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Over The Horizon

Under the Mountains

In a joint NZ-US study, scientists have obtained for the first time a clear image of the Earth's crust beneath a mountain range.

Fifteen people with some 80 tonnes of equipment spent six weeks moving from the Transantarctic Mountains down the Robb Glacier and onto the Ross Ice Shelf, making seismic measurements as they went.

Sound waves were sent through the ice and into the crust beneath. The sound reflects from various features deep in the Earth, and these echoes are recorded by a computer and later processed to give an X-ray-like image of what lies below.

The researchers were working to look at the uplift and formation of the mountain range. The Transantarctic Mountains offer a unique opportunity to study uplift because the dry polar environment minimises normal weathering and erosion processes, and because the massive glaciers provide natural roads allowing vehicle access.

It is currently believed that there is a direct link between climate and mountain uplift rates, with rainier weather leading to more erosion. At the same time, however, a process called isostasy is thought to compensate for the erosion by accelerating natural uplift, which is why researchers were keen to study mountains where erosion is minimised.