| 词源 |
delta. The Greek letter for d, delta was drawn in the form of a triangle: Δ. Delta was thus applied to the area of the mouths of the Nile, which was of a triangular shape. It has since been ap- plied to similar formations of other rivers. The Mississippi Del- ta, by the way, is not, strictly speaking, a delta. Far from the sea, it is simply a flood plain. |