評(píng)論
打印
Listen to part of a lecture in an Earth Science class. The class has been discussing volcanoes.
請(qǐng)聽地球科學(xué)課上的部分內(nèi)容。這節(jié)課討論的是火山。
Okay. We know the Earth’s surface, the crust, is made up of tectonic plates,
我們知道地球的表面也就是地殼是由地殼板塊構(gòu)成的，
and that these huge slabs of rocky crust are slowly sliding over or under or past each other.
這些巨大的巖殼慢慢地滑到彼此上方或下方，或滑過對(duì)方。
And we said that most of the world’s volcanoes occur at the boundaries of these tectonic plates
我們說世界上大部分的火山都是在這些地殼板塊的交界處噴發(fā)的，
where you have hot molten rocks squeezing up through gaps between the plates.
在這些地方熔化了的炙熱巖石通過這些板塊之間的裂縫不斷擠壓上涌。
But some volcanoes occur not at the edges, but in the middle of a continental or oceanic plate.
但是有一些火山不在邊緣處噴發(fā)，而是在一個(gè)大洲或海洋板塊的中央噴發(fā)。
The Hawaiian islands, for example, are thousands of kilometers away from any plate boundary, and yet
舉個(gè)例子來說，夏威夷群島距離任一板塊界線都有數(shù)千公里遠(yuǎn)，但
you have vast amounts of magma, molten rock or lava, flowing up through the earth’s crust, which means, of course,
卻有巨大數(shù)量的巖漿穿過地殼噴涌而出，這無疑意味著
that volcanic activity there can’t be explained simply by plate tectonics.
那里的火山活動(dòng)不能簡單地用板塊構(gòu)造論來解釋。
So, how do we explain these volcanic anomalies, these exceptions to the general rule?
那么，我們?cè)撊绾谓忉屵@些異常的火山，這些一般規(guī)則的例外呢？
Well, back in 1963, a geophysicist by the name of Wilson came up with a hot spot theory
在1963年，一位叫做Wilson的地球物理學(xué)家提出了一個(gè)熱點(diǎn)理論
to explain how this particular type of volcanic activity can occur and can go on for maybe tens or even hundreds of millions of years.
來解釋這種類型的火山活動(dòng)是如何發(fā)生并持續(xù)數(shù)千萬年甚至數(shù)億年的。
