Download The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes

The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
How do we know what the Earth is made of?
_____________________________________________________________________________________
_____________________________________________________________________________________
The Earth is divided into four main layers:
The Crust
 The Earth’s crust is like the skin of an apple. It is very thin compared to the
other three layers.

 The crust of the Earth is broken into many pieces called _____________.
 The Mohorovicic Discontinuity, or “Moho”, is the
_____________________________________________________________________________.
The word “discontinuity” is used for a
______________________________________________________________________________
_____________________________________________________________________________.
The Mantle
 The mantle is the layer below the crust.
 The mantle is the largest layers of the Earth.
 The mantle is divided into two regions:
_____________________________________________________________________________.
Outer Core
 The core of the Earth is like a ball of very hot metals.
 The outer core is liquid.
 The outer core is make of ____________________________________________________.
Inner Core
 The inner core of the Earth has temperatures and pressures so great that the
metals are squeezed together and are not able to move.
 The inner core is a ___________.
Lithosphere- the layer of Earth made of the crust and the rigid rock of the upper
mantle which is broken into tectonic plates
Asthenosphere- the layer in Earth’s upper mantle directly under the lithosphere in
which rock is soft and weak because it is close to melting
Who is Alfred Wegner?
A __________ scientist who hypothesized the _________________________________________.
What is the theory of continental drift?
A hypothesis that all the ___________________ were once joined together in a single
landmass called _________________ and has since drifted apart.
Why wasn’t Alfred Wegner’s theory accepted?
 Alfred Wegner had a lot of evidence to support his theory, but…
o He could not explain how the plates moved.
 Scientists did not accept his theory. But his theory later developed
into the ___________________________________...
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
What is the theory of plate tectonics?
 The Earth’s crust is divided into _______ major plates which are moved in
various directions.
 Pieces of Earth’s lithosphere are in slow, constant motion.
o Movement is caused by
_________________________________________________________________
o Plates move in three types of behavior:
 This plate motion causes them to _____________,
___________________, or _____________ against each other.
 Tectonic plates are made of continental and oceanic crust.
What evidence supports this hypothesis?
1. Geology/Land Features:
 He noticed that the mountain ranges on the continents of ___________ and South
____________ line up.
2. Fossils:
 Fossils—trace of ancient organisms that has been preserved in rock.
 Dinosaur fossils have been found in landmasses separated by oceans.
3. Climate:
 Evidence of _______________________ has been found in the Arctic Ocean and
glacier evidence in South Africa.
Pangaea- a hypothetical supercontinent in which all continents were once attached. It
began breaking apart about 200 million years ago.
Convection- a process by which energy is transferred to cause warmer less dense air
or liquid to rise while the dense cooler liquid or air is pushed down.
Tectonic plates- sections of Earth’s upper layer that includes both crust and mantle
material (lithosphere broken into pieces).
Continental drift- a hypothesis that Earth’s continents move on the surface
Fault lines____________________________________________________________________________________
Three Types of Plate Boundaries----Divergent, Convergent, and Transform
What is a convergent boundary and where does it occur?
 Place where two plates come together, or converge
 A “collision”
 Forms mountains and volcanoes
 When oceanic crust slips under continental crust called _______________________
o Subduction forms __________________
Convergent Boundaries
There are three types of convergent plate boundaries:
1. Continent-continent collision
Example: ___________________________
2. Continent-oceanic crust collision
Draw the arrows below
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
Example: _________________________________________________________________________
3. Ocean-ocean collision
Example: _________________________________________________________________________
What is a divergent boundary and where does it occur?
 Place where plates spread apart; or diverge
 Molten material moves up between the plates and forms ___________ ocean floor,
rift valleys, and ocean trenches.
Draw the arrows below
What is a transform boundary and where does it occur?
 Where two plates slide past each other in opposite directions.
 Earthquakes occur when two plates slide past each other.
Draw the arrows below

Example: _______________________________
Volcanoes- an opening in the Earth’s crust through which molten rock, rock
fragments, and hot gases erupt.
Volcanoes erupt many types of materials:
 Magma
 Rock fragments
 Volcanic gases (mixture of ___________________________________________________)
 Pyroclastic flow- mixture of gases and rock fragments that form a dense cloud
Magma and Lava
____________ is molten rock beneath the Earth’s surface. When magma erupts, it is
called lava.
____________ is molten rock, or magma that reaches the Earth’s surface through a
volcano.
Magma Chambers
 Magma collects in areas called ________________________.
 Volcanic eruptions occur when a chamber is not large enough to hold additional
magma that pushes in.
 Magma can remain in a chamber until it cools, forming igneous (intrusive) rock,
or it can erupt in the form of lava.
Rock Fragments (pieces) ----ash, cinders, and block
Volcanic Gases---Look like smoke rising from the volcano. They are a mixture of ash
and gases (mostly carbon dioxide). Some volcanic gases combine with water in the air
to form acids.
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
Pyroclastic Flows
Sometimes volcanic gases can mix with rock fragments, forming a pyroclastic flow.
This is a dense cloud of superhot gases and rock fragments that races downhill. It can
be as hot as _______________. And can travel faster than _________________ per hour.
Pyroclastic flows are the most dangerous type of volcanic eruptions.
Formation of Volcanoes:
 Volcanoes are common along tectonic plate boundaries where oceanic plates
_____________________________________________________________________________
 Volcanoes are also common along tectonic boundaries where plates pull apart,
_____________________________________________________________________________
 Occasionally, volcanoes are formed over a hot spot far from a plate boundary.
Volcanoes and their effects Volcanic eruptions can knock down forests and destroy homes by flowing into
the homes or by starting ____________.
 Volcanic eruptions can _________________________.
 Some volcanic gases combine with water in the air to form _____________.
 Many volcanic gases are _______________. They can make breathing difficult and
damage the lungs of people and animals.
 In ________________________, a sudden release of carbon dioxide from a volcano
at the bottom of a lake killed ________________ people in 1986.
Lava Flows- Most lava moves too slow to hurt people. However, it can knock down,
cover, or burn nearly everything in its path.
Volcanic Ash The weight of fallen volcanic ash can cause the roofs of buildings to collapse.
 Ash makes roads slippery, and it clogs up machinery, including
___________________________________________.
 Large amounts of falling _________ can suffocate plants, animals, and people.
Mudflows Mudflows are landslides that occur when loose rocks and soil are mixed with
water.
 Mudflows also form as _______________________________________________flowing
from a volcano.
 Fast-moving mudflows can bury entire towns _________________________________
from an eruption.
Landslides- Part of a volcano can collapse and start a landslide. The collapse may be
caused by an ___________________, an _____________________, or even heavy
________________. A landslide can cause a _____________________ if a large amount of
material falls into the ocean.
Steam Explosions- Steam explosions occur when magma comes into contact with
water. The entire island of Krakatau exploded in 1883, causing a tsunami that
destroyed hundreds of towns and killed more than ___________________ people. Steam
explosions can be devastating.
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
Long-Term Effects of Volcanoes:
 Volcanoes build as well as _______________. Material erupted from volcanoes can
form new land. Over time, lava flows can form ______________, _____________ soil.
 Repeated volcanic eruptions can build a magnificent landscape of
___________________ and ____________________.
 People live in a volcanic area for its natural beauty or there might be a
flourishing tourist industry such as Hawaii.
Earthquakes- Sudden movement or shaking of the Earth
 Caused by plate tectonic _____________________
 Located at plate boundaries
 Resulting in breakage of the Earth’s brittle ____________
 The waves travel in all directions.
 More than __________________ occur a year or one every ________ seconds.
 Earthquakes continue until all of the energy is used up.
 Tsunamis- Earthquakes on the ocean floor:
_____________________________________________________________________________.
Plate Tectonic Stresses
 Plate boundaries and
_____________________________________________________________ cause friction as
plates move.
 Plates in a fault zone have ___________________________________ (periods of no
movement (stick) and fast movement (slip)).
 Energy ____________ as plates stick.
 Energy ______________ as plates slip.
Earthquake Damage
 Landslides
 Building damage
 Liquefaction---when a solid (sand and soil) becomes saturated with water and
acts like a heavy liquid
o Results in a loss of soil strength and the ability of the soil to support
weight.
 Loss of life
 Can cause fires (____________________________________________________________)
 Most damage is caused by surface waves (arrive last)
Aftershocks- An aftershock is a smaller earthquake that follows a more powerful
earthquake in the same area. Sometimes structures weakened by an earthquake
collapse during shaking caused by earthquakes.
Seismic Waves
Earthquakes produce three types of seismic waves:
__________________________________________________________________________________.
Each type moves through materials differently. In addition, the waves can
_____________, or bounce off boundaries between different layers. The waves can also
_____________, or bend as they pass from one layer into another. Scientists learn about
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
Earth’s layers by studying the paths and speeds of seismic waves traveling through
Earth.
Earthquake Waves--Focus= place deep within the Earth and along the fault where rupture occurs
Epicenter= geographic point on surface directly above focus
Seismic Waves produced by the release of energy move out in circles from the point of
rupture (focus)
 2 types: surface and _____________ (travel inside and through Earth’s layers)
o ________________: back and forth movement of rock
 Travel through solid, liquid, and gas
o ________________: sideways movement of rock
 Travel through solids only
Focus and Epicenter
All earthquakes start beneath Earth’s surface. The ______________ of an earthquake is
the point underground where rocks first begin to move. Seismic waves travel outward
from the earthquake’s ______________. The ______________________ is the point on
Earth’s surface directly above the ____________.
Seismographs record earthquake waves and show:
 ______________ of seismic waves (how much rock moves or vibrates)
 ______________ to the epicenter
 ______________ direction
3 Types of seismic waves show up on seismograph:
 __________________: shake Earth in same direction as wave
 __________________: shake Earth sideways to wave direction
 __________________: circular movement of rock; travel on surface-cause most
damage
o Move through the Earth’s surface, not the interior
o Make the ground roll up and down or
_______________________________________________________________
o Slowest moving seismic wave
o Travel on top of Earth’s surface
o Cause the largest ground movements and the most damage as they bend
and twist the surface
Earthquake Magnitude- measures the size of seismic waves or the energy released by
earthquake
Richter scale_____________________________________________________________________________________
Occurrence of Earthquakes
 About ________________ of all earthquakes occur in a belt around the edges of
the ______________________.
 In the U.S., the best-known fault in this belt is the __________________________
in California.
The Layers of Earth, Plate Tectonics, Volcanoes, and Earthquakes Notes
o
This fault is a transform boundary that runs the Gulf of California
through the __________________________ area.
Kinds of Faults
The three main types of faults are:
 ______________ faults
o Here the block of rock above the fault plan slides down relative to the
other block. Stress that pulls rocks apart causes normal faults.
Example: Great Rift Valley of Africa
 ______________ faults, and
o Here the block of rock above the fault plan moves up relative to the other
block. These faults can occur near ___________________________
boundaries between plates.
Example: Himalayan Mountains
 ______________ faults
o Here the block of rock move sideways on either side of the fault plane.
These faults can occur where plates ____________ past each other.
Example: The San Andreas Fault
Tsunamis
A special type of wave that can make water rise more than the height of a
__________________________ building. This wave, known as a tsunami, is a water wave
triggered by an ____________________, ______________________, or ____________________.
Tsunamis are sometimes called ___________________________.