Earth’s Structure. The layers of Earth. Earth is divided into 3 layers based on chemical composition. Core: Dense metallic center, made up of mainly metal iron. Mantle: Liquid middle layer made up of silicon, oxygen and magnesium.
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There are two types of crust:
Continental: is thicker
Oceanic: is thinner and heavier.
Compared to the other layers, both types of crust are rocky, thin and fractured.
Earth is divided into five layers based on physical properties.
cool rigid layer, made up of the crust and upper layer of the mantle.
Lithosphere is divided into pieces called tectonic plates.
3.Mesosphere: Slow flowing layer beneath the Asthenosphere
4.Outer core: Layer of liquid Iron and Nickel.
5.Inner core: Solid iron and nickel, temperature is estimated to be between 4000ºC to 5000ºC
How can we know so much about Earth’s interior if no one has ever drilled through the crust?
Earthquakes produce seismic waves, and travel thru materials at different speeds.
Scientists use these waves to determine the density of each of Earth's layers
In the 1900’s,Scientist Alfred Wagner, viewed the continents as puzzle pieces.
Had a hypothesis that our continents used to be one large continent.
He named his hypothesis the Continental Drift Theory.
A single continent Pangaea (many thousands of years ago).
Split into two continents – Laurasia and Gondwana (thousands of years ago).
Split into today's continents.
Continents sometimes collided, forming mountain ranges and volcanoes.