fall line
fall-line的词性:
n.(名词)
1. A line connecting the waterfalls of nearly parallel rivers that marks a drop in land level.
瀑布线:连接几条平行河流上瀑布的线,标志每条河流从高地降到低地的地点
2. The natural line of descent, as for skiing, between two points on a slope.
直接下滑线:斜坡上两个地点间的天然下降路线,如滑雪用的