The discoveries, made with the help of ice-penetrating radar during an aerial survey of the polar region, came as a surprise to the scientists.
"We expected to find mountainous subglacial topography, but the size of the troughs did come as a surprise because we had no indication that they were there," Dr. Kate Winter, a research fellow at Northumbria University in the U.K. and the lead author of a paper about the discoveries published in the journal "Geophysical Research Letters," told NBC News MACH in an email.
The biggest of the three canyons, named Foundation Trough, is more than 20 miles wide and spans a distance of more than 215 miles, or roughly the distance from Washington, D.C. to New York City. Patuxent Trough spans more than 180 miles while the Offset Rift Basin spans more than 90 miles.
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If the canyons are big, so are their possible environmental implications.
Global warming could cause the polar ice sheet to thin, and the size and orientation of the canyons could speed the rate at which ice flows from the center of the continent to the sea — a phenomenon that would raise global sea levels and possibly lead to the flooding of coastal areas around the world.
"By mapping these deep troughs and mountain ranges we have therefore added a key piece of the puzzle to help understand how the East Antarctic Ice Sheet may have responded to past change and how it may do so in the future," Fausto Ferraccioli, principal investigator of PolarGAP, a European Space Agency-funded project that provided the data for the discoveries, said in a written statement.
The discoveries also seem to have surprised Dr. Robin Bell, a glaciologist at Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York. It's "still amazing that there are pieces of out planet we do not even know what the topography looks like," she said in an email to MACH. "We are all used to popping open Google Earth or even Zillow to see what things look like. In Antarctica the ice hides everything."
Bell likened the canyons to "long valleys carved by ice sheets like ruts from a mountain bike."
The research marks the first release of data from PolarGAP, which aims to fill in topological information about the area around the South Pole.
Although there is ample satellite data about other areas of the planet, there has long been a gap in data around the pole because few satellites pass over the area. To fill in the gap, radar-equipped Twin Otter airplanes operated by the British Antarctic Survey were flown over the region in 2015 and 2016.