These were, at their maxima, among the most extensive glaciations in the Earth's history.

在顶峰时期，们是地球史上最大规模冰川时期。

For one thing, 2.6 million years ago marked the beginning of the Pleistocene, when cooler temperatures and long periods of glaciation began to set in -– also known as the Ice Ages.

首先，260万年前标志着更新世开始，当时气温变凉，长时间冰川期开始——也就是所谓冰河时代。

Yuka, what do we typically see in populations of animals isolated by glaciation?

由冰川隔离动物群中，我们通常会么情况？

Even below the waters of the lake the rock in some places is still grooved and polished; the lapping of the waves and their disintegrating action have not as yet obliterated even the superficial marks of glaciation.

即使在湖水以下，一些地方岩石仍然有凹槽和抛光；海浪拍打和们分解作用甚至还没有消除冰川作用表面痕迹。

And as the 1978 review about glaciation illustrates, this importance did not appear prominently in discussions of the last ice ages.

正如1978年关于冰川作用综述所表明，重要性在讨论最近一次冰河时代时并未得充分体现。

Like, you know, we went into a period of glaciation where the pretty much the entire planet was under ice.

就像你知道，地球进入了一个冰川期，几乎整个星球都被冰雪覆盖了。

Around 34 million years ago, the Eocene-Oligocene Transition  marked the first major period of global cooling and glaciation.

大约 3400 万年前，始新世-渐新世过渡标志着全球变冷和冰川作用第一个主要时期。

Like, some things could massively harm the Earth, like comet impacts and things like that, or glaciation events.

有些事情可能对地球造成巨大伤害，比如彗星撞击之类事件，或是冰期现象。

Erosion did not stop with the end of glaciation.

侵蚀并没有随着冰川作用结束而停止。

Then a period of glaciation Locked up lots of Earth's water, which dramatically lowered sea levels.

然后一段冰川期锁住了地球上大量水分，极大地降低了海平面。

The end of the Devonian shows signs of a rapid swing from greenhouse to a sudden glaciation and then back again, a see-sawing of climate that could be responsible for many of the extinctions.

泥盆纪末期显示出从温室效应迅速转变为突然冰川作用然后再逆转迹象，气候摇摆可能是许多灭绝事件原因。

And then there are a bunch of sort of geological things that can happen, like glaciation events or axial tilt changes or weird plate tectonics.

然后还有一些地质事件可能会发生，比如冰川期、地轴倾斜变化或奇怪板块构造运动。

Like, that could get bad, although we've had glaciation events during human history, right?

就像，那可能会很糟糕，尽管在人类历史上发生过冰川期，对吧？