英语听力:自然百科 澳大利亚大堡礁 Great Barrier Reef—12(在线收听) |
All lava has a chemical signature that tells scientists where it came from and when it was erupting.” The higher up the old volcano, the more pristine the rocks will be. They are the last remaining evidence of the eruption which created this volcano more than 23 million years ago. Only these rocks can reveal the full picture.
Five hundred feet up, and Will's finally got the sample.
“Now I got to figure out a way to get down.”
Analysis of the rocks from the Glasshouse Mountains and Mount Warning reveals something amazing. The lava in these two mountains, 100 miles apart, comes from the same place. How?
The answer lies in an incredibly rare geological phenomenon. Deep below Australia, in the Earth’s molten interior is a hot spot, a mysterious area of liquid rock. It's hot enough to punch fresh lava all the way to the surface. But there is something very special about hot spots, something that allows them to reveal the story of Australia's past. Because hot spots don't move, but continents do, sliding right over.
This chain of mountains is a record of that movement. Tens of millions of years old, it proves that Australia has been moving northeast all the way from Antarctica, and about five inches every year and that makes it the fastest-moving continent on the planet.
Fifty million years ago, Australia was near the South Pole. Cold water and the darkest of winters, conditions no coral could survive, but then it began to move north. |
原文地址:http://www.tingroom.com/lesson/zrbaike/2011/259920.html |