How Did The Earth Become Seven Separate Continents?

Introduction

Have you ever wondered how the Earth became seven separate continents? When the Earth started, it didn't look the same way it does today, and it will continue to change over time.

Keep reading to find out how the Earth looked long ago and why it is always changing.

One Big Supercontinent

German scientist Alfred Wegener thought of the idea of a supercontinent, which was all seven continents combined into one big piece of land called Pangaea. (Pan-jee-uh)

The idea made sense when looking at a map, because the borders of all seven continents fit together like a big jigsaw puzzle. Wegener developed a theory that all of these continents were once joined together as one supercontinent.

There were other clues as well. For example, the Atlantic Ocean and Indian Oceans separate continents.

The continents of Africa and South America are thousands of miles apart, and yet the shapes of these continents fit perfectly together. But there are also matching rocks and matching fossil evidence on both continents thousands of miles apart from each other. This gives a clue that these continents used to be joined together but have drifted apart from each other over time.

Layers of the Earth

Before you learn about how the continents moved, you need to understand how the Earth is made.

The Earth is divided into four main layers: the inner core, the outer core, the mantle, and the crust. The crust is the outer layer of the Earth. It is made of a thin layer of soil on top of rock. All of the land masses and continents of the Earth (as well as all of the people, animals, and plants) are found on the Earth's crust.

Think of the Earth like a giant egg. The Earth's crust is like the eggshell. Now think of the eggshell having lots of cracks all over it. The Earth's crust is divided into lots of broken pieces. These broken pieces of the Earth's crust are called plates.

The Plate Tectonic Theories

Over the last billions of years Earth’s plates have shifted away from each other. The theory of plate tectonics claims that the Earth’s surfaces are slowly shifting away right below our feet.

Plate tectonics is a theory that explains how the Earth's crust is made up of large broken pieces called tectonic plates. The plates don't stay in one place, but instead they move around because of current in the Earth's mantle.

Earthquakes and volcanoes happen in the places where the edges of the tectonic plates bump into each other or pull apart. Mountains are formed when the plates squeeze into each other and push upwards.

The Wilson Cycle

Millions of years ago, Earth looked a lot different from what it does today. That's because of the constant movement of the Earth's tectonic plates.

The Wilson Cycle explains how the Atlantic Ocean, and its predecessor, the Iapetus Ocean, formed as the supercontinent split apart. As the plates move apart, the newly formed ocean starts out small and gradually grows larger and larger. As the plates move closer together, the ocean gradually grows smaller.

Did you know that the Atlantic Ocean is actually growing about 4 to 10 centimeters wider every year? And the Pacific Ocean is shrinking by about 3 centimeters each year.

How Has Pangaea Changed Overtime

Pangaea is the name of the supercontinent that existed from about 300 million years ago to about 200 million years ago, when it started to break up.

About 195 million years ago, the supercontinent Pangaea slowly began to break apart and form the seven continents we see on maps and globes today. The separation of supercontinents over millions of years is responsible for the abundance of marine life in the world's oceans.

The locations of the continents and the size of the oceans have changed throughout the history of the Earth, and they will keep changing as the continents move apart from each other or bump into each other again.

Other Supercontinents

Scientists believe that Pangaea is not the only supercontinent that existed on Earth. Pangaea was only one of five supercontinents to join together (and then split apart) over the time of geological history. The names of the other supercontinents are Kenorland, Nuna/Columbia, Rodinia, Pannotia, and then finally, Pangaea.

Scientists prediction that in about 200 to 300 million years, a supercontinent will reform on Earth.

Animals on Pangaea

During Pangaea's existence there were many animals. For example, in the water there were sharks and fish with bony skeletons. Also, there were insects, amphibians, reptiles and the first dinosaurs that had ever lived.

Humans did not exist at the same time as Pangaea. Pangaea started to break up about 200,000,000 years ago. The earliest humans did not start to appear on Earth until about 200,000 years ago.

Fossil Evidence

Rocks that look exactly alike (identical rocks) were found on separate continents. Those kinds of rocks came from minerals that all had the same conditions. Also, fossils of dinosaurs that lived on the Earth before the continents broke apart have been found in South America and Africa because those continents used to be connected.

Author's Note

I was interested in making this website because I saw a photo of the Earth from long ago, and it looked really funky! So I asked myself a bunch of questions: “If Earth looked like this long ago, why does a map of Earth today show seven separate continents? How did they move? Why did they move? And are they still moving?

Now I know the answers, and I hope you've enjoyed discovering the answers, too.

Earth didn't always look like seven separate continents. It used to look like one HUGE continent.

Based on the theory of plate tectonics, all of the continents of the Earth fit like a jigsaw puzzle.

This image shows the layers of the Earth. The moving continents are all located on the outermost later called the crust.

An eggshell is a great comparison to the Earth. The shells equals the crust. The white of the egg equals the mantle. The yolk equals the core.

Volcanoes occur where the Earth's tectonic plates bump together and move apart from each other.

The Wilson Cycle describes the cyclical opening and closing of ocean basins as a result of plate tectonics.

Continental Drift refers to the drifting movements that separates the continents over time.

These maps show how the location of the continents have changed after Pangea split apart. Each map jumps ahead 50 million years in time.

Early reptiles, mammals, and dinosaurs existed during the time of the supercontinent of Pangaea.

Giant dragonflies called griffenflies ruled the skies during Pangaea. Birds and flying reptiles did not evolve until later.

This is a skeleton of a Lystrosaurus, an animal that lived on Pangaea about 250 million years ago.

Antarctica has not always been an icy world. Antarctica and Africa were once connected. 90 million years ago, Antarctica was a swampy land of rainforests where dinosaurs lived.

This photo shows how Africa and South America fit together like a jigsaw puzzle.

Earthquakes are also a result of the pressure from the bumping, grinding, and movement of tectonic plates.

The supercontinent of Rodinia existed from about 1.2 to 0.75 billion years ago.

This picture represents the supercontinent Pangaea, which split apart about 200 million years ago and will reform in approximately 250 million years.

Visit these sources to find more information:

Websites about Pangaea/Earth:

Books about Pangaea/Earth:

The Book Of Planet Earth by Clint Twist
From a Super Continent to Seven by Baby Professor
Continental Drift by Martin Ince

What will the Earth look like in 250 million years?

Scientists have made some predictions about what the Earth may look like in 250 million years. It is estimated that between 200-300 million years from now, the continents of the Earth will again reform into a supercontinent like Pangaea. But what will it look like?

The diagrams below show four different scenarios of possible futures for the continents of planet Earth:

Pangaea Ultimate

In this scenario, the Atlantic Ocean closes as North America and South America collide with Europe and Africa. A supercontinent forms near the earth's equator, with continents squeezing together to turn ocean into a giant lake surrounded by land.

Novopangaea

The Pacific Ocean keeps getting smaller and smaller until it disappears, while the Atlantic Ocean keeps getting wider and wider. The continents eventually join to form a new Pangaea on the opposite side of the Earth than the old Pangaea. Australia moves northward to collide with Asia, and Antarctica also moves northward to join the supercontinent.

Aurica

In this model, both the Atlantic Ocean and the Pacific Ocean get closed in by land. The seven continents of today's Earth collide into one supercontinent, located around where Australia is today.

Amasia

The continents will drift northward and collide in the Arctic circle. North and South America will join connect with Eurasia, making the Arctic Ocean disappear. Australia and Africa will also drfit north to join them as a supercontinent, while Antarctica remains in the south.

Go to Mr. Beekman's Big Question Website to explore our HUGE collection of Big Question Projects...

Report abuse