Cryogenian

The Cryogenian was a very old time in Earth's history. It happened from 720 to 635 million years ago. This was a part of what we call the Neoproterozoic, a time long before dinosaurs or humans lived.

During the Cryogenian, Earth had very cold weather. There were two big times of ice called the Sturtian and Marinoan glaciations. During these times, huge glaciers covered many parts of the planet. Some scientists think Earth might have looked like a big snowball covered in ice!

Even though it was very cold, life was starting to change. Tiny plants and animals began to appear in the oceans. These small creatures were important because they helped make the oceans a better home for other life. The Cryogenian helps us understand how Earth's climate and life have changed over millions of years.

The Cryogenian was named in 1990 by the International Commission on Stratigraphy. It is special because it marks a time when Earth went through big climate changes. Scientists study rocks from this time to learn more about our planet's past.