Sturtian glaciation

A long time ago, the Earth was very cold. Ice covered much of the world. This lasted for a very long time. It went on for 57 million years.

Rocks from this time are everywhere. You can find them in many lands. They are in Canada and China. They are in Africa too.

Some think the Earth was a snowball. This means ice was all over. This happened when big lands broke apart. This change made the world cold.

After the ice melted, life changed. New kinds of life began to grow. Life became more complex. It is a big part of our history.

A long time ago, the Earth was very cold. This was called the Sturtian glaciation. It lasted for about 57 million years. It began around 717 million years ago. It ended around 660 million years ago.

Some scientists think this was a Snowball Earth event. This means ice might have covered the whole world. Other people think it was just many regional ice ages. We know this happened because of special rocks. These rocks are found on every continent. You can find them in Canada and China. They are also in Australia and Ethiopia.

Rocks in Australia show how ice moved. They show the ice grew and then melted. This happened in cycles.

Why did it get so cold? One idea is about a supercontinent called Rodinia. This was a very large landmass. Rodinia began to break apart. This caused low levels of degassing. Degassing is when gases come out of the ocean floor. This change made the Earth very cold. After the ice melted, life changed. New fossils show that life became more complex.

The Sturtian glaciation was a very cold time for our planet. It happened during the Cryogenian Period. This event lasted for about 57 million years. It began around 717 million years ago. It ended around 660 million years ago. Scientists think it was a Snowball Earth event. This means ice might have covered the whole world. Other people think there were just many regional ice ages. It was a very severe and long glacial event. It is the longest one we know of in the geologic record after the Huronian glaciation.

We can see how this worked by looking at rocks. These rocks show how the ice moved. They show the ice grew and then melted. These are called advance and retreat cycles. The rocks show two major sequences of mudstone and diamictite. These rocks are found on every continent. You can find them in Canada and China. They are also in Ethiopia, Namibia, Siberia, and Svalbard. In Norway, there is a place called Reusch's Moraine. This might have been made during this cold time.

People have studied these rocks for a long time. Douglas Mawson and Reg Sprigg defined the term in 1950. They used it to describe a specific unit of rock. This helped scientists learn about ice ages in the Neoproterozoic era. The name comes from the Sturt Formation in Australia. This formation is in the Adelaide Superbasin. It is named after Sturt Gorge. That gorge is named after the Sturt River. A man named Captain Collet Barker named the river in 1831. He named it after Charles Sturt.

Why did the Earth get so cold? Scientists have a new idea about this. Researchers from the University of Adelaide and University of Sydney studied it in 2024. They used EarthByte computer models. They also used plate tectonic modelling. They think the cold came from the break-up of a supercontinent. This supercontinent was called Rodinia. As it broke apart, there was low degassing. Degassing is when gases come out of the ocean floor. This happened at mid-ocean ridges.

This cold time changed the world for living things. The ice eventually melted away. After the glaciation, life began to change. We can see this in fossils and biomarkers. These fossils show an increase in biological complexity. This means life became more complex. It is amazing to think how much the Earth changed. Even the rocks tell a story of a very different world. We use these clues to understand our history. This helps us see how our planet works today.

The Sturtian glaciation was a massive, global cooling event. It occurred during the Cryogenian Period of Earth's history. This event is one of the most significant in our planet's past. It is considered the longest and most severe glacial event in the geologic record, following the much earlier Huronian glaciation. Scientists debate exactly how cold the planet became. Some hypothesize it was a Snowball Earth event. This theory suggests ice may have covered the entire globe. Others suggest it consisted of multiple regional glaciations.

Geologists study this period by looking at specific rock sequences. The Sturtian succession includes two major diamictite-mudstone sequences. Diamictite is a type of rock formed from unsorted sediment. These sequences represent cycles of glacial advance and retreat. An advance occurs when ice sheets grow and move forward. A retreat occurs when the ice melts and moves back. These rocks show how the climate shifted over long periods. In North America, this succession is correlated with the Rapitan Group.

Evidence of this glaciation is found on every single continent. Notable geological sections exist in Australia, Canada, China, and Ethiopia. You can also find evidence in Namibia, Siberia, and Svalbard. In northern Norway, a feature called Reusch's Moraine may have formed during this time. In Australia, the Sturtian glaciogenic succession sits unconformably over the Burra Group. This means there is a gap in the rock record between them. The ice sheet advance at the start of the glaciation lasted less than one million years.

The name for this period comes from the Sturt Formation. This formation is located within the Adelaide Superbasin in Australia. The name honors Sturt Gorge and the Sturt River. Captain Collet Barker named the river in April 1831. He named it after the explorer Charles Sturt. In 1950, Douglas Mawson and Reg Sprigg defined the term. They originally used it as a chronostratigraphic unit. This helped researchers study the Neoproterozoic era. This research eventually led to the Snowball Earth hypothesis.

Scientists are still discovering why this glaciation happened. In 2024, researchers from the University of Adelaide and University of Sydney proposed a new idea. They used plate tectonic modelling and EarthByte computer models. They believe the extreme cold resulted from the break-up of a supercontinent called Rodinia. As Rodinia broke apart, it changed the activity at mid-ocean ridges. This led to low levels of degassing. Degassing is the process where gases are released from the Earth's interior. This reduction in gases likely caused the drop in temperature.

The timing of this event is very specific. The Sturtian glaciation lasted for approximately 57 million years. It is thought to have begun around 717 Ma. It lasted until about 660 Ma. The "Ma" stands for millions of years ago. This was the older of two worldwide glacial events in the Cryogenian. The other event is known as the Marinoan or Elatina glaciation. Understanding these exact dates helps scientists map the history of Earth's climate.

This period of ice had a profound effect on life. Although the ice was severe, life continued to change. In the aftermath of the glaciation, scientists found new clues. They identified biomarkers, which are chemical signatures of life. They also found body fossils. These biological clues indicate an increase in biological complexity. This means that life became more intricate and varied after the ice melted. The transition from the Sturtian glaciation helped shape the future of biological evolution on Earth.