The Work of Waves
Waves erode, transport and deposit material along the coast. Strong wave energy produces rugged erosional landforms, while weak waves deposit material to form gentle landforms. Constructive waves deposit material, while destructive waves erode the coast.
Erosional Landforms
On a coast with alternating hard and soft rock, the soft rock is eroded faster to form bays, while the more resistant hard rock juts out into the sea as headlands. Continuous wave attack on a headland forms a cliff and a wave-cut platform, along with the erosion sequence: crack → cave → arch → stack (when the arch roof collapses) → a low stump. As the cliff keeps eroding, it retreats inland and leaves a wide wave-cut platform behind.
Key idea
Headland erosion sequence: cave → arch → stack → stump.
Depositional Landforms
Material deposited by waves forms a beach of sand and pebbles. Longshore drift happens when waves strike the shore at an angle, carrying sand along the coast in a zig-zag path to build a spit that extends into the sea. Further deposition can form a bar that joins two areas of land, with a lagoon behind it, while a tombolo forms when a spit links a small island to the mainland. Pantai Cenang in Langkawi is a beautiful example of a depositional beach.