GO_Ocean Formation Lesson
Have you ever wondered how our vast and shimmering oceans came into existence? It's easy to assume they've always been there, but that's not quite the case. The story of our oceans is a tale of billions of years of change.
Picture this: Earth, about 4.5 billion years ago. There were no oceans as far as the eye could see. Why? Because our planet was sizzling hot – way too hot for water to exist in liquid form. But as time passed, Earth began to cool below the boiling point of water (that's 212 degrees Fahrenheit, by the way). This cooling allowed our early oceans to take shape around 3.8 billion years ago, as atmospheric water vapor condensed and rained down into the Earth's basins.
Watch the following video: How the Earth Got its Oceans.
Now, you might be wondering where all this water came from in the first place. Well, that's a topic of debate among scientists.
It wasn't as easy as filling up a pool or a bathtub.
Nobody just turned on the faucet and filled up the oceans.
Some think volcanic activity might have released water vapor and gases from within the Earth, while others believe icy comets might have delivered it when they smacked into our young planet. The truth could be a mix of these theories and the idea that a colossal collision event, which also formed the moon, played a role.
Now, let's shift our gaze beneath the ocean's surface. The ocean isn't just a static feature; it's a dynamic part of our planet. And it owes some of its dynamism to what's happening below – tectonic plates. While we will talk about plate tectonics in a later lesson, let’s explore how these plates shape the ocean.
Think of it this way: some parts of the ocean floor are spreading apart, while in other areas, it's contracting.
Where these plates meet, deep beneath the waves, you'll find something fascinating – the Mid-Atlantic Ridge. It's like an underwater mountain range running through the middle of the Atlantic Ocean. Here, magma from Earth's mantle surges and cools underwater, creating a brand-new ocean crust. It's spreading at a rate of a couple of centimeters yearly – not exactly a speed record, but over millions of years, it's a game-changer.
Imagine pulling a piece of Play-Doh apart until it forms a thin spot in the middle – that's a bit like what's happening with tectonic plates. As they move apart, the ocean floor expands. The low points naturally fill with water because gravity guides it there. So, as you keep "pulling" the Play-Doh apart (or, in this case, the tectonic plates), the ocean gets wider and wider.
On the flip side, the Mediterranean Sea basin is doing the opposite – it's getting smaller and contracting over time. But here's the catch, all of these changes occur on a timescale way longer than a human lifetime. The movement of a tectonic plate is about as slow as your fingernail growing, practically invisible to us. Yet, these slow movements shape our ever-changing oceans over millions of years.
Test your knowledge with the practice below.
The oceans were formed billions of years ago due to the cooling of the planet and the condensation of water vapor. Scientists still debate the origin of water on Earth. Furthermore, the ocean floor is constantly changing due to the movement of tectonic plates, which can create a new ocean crust and expand the ocean.
UP NEXT: Plate Tectonics
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