Ask A Scientist

How did our one continent get separated into seven? 

Asked by: Nick Petchenyi
School: Johnson City Intermediate School
Grade: 3
Teacher: Jill Swartz
Hobbies/Interests: Cooking 
Career Interest: Photographer

 

Answer from Siva Adusumilli

Research Assistant and PhD Candidate

Research area: Thin films, semiconductors, nano materials and solar cells
Interests/hobbies: Volunteering, playing with kids, listening to music and cooking

To answer this question, I have to explain one of the most fascinating acts of Mother Nature -- continental drift. This is the movement of Earth’s continents relative to each other. Have you seen the movie Ice Age: Continental Drift? Scrat, the little squirrel in the movie, in an attempt to catch an acorn, unintentionally breaks up the continent Pangaea! Yes, all the seven continents we see today, millions of years ago, were all together as one supercontinent called Pangaea. It’s not Scrat who broke this supercontinent, but the tectonic plates inside the Earth. Earth’s surface is made up of series of these plates. Convection currents in the Earth’s mantle cause these plates to move.

To explain convection currents, imagine heating a pot of water. The water at the bottom of the pot, close to the flame, heats up quick and rises to the top surface, because with heat it expands and density becomes lower. When this hot water rises to the surface, it pushes the water that was there out of its way; at the same time, new water (which is cooler) from the surface fills the space vacated in the bottom. This creates a circular motion of being heated at the bottom, traveling to the top, getting cooled and getting denser, falling again to the bottom and getting heated up again, and this cycle repeats. It’s a similar process that takes place inside the Earth, but instead of water it’s hot magma that goes through this convection current. In this process, it leads to volcanoes where the hot magma comes out from the Earth, just like hot water rising from the surface of the pot. It can also lead to earthquakes by moving the plates; this movement of plates led to breakage of the supercontinent in the past to the present-day multiple continents. In this process, the continents can collide with each other. An example of this is that the Indian subcontinent it still moving and colliding with the Asian continent. This led to the formation of the Himalayan mountain range and is also the cause of the recent earthquake in Nepal.

Imagine putting together a small jigsaw puzzle, with the seven continents as seven pieces. Try connecting them together to form Pangaea again. I will give you a hint: start from connecting west Africa to east South America (Brazil) and continue to reveal the history that was made. The continents are still moving today and will be moving in the future. The world map that we see today might not be the same that we see in the future. For example, North America and Europe are moving away from each other at a rate of 2.5 centimeters per year. We might see more than seven continents in the future, or might even end up with all continents joining together to form a supercontinent again!

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Last Updated: 9/25/14