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Fossils and Plate Tectonics
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NASA Sci Files segment explaining what fossils are and how plate tectonics work.
Wow!
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This is amazing!
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This is so cool!
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I can't believe I'm touching a dinosaur bone!
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Is this real?
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Yes it is!
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Hi, I'm David Wittman, I'm a park ranger here, and these bones are 150 million years
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old.
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Wow!
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Want to see something really neat?
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Yes!
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Follow me.
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Amazing!
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I've never seen anything like this!
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Did you just put these bones in the wall?
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No, we didn't.
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The excavation started here in 1909 and ended in 1990.
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We're doing excavations elsewhere, but during that period of time, we uncovered over a thousand
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dinosaur bones.
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How did they all get here?
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A lot of them died of natural causes, and some of them died when the river dried up
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and they didn't have enough water.
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Oh, I almost forgot.
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My friends wanted to find out for sure if fossils are clues towards plate tectonics
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and earthquakes.
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Oh, I can help you with that.
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I have lots of questions.
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What was the environment like?
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Well, this was the bottom of a river, and the area was flat, arid, there were a lot
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of plants growing along the rivers, and of course that's where the dinosaurs congregated.
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Another question.
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How warm was the climate?
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It was hot year-round, and the reason for that was that this area was a lot closer to
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the equator 150 million years ago.
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So over the last 150 million years, because of plate tectonics or continental drift, this
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area has moved northward 400 miles.
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It's hard to believe that land can actually move that far.
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I read in a book once that no one believed Alfred Wagner in the early 1900s when he proposed
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the idea known as continental drift.
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What is continental drift?
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It was a theory that stated that the continents were once one large land mass called Pangaea.
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Clues indicate that in the last 200 million years, the continents have moved or drifted
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horizontally to their current locations.
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A revised theory called plate tectonics explains why continents drift.
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Continents are a part of large plates that move across the Earth's surface and bang into
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one another, causing earthquakes and pushing up mountain ranges.
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You mean fossil clues?
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Yes, fossils can be clues to continental drift.
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For example, fossils of the reptile Messosaurus have been found in South America and Africa.
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These reptiles live in freshwater and on land, so how could they be found on different continents
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unless the continents had at one time been together?
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Well, another clue could be found in rocks.
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Strange.
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How do you know that a rock found here is the same as another rock found in the Colorado
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Plateau?
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Well, why don't you come with me?
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We'll take a walk and find out.
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Great.
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Well, Jacob, this is the Green River.
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Wow.
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I know I'd never seen anything like this before.
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As you can see, there's lots of different kinds of rocks here.
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Rocks can be clues to continental drift, but that's not the case here.
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They all look the same to me.
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How can you tell the difference between rock structures?
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Well, it's like a detective story.
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We look over at this sandstone over here.
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It looks like six other types of sandstone that we have in the monument.
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So how do we tell the difference?
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We have to look at the rocks that are associated with it.
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We look at the rock that's just below that sandstone, we can tell it's the Chinle Formation.
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Chinle looks the same all across the Colorado Plateau.
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So now we know the rock above it, this sandstone, is the Glen Canyon Sandstone.
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Do you have earthquakes here?
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Earthquakes are caused by mountain building forces.
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So 65 million years ago, as these flat rocks were being pushed up into an arch, earthquakes occurred.
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If you've ever seen a cake in an oven, it'll rise and rise and rise, but at some point, what happens to the cake?
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It rises too much.
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It has to sink back down eventually.
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It'll collapse.
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Well, the same thing happens with rocks.
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They'll be bent, but they can only bend so far, and at some point, they'll eventually break.
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And when the rocks break, is that what causes an earthquake?
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That's correct.
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That break is the fault line, and when the rocks move along the fault line, it creates an earthquake.
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Well, have I answered all your questions?
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Yeah, I can't wait to go email the treehouse detectives.
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Well, do you have some time to go look for some fossils?
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Sure.
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All right, let's go.
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- Idioma/s:
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- NASA LaRC Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 329
- Fecha:
- 28 de mayo de 2007 - 15:33
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 04′ 37″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 27.81 MBytes