- Who
- Denman Glacier canyon
- What
- 3,500 metre(s)
- Where
- Antarctica ()
- When
A high-precision mapping project of the bedrock lying beneath the Antarctic Ice Sheet, known as "BedMachine Antarctica", has revealed an ice-filled trench under the Denman Glacier in East Antarctica that reaches more than 3,500 metres (11,500 feet) below sea level – some 2,000 metres (6,560 feet) deeper than previously estimated. The findings were reported in the journal Nature Geoscience on 12 December 2019. There are submarine trenches that go far beyond this (such as the Challenger Deep in the Pacific Ocean, the deepest point on Earth, at almost 11 kilometres (7 miles) below sea level), plus there are gorges with a greater vertical extent – i.e., higher walls (such as the Yarlung-Zangbo Canyon in Tibet), but no other known point on land descends to a lower elevation than this subglacial trough.
Previous attempts to sound the bed of the valley using primarily airborne radar had failed owing to "side echoes" from the walls that masked the trough's full depth. The "BedMachine" project, which began in 2014, circumvented this issue by combining comprehensive radar data (dating back to 1967) along with satellite-derived ice flow motion data to create the most detailed map of Antarctica's subglacial topography ever produced.
The deepest exposed land on Earth, meanwhile, is the shore of the Dead Sea which reaches only c. 413 m (1,355 ft) below sea level.
The research was led by Dr Mathieu Morlighem of the University of California, Irvine (USA) in collaboration with University of Texas at Austin, Ohio State University, University of Kansas, California Institute of Technology (all USA); Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Federal Institute for Geosciences and Natural Resources (both Germany); the British Antarctic Survey, Northumbria University (both UK); Technical University of Denmark (Denmark); National Centre for Polar and Ocean Research (India); Polar Research Institute of China (China); Korea Polar Research Institute (South Korea); Norwegian Polar Institute (Norway); Université libre de Bruxelles (Belgium); University of Tasmania (Australia); and Utrecht University (Netherlands).
