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Inside the Earth
The Composition of the Earth
• Crust• Mantle• Core
The Crust
• The crust is the outermost layer of the Earth.• It is the thinnest layer of the Earth• Two types of crusts– Continental – Oceanic
Continental Crust
• Made of light substances– Silicon • Si
– Oxygen• O
– Aluminum• Al
Oceanic Crust
• Contains heavy substances– Iron• Fe
– Calcium• Ca
– Magnesium• Mg
• Because it contains heavier substances it is denser than the continental crust.
The Mantle
• The mantle is the layer of the Earth between the crust and the core.– The mantle is very thick– Contains most of the Earth’s mass
• No one has really seen what the mantle looks like.– The Ocean floor gives us many clues about the
mantle• Underwater Volcanoes
The Core
• The core is the layer that begins at the bottom of the mantle and ends at the center of the Earth.– The core is made mostly of Iron
• There is a Inner and Outer Core
Inner and Outer Core
• The outer core is the liquid layer of the earth’s core.
• The inner core is the solid, and dense center of the planet.
Earth’s Core
The Physical Layers of the Earth
• Lithosphere– Greek for “Rock Sphere”
• Divided into pieces called tectonic plates• Made up of the crust and the rigid upper part of the mantle.
• Asthenosphere– Greek for “Weak Sphere”
• Lies between the Lithosphere and Mesosphere• Made of solid rock
• Mesosphere– Greek for “Middle Sphere”
• Lies between the Asthenosphere and the Earth’s Core
Earth’s Physical Layers
• Temperature and Pressure increase as you move towards the center of the Earth.
• Plasticity is a solid that has the ability to flow.
• Convection currents are hot material that becomes less dense and rises while cooler material becomes denser and sinks.– This occurs in mantle layer of the Earth.
Mapping the Earth’s Interior
• Scientist use Earthquakes to find out information about the interior of the earth– Seismic waves are vibrations produced by
earthquakes• The waves traveling speed determines the Earth’s
density.
– Seismographs are used to measure the travel times of the waves