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An ozone hole over Antarctica, 17,700 years before the aerosol can

Mount Takahe is a huge, ice-buried shield volcano rising from the remote interior of West Antarctica, far from any research stations or supply routes. Named after a flightless New Zealand bird by an exploring party's aircraft nickname, it forms a near-perfect 30-kilometre-wide cone topped by a broad snow-filled caldera, with small parasitic cones and vents scattered across its flanks. Almost the entire mountain is swallowed by the ice sheet, leaving only a handful of small rock outcrops exposed, so geologists have had to piece together its history from scraps of lava and ash rather than a clear cross-section. It belongs to a chain of roughly eighteen volcanoes strung along a rift system beneath Marie Byrd Land, and by some estimates it may be the largest of them all, rivalling Kilimanjaro in bulk once its buried base is counted.

The volcano seems to have grown remarkably quickly, reaching close to its present height within a few hundred thousand years, with its rocks dated from roughly 300,000 down to under 200,000 years old. Much of it built up through lava flows erupting above the ice, interspersed with occasional explosive and hydrovolcanic episodes that left pyroclastic deposits and odd ice-contact rock formations like hardened lava deltas where flows met meltwater lakes. Chemically its lavas belong to an alkaline suite dominated by trachyte, hinting at magma that fractionated at depth before rising from deep in the lithosphere. Activity seems to have been most intense between about 60,000 and 7,500 years ago, tapering off through a string of smaller eruptions into the early Holocene.

Much of what is known about Takahe's eruptive past comes from tephra layers trapped in Antarctic ice cores, though distinguishing its ash from that of neighbouring volcanoes like Mount Berlin remains tricky and occasionally disputed. One particularly significant eruptive episode around 17,700 years ago released large amounts of halogen gases into the stratosphere, and some researchers argue this punched a temporary hole in the ozone layer that may have nudged the pace of deglaciation at the end of the last ice age, though later work questions whether the warming was really volcanically driven. The volcano's last known eruption occurred thousands of years ago, and today it shows no fumaroles, warm ground, or other signs of unrest, aside from some deep seismic activity hinting at a lingering magmatic system. Despite its dormancy, scientists have even looked into whether Takahe's buried heat could one day be tapped for geothermal energy.

The volcano's visible 30-kilometre-wide bulk holds roughly 780 cubic kilometres of rock — and the portion sealed beneath the ice sheet is probably larger still.

Read the whole of Mount Takahe on Wikipedia

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