Age: 175 million years, Middle Jurassic
Location: Leslie Vale, near Mt Wellington, south of Hobart
Formation: During the breakup of Gondwana, dolerite magma was injected as subsurface dykes and sills (sheets), across most of Tasmania. As the magma cooled and crystallised, regular vertical cracks propagated through the sills, forming polygonal columns.
Significance: Dolerite is unusually widespread in Tasmania, and is appropriately referred to as ‘the rock that made Tasmania’. It forms the iconic ‘organ pipes’ landscape above Hobart, as well as on Tasman Peninsula and the Central Plateau.
Donated by: The Government of Tasmania and Hazell Bros Resources