 Where Plates Collide A subduction zone also can form
where two oceanic plates converge. In this case, the
colder, denser oceanic plate bends and sinks down into
the mantle. Mariana Islands in the western Pacific are a
chain of volcanic islands formed where two oceanic
plates collide.
Usually, no subduction occurs when two continental
plates collide, as shown in the previous diagram.
Because both of these plates are less dense than the
material in the asthenosphere, the two collide and
crumple up, forming mountain ranges. Earthquakes are
common at these convergent boundaries. However,
volcanoes do not form because there is no, or little,
subduction. The Himalayas in Asia are forming where
the Indo-Australian Plate collides with the Eurasian
 Where Plates Slide Past Each Other The third type of
plate boundary is called a transform boundary.
Transform boundaries occur where two plates slide
past one another. They move in opposite directions or
in the same direction at different rates. When one plate
slips past another suddenly, earthquakes occur. The
Pacific Plate is sliding past the North American Plate
forming the famous San Andreas Fault in California, as
seen the figure to the right. The San Andreas Fault is
part of a transform plate boundary. It has been the site
of many earthquakes.
1.) Plates Moving Apart
The boundary between two plates that are moving apart is
called a divergent boundary
What forms when two plates move apart?
Rift Valleys
Ocean Ridges
* Magma from these ridges forms new ocean crust
2.) Plates moving together
• Plates move together at convergent boundaries
• When an oceanic plate meets a continental plate the oceanic
plate subducts, or goes down, into the mantle.
• What forms when two plates converge?
* Volcanoes (oceanic and oceanic)
* Deep sea-trenches (continental and oceanic)
* Mountain ranges (continental and continental)
3.) Plates sliding past each other
• Transform boundaries occur where two plates slide past one
• What occurs when one plate slips past another suddenly?
This is what is happening in California at the San Andreas fault
(Figure 11 on page 404)
Review: What are the 3 ways
plates move?
• Apart at divergent boundaries
• Together at convergent boundaries
• Past each other at transform boundaries
In your notebook, answer the following questions:
Between what two plates is there a convergent boundary?
Between what two plates is there a divergent boundary?
Between what two plates is there a strike-slip (transform) boundary?
Picture of the Major Plates of the Earth: page
Science Notebook
Number your paper 1 thru 7 and use each of the
following vocabulary in a complete sentence:
2. mantle
3. inner core
4. outer core
5. asthenosphere
6. lithosphere
What do you think
happens when
plates move?
Can you give some examples of
A catastrophe is a
major event of
•EaRthQua es
• Tsunamis
We are going to learn what
happens when the Earth’s plates
It might get dangerous!
Do you want to draw?
Too bad if you don’t,
you are about to
become an artist
Continental Drift
This is the belief that the
continents were all connected
into one large landmass.
Does anyone know what this one
large landmass was called?
Let’s look at the first map in your
Do you see how if we cut them out,
they would sort of, kind of fit
together? It would not be a perfect
fit, but they would come close.
Let’s see if it works!
Get out your packet.
Find the blank world map.
 Cut out each of the pieces from Pangaea.
 Place them on the correct continent that they would
represent today.
 Once you have placed them where you think they
belong, RAISE your hand so that I or a classmate can
verify your answers.
 Once you have correctly placed ALL 7 continents you
need to glue them to the World Map and LABEL the
continents correctly.
 When you have completed the activity, you may turn in
your completed map.
 You MUST clean up your area. ALL scraps of paper
MUST be put into the trash, glue and scissors MUST be
returned to their proper places.
Remember learning about Pangaea
and the continental drift? Let’s go
back and see what supports the
belief that all continents were once
Turn to page 392 in your OLD science
Alfred Wegener
• A German meteorologist who made the
hypothesis that the continents were once all
connected as one large landmass (Pangaea).
However, over time the continents have
slowly moved to their current location.
What Is the Evidence Wegener
Used to Support His
• Turn to page 393
• Fossil Clues (Read page 393 – old book)
• Climate Clues (Read page 394 – old book)
• Rock Clues (Read page 394 – old book)
But How Did the Continents Move?
• He couldn’t explain it!
• But others did.
Sea Floor Spreading
 What do you think that means?
How do we know what the seafloor looks like?
Let’s read about this on page 396 of the OLD text book.
Seafloor Spreading
• Seafloor spreading is when hot, less dense material
below Earth’s crust rises toward the surface at the midocean ridges. Then, it flows sideways, carrying the
seafloor away from the ridge in both directions
Let’s Read
Turn to page 397 in the old green textbook
• Once we have completed the reading in the
OLD text book you need to answer the Section
Assessment questions, 1 – 5 on your own
What do you know
Landforms are natural
features of the landscape,
natural physical features of
the earth's surface.
What are some of
the landforms
you know?
From this picture,
what do you
think a valley is?
A VALLEY is a hollow or surface
depression of the earth bounded by
hills or mountains, a natural trough in
the earth's surface, that slopes down
to a stream, lake or the ocean,
formed by water and/or ice erosion.
A PLATEAU is a large highland area of
fairly level land separated from
surrounding land by steep slopes.
Some plateaus lie between mountain
ranges. Others are higher than
surrounding land.
Over long periods of time, mountains are
created by tremendous forces in the earth
with a steep top usually shaped up to a peak
or ridge. Mountains occur more often in
oceans than on land; some islands are the
peaks of mountains coming out of the water.
Mountains are formed by volcanism, erosion,
and disturbances or uplift in the earth's crust.
Turn to page 407 in the OLD
text book and let’s read about
Mountain formation and
Brainpop Video
• Mountains
Plains are broad, nearly level
stretches of land that have no
great changes in elevation.
Plains are generally lower
than the land around them
Hills are elevations of the
earth's surface that have
distinct summits, but are
lower in elevation than
A GLACIER is a huge mass of
ice that flows slowly over
land. They form in the cold
polar regions and in high
Brainpop Video
• Glaciers
Let’s see if you can pick out specific
1. Get out a sheet of paper.
2. Look at the picture on the
3. Write which landform you think
it is.
What else do you think can cause
the surface of the Earth to change
forms other than what we have
already talked about?
An Asteroid
• What are some characteristics of an asteroid?
In other words, what makes an asteroid an
asteroid and not something else.
• Asteroid - Any of numerous small celestial
bodies that revolve around the sun, with
orbits lying chiefly between Mars and Jupiter
and characteristic diameters between a few
and several hundred kilometers
More Catastrophes
• What do you think would happen if an
Asteroid hit the Earth?
What is the difference between an asteroid an a
What do you think?
Comets - are distinguished from asteroids by
the presence of a tail behind them. Comets
are thought to consist chiefly of ammonia,
methane, carbon dioxide, and water.
Haley’s Comet (2061)
Let’s read about Haley’s Comet
Who is Haley anyway?
Who can tell me
what weathering
Weathering breaks down and
loosens the surface minerals of
rock so they can be transported
away by agents of erosion such
as water, wind and ice.
Nearly all weathering
involves water, mostly
from: frost shattering,
wetting and drying, and
salt weathering
What do you
think happens
because of
United Streaming Video
• Weathering
Frost Shattering
The force of water in rock
fractures as it freezes and
expands, or is forced into the
rock by the pressure of
freezing water
Sandstone, shattered by frost action.
Salt Crystallization
It causes disintegration of rocks when
saline or salt solutions seep into cracks
and joints in the rocks and evaporate,
leaving salt crystals behind. These salt
crystals expand as they are heated up,
exerting pressure on the confining rock.
Salt Crystallization
Salt Crystallization
When rock minerals take up
water, the increased
volume creates physical
stresses within the rock.
What do you
The movement of
soil from one
place to another.
Let’s look at page 72 in
your NEW science book.
This is about erosion
and weathering.
We know that
rock can erode.
What else can
Let’s look at
page 574 in
your new text
and find out.
Soil Erosion
Law of Superposition and Fossils
Open your CCT Coach book
to page 114 and let’s read
about Law of Superposition
and Fossils.
Law of Superposition
In a bed of undisturbed layered,
sedimentary rocks, the rocks on top are
younger than the ones below.
The oldest sediments must be laid sown
before the younger ones pile up on top.
The imprints of remains
of once-living things
often preserved in
sedimentary rocks.
Brainpop Video & Quiz (Fossils)
Trace fossils
• Fossilized impression
made by an
organism (plant or
animal) in a
substrate (sand, soil,
or clay)
• They include
footprints, burrows,
feeding marks,
dragging tails, and
Mold fossils
Mold fossils are
created when the
organism leaves and
imprint of itself in the
It is similar to having a
picture of the
organism without
having any remains of
the organism.
Cast fossils
Cast fossils are created
when a Mold Fossil of
an organisms is filled
with a substrate like
sand, soil, or clay.
The cast is like having
a model of the
organism without
having any remains of
the organism.
The process by
which organic
material is
converted into
stone or a similar
substance. It is
synonymous with