Unit 3
Dynamic Earth
The Earth is divided into 4 layers
 1.
Crust (Lithosphere)
 2. Mantle (Magma)
 3. Outer Core
 4. Inner Core
Layers of the Earth
(List the 4 layers of the earth, choose a color for each layer
and color diagram the appropriate color)
Why does the Earth have
layers?
 The
layers formed because of their
different densities.
 The less dense material is found in
the crust.
 The more dense compounds sank to
the center of Earth.
Crust
 Outermost layer
 Thinnest layer (5-100 km thick)
 Two types: Continental and Oceanic
 Click here to see the 2 types of crust
Oceanic and Continental Crust
Mantle
 Just beneath crust
 Contains most of Earth’s mass (67%)
 Thickest layer (2900 km thick)
 Hot, gooey layer made of magma (liquid
rock – molten rock)
Outer Core
 Hot liquid Iron
 2,200 km thick
Inner Core
 Solid Iron/Nickel (metal)
 1250 km thick
Earth’s Layers
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The crust is also known as the lithosphere.
The broken sections of the crust are referred to
as plates (tectonic).
These plates fit together along Earth’s surface
like a puzzle.
The plates move along the surface very slowly.
The upper part of the mantle acts like a plastic
and is called the asthenosphere. It allows the
plates to move.
Layer
Description
Composition
(make-up)
Made of rock
Physical
Properties
Crust
(Lithosphere)
Thinnest layer
(5-100 km thick)
• Rock
• Solid
• Thinnest layer
Mantle
Thickest Layer just Made of molten
beneath the crust (liquid) rock –
(2,900 km thick)
MAGMA
More dense than
the crust
• Hot molten
rock
• 2/3 of Earth’s
Mass
• MOVE
Outer Core
Liquid layer of the
core
(2,200 km thick)
Hot liquid iron
• Liquid
Inner Core
Solid layer of the
core (METAL)
(6,380 km below
surface)
Solid iron and
nickel
• Solid
Tectonic Plates
• Plate tectonics is the theory that the
lithosphere is divided up into plates that
move along the asthenosphere. (upper
part of the mantle)
Three types of Plate Boundaries
• 1. Convergent – where two plates are
colliding
• 2. Divergent – where two plates are
separating
• 3. Transform – where two plates slide
against each other
Convergent Boundaries
Divergent Boundary
Transform Boundary
Wegener’s Hypothesis of
Continental Drift
• Continental Drift – is the hypothesis that
the continents once formed a single
continent called Pangaea. This continent
broke up and the pieces have moved to
their present locations.
Evidence that helps support
Continental Drift
Similar findings on opposite sides of the
Atlantic include:
• Fossils
• Plants
• Mountain Ranges
• Matching Rock Types
Movement of Tectonic Plates
• What causes the tectonic plates to move?
Convection Currents
• Convection – the movement of thermal
energy through a fluid.
Hottest magma rises Cooler magma sinks
Forces that move Tectonic Plates
Type of Force
Force Description
Ridge Push
Lava coming out of the mantle
‘pushes’ the plates apart
View Ridge Push
Convection
Hot liquid rock rises and cooler liquid
rock sinks causing the crust to go
away from the ridge.
Slab pull
Oceanic Crust slides downward
because of the force of Gravity
View Slab Pull
Deformation of the Earth’s Crust
• Deformation – Shape of rock changes
(folds).
• Compression – Stress that occurs when
forces act to squeeze an object.
• Tension – Stress that occurs when forces
act to stretch an object.
Types of stress that deform rock:
• Folding – the bending of rock layers
• Faulting – the surface along which rocks
break and slide past each other.
• Fault
Line
Google Earth
EARTHQUAKES
• An earthquake is the shaking of the Earth’s
crust.
• The study of earthquakes is called Seismology
• The instrument used to measure an
earthquakes magnitude (strength) is a
seismometer and seismograph
Seismometers and Seismographs
EARTHQUAKE
DAMAGE
EARTHQUAKES
• Earthquakes occur along PLATE
BOUNDARIES (edges of the crustal
plates)
• The most active earthquake zone is along
the pacific ocean, also known as THE
RING OF FIRE.
EARTHQUAKES
Three Types of Plate Boundaries
• Convergent
• Divergent
• Transform
This motion creates:
Mountains
Volcanoes
Seafloor
spreading
Ridges
Earthquakes
Seismic Waves
• When an earthquake occurs it produces
vibrations, also known as seismic waves.
• Seismic waves are the reason we know the
interior of the Earth.
Seismic Waves
• Speed: FAST
Speed: SLOW
Shadow Zones
• The solid core of the Earth blocks and bends
the vibrations from an earthquake from
reaching the other side of the Earth.
•
•
P-waves can travel through the interior of
the earth
S-waves can not pass through the liquid
portions of the earth.
Measuring Earthquakes
• Richter Scale – measures the magnitude
(strength) of the earthquake from 1 to 10.
• Mercalli Scale – measures the amount of
damage done from an earthquake from I-XII.
Earthquake Safety
Before the shaking:
• 1. Prepare emergency kit
–
–
–
–
Water
First Aid Kit
Radio / Batteries
Canned food / Can opener
• 2. Prepare escape route
• 3. Home Safety Plan
– Remove objects from high shelves
Earthquake Safety
During the shaking:
1. Get under a table
2. Get in a doorway
3. Stay away from objects that may fall on you
Earthquake Safety
After the shaking:
1. Get away from danger
2. Go to your previously appointed emergency
location
3. Do not go back indoors until advised