Name: Ancient Earth may have had Red Oceans
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How did oxygen escape from the oceans to form Earth’s atmosphere and create breathable air? Rust played a critical role in the process.

On Ancient Earth, rust deep in the oceans played a critical role in the formation of Earth

Ancient Earth May Have Had Red Oceans

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How did oxygen escape from the oceans to form Earth’s atmosphere and create breathable air? Rust played a critical role in the process.

On Ancient Earth, rust deep in the oceans played a critical role in the formation of Earth’s atmosphere.

On Ancient Earth, rust deep in the oceans played a critical role in the formation of Earth’s atmosphere.

Ancient Earth may have had Red Oceans

Planet Earth

Speaker 1This key that we see here is rusty. And in order to form rust, we need three ingredients. The first is iron, which is what this key is made of. The second is water or water vapor in the air. And the third crucial ingredient is oxygen.NarratorAnd in Earth's early oceans, oxygen began to react more and more with iron and other metals as cyanobacteria spread across the oceans.Below the surface, it's raining. As oxygen and iron interact, rust particles form in the water and sink down to the seabed, trapping the oxygen and iron to form solid rock at the bottom of the ocean. Vast swathes of the water turn red.Speaker 2There are many, many ingredients in the ocean at that time that would readily react with oxygen.Speaker 3So there was no way for atmospheric oxygen to build up to any significant level.NarratorA record of the reactions that happened long ago can be seen in formations today.Speaker 1This is a sedimentary rock, meaning it's made up of many different layers that were all deposited on the sea floor over millions of years.NarratorAnd this sample is evidence of how iron can react to form solid rock.Speaker 1This particular sedimentary rock is a banded iron formation. And we can see red color in the rock here. And that red is evidence of iron oxidation or rust.NarratorAs these reactions continued, the metals in the ocean water started to diminish, locked away in the sea floor.Speaker 4Eventually, the oceans would have been depleted of the things that would readily react with the oxygen that was being released.NarratorBut cyanobacteria continued to produce oxygen. For up to half a billion years, this oxygen has been trapped in the oceans. But now, increasing amounts are free to escape. Over just a few million years, oxygen floods into the atmosphere. The very composition of the atmosphere itself is changing.

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Ancient Earth May Have Had Red Oceans

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Ancient Earth

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