纪录片《恐龙灭绝真相》 第07期 寻找陨石坑（在线收听）

Alan Hildebrand who was based in Calgary in western Canada, was determined to be the one to discover the crater.

Alan Hildebrand一直在加拿大西部的卡尔加里从事研究，他一心想找到这个陨石坑。

He knew the spherule layers should be thicker, the nearer he got to the crater itself...

他知道，越接近陨石坑，小球体层就应该越厚，

so he followed the trail of the spherules.

于是，他开始追寻小球体的踪迹。

Here in western Canada we have a layer at the Cretaceous-Tertiary boundary,

在加拿大西部的这个地方，我们找到了处于白垩纪的第三纪界线层，

it's about one centimetre thick on average.

它平均有1厘米厚。

In Colorado and New Mexico it's two or two and a half centimetres thick.

但在美国的科罗拉多和新墨西哥，它的厚度有2-2.5厘米。

Still further south in the Caribbean as in Haiti it's about a half metre thick

往南直到加勒比海的海底，厚度又达到了半米左右，

so by nineteen eighty nine we knew that the source crater had to be somewhere between North and South America.

所以在1989年，我们推测陨石坑一定就在北美洲和南美洲之间的某个地方。

Then Alan Hildebrand had a stroke of luck.

不久，Alan Hildebrand的好运来了。

He happened to be looking at an old oil company map,

他无意中看到了一幅石油公司的老地图，

he was looking at the Yucatan Peninsula in Mexico, near a village called Chicxulub, then he noticed something odd.

他在研究墨西哥的尤卡坦半岛时，在一个叫做希克苏鲁伯的小村庄附近他注意到了一些奇怪的东西。

This is when I spotted: a horseshoe shape feature, we can see it better on this map.

我发现的就是这个：一个马蹄铁形的地貌，用这张地图可以更清楚地看到它。

The anomaly is a hundred and eighty kilometres across

这个特别的地方有180公里宽，

which was in the range of sizes predicted for this crater

这正好符合对陨石坑大小的推测，

and laying on the Yucatan Peninsula, between North and South America,

它位于尤卡坦半岛上，在南北美洲之间，

it's within the region where the ejecta thickness says the crater should lie.

这个地区的火山喷出物也表明了陨石坑的存在。

So this suggested that this might indeed be the crater that killed the dinosaurs.

这些都说明它极有可能就是导致恐龙灭绝的那个陨石坑。