In the overlying basalt, there is high dip and wide tension fissure zone, which is combined with surface of unconformity which is as basal sliding face, to form loosening rock mass.

在上覆玄武岩层中见有高倾角的宽张裂隙带，与不整合面一起构成松动岩体，不整合面为底滑面。

youdao

Basal slip or sliding as it's often called, basically refers to the slipping or sliding of a glacier across bedrock, actually across a thin layer of water on top of the bedrock.

底部滑移，也通常被称为滑动，大致指的是冰川在基岩上的滑动，实际上是在基岩上部的一层薄薄的水上的滑动。

youdao