Layers of the Earth

Layers of the Earth

Middle School

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Learning Objectives

• Describe Earth's layers: the crust, mantle, and core based on their composition.

• Differentiate between the lithosphere and asthenosphere based on their physical properties.

• Identify and define Earth's major spheres: the atmosphere, hydrosphere, and biosphere.

• Explain how the different layers and spheres of the Earth interact with one another.

Key Vocabulary

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Crust

The outermost solid layer of the Earth, which makes up less than 1% of the planet's mass.

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Mantle

The hot rock layer between the crust and core, representing about 68% of the Earth's total mass.

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Lithosphere

The rigid outer part of Earth, consisting of the crust and the solid upper portion of the mantle.

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Asthenosphere

The partially molten upper mantle that behaves plastically and can flow over geological time.

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Atmosphere

The thin layer of gases, mostly nitrogen and oxygen, that completely surrounds our entire planet.

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Hydrosphere

The combined mass of all the water that is found on, under, and over the surface of Earth.

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Earth's Layers by Composition

• The crust is the outermost layer, making up less than 1% of Earth's mass.

• It has two types: oceanic crust under the oceans and continental crust for continents.

• The mantle is a hot layer of rock, making up 68% of Earth's mass.

• The core is the dense, iron metal center, making up 31% of Earth's mass.

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Multiple Choice

Which layer of the Earth is made of hot, ultramafic rock and represents about 68% of Earth's mass?

• Core

• Crust

• Mantle

• Lithosphere

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Earth's Layers by Mechanical Properties

• The lithosphere is made of the crust and rigid upper mantle.

• ​It is a brittle, rigid solid that includes Earth’s continents.

• The asthenosphere is a partially molten layer below the lithosphere.

• It behaves plastically, meaning it can slowly flow and move.

Multiple Choice

What is the key difference between the lithosphere and the asthenosphere?

• The lithosphere is a brittle solid, while the asthenosphere is plastic and can flow.

• The lithosphere is the planet's core, while the asthenosphere is the crust.

• The lithosphere is molten, while the asthenosphere is a rigid solid.

• The lithosphere is made of gas, while the asthenosphere is made of rock.

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Earth's Major Spheres

• Earth's surface has several spheres with all its gases, water, and life.

• The atmosphere is the layer of air surrounding the entire planet.

• The hydrosphere has all the water, and the biosphere has all living things.

• All of Earth's spheres are interconnected and constantly interact with one another.

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Multiple Choice

Which part of the hydrosphere penetrates the lithosphere?

• Magma

• Groundwater

• Surface water

• Water vapor

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Common Misconceptions About Earth

Misconception	Correction
The Earth's crust is a single, unbroken layer.	The crust is broken into several tectonic plates.
The mantle is completely liquid.	Most of the mantle is solid rock, not liquid.
Earth's different spheres are separate and do not interact.	All of Earth's spheres constantly interact with each other.

Multiple Choice

How does the primary composition of the Earth's core differ from its mantle?

• The core is made of gases, while the mantle is made of ice.

• The core is ultramafic rock, while the mantle is mainly iron metal.

• The core is mainly iron metal, while the mantle is hot ultramafic rock.

• The core is liquid rock, while the mantle is solid metal.

Multiple Choice

Why is the lithosphere considered a rigid solid, unlike the asthenosphere?

• Because it is much hotter and denser than the asthenosphere.

• Because it is located at the center of the Earth.

• Because it is composed of the crust and the solid part of the upper mantle.

• Because it is made of gas and liquid, while the asthenosphere is solid.

Multiple Choice

A landslide, where rocks and soil move down a slope, is a direct example of an interaction between which two of Earth's spheres?

• The hydrosphere and the atmosphere.

• The core and the mantle.

• The lithosphere and the hydrosphere (as water can be a trigger).

• The atmosphere and the biosphere.

Multiple Choice

Based on the properties of the layers, how does the plastic nature of the asthenosphere influence the brittle lithosphere above it?

• The asthenosphere has no effect on the lithosphere.

• The asthenosphere's flow allows the rigid plates of the lithosphere to move.

• The asthenosphere cools the lithosphere, making it brittle.

• The asthenosphere erodes the bottom of the lithosphere.

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Summary

• Earth has layers based on composition and mechanical properties.

• The crust is the thin outer layer; the core is the dense iron center.

• The lithosphere is a rigid layer, while the asthenosphere is a flowing layer.

• Earth's spheres interact, causing continuous changes to the Earth's surface.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4