Continents still adrift | Brantford Exhibitor

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We are lucky to live in a relatively stable part of the world. The ground under our feet seems solid and immovable. There are rare times when the earth gives a little tremor that we can feel if we sit quietly, but usually we don’t notice anything.

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I remember my first earthquake was a curious phenomenon where some hanging lights started swaying and some glasses clinked together, but other than that not much changed. Most people weren’t aware of this until the evening news told them that a 4.0 earthquake hit Southern Ontario.

However, in other less stable places, the earth moves with a certain frequency and sometimes these movements are dramatic. History records massive earthquakes that destroyed entire cities as the earth moved several meters in just a few minutes. Great upheavals uprooted houses from their foundations and destroyed entire towns. Alaska in 1964 was hit by a magnitude 9.2 earthquake that caused $311 million in damage, which would be over $2.6 billion today. San Francisco is prone to many micro-earthquakes and sometimes huge movements that disrupt everything.

So, it is clear that the earth’s surface is indeed moving, but most people are unaware that the continents themselves are on a slow, steady march that has dramatically changed the time scale map of the world. geological. This is called continental drift.

It’s hard to imagine something as large as a continent wandering all over the earth, but it’s been a suspicion since the mid-16th century and became a scientific theory in the 19th and early 20th centuries.

The first clue was the shape of the continents. There is a very nice match between the coast of Africa and South America. Moreover, the geological structures of one continent appear to continue onto another now thousands of miles away.

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It was not until the 1950s that the theory became generally accepted. Indeed, the final proof came when we were able to measure this rate of change using global positioning satellites (GPS) to directly measure this drift. It has been found, for example, that North America is moving away from Europe at about the same rate as your fingernails grow.

This caused huge changes in the layout of the continents, causing them to drift and collide with each other. This activity also explained why many mountain ranges exist. For example, the Indian subcontinent is moving north and has collided with Asia. This raised the land ahead of India into the Himalayas, the highest mountains in the world.

As North America drifts west, it has piled mountains on the west coast. This pattern is repeated all over the world.

Sometimes continents come together to form large super continents. This has happened at least twice and perhaps more often in our planet’s 4.3 billion year history. To understand this, you can visit a website (www.dinosaurpictures.org/ancient-earth#750) that shows the march of the continents over the past 750 million years, allowing you to see the world as it was from ancient times. Until today. Even better, you can enter your city address and the map will show where that city was in relation to the rest of the world as the continents wandered around the globe.

One of the most interesting aspects to this is the changing geography of a particular place. What is now dry land may have been on top of a mountain or at the bottom of the ocean. This is particularly interesting as we consider climate change that will influence sea levels. For example, Florida is not a good place to live if the Antarctic ice sheet were to melt. Indeed, Florida has spent much of the past million years under water.

“On solid ground” has always been the expression of an immutable solidity. We now know that it is anything but solid because light continents float around the globe on Earth’s mantle as sea levels rise and fall. It seems that solid ground is anything but solid.

Tim Philp has loved science since he was old enough to read. Having worked in technical fields all his life, he shares his love of science with his readers every week. He can be reached by email at: [email protected] or by regular mail c/o The Expositor.