 The western side of Schouten Island is composed of Jurassic dolerite.Forty-nine endemic species to Tasmania are found at Freycinet.Mammals found include the brushtail possum, ringtail possum, sugar glider, eastern pygmy possum, little pygmy possum, echidna, wombats, New Holland mouse, swamp rat, water rat, Tasmanian bettong and the long-nosed potoroo.