This is an geology assignment about plate motion. The detailed instruction is in the PDF file I have posted below.
Geology 1203 Earth history
Assignment- plate motion
One of the great advances of the twentieth century for geologists was the formation of the theory of plate
tectonics. We now know that the Earth is made up of many rigid plates, composed of the crust and upper
mantle, called the lithosphere. These lithospheric plates float on the underlying less ridged layer of rock
called the asthenosphere. This rigid outer layer of the Earth is divided into seven major and a number of
smaller tectonic plates. There are also some very small “microplates” as well as areas that are very
complex structurally and in some cases still not well understood. These plates all in motion (albeit very
slowly) and where they contact each other along the edges zones of deformation and seismic activity as a
result of this motion.
The boundaries between the plates can be divided into three basic types:
Divergent – the direction of relative plate motion is away from the boundary.
Basaltic lava flows upwards from the mantle to the surface where it cools and
solidifies. These types of boundaries are most often found in oceans, where
the lava forms new ocean crust, and so will be often called mid-ocean ridges
(MOR). But divergent-type boundaries have also formed in continents where
the early stages are rifts systems – regions marked by deep valleys and
volcanic activity. The predominant force at work along divergent boundaries is
tension – pulling apart.
Convergent – the direction of relative plate movement is toward the boundary.
Usually one plate is forced under the other (subducted) where it is eventually
absorbed into the mantle. This region is usually, but not always, marked a deep
trench that parallels the boundary, and so are often referred to as a subduction
zone. A subduction zone marks the location of a convergent-type boundary but
not all convergent boundaries will have a subduction zone.
The predominant force at these plate boundaries is compression – pushing
together.
There are three different types of convergent boundaries based upon the types
of crust that collide.
Ocean crust collides with continental crust – the ocean is denser
and so is subducted.
Ocean crust collides with ocean crust – the older, colder crust is
subducted.
Continental crust collides with continental crust – because both are
considerably less dense than the mantle this results in deformation, uplift and
mountain building.
Conservative – the direction is parallel to the plate boundary where the two
plates slide past each other. They are marked by long transform faults and they
are often referred to as transform boundaries.
Because the Earth has remained the same size any new crust that is created
at divergent boundaries must be balanced by the same amount of old crust
being destroyed at convergent margins.
Note: When I use the term “crust” I am referring to the lithosphere that is
composed of the crust and upper mantle – it is just easy for people to grasp
plate boundaries if they think in terms of ocean and continental crust.
OCEANIC CRUST
LITHOSPHERE
MAGMA
ASTHENOSPHERE
OCEANIC
CRUST
TRENCH
LITHOSPHERE
VOLCANIC
ISLAND ARC
MAGMA
ASTHENOSPHERE
transformboundary
What do I have to do?
Print the map figure of plate boundaries on the last page and use it to answer the following
questions. I have included a colour version with brief explanation of the symbols used to identify
the boundaries on this figure.
You will be required to submit a photo of your annotated map figure with your assignment
answers. You should use coloured pen or pencils to mark on the figure so that it will show up.
Take some care when drawing the arrows on your figure – if they are in the wrong location,
indicate the wrong direction, or are just too messy I will mark them wrong.
Do not use the internet to try to look up the answers!. All answers will be based up on the plates
as identified in this assignment.
Refer to the figures on plate boundaries in this module and/or figure 1.16 on pages 18 -19 of your
textbook.
Questions:
Mid-Atlantic Ridge
Locate the Mid-Atlantic Ridge on the map. [it will extend from north of the figure and end on the
east side]
Draw a red line along this boundary. Add arrows on either side to indicate the direction the
direction of plate motion.
1.If you have drawn you line correctly there will be 4 major plates bounded by the Mid-Atlantic
Ridge. What are their names?
2. If you were standing at Point A in which direction would someone at Point B be moving?
Towards you
Away from you
Parallel to you
South America
Locate the west coast of South America on the map.
3. What type of boundary do you think runs just along the coast?
Draw arrows on either side of the boundary to indicate the direction of plate movement.
4. If you were standing at Point C in which direction would someone at Point D be moving?
Towards you
Away from you
Parallel to you
East Pacific Rise
The East Pacific Rise is a long divergent boundary. [it extends from near Antarctica to southern
California]
Locate it on the map; mark it with a red line. Now draw arrows on either side of the boundary to
indicate the direction of plate movement.
5. If you have drawn your line correctly there should be 5 plates that have a boundary on the
East Pacific Rise. What are their names?
China
Locate China on the map figure. This region is subject to frequent and often devastating
earthquakes.
6. What two plates do you think are responsible for these earthquakes?
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
7. What type of boundary is it?
8. If you were standing at Point E in which direction would someone at Point F be moving?
Towards you
Away from you
Parallel to you
California
Next locate the state of California, on the West coast of North America.
9. What two plates are in contact here?
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
10. If you were standing at Point G in which direction would someone at Point H be moving?
Towards you
Away from you
Parallel to you
British Columbia
Located the province of British Columbia, on the west coast of North America. This area
experiences an earthquake almost every day; most are never noticed. However, in recent years
this area has experienced several larger earthquakes that have been noticed.
11. Looking at the map of plate boundaries what 2 plates do you think are responsible?
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
12. What type of boundary is this?
13. If you were standing at Point I in which direction would someone at Point J be moving?
Towards you
Away from you
Parallel to you
0
60o
30o
o
o
Afr
0o
ica
30o
60o
0
45
o
o
90
o
90
o
IndianAustralian
plate
Arabian plate
Eurasian plate
45
np
late
convergent or subduction
boundary
The triangles indicate the direction
of the plate being subducted. n
this example the pinkish plate is
being forced under the other plate.
The black arrows indicate the
direction of movement relative to
the plate boundary.
135o
135o
180
o
135o
Antarctic plate
135o
90
o
90
o
Nazca
plate
North American
plate
Juan de Fuca
plate
o
Philippine plate
Cocos
plate
Pacific plate
180
divergent and transform
boundaries
The black arrows indicate
the direction of movement
of the two plates along the
divergent boundary. The
red arrows show the
relative movement along
the transform boundary.
45
o
Caribean
plate
South
American
plate
o
Scotia plate
45
0
o
o
0
unknown type of
boundary
In some regions the
exact nature of the
boundary is not clear.
What do I submit?
Print the next page with the map figure. Annotate it as instructed in the question section.
Make sure the arrows are neat and correctly placed. Do not forget to include your name and student
number.
Upload a picture of your annotated map figure -if the map is missing you will be given only half the
value for any questions you get correct.
You must also submit the answers to the questions – this can simply be the question number
followed by your answer. But do not mix them up – I will mark them in the order they are numbered
above and if you have the wrong answer with the wrong number it will be considered wrong.
If you want to be sure then you can repeat the question with the number. Do not scribble the
answers to the questions on this sheet.
When indicating a direction of movement for a plate boundary the arrows should show the main
direction the plate is moving at that point.
divergent
convergent
conservative
0
60o
30o
0o
o
o
Afr
ica
30o
60o
0
np
late
Name:
45
o
o
90
E
o
90
o
IndianAustralian
plate
F
Arabian plate
Eurasian plate
45
Student Number:
135o
135o
180
o
135o
J
H
G
Antarctic plate
135o
90
o
90
o
Nazca
plate D
North American
plate
I
Juan de Fuca
plate
o
Philippine plate
Cocos
plate
Pacific plate
180
45
o
A
Caribean
plate
C
B
South
American
plate
o
Scotia plate
45
0
o
o
0