Ellsworth Trough: Giant Subglacial Trench Discovered in Antarctica

Jan 14, 2014 by Sci-News.com

UK scientists have recently discovered a huge subglacial trough – deeper than the Grand Canyon – in Antarctica.

This map of Antarctica shows the rough location of the recently discovered Ellsworth Trough. Image credit: American Geological Society / Polar Geospatial Center.

This map of Antarctica shows the rough location of the recently discovered Ellsworth Trough. Image credit: American Geological Society / Polar Geospatial Center.

Dr Neil Ross from Newcastle University and his colleagues spent three seasons investigating and mapping the Ellsworth Subglacial Highlands, an ancient mountain range buried beneath several km of Antarctic ice.

By using data from ground-based and aerogeophysical radio-echo sounding surveys and the moderate-resolution imaging spectroradiometer mosaic of Antarctica, they discovered a previously unknown subglacial trough, named the Ellsworth Trough.

“The discovery of this huge trough, and the characterization of the surrounding mountainous landscape, was incredibly serendipitous,” said Dr Ross, who is the lead author of the paper appearing in the Geological Society of America Bulletin.

First observed in 2011, the Ellsworth Trough is up to 3 km deep, more than 300 km long and up to 25 km across.

“We had acquired ice penetrating radar data from both ends of this huge hidden valley, but we had no information to tell us what was in between. Satellite data was used to fill the gap, because despite being covered beneath several km of ice, the valley is so vast that it can be seen from space.”

The Ellsworth Subglacial Highlands and the Ellsworth Trough were carved millions of years ago by a small ice-field similar to those of the present-day Antarctic Peninsula, or those of Arctic Canada and Alaska.

Subglacial topography of the northwestern parts of the Ellsworth Trough. Image credit: Ross N et al.

Subglacial topography of the northwestern parts of the Ellsworth Trough. Image credit: Ross N et al.

The study also provides an unprecedented insight into the extent, thickness and behavior of this ancient ice-field, and the configuration and behavior of the early West Antarctic Ice Sheet.

The subglacial landscape shows where and how the West Antarctic Ice Sheet originated and grew. It also provides important clues about the size and shape of the ice sheet in West Antarctica in a warmer global climate.

“While the idea of West Antarctic Ice Sheet growth and decay over the past few million years has been discussed for decades, the precise location where the ice sheet may originate from in growth phases, and decay back to in periods of decay, has not been known,” said senior author Prof Martin Siegert from the University of Bristol.

“By looking at the topography beneath the ice sheet using a combination of ice-penetrating radio-echo sounding and satellite imagery, we have revealed a region which possesses classic glacial geomorphic landforms, such as u-shaped valleys and cirques, that could only have been formed by a small ice cap, similar to those seen at present in the Canadian and Russian High Arctic. The region uncovered is, therefore, the site of ice sheet genesis in West Antarctica.”

Dr Ross concluded: “to me, this just goes to demonstrate how little we still know about the surface of our own planet. The discovery and exploration of hidden, previously-unknown landscapes is still possible and incredibly exciting, even now.”

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Ross N et al. 2014. The Ellsworth Subglacial Highlands: inception and retreat of the West Antarctic Ice Sheet. Geological Society of America Bulletin, 126 (3-15); doi: 10.1130/B30794.1