Kōrero: Coastal erosion

This hand-coloured engraving was made by Sydney Parkinson, the artist on board Lieutenant James Cook’s Endeavour in 1769. It shows a fortified pā on top of an arched rock at Mercury Bay, on the east coast of the Coromandel Peninsula. Arches form when waves pound headlands from both sides. Over time, the waves follow lines of weakness in the rock, and carve out caves on either side of the headland. When the caves meet, a natural arch is produced. This arch has since collapsed.