Can we explore inside earth?
The extreme temperature and pressure conditions inside of
Earth’s interior prevent direct exploration by geologist.
What is a geologist?
How do geologist study earth’s interior?
Scientist who study the origin, history and structure of the
Earth.
Geologist have used two main types of evidence to learn about earths interior: direct evidence from rock samples and indirect evidence from seismic waves.

What are seismic waves?
What are the layers?
Vibrations that travel through earth. Using the data from seismic waves – the speed that they travel and the paths that they take, geologists have learned that the earth is made up of several layers.
From outermost to innermost the layers are the crust, mantle and the core. Each layer varies greatly in size, composition, temperature and pressure.

What is the crust?
This is the layer of solid rock that forms the earth’s outer skin. It includes both dry land and ocean floor. The crust is the thickest under mountains and thinnest at the ocean floor. Oceanic crust consists of rocks such as basalt. Continental crust consists of rock such as granite.

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Earth’s hard outer shell
Light and brittle
It is cooler and more rigid than the core and mantle

What is the mantle?
The layer of hot, solid rock beneath the crust. This is also where magma resides. This portion of earth’s interior is divided into layers based on physical characteristics.
What are the layers of the mantle?
The lithosphere, asthenosphere and lower mantle.
Lithosphere This is the uppermost part of the mantle and is similar (rigid/solid) to the crust.

Asthenosphere This part of the mantle is somewhat soft and can bend.
Although it is softer than the lithosphere, it is still solid.
Lower Mantle Located below the asthenosphere this portion of the mantle is solid all of the way to the core.

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Thick shell of rock surrounding the outer core
Part of the mantle is flexible, allowing it to bend
Makes up most of the Earth’s mass

What is the core?
Outer core
Inner core
This is the inner most layer of the earth. Composed of the metals iron and nickel. Contains an outer portion and an inner portion.
This is a layer of liquid (molten) metal that surrounds the inner core.
Made up of a dense ball of solid metal. Extreme pressure squeezes the atoms of iron and nickel so much that they cannot spread out and become liquid.

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Why is the inside of the earth hot?
It is hot as a result of the heat left over from the formation of the planet. Also, the interior is further heated from the release of energy from radioactive substances inside the earth.

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Label the picture to the right.
What is the main type of rock in the oceanic crust?
What are the layers of the mantle from top to bottom?
What is the main difference between the outer core and inner core?
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SEE BELOW.
The main type of rock in the oceanic crust is basalt.
The layers from outside to inside are the lithosphere, asthenosphere and lower mantle.
The outer core has the characteristics of a liquid and the inner core is solid.
CRUST
MANTLE
INNER CORE
OUTER CORE