纪录片《地球劫难日》 第13期 界线层（在线收听）

The Permian rocks lie just below the next geological period, the Triassic.

二叠纪岩层的上方自然是下一个地质年代，三叠纪。

This is the Permian/Triassic boundary, the boundary between the Permian rocks below us and the Triassic rocks above us,

这就是二叠系-三叠系界线层，这个界线层是在我下方的二叠纪岩层和我上方的三叠纪岩层之间，

and this is the boundary where the mass extinction takes place.

这个界线层就是生物大灭绝发生的时期。

What we're trying to do here is to determine

我们在此的工作就是测定

how long it took for the sediments at the boundary in which the mass extinction took place to be deposited.

在这个发生大灭绝的地层中的沉淀物的堆积经过了多长时间。

Rampino's system relied on the observation that the earth's orbit round the sun alters minutely every 23,000 years.

Rampino的系统依赖一个现象，即地球围绕太阳运行的轨道每隔23000年就会发生微小的改变。

This produces small changes in the climate.

这也导致气候发生些许变化。

This, in turn, produces distinctive bands in the rock one every 23,000 years.

继而造成每隔2.3万年形成一个独立的岩层。

Rampino took photos of the rock bands and fed them into a laptop.

Rampino拍下了岩层的照片，并把它们输入手提电脑。

When I digitally enhance the photographs, I can manipulate the data to bring out the 23,000 year cycle,

我增强照片的分辨率，通过分析数据我就能找出2.3万年的周期，

and that gives me a time-frame in which to put the mass extinction.

由此我也能找出大灭绝发生的时段。