The erosion of the ancient landscape was a slow process caused by wind and rain over centuries.

erosion 是名词，来自动词 erode（侵蚀、腐蚀）。词根 rod- 表示"咬、啃食"，前缀 e- 表示"向外"，所以字面意思是"被外力一点点啃食掉"，引申为"侵蚀"的过程或结果。