Wet Tropics & Daintree Coast

Fitzroy Island

It only became an island 7,400 years ago. From the air, you can still read where the connection was.

Fitzroy Island looks permanent — a solid granite mountain rising from the Coral Sea. But it has only been an island for the briefest moment in geological time. The sea level rise that followed the last ice age drowned the connection to the mainland within the last 400 human generations. The granite beneath your feet was part of mainland Australia until very recently.

The island is composed entirely of granite — specifically, a uniform, light-coloured medium to coarse-grained biotite granite forming part of the northern end of the enormous Bellenden Ker Batholith. This batholith intruded during the early Permian, roughly 280 million years ago, and extends from Babinda to False Cape near Yarrabah on the mainland.

The relationship between Fitzroy Island and the mainland is not simply geographical. The same granite that forms the island's steep ridges and boulder-strewn headlands underlies the Bellenden Ker ranges directly behind Cairns — the ranges that catch the wet season rainfall and feed the rivers of the coastal plain. From the air on a clear day, the visual connection between the island and the ranges is unmistakeable.