Print the map figure that does not have the background colour (this will make it easier for you to annotate) and the two question pages.
Annotate the map figure as instructed and answer the questions (by hand) on the sheets. Submit either a photo or scan of the completed sheets.
If you do not submit the figure you will only get half the value for any questions you get correct.
Do not edit the file or use a word processor to complete the questions.
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.
OCEANIC CRUST
LITHOSPHERE
MAGMA
ASTHENOSPHERE
OCEANIC
CRUST
TRENCH
LITHOSPHERE
VOLCANIC
ISLAND ARC
MAGMA
ASTHENOSPHERE
transformboundary
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 easier for people to grasp plate boundaries if they think in terms of ocean and
continental crust.
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 have to do?
Print the next two pages – a simplified map figure and question page. Annotate the map figure as
instructed in the question section.
Answer the questions by hand on the question sheet.
Do not forget to include your name and student number.
Upload a picture of your annotated map figure, and the completed question page – if the map is
missing you will be given only half the value for any questions you get correct.
Helpful Tips
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.
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
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.
NAME:
STUDENT NO:
Instructions
Annotate the map figure as instructed below and answer the questions on these pages.
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.
Question 1. If you have drawn you line correctly there will be 4 major plates bounded by the MidAtlantic Ridge. What are their names?
_____________
_____________
_____________
_____________
Question 2. If you were standing at Point A in which direction would someone at Point B be moving
(relative to you)?
Towards you
Away from you
Parallel to you
South America
Locate the west coast of South America on the map.
Question 3. What type of plate boundary runs just along the coast?
Draw arrows on either side of the boundary to indicate the direction of plate movement.
Question 4. If you were standing at Point C in which direction would someone at Point D be moving
(relative to you)?
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.
Question 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?
_____________
_____________
_____________
_____________
_____________
NAME:
STUDENT NO:
China
Locate China on the map figure. This region is subject to frequent and often devastating earthquakes.
Question 6. What two plates are responsible for these earthquakes?
___________________
__________________
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
Question 7. What type of boundary is it?
Question 8. If you were standing at Point E in which direction would someone at Point F be moving
(relative to you)?
Towards you
Away from you
Parallel to you
California
Next locate the state of California, on the West coast of North America.
Question 9. What two plates are in contact here?
___________________
__________________
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
Question 10. If you were standing at Point G in which direction would someone at Point H be moving
(relative to you)?
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.
Question 11. Looking at the map of plate boundaries what 2 plates are responsible?
___________________
__________________
Outline this boundary and draw arrows on either side to indicate the direction of plate movement.
Question 12. What type of boundary is this?
Question 13. If you were standing at Point I in which direction would someone at Point J be moving
(relative to you)?
Towards you
Away from you
Parallel to you
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