渗透下来的表层土壤。