According to an analysis of satellite data published last month in the journal Geology, the world’s largest canyon system and a large lake may lie under the ice sheet in Princess Elizabeth Land, East Antarctica.
Although the discovery needs to be confirmed by direct measurements, the previously unknown canyon system is comparable in depth to the Grand Canyon, but many times longer. It is thought to be over 685 miles (1,100 km) long and in places as much as 0.6 mile (1 km) deep.
The canyon system is made up of a chain of winding and linear features buried under several miles of ice in Princess Elizabeth Land (PEL), one of the last unexplored regions of the Earth’s land surface.
“The subglacial landscape of Princess Elizabeth Land is poorly known due to a paucity of ice thickness measurements,” said lead author Dr Stewart Jamieson, of Durham University, and his colleagues from UK, the United States, Australia, and China. “This is problematic given its importance for understanding ice sheet dynamics and landscape and climate evolution.”
“To address this issue, we describe the topography beneath the ice sheet by assuming that ice surface expressions in satellite imagery relate to large-scale subglacial features.”
Dr Jamieson and co-authors believe that the landscape beneath the ice sheet has probably been carved out by water and is either so ancient that it was there before the ice sheet grew or it was created by water flowing and eroding beneath the ice.
“We find evidence that a large, previously undiscovered subglacial drainage network is hidden beneath the ice sheet in PEL. We interpret a discrete feature that is 87 x 12.4 miles (140 x 20 km) in plan form, and multiple narrow sinuous features that extend over a distance of 685 miles,” the scientists said.
The presence of the deep canyons is confirmed at a few localities by radio-echo sounding data, and drainage analysis suggests that these canyons will direct subglacial meltwater to the coast between the Vestfold Hills and the West Ice Shelf.
“Linked to the canyons, a large subglacial lake may exist that may be the last remaining large (more then 62 miles in length) subglacial lake to be discovered in Antarctica,” they said. The data suggests the area of the lake could cover up to 1,250 sq.km.
“Discovering a gigantic new chasm that dwarfs the Grand Canyon is a tantalizing prospect,” said co-author Prof. Martin Siegert, of Imperial College London.
“Our analysis provides the first evidence that a huge canyon and a possible lake are present beneath the ice in Princess Elizabeth Land. It’s astonishing to think that such large features could have avoided detection for so long,” Dr Jamieson said.
“This is a region of the Earth that is bigger than the UK and yet we still know little about what lies beneath the ice. In fact, the bed of Antarctica is less well known than the surface of Mars. If we can gain better knowledge of the buried landscape we will be better equipped to understand how the ice sheet responds to changes in climate.”
“Antarctic scientists have long recognized that because the way ice flows, the landscape beneath the ice sheet was subtly reflected in the topography of the ice sheet surface. Despite this, these vast deep canyons and potential large lake had been overlooked entirely,” said co-author Dr Neil Ross, of Newcastle University.
Stewart S.R. Jamieson et al. An extensive subglacial lake and canyon system in Princess Elizabeth Land, East Antarctica. Geology, published online December 22, 2015; doi: 10.1130/G37220.1
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