For my first blog post I wanted to talk about how our beautiful oceans came into being. The oceans make up about 2/3 (or 70%) of the Earth’s surface. However, the Earth itself is much older than the oceans that have formed on it. That’s right! About 4.5 billion years ago, this planet was a dust bowl. It wasn’t until around 3.8 billion years ago that the oceans started to form. So how did that happen?
Well, there are a two main theories out there regarding how these bodies of water came into being. The first one is a theory that, when the Earth was formed, water was part of the process. But the water itself came from deep within the Earth. So the belief is that the water was always there, it just needed time to rise to the surface and gather into pools that would continue to grow.
The second theory is that the Earth was not formed with water at all. So where on Earth did all of that water come from? It is believed that water was brought to this planet via other sources as they crossed our planet’s path when it was very young.
The majority of science follows the first theory though, so let’s have a look at that. Earth was believed to be a boiling hot and arid planet when it started out. Materials and gases where trapped in its atmosphere but it was far too hot for any liquid water to form. It would have just boiled away into steam and gas again.
However, over time the Earth started to cool. Once temperatures hit below boiling point, all of that water vapour began to fall as rain. It is said that it continued to fall for centuries. As it did this, water was able to remain in its liquid state on the ground, draining into all of the Earth’s hollows until they grew into what we know as our oceans today. It’s the force of gravity that keeps our oceans from departing from this planet.
All of those billions of years ago, the seas more than likely covered our entire planet and reached depth unknown as water kept falling and collecting. It wasn’t until things settled a bit and geological processes started to take over to raise the lands that would shape and divide this huge body of water covering the planet.
It was the tectonic plates and a lot of shifting that played a big role in shaping the surface of the Earth and its oceans. It was around 120 millions years ago that the oceans we know as the Pacific, Indian and Atlantic took shape as landmasses broke apart.
One aspect of the formation of the oceans, that remains partly misunderstood, is how each ocean got its specific characteristics, like its salt content. Where did all of that salt come from? The theory here is that it was the volcanic activity releasing huge amounts of chlorine into the Earth’s atmosphere alongside water in its vapour state combining to create hydrochloric acid. When hydrochloric acid fell back to the ground trapped in rainwater it would flow over the Earth’s surface. This acidic mix would strip away at the rocks and strip out the salts along the way, sodium in particular. When the atoms of sodium mixed with chlorine atoms it created what is now known as our common table salt, sodium chloride. This is the primary salt content found in the oceans today.