Geological history: from the mountains to the sea
270 million years ago mud, silt and sand was eroded from mountains along the east coast of the supercontinent, Gondwana, and deposited here in horizontal layers by ocean currents in a shallow sea. Gondwana had drifted down to the Antarctic Circle so, further south, glaciers carried rock debris from the mountains to the coast. There, icebergs floated north and, as they melted in the shallow waters here, dropped their loads including boulders weighing 10 tonne into the mud and silt.