Mr. Ruark’s Earth Science
Thought of the Day- What is the Earth composed of?
Using this week’s notes, illustrations, readings (pages 29-32 in your
text), please answer the following questions in complete sentences.
1. What layer of the Earth has a “plastic layer” of rock that flows
slowly?
2. What does the word “mesosphere” literally mean? (look at definition
on page 31).
3. True or false: Continental crust is thinner than oceanic crust.
Daily Objective(s):
We will describe the composition of Earth and its
layers.
Unit 1: Introduction to Earth Science
Day
12
Earth’s Structure and
Processes
What is Geology?
• Geology: the study of
planet Earth
• A geologist studies the
forces that make and
shape planet Earth
• They study the
processes that create
Earth’s features and
search for clues
about Earth’s history
What forces cause Earth’s
surface to change?
Two main forces:
1. Constructive
forces: shape the
surface by building
up mountains and
landmasses
Surtsey- new island forming
off the coast of Iceland
What forces cause Earth’s
surface to change?
2. Destructive
forces: slowly wear
away mountains,
and eventually,
every other
feature on the
surface
(weathering,
erosion, etc)
What’s inside Earth?
• Earth’s interior is
made up of three
main layers:
• Crust
• Mantle
• Core
Each layer has its
own conditions and
materials
How do you know what’s
inside?
• Geologists can
learn about the
interior of Earth
by studying the
paths of seismic
waves
• These are
produced by
earthquakes
Earth’s lithosphere is broken
into about 20 pieces
Layer
Crust
Relative Position
•
•
•
•
Outermost layer
Thinnest under
oceans
Thickest under
continents
Crust and top part
of mantle make up
the lithosphere
Density
•
•
Least dense
layer
Oceanic crust is
more dense than
continental crust
Composition
•
•
•
•
Solid rock
Mostly oxygen
and silicon
Oceanic crust –
Basalt
Continental
crust - Granite
Mantle
• Middle layer
• Thickest layer
• Top portion under
lithosphere is called
the asthenosphere
• Density increases
with depth
because of
increasing
pressure
• Hot softened
rock
• contains iron and
magnesium
Core
• Inner layer
• Consists of 2 parts
outer core and inner
core
• Heaviest material
• Most dense layer
• Mostly iron and
nickel
• Outer core- slow
flowing liquid
• Inner core- solid
Layers of the Earth Rap
https://www.youtube.com/wat
ch?v=yGO1foDhDb8
Mr. Ruark’s Earth Science
COOL DOWN
Where is the asthenosphere and what is it made of?
Earth’s Layers 2-D Diagram
A. Construct the following layers that make up Earth’s interior
structure: (30 points) (DONE ALREADY!~)
B.
1.
2.
3.
4.
5.
Label each layer:
Lithosphere
Asthenosphere
Mesosphere
Outer core
Inner core
C. Define each layer, including the following information: (30 points)
1. Write the definition.
2. Write was it is composed (made) of.
D. Include a title (10 points)
FINISH EARLY? COMPLETE CROSSWORD PUZZLE!
The Grand
Canyon
Image taken from
the International
Space Station
The Himalayan Mountains
Journey to the Center of the Earth
• Write a short
story or create a
drawing about a
fictional journey to
the center of the
Earth.
• Include the
following:
– Name of each layer
– Description focused
on composition,
temperature, and
density
Giant Crystal Cave – Naica, Mexico
WarmUp
• Use your notes to answer the
following questions:
1. What is the main type of rock that
makes up continental crust? Oceanic
crust?
2. What layer of Earth is made of the
crust and uppermost layer of the
mantle?
3. What three factors increase with depth?
4. What three natural forces erode
sediment?
5. How is the outer core different from the
inner core? How are they similar?
WarmUp
•
1.
2.
3.
4.
5.
Answer the following
questions:
Earth’s inner core spins
inside the hot, molten metal
of which layer?
The asthenosphere is part
of which layer?
Which layer of Earth is
made of oceanic and
continental crust and upper
mantle?
Which layer has the
highest temperatures?
What happens to pressure
as you travel deeper into
Earth?
Continental Drift
• Hypothesis proposed
by Alfred Wegener
– Continents move
slowly over Earth’s
asthenosphere
– All continents were
once a giant landmass
called Pangaea
Evidence for Continental
Drift Hypothesis
1. Landforms: matching up
like puzzle pieces
2. Fossils: fossils of same
species found on widely
separated continents
3. Climate:
–
–
fossils of tropical plants
found in Arctic and
Antarctica
Scratches in rock in
tropical climates caused by
glaciers
Fossil Evidence
Climate Evidence
Scratches in equatorial
rock from glaciers
Hypothesis Rejected
• Wegener couldn’t
prove HOW the plates
moved
• Changed in 1970s when
geologists used sonar
to map the ocean floor
• They found underocean mountains and
trenches
• This led to modernday Theory of Plate
Tectonics
Mid-ocean Ridges
Pangea Ultima
Do Now – FridayMarch 15
•
1.
2.
3.
4.
Define the following
terms in your
notebook (use
textbook and PASS
Coach book):
Continental drift
Pangaea
Sea-floor spreading
Theory of plate
tectonics
5. Mid-ocean ridge
6. Convection
7. Convection current
Spreading center along
the Pacific mid-ocean
ridge
Theory of Plate
Tectonics
• Plate Tectonics: pieces of
Earth’s lithosphere are in
constant, slow motion
• Caused by convection
currents in the mantle
• The movement of plates
changes the size, shapes,
positions, and features of
Earth’s continents and
oceans
• No plate can budge without
affecting the other plates
around it
Types of Plate Boundaries
• Three types of
plate boundaries:
– Divergent boundary
– Convergent
boundary
– Transform
boundary
Divergent Boundaries
• Divergent boundaries =
Where two plates are moving
apart
• Most located along midocean ridges: this is called
sea-floor spreading
• New crust forms
– Magma pushes up, cools, and
hardens between separating
plates
– Older rock is found farther
away from the ridge
Seafloor spreading is a
constructive force – new
ocean crust is formed along
the mid-ocean ridge.
What is happening to the old
crust as new crust forms?
Newly formed ocean crust (basalt rock)
•As new
ocean crust
is forming,
old crust is
destroyed
at the same
rate
•Earth stays
the same
size
Pillow
lava
Divergent Boundary
• Divergent continental
plates form rift valleys
• Rift valley: a deep valley
formed as tectonics plates
move apart, such as along a
mid-ocean ridge
• Great Rift Valley in east
Africa is 3,000 kilometers
long (1, 860 miles)
• As plates continue
separating, someday the
continent will split
When plates
move apart, rift
valleys and midocean ridges
form.
Which types of
diverging plates
would create a
rift valley? A
mid-ocean ridge?
Convergent Boundary
• Convergent Boundary:
plates are coming together
and colliding
• Activity depends on types
of crust that meet
 Oceanic + oceanic =
subduction (forms trench
and volcanoes)
 Oceanic + continental =
subduction (forms trench
and volcanoes)
 Continental + continental
= mountain ranges
Subduction Zone
• Subduction:
oceanic
plate slides under less
dense continental plate or
another oceanic plate
• Some crust is destroyed
(destructive force)
• Volcanoes common near
subduction zones
All along the
subduction
zone, volcanic
arcs form,
caused by the
sinking
oceanic plate
melting into
the mantle.
Pacific Ring of Fire
Continental crust
collides with
continental crust 
forms folded mountain
ranges
Examples of folded
mountains:
•Appalachian Mountains
•Himalayan Mountains
Mt. Everest is
the tallest
mountain in
the world –
approximately
30,000 ft.
The Himalayan Mountains are still growing because of the
compression of the Eurasian and Indian plates.
Transform Boundary
• Transform boundary:
where two plates slide past
each other
• Crust is neither created
nor destroyed
• Earthquakes occur
frequently along this
boundary due to breaking
rock
San Andreas Fault – formed at a
transform boundary
The San Andreas fault is 800 miles long and up to 10 miles deep.
Plate Boundaries
Movements form
Movements form
Movements form
http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave
.html
http://Interactives . Dynamic Earth . Introwww.learner.org/inte
www.education.sdsc.edu/optiputer/flash/convection.htm