Download Oceanic Crust - RRMS 8th Grade Science

The Structure of the Earth and
Plate Tectonics
Warm Up –Give as much information as
you can about the following. This may
include a diagram
What are the layers
(structure) of the Earth? Give
as much detail as you can.
Structure of the Earth
• The Earth is
made up of 4
main layers:
– Inner Core
– Outer Core
– Mantle
– Crust
inner core
Outer core
Mantle
crust
The Crust
• This is where we live!
• It is thin, very hard and brittle
• The Earth’s crust is divided
into two types.
Continental Crust
- Forms the land
-thick (10-70km)
- buoyant (less dense
than oceanic crust)
- mostly old
Oceanic Crust
- Ocean floor
-thin (~7 km)
- dense (sinks under
continental crust)
- young
Label This
Continental Crust
Oceanic Crust
Sublevels
Lithosphere – the crust and
the very top of the mantle
makes this zone of rigid,
brittle rock
Asthenosphere – a layer
of hot soft semi-rigid
rock in the middle mantle
thatflows
Label This
Lithosphere
Upper Mantle
Convection Currents
Lower Mantle
Asthenosphere
Middle Mantle
Vocab words
•
•
•
•
•
•
•
Sedimentary Rock
Metamorphic Rock
Igneous Rock
Inner core
Outer core
Mid-ocean ridge
Rock cycle
•Divergent boundary
•Convergent boundary
•Transform boundary
•Mantle
•Crust
•Hot spot
• Theory of plate tectonic
•Pangaea
•Continental Drift Theory
• asthenosphere
• lithosphere
• Convection currents
Faults
• Tectonic plate
Vocab p. 38A
Name: 4 Square
Definition
Sentence
using Word
Example
Characteristics
Inner Core
A hot solid ball of
metal that is the
Inner most part of
the Earth.
The inner core is the
most dense layer of
the Earth
Example
Outer surface
Liquid
cold
Warm Up
• Get a Textbook and turn to page 15A
• Looking at the picture, what do you think the
shaded area on the outline maps of South
America and Africa represent?
• Read Evidence for Continental Drift on
pg.15A and answer the following:
1. List the 3 pieces of evidence used to
prove continental drift?
2. Which evidence do you think is the
most convincing and explain your answer?
Continental Drift Theory
• Proposed by Alfred Wegener in 1912
• 250 million years ago, all of the
continents were combined into one
super-continent called “Pangaea”
• The continents gradually drifted apart to
where they are today
“Puzzle Pieces”
• Continents look like
they could be part of
a giant jigsaw puzzle
Distribution of Fossils
• Plant and animal
fossils found on the
coastlines of different
continents
Sequence of Rocks
• Same rock patterns
found in South
America, India, Africa,
Antarctica and
Australia
Ancient Climates
• Tropical plant remains
(coal deposits) found
in Antarctica
• Glaciation in Africa,
South America, India,
and Australia during
the same time
Problems With The Theory
• No mechanism for movement of
continents
• Wind and currents could possibly move
fossils
• Theory was not accepted by scientists
Warm Up
• Need Glue stick today
• Get warm up off book shelf and
copy to tectonic plate map.
• Warm up is the half sheet with
layers of the earth. DO NOT
WRITE ON IT
What is The Theory of Plate
Tectonics?
Generally Speaking
The theory of plate tectonics explains
how the Earth’s surface has changed
over geologic time.
The Earth’s outer crust is made of plates
of rock that continues to shift and collide
resulting in earthquakes and volcanoes,
mountain ranges, rift valleys, etc…
What are the specifics of Plate Tectonics?
• The Earth’s crust is divided into 9 major plates
which move in various directions. Which consist
of seven major continents.
• This plate motion causes them to collide, pull
apart, or scrape against each other.
• Each type of interaction causes a characteristic
set of Earth structures or “tectonic” features.
• The word, tectonic, refers to the deformation of
the crust as a consequence of plate interaction.
What causes the
plates to move?
How and Why do Tectonic
Plates move around?
What is the Mantle?
• Located between the core
(inner surface) and the crust
(on its outer).
• The thickest layer. It is more
than two thousand miles thick
and accounts for more than
three-quarters of the volume
of the Earth.
• Has a soupy or slouchy
consistency (magma…liquid
rock).
Mantle
Convection currents
The middle mantle
"flows" because of
convection currents.
Convection currents
are caused by the very
hot material at the
deepest part of the
mantle rising, then
cooling and sinking
again --repeating this
cycle over and over.
Plate Movement
• “Plates” of lithosphere are moved around by
convection cells in hot mantle. Hot magma
rises and cools then fall back toward the
core.
What are tectonic plates
made of?
What lies beneath the
tectonic plates?
What are tectonic plates made of?
• Plates are
made of rigid
lithosphere.
The lithosphere is
made up of the
crust and the upper
part of the mantle.
What lies beneath the tectonic plates?
• Below the
lithosphere
(which makes
up the tectonic
plates) is the
asthenosphere.
Where are the World Plates
located?
• If you look at a map of the world, you may notice that
some of the continents could fit together like pieces of a
puzzle.
World Plates
Copy and answer the following questions:
• How many major tectonic plates are there
on earth?
• What causes these plates to move?
• Look at the diagram on page 19A, are more
plates moving apart or pushing together?
• Look at the diagram on page 18A to answer
the following questions:
• In what direction do convection currents
move on each side of a spreading center?
• In what direction would the plates move?
Plate Movement
• “Plates” of lithosphere are moved around by
convection cells in hot mantle. Hot magma
rises and cools then fall back toward the
core.
• Use Rock cycle powerpoint
Rock Poster
1.Title: Name of rock
2.Definition (what it is)
3.How it’s formed
4.How it fits in the rock
cycle
5.Examples
6. Visual
Rock Cycle (Only)
1.Definition
2.The processes
that occurs to
form each
rock
3. Where each
rock goes
4. A visual
representation
of the cycle
Practical Exercise 1
Supercontinents!
Copy and answer the following questions:
• What are supercontinents?
• How do they form and how do
they break apart?
What are supercontinents?
a landmass comprising more than one
continental core, or craton (Pangea)
How do they form and how do they
break apart?
Through continental collision fewer and
larger continents are formed while rifting
makes more and smaller continents.
How was Pangea made?
What happens at tectonic
plate boundaries?
https://www.youtube.com/watch?v=Kg_UBLFUpYQ
1. What might have made this huge crack?
2. How could this crack (over time ) change
the landscape of the Earth’s surface?
Copy this chart on next notes page
TYPES OF PLATE BOUNDARIES
Type of
Boundary
Sketch of
Boundary
Direction of
Movement
Description/Features of
Plate Boundary
Examples
Ocean-Ocean
Ocean-Ocean
Ocean-Ocean
Ocean-Ocean
OceanContinent
Ocean-Continent
Ocean-Continent
OceanContinent
Divergent
Plate
Boundary
Transform
Boundary
Convergent
Boundary
***continentcontinentCollision
Collision
Boundary
***
Subduction
Divergent Boundaries
Divergent Boundaries
• Spreading ridges
– As plates move apart new material is
erupted to fill the gap
Divergent Boundaries
• Spreading ridges ex. Mid-ocean ridge, rift valley
– As plates move apart new material is erupted to fill the gap
Three types of plate boundary
Divergent boundaries are
where plates move away
from each other
Iceland: An example of continental rifting
• Iceland has a divergent
plate boundary running
through its middle
Age of Oceanic Crust
Youngest Crust
Oldest Crust
Courtesy of www.ngdc.noaa.gov
Warm Up
Draw the figure below then answer the following questions.
1.What type of boundary is this and how do you know?
2.What type of crust is this activity occurring in?
3.Identify A, B, C and D then explain what is occurring at each
site.
D
B
A
C
Warm Up
1.This is a Divergent boundary because the plates are moving
apart
2.Because it is under water this is the oceanic crust which is
located in the lithosphere
3.A, B, C and D then explain what is occurring at each site.
D rifts
B
A Middle Mantle
Asthenosphere
C
Convection currents –magma
rises and falls as it heats and cools
Transform Boundaries
Transform Boundaries
The San Andreas fault, adjacent to which the US city of San Francisco
is built is an example of a transform boundary between the Pacific
plate and the North American plate. (Earthquake zones)
Transform Boundaries
• Where plates slide past each other
Above: View of the San Andreas
transform fault
Convergent Boundaries
the plates move towards each
other
Convergent Boundaries
• There are three styles of convergent
plate boundaries
– Continent-continent collision
– Continent-oceanic crust collision
– Ocean-ocean collision
Continent-Continent Crust Collision
Continent-Continent Crust Collision
• Forms mountains, e.g. European Alps, Himalayas
Continent-Oceanic Crust Collision
SUBDUCTION Zones
Occurs along Continent-Oceanic collision and Ocean-ocean
collision
•
Subduction
• Oceanic lithosphere
subducts underneath the
continental lithosphere
• Oceanic lithosphere heats
and dehydrates as it
subsides
• The melt rises forming
volcanism
• E.g. The Andes
Ocean-Ocean Plate Collision
• When two oceanic plates collide, one runs over the
other which causes it to sink into the mantle forming
a subduction zone.
• The subducting plate is bent downward to form a very
deep depression in the ocean floor called a trench.
• The worlds deepest parts of the ocean are found
along trenches.
– E.g. The Mariana Trench is 11 km deep!
Ocean-ocean collision
Type of
Boundary
Direction of Description/Features
Examples
Sketch of OF
TYPES
PLATE
BOUNDARIES
Movement
Boundary
of Plate Boundary
Diverging
Plate
Boundary
plates move away from
each other
Mid-Ocean
Ridge
Transform
Boundary
plates slide past each
other
The San
Andreas
fault
Conversion
Boundary
***
Collision
plates move towards
each other
Collision
Boundary
***
Subduction
Ocean-Ocean
OceanContinent
Ocean-Ocean
Ocean-Continent
Ocean-Ocean
two oceanic plates collide one
rolls on top while pushing the
other into the mantel
Ocean-Continent
Continent plate collides with
Oceanic plate. CP rolls on top
of the more dense OP
Ocean-Ocean
Mariana Trench
Ocean-Continent
many volcanoes
Andes mountain
Three types of plate boundary
• Divergent
• Convergent
• Transform
Need Chromebook today. Answer questions
in complete sentences.
1. What might have made this huge crack?
2. How could this crack (over time ) change
the landscape of the Earth’s surface?
Volcanoes and Plate
Tectonics…
How can hot-spot volcano be used to
track plate movement?
Pacific Ring of Fire
An area in the
basin of the
Pacific Ocean
where a large
number of
earthquakes
and volcanic
eruptions
occur
Volcanism is
mostly
focused at
plate
margins
Pacific Ring of Fire
Hotspot
volcanoes
What are Hotspot Volcanoes?
• Hot mantle plumes (coming from core –
mantle boundary) rises to the surface in
the middle of a tectonic plate.
The Hawaiian island chain are
examples of hotspot volcanoes.
Photo: Tom Pfeiffer / www.volcanodiscovery.com
The tectonic plate moves over a fixed hotspot forming a
chain of volcanoes.
The volcanoes get younger from one end to the other.
Mantle
Hot plumes occur
Due to lower
pressure this
layer consist of
liquid metal that
surrounds the
inner core
Outer Core
Inner
Core
Hottest, densest layer
but because of extreme
it remains a ball of hot
solid metal
What are hot spots?
• Not all volcanoes come from hot spots.
Volcanoes are formed by:
- Subduction - Rifting - Hotspots
Through rifting pates
pull apart magma rises
Himalayas
Practical Exercise 2
Where will the UK be in:
1,000 years?
1,000,000 years?
1,000,000,000 years?
Warm Up
• Turn to page 41A in your textbook.
• Complete questions 1-9. You only need
to write the letter of the correct answer.
Take out notebook, turn to vocab
http://www.youtube.com/watch?v=Kg_UBLFUpYQ
• As with volcanoes, earthquakes are not
randomly distributed over the globe
Figure showing
the distribution of
earthquakes
around the globe
• At the boundaries between plates, friction
causes them to stick together. When built up
energy causes them to break, earthquakes
occur.
Where do earthquakes form?
Figure showing the tectonic setting of earthquakes
Plate Tectonics Summary
• The Earth is made up of 3 main layers (core,
mantle, crust)
• On the surface of the Earth are tectonic
plates that slowly move around the globe
• Plates are made of crust and upper mantle
(lithosphere)
• There are 2 types of plate
• There are 3 types of plate boundaries
• Volcanoes and Earthquakes are closely
linked to the margins of the tectonic plates
Structure of the Earth
asthenosphere
• The Earth is
made up of 4
main layers:
Mantle
Outer core
– Inner Core
– Outer Core
– Mantle
– Crust
Inner core
Crust
Volcanoes are formed by:
- Subduction - Rifting - Hotspots