The world's largest canyon may lie under the Antarctic ice sheet, according to analysis of satellite data by a team of scientists, led by Durham University.Although the discovery needs to be confirmed by direct measurements, the previously unknown canyon system is thought to be over 1,000 km long and inplaces as much as 1km deep, comparable in depth to the Grand Canyon in USA, but many times longer.
The canyon system is made up of a chain of winding and linear features buried under several kilometres of ice in one of the last unexplored regions of the Earth'sland surface: Princess Elizabeth Land (PEL) in East Antarctica. Very few measurements of the ice thickness have been carried out in this particular areaof the Antarctic, which has led to scientists dubbing it one of Antarctica'stwo 'Poles of Ignorance'.
The researchers 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.
Althoughnot visible to the naked eye, the subglacial landscape can be identified in the surface of the ice sheet.
Faint traces of the canyons were observed using satellite imagery and small sections of the canyons were then found using radio-echo sounding data, where by radio waves are sent through the ice to map the shape of the rock beneath it. These are very large features which appear to reach from the interior of Princess Elizabeth Land to the coast around the Vestfold Hills and the West Ice Shelf.
The canyons may be connected to a previously undiscovered subglacial lake as theice surface above the lake shares characteristics with those of large subglacial lakes previously identified. The data suggests the area of the lake could cover up to 1250km², more than 80 times as big as Lake Windermere in the English Lake District.
An airborne survey taking targeted radio-echo sounding measurements over the whole buried landscape is now underway with the aim of unambiguously confirming the existence and size of the canyon and lake system, with results due later in 2016.
Lead researcher, Dr Stewart Jamieson, from the Department of Geography at Durham University in the UK, said: "Our analysis provides the first evidence thata 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.
"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."
1 canyon
n.峡谷，溪谷
参考例句：
• The Grand Canyon in the USA is 1900metres deep.美国的大峡谷1900米深。
• The canyon is famous for producingechoes.这个峡谷以回声而闻名。
2 previously
adv.以前，先前（地）
参考例句：
• The bicycle tyre blew out at a previouslydamaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explainwhat had happened previously.让我岔开一会儿，解释原先发生了什么。
3 winding
n.绕，缠，绕组，线圈
参考例句：
• A winding lane led down towards theriver.一条弯弯曲曲的小路通向河边。
• The winding trail caused us to lose ourorientation.迂回曲折的小道使我们迷失了方向。
4 dubbing
n.配音v.给…起绰号( dub的现在分词 )；把…称为；配音；复制
参考例句：
• There are mainly two forms of filmtranslation: dubbing and subtitling. 电影翻译通常主要表现为两种形式：配音和字幕翻译。 来自互联网
• Its auspices, dubbing the program has wonnational awards in China. 其主持配音的节目多次获得中国全国奖项。来自互联网
5 eroding
侵蚀，腐蚀( erode的现在分词 )； 逐渐毁坏，削弱，损害
参考例句：
• The coast is slowly eroding. 海岸正慢慢地被侵蚀。
• Another new development is eroding theage-old stereotype of the male warrior. 另一个新现象是，久已形成的男人皆武士的形象正逐渐消失。
6 canyons
n.峡谷( canyon的名词复数 )
参考例句：
• This mountain range has many high peaksand deep canyons. 这条山脉有许多高峰和深谷。来自辞典例句
• Do you use canyons or do we preserve themall? 是使用峡谷呢还是全封闭保存？
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