December 20, 2011

Dolerite in the Gorge

Dolerite is rife in Tasmania. Rampant. Come to Launceston, and pick up a rock - chances are good that it's dolerite. In fact, an eminent geologist once wrote an entire book about it which he titled "The Rock Which Makes Tasmania". It's not mere hyperbole - dolerite caps our mountains, dominates our soils, and is quarried for our roads. Tourists come from all over to take photos of columnar jointed dolerite at the Cataract Gorge (as above), on Mount Wellington, and along the Tasman Peninsula. Some of our best rivers and waterways are flanked by the stuff.

It even describes the geological history of Tasmania - this is a rock that was born from the moment when Tasmania and Antarctica finally said goodbye to a united Gondwana, and the fact we can see so much of it is mostly because glaciers in the last few ice ages scraped all the overlying rocks away.

Yes, dolerite is awesome. It's not unique to Launceston or Tasmania, but we do the stuff better (and in larger quantities) than anywhere else in the world. True.

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