Is an arete a result of erosion or deposition?

Answer 1

An arête is a thin, almost knife-like, ridge of rock which is typically formed when two glaciers erode parallel U-shaped valleys, or else when two corrie glaciers erode back-to-back. An arête is a formed as a result of erosion, though the material it is made of may be an ancient deposition (this, however, is irrelevant).