Snowball Earth: Planet Covered in Ice

The Lascaux cave paintings in modern-day France date back to around 17,000 years ago, during a time of great upheaval on our planet. The world was then experiencing an intense ice age when snow and ice covered almost a quarter of the Earth's surface. This period would be the last major glacial maximum, and while it was tough for the paleolithic humans to survive, it was not impossible. There were still places that were not totally frozen, particularly the Southern parts of Europe, including Lascaux. Many humans would go there and seek refuge from the cold and regroup as they recorded their hunting expeditions.

However bad this last ice age was, geological clues found worldwide hint at an even harsher - and colder - time on Earth. About 500 million years before the artists at Lascaux painted their caves, the Earth might have been covered in snow. This theory is informally called "Snowball Earth" within the climate scientists community today, and if these total "global glaciations" did occur, how did it affect whatever lifeforms existed back then? Did anything survive? What circumstances led to this phenomenon, and how did it end?

Fast forward to 1913, when Australian geologist Douglas Mawson finally made it back to Australia after surviving a disastrous expedition to map the coastline of the Australian portion of Antarctica. As a Professor of Geology, he soon came up with the theory that ice must have once covered Australia to explain why mysterious rocks and other glacial-type sediments would turn up in the middle of the sun-baked Outback.

His theory was eventually shot down when science explained that plate tectonics caused them. But the idea of a prehistoric, ice-covered Australia stuck and evolved into an ice-covered planet, especially when other geological puzzles began to emerge. These include 650 million-year-old glacial deposits found in places that were once in tropical areas and "drop stones", or large pebbles that look like they were dropped from high ground and may have once been on top of icebergs that melted.

But if ice and snow covered the world, life would not have been able to survive at all. Or would it? It was thought that while many of the planet's cycles and processes stopped due to the frozen temperatures, the planet's interior tectonic activities continued, allowing earthquakes and volcanoes to erupt and forcing gases into the atmosphere leading to temperature changes and beyond.

These temperature swings could have served as "evolutionary triggers" that drove simple organisms, such as aquatic algae, out of the oceans to cross over and become land plants. These simple plants would have then evolved into more complex lifeforms; the rest is history.

"Snowball Earth" would have been one of the most difficult and challenging times on the planet, yet, if the theory is proven true, the Earth's still found a way to reinvent itself, and for the tenacity of life, it still found a way to evolve.