Earth’s Structure
Forces on Earth’s Surface
Forces Inside Earth
Core Concepts 2.3, 2.4, 2.5; p. 22-27 MyWorld Geography
Earth’s Structure
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Earth’s structure is made up of different parts above and
below its surface.
These parts are the core, mantle, crust, atmosphere,
landforms, and water.
atmosphere
Outer core
Inner core
mantle
water
landforms
Earth’s Structure
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Earth’s Core- a sphere of very hot metal at the center
of Earth that has temperatures greater than 5000 degrees
F. The inner core is solid, while the outer core is hot
liquid metal.
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Mantle- thick, rocky layer around the core with
temperatures greater than 3,300 degrees F. It is solid but
its temperature allows it to flow like fluid.
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Crust-the thin layer of rocks and minerals that surrounds
the mantle and includes the land areas where people live
as well as the ocean floor.
Earth’s Structure
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Atmosphere- a thick layer of gases or air that includes
life-giving oxygen and acts like a blanket by holding in heat
from the sun, which makes life possible.
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Landforms- 25% of the Earth’s surface with many didn’t
shapes and types and are formed by processes beneath
Earth’s surface that push Earth’s crust up.
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Water- 75% of Earth’s surface which forms a layer above
Earth’s crust and holds 97% of Earth’s water. This water is
salty.
Forces on Earth’s Surface
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Key Ideas
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Forces such as wind, water, and ice shape Earth’s surface
These forces produce a variety of different landforms
Forces on Earth’s surface wear down and reshape the land and help
create the landforms we see around us.
Key Terms
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Weathering
Valley
Erosion
Deposition
Plateau
Plain
Delta
Wearing Away Earth’s Surface
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Weathering- is a process that breaks rocks down into tiny
pieces.
Rainwater or acids carried by rainwater dissolves rocks in
Chemical Weathering.
Moving water, ice, or sometimes wind breaks rocks into little
pieces is called Mechanical Weathering.
Weathering helps create soil, which is made from tiny pieces
of rock combined with decayed animal and plant material.
Soil and pieces of rock undergo erosion, which is a process in
which water, ice, or wind removed small pieces of rock.
Soil is required to sustain plant and animal life, and for
agriculture and is very importing to human settlement
patterns.
Shaping Landforms
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Weathering and erosion have shaped many of Earth’s
landforms including mountains and hills.
Mountains are wide at the bottom and rise steeply to a
narrow peak or ridge.
Hills are lower than mountains and often have rounded
tops.
An area in which a certain type of landform is dominant is
called a landform region.
Rebuilding Earth’s Surface
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Deposition- is the process of depositing eroded material
carried by water, ice, or wind and creates landforms.
Plains- or large areas of flat or gently rolling land are
often formed by the deposition of material carried
downstream by rivers.
Forces Inside Earth
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Key Ideas
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Movements of hot, soft rock in Earth’s mantle affect Earth’s
surface, forming volcanoes and pushing continents together or
apart.
Key Terms
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Plate tectonics
Plate
Magma
Fault
Forces Inside Earth
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Plate tectonics is a theory that states that Earth’s crust
is made up of huge blocks called plates.
Plates include continents or parts of continents along
with parts of the ocean floor.
Magma is molten, nearly melted, rock that act as a
conveyor belt moving the plates in different directions.
This movement slowly builds mountains; when 2 plates of
crust push against each other, the pressure makes the
crust bend to form steep mountains.
Earthquakes and Volcanoes
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Earthquakes occur when plates slide against each other.
Earthquakes happen most often occur at seams in the
Earth’s crust called faults which are near the plates.
Movement of plates creates great pressure inside Earth
which sometimes forces magma up through Earth’s crust
which forms volcanos.
Volcanos spew magma from inside Earth and is called
lava, which forms new land forms when the lava cools.
Natural Hazards
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Volcanoes and earthquakes are examples of natural
disasters, also known as natural hazards.
Other natural hazards include hurricanes, tornados,
landslides, and floods.
These events threaten lives and property, but people can
take steps to prepare.