This motion is responsible for temblors. The crust is the topmost part.
Seismic waves and how we know earth's structure Video transcript Let's think a little bit about the different clues that have led us to conclude that we have these lithospheric plates moving relative to each other. Now, the first clue, and this is something that I think many students even in elementary school first experience when they first learn about geography, is that it looks like the continents could kind of fit into each other.
And the most obvious one of these is when you look at this kind of little pointy part of South America, and if you have a more detailed map it really is amazing, how well it seems to fit into the Nigerian Basin right here in Africa.
It looks like at one time this little pointy part was nudged into this part of Africa, that they were actually connected. And if you're a little bit more creative, there are other parts of the world that Plate techtonics essay can kind of start to see how they might have fit in with each other in the past.
And that by itself, that's just a very small clue, but it kind of hints at well, maybe if they at one time were fitting next to each other, if this was kind of connected, then they've had to moved apart at some time. Although it doesn't tell us that it's still moving or what might have caused the movement.
And it definitely doesn't definitively tell us that they even moved. Maybe this is just a coincidence that this coast of South America looks very similar to this coast right here of Africa.
Now, the next clues truly came over I would say about the last 60 or 70 years. Let me look at this photograph right over here. You don't normally see the oceans highlighted like this.
So let me make it very clear to you. This right here is South America. This right here is Africa. This right here is North America.
And so if you actually look at the elevations in the middle of the ocean people noticed in the middle of the 20th century that gee, there's a ridge in the middle of the Atlantic Ocean.
There's kind of a mountain range that goes straight up the middle of the Atlantic Ocean. So that by itself doesn't tell you that you have these plates that are moving apart, but it is kind of a curious thing to look at. And not only is there this ridge.
There's lot of underwater volcanic activity.
You have magma flowing out and lava flowing out into the water, and it's kind of forming this ridge that really goes across the whole Atlantic Ocean. There are other ridges in the world like that, underwater ridges. You have one over here in the Pacific Ocean.
You have these here in the Indian Ocean. That's just a little clue, but that by itself doesn't tell you that these plates are actually moving apart at the ridge.
The more conclusive-- this is just the beginning of the clue-- but what made this conclusive is one, the separate discovery.
And this is what's interesting is that you have these separate discoveries in different domains that eventually let you come to a pretty neat conclusion. So you've had a separate discovery that if you look at different eras of magnetic rock, or maybe I should say magnetic rock from different periods in geologic time.
And you can tell where they are in geologic time by how they're layered. So this would be newer rock. And then this would be a little bit older. And then this would be even, even older. Geologists noticed something interesting. If I were to take magnetic rock, and if it was molten lava, and if it were to harden, remember it's magnetic rock so it would want to align with the poles the same way a compass would.
So if I had a bunch of magnetic-- so let's say this is some lava right here. And so the molecules can align themselves.Introducing the first chapter in the Earth Science Interactive Notebook Series: Plate Tectonics. Each chapter in the series will showcase many activities for the students (both middle and high school) to process the information given by teachers.
Plate Tectonics - Topic Definition Plate Tectonics is a scientific theory which study how the Earth’s plates are driven and shaped by geological forces to keep them in constant movement. Scientists have identified an expanse of rock in Greenland as a remnant of Earth's crust dating back billion years, a finding that shows the dynamic geological process called plate tectonics was occurring early in the planet's history.
Earthquakes and Plate Boundaries. Earthquakes are used to identify plate boundaries (Figure below).When earthquake locations are put on a map, they outline the initiativeblog.com movements of the plates are called plate tectonics. The hot spot magma source is thought to be fixed in the deeper mantle.
Above a hot spot, a slab of oceanic crust and uppermost mantle - a tectonic plate - moves laterally above the hot spot. As the Pacific Plate moves over the Hawaiian hot spot, magma punches up through the Pacific Plate. Plate tectonics are important to understand the way in which our planet evolve.
They are responsible for many of the structures and features that exists in our planet. Gathering an understanding of the information provided in this site will provide a better idea of how the Earth underwent through.