纪录片《恐龙灭绝真相》 第16期 海绿石

In other words, Stinnesbeck thought the rock had been formed slowly, by sedimentation¹.

也就是说，Stinnesbeck认为岩石是因为缓慢的沉积作用形成的。

There must have been a long time, between the impact below the core and the arrival of the Iridium at the top.

所以岩芯下的碰撞坑和顶部的铱元素层必然间隔了很长一段时间。

Then they noticed something else in the core.

后来他们在岩芯中又有了其它发现。

Traces of what looked like a green clay mineral.

看上去像是某种绿色粘土矿物的痕迹。

Samples were sent for analysis by a technique called x-ray diffraction.

样本经过了一种叫做X射线衍射技术的分析。

Every mineral has its own unique signature when exposed to x-rays.

在X光下，每种矿物都有其独特的标记。

The analysis revealed a clay mineral called Glauconite, and Glauconite has one vital characteristic.

分析显示这是一种叫做海绿石的粘土矿物，而海绿石有一个重要特征。

Glauconite needs many thousands of years to form,

海绿石需要上万年才能形成，

so it's indicating interruptions in the sedimentation of this limestone²,

它表明这些石灰岩的沉积过程曾经中断过，

so it extends even more the time, the period of time which is needed for the deposition³ of this limestone.

因此这些石灰岩的沉积形成时间可能更长。

1 sedimentation   

n.沉淀，沉积

参考例句：

• Sedimentation, the damage of a breach are problems, too. 而且沉积和决口的问题，也是存在的。 来自英语晨读30分（高二）
• Sedimentation and denudation play a role in exceptional cases. 沉积和剥蚀作用的影响只在特殊情况下起作用。

2 limestone   

n.石灰石

参考例句：

• Limestone is often used in building construction.石灰岩常用于建筑。
• Cement is made from limestone.水泥是由石灰石制成的。

3 deposition   

n.免职，罢官；作证；沉淀；沉淀物

参考例句：

• It was this issue which led to the deposition of the king.正是这件事导致了国王被废黜。
• This leads to calcium deposition in the blood-vessels.这导致钙在血管中沉积。