由于向源侵蚀的结果，它不断延长并且穿过软硬岩石从中切出一条河谷来。

It will lengthen as a result of headwater erosion and thereby will cut a valley through both hard and soft rock.

youdao

由于向源侵蚀的结果，它不断延长并且穿过软硬岩石从中切出一条河谷来。

It will lengthen as a result of headwater erosion and thereby will cut a valley through both hard and soft rock.

youdao