The result is asymmetrical mountains with one side plunging precipitously toward the sea and the other side sloping gently inland. Cuesta formations are especially prevalent along a stretch of erosional coast not far north of Black Rock Harbor, extending for over 20 kilometers from Daxi to Wai ’ ao.
在頭城鎮大溪到外澳一帶，二十多公里的海岸線是典型的侵蝕海岸，有著發達的海蝕平台與單面山等特殊地形。尤其距離蘭博不遠的北關海潮公園，就是一座最具代表性、巨大而完整的單面山地形。