When we visited the Blowhole at Kiama, south of Sydney in New South Wales, the huge waves were making it erupt with a “whoomp”. People would stand for ages watching the action. It was fun seeing some little kids (and their parents) stand up close on the obviously-wet platform, only to be soaked when an erupting water column dropped on top of them.
The headland is composed of a black basaltic-looking volcanic rock called latite. Called the Blowhole Latite Member, it is up to 50 m thick and displays tall, well developed columns (visible around sea level at the Blowhole). It is exposed along the coast for about 11 km, dipping slightly to the north and dropping below sea level at Kiama. The eruption involved massive volumes of lava.
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