It’s safe to say Macquarie Island is off the radar for your regular Aussie adventurer. For starters, it’s located halfway between New Zealand and Antarctica, technically a part of Tasmania and the Australian Antarctic Division; let’s just say the word “remote” applies. But the most striking part of the island is what’s on it – in 1997, Macquarie was placed on the UNESCO World Heritage List as the only place on earth where rocks from the earth’s mantle are exposed above sea level.
If you’re a geologist, you’re probably aware of how cool that is. But for the rest of us, here’s a little explainer.
Back in science class you probably learnt that the earth is made up of several layers. Starting from the centre, there’s the inner core, the outer core, the mantle and then the earth’s crust. The crust is relatively thin, but you have to dig pretty deep to get close to the upper mantle – even on the sea floor, you’ll still need to dig through a few kilometres of the oceanic crust to even touch the mantle. So then, how is it possible that on Macquarie Island the earth’s mantle has emerged into the atmosphere?
You can blame it all on a very powerful geological process which pushes rocks up from the mantle to the earth’s surface. These mantle rocks are usually characterised by their green colour, and are often called ophiolites, which is Greek for ‘snake stones’. On Macquarie Island, mantle rose up towards the surface at a rate of one millimetre per year. Two tectonic plates under the earth’s surface pushed a chunk of oceanic crust and mantle up out of the water and formed the 35 kilometre long island we see today – cool, huh?
Macquarie Island is a pretty awesome site to see, in more ways that one. During the day, maximum temperatures range from around 4.9ºC in July to 8.8ºC in January (hello, summer!). It also holds the crown as one of the cloudiest places on Earth, with an average of only 856 hours of sunshine per year. But – and it’s a big but – the miserable weather does mean it’s ripe for penguin breeding. Macquarie Island is actually the only nesting place of the Royal Penguin and at several points throughout the year you can witness this impressive sight.
Macquarie Island is often a stopover on cruises to Antarctica. The island’s only human inhabitants are from the Australian Antarctic Division, who set up a permanent base there back in 1948. With only around 20 to 40 people populating the island year-round, it’s a great place for your friend who hates crowds. And loves penguins.[related_articles]30391,3315,19928,27929[/related_articles]
(h/t CN Traveller, lead image by Barend (Barry) Becker/Australian Antarctic Division)