By charting an ancient mountain range buried far beneath Antarctic ice, scientists have uncovered a subglacial trough deeper than the Grand Canyon.

For three seasons now, UK researchers have used data from satellites and ice-penetrating radars to map the Ellsworth Subglacial Highlands located in Western Antarctica. In doing so, they uncovered a 3 kilometer-deep, 300 kilometer-long valley carved millions of years ago by an icefield similar to those seen today in Alaska, Arctic Canada and the Antarctic Peninsula. Up to 25 kilometers wide at some place, the valley plunges to more than 2,000 meters below sea level at times. The Grand Canyon, in contrast, is less than 2 kilometers deep at its deepest point. 

Published in the Geological Society of America Bulletin, the study included researchers from Newcastle University, the University of Bristol's Glaciology Center, the British Antarctic Survey and the universities of Edinburgh, Exeter and York.

The analysis is the most detailed look yet at the thickness, behavior and overall size of the ancient icefield. It also provides a look back in time at the layout and behavior of the early West Antarctic Ice Sheet, the subglacial landscape revealing where and how it began and grew. Clues as to what the ice sheet may resemble in a warmer climate are also embedded in the buried landscape and its analysis.

"The discovery of this huge trough, and the characterisation of the surrounding mountainous landscape, was incredibly serendipitous," Neil Ross, the study's lead author and a researcher from Newcastle University said.

The scientists gathered radar data from each end of the valley but couldn't tell what lay in between. Satellite data ultimately connected the dots as the valley's size makes it visible from space - despite being buried beneath layer after layer of snow and ice.

The study is not the first to report the presence of an ancient world kept hidden by ice. In August, researchers announced the discovery of a canyon stretching 740 kilometers long and nearly 10 kilometers wide beneath the Greenland ice sheet. The canyon, which measures more than 800 meters deep in some places, is thought to predate the ice sheet that has existed for millions of years.

Of the latest study, Ross said: "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."