Unit 2 Topic 1: The Earth’s Layers
Key Vocabulary:
1. Crust: solid outermost layer of Earth.
2. Mantle: thickest layer of Earth; located between the crust and the outer core.
3. Outer Core: liquid part of the Earth just beneath the mantle
4. Inner Core: solid innermost part of the Earth
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Earth’s Layers:
Earth is made up of layers.
These layers make up rocks.
There are 3 types of rocks forming from Earth’s layers (sedimentary, igneous, and
metamorphic).
These layers have different densities.
Density is the amount of mass per unit of volume.
Density is related to the thickness of an object.
Earth’s layers have different densities because each layer is made up of different
substances.
Each of Earth’s layers has a different temperature and pressure.
As you travel deeply through Earth’s layers the temperature, pressure, and density of its
layers increase.
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Earth’s Crust:
The crust is the outermost layer of the Earth where we live.
The crust ranges from 5 km to 70 km thick.
The Earth is thicker underneath continents.
The Earth is thinner underneath the ocean floor.
The crust is the least dense layer and cool in temperature.
The crust is made mostly of silicon and oxygen.
Silicon and oxygen form minerals that make up the Earth’s crust.
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Earth’s Mantle:
The mantle is the thickest layer of Earth.
The mantle is about 2900 km thick.
Pressure and temperature is higher in the mantle than in the crust.
The mantle is made up of more dense elements.
The mantle is made up of silicon, oxygen, magnesium, and iron.
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Earth’s Core:
The layer underneath the mantle is the core.
The core is made mostly of iron and nickel.
The core makes up the innermost layer of the Earth.
The core is divided into two parts: outer core and inner core.
E. Outer Core:
1) Because of high temperatures, the outer core is liquid.
2) Temperatures can reach 6700 degrees Celsius.
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3) The outer core is about 2270 km thick.
4) The outer core is made mostly of iron and nickel.
5) The outer core is very dense.
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Inner Core:
The inner core is solid.
The high pressure in the inner core makes it very dense.
Pressure is highest in the inner core.
Even thought temperatures are high, the rocks do not melt.
The radius is about 1216km.
The inner core is the densest layer.
The inner core is made up mostly of iron and nickel but contains small amounts of
oxygen, silicon, and sulfur.
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