Curio Bay Petrified Forest dates from the Jurassic Period, some 170-180 million years ago, when conifers, tree ferns and cycads growing in swampy ground during a semi-tropical climatic phase were overwhelmed by volcanic ash and mud flows. Silica gradually replaced the timber to produce the fossils that have now been exposed by the sea. The present rock shelf around the remains is the original Jurassic forest floor.