End of Unit Assignments –Unit 3
Geo 12
Name______________
Each question is to be answered and passed in for grading. Each will be marked out of 5 points
except Question 5 will be out of 25 points.
1. The figure to the right depicts the seismic
wave velocity profile with depth for an
imaginary planet. Use the profile to answer the
following questions.
a) What is the radius of the planet?
b) Is the material that comprises the imaginary
planet generally denser or less dense that the
material that comprises Earth? Explain your
reasoning.
c) How many layers are present in the interior
of the imaginary planet? How do you know?
d) For each layer present (going from the
surface to the center of the planet), give the
following information:
i) thickness
ii) state (solid or liquid)
iii) change in density with depth
2. If you were told that you could have a cubic centimetre of any portion (which layer) of the
Earth, where would you take your sample to obtain:
a) an iron and sulphur-rich portion?
b) a silicon and aluminum-rich portion?
c) a liquid sample?
d) a plastic or toothpaste-like sample?
3. Using the evidence Alfred Wegener garnered, write an argument (one to two sentences)
against each of the following statements that counter the Continental Drift Theory.
a) Mesosaurus fossils are found in both South America and Africa because the creature swam
across the Atlantic Ocean.
b) Glacial deposits are presently found near the equator because in the past, the tropics were
much colder than they are today.
c) Mountain chains abruptly end and begin at coastline because in the past the mountain chains
were joined by a land bridge. The land bridge has since sunk below sea level or has eroded.
4. If you were Alfred Wegener, how would you explain:
a) coal deposits in Cape Breton, Nova Scotia?
b) dinosaur bones on Baffin Island, Nunavut?
c) glacial deposits in Kenya?
d) similar mountains in Scotland and Nova Scotia (New Scotland)?
5. In the following exercise, you will be simulating (using a hypothetical ocean floor) the
process by which geologists calculate the rate of movement of the ocean floor. The figure 3.5.2
below depicts the magnetic polarity reversal of a section of Ocean Make-Believe. Normal
polarity periods are indicated in black and periods of reversed polarity are shown in light grey.
a) Mark the periods of normal and reversed polarity with the letters A to F along either side of
the ridge, starting at the ridge crest. The first two periods have been done for you. Describe the
pattern of polarity in relation to the ridge.
b) Imagine that drilling of the ocean floor has revealed that the rocks at the beginning of the
normal period E are 5 million years old. Using the scale provided on the diagram, determine the
distance from the ridge to the beginning of the normal period E.
c) If the answer for b) represents the distance the solidified lava travelled since its formation at
the ridge, calculate the total distance the seafloor has spread (or expanded) in the last 5 million
years.
d) If both the distance the ocean basin has expanded and the time it took for the expansion are
known, then the rate of expansion or seafloor spreading can be calculated using the following
formula:
𝑟𝑎𝑡𝑒 𝑜𝑓 𝑠𝑒𝑎𝑓𝑙𝑜𝑜𝑟 𝑠𝑝𝑟𝑒𝑎𝑑𝑖𝑛𝑔 =
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒
Calculate the rate of spreading of Ocean Make-Believe and give your answer in centimetres per
year. You can use data for one half of the ocean or the entire ocean. Also, remember to convert
km to cm.
6. a) What type of plate boundary is located in the middle of the Atlantic Ocean? Are the plates
upon which the Atlantic Ocean is located, moving away or toward each other? Is the Atlantic
Ocean expanding or decreasing in size?
b) What type of plate boundary is located along the edges of the Pacific Ocean? Is the Pacific
Plate moving towards or away from the plates that form its boundary? Is the Pacific Ocean
expanding or decreasing in size?
7. Knowing the location of Nova Scotia:
a) Upon which plate is Nova Scotia located?
b) Where on the plate is Nova Scotia located (e.g. edge, central, etc.)?
c) Is Nova Scotia located at or near a plate boundary?
d) Based on the location of Nova Scotia relative to the plate boundary, deduce whether or not
Nova Scotia is characterized by earthquakes or volcanic activity.
8. Convergent plate boundaries (all three types) are strongly associated with geological disasters
that directly affect humans. Why is this so?
9. Some people think that California will eventually sink into the Pacific Ocean and eventually
disappear. Using your newly acquired knowledge of plate boundaries, how would you respond
to this idea?
10. Having studied the formation of the Hawaiian Islands you may have noticed that the island
of Hawaii is the largest island, and the islands become progressively smaller as one moves in a
north westerly direction. Why is this so?
11. If you were given aerial photographs of an unknown planet, what features would you look for
to determine if plate tectonics is presently active or if plate tectonics was active on the planet in
the past? Describe at least five features