評論
打印
The arguments are so bitter because Gerta Keller has re-opened the case which most others considered closed.
辯論相當激烈，因為Gerta Keller又重新提起了大多數人認為已經蓋棺定論的事件。
In doing so she has sparked a scientific civil war.
由此，她的行為引發了一場科學論戰。
And all because she questioned the accepted theory about what wiped out the dinosaurs.
而這一切都源于她對早已公認的恐龍滅絕原因提出了質疑。
Scientists began to investigate a layer of rock formed sixty five million years ago.
科學家們開始調查6500萬年前形成的巖石層。
It's seen in mines and rock outcrops around the world.
它們遍布世界各地裸露地表的礦藏和巖石中。
Below this layer there are lots of dinosaur fossils, above it there are none. It's called the KT boundary.
這個地層下面埋藏著許多恐龍化石，而它的上面卻沒有。這個地層被稱作第三紀界線層。
This is the KT boundary, and because it's such a thin, sharp line
這就是第三紀界線層，由于它是一條窄而清晰的地層，
we know something dramatic must have happened here, some catastrophe
我們斷定當時發生過一些劇烈事件，某種大災難，
and until recently we have almost no clue what happened whatsoever here, so it remained a total mystery.
但直到最近我們都還沒有發現有關真相的線索，所以它仍然還是個謎。
Then in 1979 they discovered a clue in the KT boundary.
后來在1979年，他們在第三紀界線層中發現了相關線索。
A high concentration of an element called Iridium.
極高濃度的銥元素。
Such quantities are extremely rare on earth and usually come from outer space.
這種元素在地球上極其稀少，一般都來自外太空。
So as soon as you find ten thousand times more Iridium at the very moment when the dinosaurs disappear,
我們發現銥元素濃度比平常高1000倍，而正是在這個時候恐龍消失了，
you know somewhere on earth a very big impact must have happened by an asteroid or a comet.
所以推測地球上某個地方一定發生了由小行星或彗星造成的大碰撞。
