outer-arc ridge

例句：

1. 1.The outer arc ridge of the mountain is visible from the top of the peak.
   从山顶可以看到这座山的外弧脊。
2. 2.The outer arc ridge of the river is a natural barrier that separates two sections of the river.
   河流的外弧脊是一道天然的屏障，将河流分成两部分。
3. 3. The outer arc ridge of the plateau is formed by the convergence of two tectonic plates.
   高原的外弧脊是由两个构造板块的汇聚形成的。