How was the cave formed? It started millions of years in a time when the earth's crust was being compressed.
If you lay a piece of paper flat on a table, then start to press the two ends together, the paper begins to rumple up and fold into curves. Whenever the earth's crust is being compressed it too starts to fold up and down. The "down" folds are like Saucers and are called Synclines.
The "up" folds like Arches are called Anticlines. This Earthcache is an ancient anticline arch. The softer rock under the arch has been carved out by the forceful action of the waves and loose pebbles pounding it over many years. This has left the natural archway that forms the cave.
To prove you have been there, have your photo taken with the cave as a background, and answer the following question in your log:
WHAT IS THE APPROXIMATE WIDTH OF THE CAVE ENTRANCE IN METRES?