The Gap forms part of the Torndirrup National Park. The continents of Australia and Antartica were bound together along this rugged coastline for more than one billion years forming part of the super-continent Gondwana. The continents were formed mainly of gneiss, a rock created deep in the Earth's crust. Pressure and friction at the base of the two fused contents caused rock to melt and slowly rise up through the gneiss. This molten rock slowly cooled, hardening into granite and helping to cement the continents together.
Australia and Antartica separated about 45 million years ago. Rock formations on Australia's southern coast can still be matched to identical rocks on the norther coast of Antartica.
Waves relentlessly pounded on the coast eventually tearing away loose blocks of granite to create the gap and the natural bridge.
Sometime in the future the gap will widen and disappear; the natural bridge will collapse and become a new gap.