Sea ice in the North Atlantic. Image Credit: NASA

What is an Ice Age

Article Updated: 24 Dec , 2015


An Ice Age is a period of geologic time in which the Earth’s climate sees a dramatic drop in temperatures. This drop often is followed by larger ice fields in the Polar Regions. However even this basic definition does not fully explain what is an Ice Age. Ice Age while scientific is a blanket term for different types of glacial periods.

The most accurate use for Ice Age is geologic period of time that spans millions of years. As a matter of fact it is believed that Earth is in the middle of an Ice Age right now. You might think that is certainly doesn’t feel like one. That is because an Ice Age is more a relative term. It basically means it is much cooler now than in previous times in Earth’s geologic history. Shorter glacial periods like the one most people are familiar with also applies.

The first investigations into the origins of the Ice Age started in 1724 with Pierre Martel. As Monsieur Martel was on vacation in the Alps he came across villager who claimed the relatively out of place boulders in their region were brought down by ancient glaciers that extended much further than modern ones. This lead to further investigation as scientist started to look for evidence of ancient glaciers. As evidence and data started to be gathered geologists started to form theories about the Ice Age and how it came about.

Scientist from that time onward relied on different types of evidence to learn more about the Ice Age. The first is geologic evidence. As a glacier moves it alters the ground beneath it picking up sediments and rocks. The process helps to create unique geologic features such as valleys and glacial lakes. There are also visible trails of rock debris that most geologists can tell were not moved by normal means

The next type of evidence is chemical. By examining isotopes of sediment and cores of glacial ice scientists can learn more about the climate of a given geological period and whether the climate was much colder than the current one. This tends to be the most accurate for dating the time of ice ages through carbon dating and other time measurement methods

The last type of record is the most obvious and interesting. It is looking at the fossil record. There are many animals preserved in ice or whose bones are found that obviously would not have done well in a warmer climate. The most famous is the wooly mammoth and early mammalian predators like the Sabertooth tiger.

Learning more about the longer ice ages as well the shorter glacial periods is important to finding out more about how Earth’s climate changes over time. This is especially important as scientists seek to determine how much of modern climate change is manmade.

We have written many articles about the Ice Age for Universe Today. Here’s an article about the Little Ice Age, and here’s an article about Mars coming out of an Ice Age.

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.


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