纪录片《地球劫难日》 第13期 界线层

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 extinction¹ 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 sediments² 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 distinctive³ 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。

1 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

2 sediments   

沉淀物( sediment的名词复数 )； 沉积物

参考例句：

• When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
• Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。

3 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。