A feature of coastal processes formed by erosion of a
cliff or headland.
Waves quickly exploit joints, cracks and bedding planes in rock through hydraulic action. (Pressure is created when waves force
air into crevices, pressure is released as waves retreat creating mini explosions.) Along the joint the sea
will cut inland to form a cave. If the erosion continues upwards then with a little help from
sub-aerial processes the line of erosion continues through the
cliff to the top forming a blowhole. Blowholes get their name due to sea spray coming up and out in stormy weather much like a dolphin or whales blowhole.