雅思考试的每一部分都不是容易的,听力,口语,阅读,写作,都是一点点的积累,然后运用之。阅读题最是展现你词汇量,逻辑理解的时候了,平时的阅读积累就显得尤为重要,多看多读多练习。下面是有出国留学网为你整理的《雅思阅读考前必看:Tilt of continent》,希望对你的雅思考试有所参考价值,考出一个好的成绩。
雅思阅读:Amazon River shaped by see-saw tilt of continent
SOUTH AMERICA'S AMAZON RIVER Basin was a vast wetland for millions of years. That was until tectonic processes deep in the Earth transformed it into the world's largest drainage system, new research suggests.
Geoscientists from the University of Sydney and the California Institute of Technology believe a process called 'continental tilting', which began about 30 million years ago and continued for about 16 million years, tipped South America like a see-saw and drained its wetlands.
The event, funnelled water over 6400 km east to the Atlantic Ocean in what the team describes as the world's largest water slide. "What we're describing involves the whole continent," lead author Grace Shephard told Australian Geographic. "This tilting led to the formation of the Amazon River as we know it today."
Sinking slabs
The team used computer simulation to demonstrate the continent's movement across a subduction zone, where slabs of the Earth's crust sink into the softened rocks of the mantle, causing it to tilt. With time, as South America moved further west of these sinking slabs, the northeast subsided by up to 400 m, while the west was uplifted.
"We had a hunch ...