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Do Now
Tuesday, March 11, 2014
•Take out your notebook / Be seated
•Take out your reading “The Earth’s Interior”
from yesterday
•If you have a highlighter, take one out…
•In your notebook, set up TOC with “Layers of
the Earth” and today’s date
•Set up a new page with date and title and
Essential Question: “What are the layers of the
Earth and how do they move?”
E.Q.: “What are the layers of the Earth and how
do they move?”
Set up a diagram and pick 4 colors…
• Please draw this
diagram of a circle
with three inner
circles
• Add these labels:
1.
2.
3.
4.
Crust
Mantle
Outer core
Inner core
Earth’s Layers
1
2
3
4
color-code each layer’s note by
underlining with that color
The Layers of the Earth
Don’t draw
this – just
listen!
•There are 4
basic layers, but
there are also
subdivisions to
each layer
•As we go
through these
notes, colorcode them!
•Click on image for short video
© Copyright 2006. M. J. Krech. All rights reserved.
Earth’s
Interior
How do we know about
these layers?
Scientists discovered
these layers using
seismic waves from
Earthquakes.
The Four Layers – basic stuff
The Earth is composed of
four different layers.
• The crust is the layer that
you live on, and it is the most
widely studied and
understood.
•
The mantle is much hotter
and has the ability to flow.
• The outer core and
inner core are even hotter
with pressures so great you
would be squeezed into a ball
smaller than a marble if you
were able to go to the center
of the Earth!
The Crust
• The Earth's Crust is like the
skin of an apple. It is very
thin in comparison to the
other three layers.
• The crust is only about 3-5
miles (8 kilometers) thick
under the oceans (oceanic
crust) and about 25 miles (32
kilometers) thick under the
continents (continental
crust).
The Crust
The crust is composed of two rocks. The continental
crust is mostly granite. The oceanic crust is basalt.
Basalt is much denser than the granite. Because of this
the less dense continents ride on the denser oceanic plates.
Crust Rock Types
– Both Igneous
• Granite
• Continental crust
• Density = 2.6 g/cm3
• Basalt
• Oceanic Crust*
• Density = 2.8 g/cm3
*oceanic crust subducts under continental crust
Do Now
Wednesday, March 12, 2014
•Take out your notebook / Be seated
•Open your notebook to the “Layers of the
Earth” NOTES
•Be prepared to answer:
•What is the least dense layer of the
earth?
•What is oceanic crust made of?
•What is the lithosphere?
The Lithosphere
The crust and the upper layer of the
mantle together make up a zone of rigid,
brittle rock called the Lithosphere.
The Lithospheric Plates
The crust of the Earth is broken into many
pieces called tectonic plates.
The plates "float" on the soft, semi-rigid
asthenosphere.
The Mantle
The mantle is the largest
layer of the Earth. The
middle mantle is
composed of very hot
dense rock that flows like
asphalt under a heavy
weight and is 1800 miles
thick. The movement of
the middle mantle
(asthenosphere) is the
reason that the crustal
plates of the Earth move.
Mantle and Asthenosphere
• The upper/middle mantle is the asthenosphere,
which is responsible for the movement of plates
• Composed of mostly silicon, oxygen, magnesium
and iron
• Texture is plastic like which has the characteristic
of a solid but flows like a liquid when under
pressure
• Approx 2885 km thick
• Has large convection currents
that drive the movement of the
plates
click on image
The Outer Core
The core of the Earth
is like a ball of very
hot metals. The outer
core is so hot that
the metals in it are all
in the liquid state.
The outer core is
composed of the
melted metals of
nickel and iron.
The Inner Core
The inner core of the
Earth has temperatures
and pressures so great that
the metals (nickel and
iron) are squeezed
together and are not able
to move about like a
liquid, but are forced to
vibrate in place like a
solid. 800 miles thick.
200 million years ago • Scientist believe that all
the land on Earth was
originally connected in a
“super continent” called
Pangaea (or “Pangea”)
• Due to the movement of
chunks of lithosphere,
we now that the
arrangement that you
see on a map click on map
Plate Tectonics Theory
• The Lithosphere is the Earth’s crust and upper
mantle
• Lithospheric plates are thin, rigid sections of
the outermost layer of the Earth that include
the crust and upper mantle.
• New lithosphere is created at mid-ocean
spreading ridges which causes them to move
apart.
Plate Tectonic Theory (cont.)
• The size of the Earth is not increasing, so in
areas where these plates meet some sections of
the plates may be lost by dissolving into the
mantle.
• Plate Boundaries are the areas where the
plates meet.
• Plate tectonics is study of the movement and
interaction of these plates of the Earth’s
lithosphere
Map of Major Tectonic Plates
click on map
Types of Plate Boundaries
Quick Overview
1. Divergent- new crust is generated and the
plates pull AWAY from each other
2. Convergent- Crust is being destroyed or
uplifted and the plates move TOWARDS
each other
3. Transform- where crust is neither created
or destroyed and the plates that slide
horizontally past each other
Divergent Boundaries
There are two types of Divergent Boundaries
where the crustal plates are pulling away from
each other
1. Oceanic-Oceanic: Mid Ocean Ridges
o
This is responsible for Sea floor spreading where new crust is
being made as magma rises and cools in the mid ocean ridges
Divergent Boundaries (cont.)
2. Continental- Continental Divergent
– When a divergent boundary cuts through a piece of land, the
feature called a Rift Valley is formed.
– Example is Iceland where the North American and Eurasian
Plates are pulling apart and the African Rift Valley
– Volcanoes are created in Rift Valleys as magma plumes up
from the separation of the plates
Iceland
Convergent Boundaries
• Two plates move toward each other pushing together
• Subduction Zone - zone where one plate subsides (goes
underneath) another plate
– Responsible for active volcanism and deep subduction
earthquakes
• “3 Subtypes of Convergent Boundaries:
1. Oceanic-Continental convergence - subduction
2. Oceanic-Oceanic convergence - subduction
3. Continental-Continental convergence - minimal or ancient
subduction and uplifting of large mountains
Oceanic-Continental Convergence
• When an oceanic plate collides with a continental plate, there is a
Subduction Zone
– A volcanic arc is created inland 100-300km from the coast
– Trenches are formed off the coast of a subduction zone
– Oceanic Crust subducts under continental crust because it is
more dense
– Ex: Pacific Northwest and Cascade mountains
Oceanic-Oceanic
Convergence
• When two oceanic plates converge
there is a battle between basaltic
crusts until one subducts
– Volcanic Island arcs are created
100-300km away from the plate
boundary – Example: Japan,
Aleutian Islands
– Trenches are created off the plate
boundary
Cleveland Volcano
Aleutian Islands,
Alaska
Continental-Continental
Convergence
• When two continental plates collide
both are very buoyant and want to
stay above each other. They battle
towards each other but neither one
subducts under the other
– Builds large mountain chains
with very tall mountains
– No volcanoes because there is
not any
subduction causing melting of
the plates and rising magma
– Ex: India collides with Asia
forming the Himalayas
The ancient Himalayas
were volcanoes because as
India was pushing towards
Asia, there was an ocean
between them. This caused
a subduction of ocean crust
resulting in volcanoes.
INDIA
Do Now
Wednesday, March 19, 2014
•Take out your notebook
•Have a pencil/pen out and be ready to go!
•OPEN YOUR NOTEBOOK to the last
notes we took on plate boundaries
NOTES
•Retakes for test Thursday/Friday before/after school
•6th period – Test back today; Field study procedure
tomorrow
•5th & 6th – Ms. Edwards here on Friday
Transform Boundary
• Transform boundaries are
where two plates slide past each
other
– Usually a part of a system of
divergent or convergent
boundaries
– Responsible for frequent shallow
earthquakes
– Ex: San Andreas Fault in
California
Hot Spots
• There are several other volcanoes that are not created
near a plate boundary but instead in the middle of a plate
• They are created when a mantle plume is super heated by
the core and burns through the crust building a volcano
• In the case of an oceanic hotspot, the plate continues to
move and the volcano moves off the hotspot, and
becomes inactive and just an island. A new volcano will
begin to form on the ocean floor and as it peaks above the
ocean surface it will become the new active volcanic
island in the chain (ex. Hawaiian Islands)
• In the case of a continental hotspot, the caldera moves off
the hotspot and when there is a new volcanic explosion, a
new caldera forms in the chain (ex. Yellowstone)
Examples of Hot Spots
1.
2.
Hawaiian Islands - The active and newest island is the big island of
Hawaii, and the oldest inactive island is Kauai. Since the inactive volcanoes
are no longer adding to the size of the island, the island will erode away over
millions of years until it becomes a seamount where is no longer above the
ocean surface. Formation over hotspot;
Yellowstone - this is in the middle of a continent causing large scale
eruptions that form calderas or collapsed volcanoes. The continental crust is
too thick to produce tall standing volcanoes from a hotspot. Yellowstone
Supervolcano video; other CNN clips
Pacific Ring of Fire
• The area around the
Pacific Plate is a
subduction zone and
there is a lot activity
• Many volcanoes and
volcanic islands!
Near Us
• You are currently on the
North American Plate
• We are in a subduction
zone.
• The Juan de Fuca plate
is between the Pacific
Plate and the North
American Plate.
• We are vulnerable to
earthquakes from plate
movement and to
tsunamis that might
result from them.
So, what do you remember?
Please number your paper 1-5
1. How old is our Earth?
2. What are tectonic plates?
3. Which tectonic plate are you currently on
and which one is subducting under you?
4. Are all plate boundaries the same? If not,
how many types are there?
5. Do all volcanoes result from plate
boundaries?
So, how did you do?
1. How old is our Earth? 4.6 billion years
2. What are tectonic plates? Chunks of the
Lithosphere that float on the Mantle’s
convection currents
3. You are currently on North American Plate
and the Juan de Fuca Plate is subducting
under you?
So, how did you do?
4. Are all plate boundaries the same? No! If
not, how many types are there? 3 Types:
Convergent, divergent, and transform
5. Do all volcanoes result from plate
boundaries? No, “Hot Spots” can form in
the middle of a plate.