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Unit 4
Earth: Systems, Structures and Processes
Goal: Understand the structure of the earth
and how interactions of constructive and
destructive forces have resulted in changes in
the surface of the Earth over time and the
effects of the lithosphere on humans.
Unit 4
Earth: Systems, Structures and Processes
 Summarize the structure of the Earth, including the layers, the mantle,
and core based on the relative position, composition, and density.
 Explain how crustal plates and ocean basins are formed, move, and
interact using earthquakes, heat flow, and volcanoes to reflect forces
within the earth.
 Explain how the formation of soil is related to the parent rock type and
the environment in which it develops.
 Conclude that the good health of humans requires: monitoring the
lithosphere, maintaining soil quality, and stewardship.
How do we know about Earth’s interior?
Geologists have used two main types of evidence to
learn about Earth’s interior:
1. Direct evidence from rocks.
rocks give clues about Earth’s structure.
2. Indirect evidence from seismic waves (produced
by earthquakes)
speed and path tell about the Earth’s structure.
https://app.discoveryeducation.com/learn/videos/af8aea
ca-f326-442b-a837-546e77bd2358?hasLocalHost=true
What are the main layers of the earth?
The 3 main layers of the Earth are:
 Crust
 Mantle
 Core
Crust:
solid rock that includes:
- continental crust (dry land)
- oceanic crust (ocean floor)
- lithosphere
thinnest layer
5 – 70 km thick
• continental crust: thicker than oceanic crust made of
igneous rock (granite)
• oceanic crust: ocean floor is igneous rock (basalt)
• lithosphere: rigid layer formed from the uppermost part of
the mantle and the crust
Mantle:
* 2 layers: - asthenosphere
- lower mantle
* very hot solid rock
* thickest layer
* 2,900 km thick
• asthenosphere: soft rock, like hot road tar (400 km)
• lower mantle: hard rock
Core:
made of iron and nickel
2 layers: outer core
inner core
outer core:
- liquid metal
- flows in currents
- giant magnetic fields
created
inner core
- hottest layer
- solid metal
- under extreme pressure
Journey to the Center of the Earth
- Temperature: Increases going deeper into
Earth; high temperatures are result of heat left
over from the formation of the planet.
- Pressure: Increases going
deeper into Earth; results
from a force pressing on an
area.
Exploring the Layers of the Earth
5 min