Introduction to Geoscience Assignment 2022

GEOL 1011: Introduction to Geoscience 1
Assignment 5
This assignment is worth 12% of your total course mark. Please type your answers
directly into this document and submit the assignment to your Open Learning
Faculty Member.
Part A: Short-Answer Questions (20 points in total)
Answer the following questions as succinctly as you can. None of the answers
should be more than a couple of sentences (100 words or less).
1. List the various factors that govern the wavelength and amplitude of wind
waves. (2 points)
Velocity of the wave
Frequency of the wave
2. Explain why waves get refracted in near-shore areas and describe some of
the implications of this refraction. (3 points)
Waves in the deep waters bend as they approach the shore so as to be parallel
with the shore line. The friction created between the continental shelf and the
water carrying waves slows down the waves at that point causing the waves to
bend. This causes the waves to face the shoreline directly which results to the
wave crest bending.
3. Explain the mechanism that has resulted in the presence of post-glacial
aged marine deposits tens of metres above present-day sea level at
numerous locations along the British Columbia coast. (2 points)
This is the post glacial rebound (PGR). It brings about the ascent of the large
landmasses after the lifting period of the tremendous loads of the ice sheets during
the last glacial time frame. The huge load of the ice sheets had caused isostatic
depression. Both of these, PGR and isostatic depression, are periods of cold
isostasy which is the twisting of the Earth's outer layer from the modifications in
ice mass changes and dissemination.
Now in glacial phase when the ice sheets that are a few kilometers thick push
down the Earth's outer layer to produce a depression. When the glacier retreats,
the loss of the weight results to the land elevation and mantle material return
simply under the deglaciated area. This is why we have marine deposits tens of
meters above the existing sea level along the coast of British Columbia.
4. Describe the property of greenhouse gases that enables them to trap heat
within the atmosphere. (2 points)
A greenhouse gas has three basic properties associated with them, which are, the
wavelength of the energy which the gas absorbs from sun’s radiation, how much
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2 Assignment 5
energy it absorbs from the radiation, and how long the gas molecules stays intact
in the atmosphere without disintegrating. In the infrared region of the light
spectrum is where the greenhouse gas molecules absorb the energy. This region is
usually associate with heat.
5. Explain the role of albedo in the Earth’s climate and give an example of an
albedo change that is a positive feedback mechanism. (3 points)
Albedo is a function of the reflectivity of the surface of the Earth. Ice-albedo
feedback is a clear positive response to the climate system. Hotter temperatures
result to ice masses on the poles (North and South) and high elevated areas such
as mountain peaks to melt. This ice mases are useful because they reflect a
percentage the solar energy back to space.
Ice–albedo feedback is a positive feedback climate process. This means the change
in the surface area of ice masses on the planet will alter accordingly the albedo and
the surface temperature of the entire planet. For example, global warming tends to
decrease the ice surface area of the earth which leads to less sun’s radiation being
reflected to the space which lead to more global warming.
6. Summarize the main human activities that contribute to climate change.
(2 points)
Clearing of forests, burning of fossil fuels and the green gases produced from
industrial activities that cause air pollution contribute to climate change.
7. Describe the geological origins of the Appalachian fold belt of eastern North
America. (2 points)
At about 350 Ma, the fragment of Gondwana currently Africa smashed into North
America's eastern coast, pushing volcanic islands and sedimentary layers far
inland to form the Appalachian crease belt. During the Devonian the Appalachian
Mountains would have been equal in degree and height to the Himalayas.
8. Which of the individual terranes of the Intermontane Super terrane (listed in
Figure 21.14 in your textbook) do you think might have reached North
America first? Explain your answer. (2 points)
The Quesnel terrane of the intermontane outstanding terrane is reached at North
America due to the fact it is moving with excessive speed from Mesozoic time
towards the North American plate.
9. Explain what makes the Queen Charlotte Fault a transform fault. (2 points)
The fault has been the source of large, very large, and great earthquakes.
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GEOL 1011: Introduction to Geoscience 3
Part B: Exercises (45 points in total)
B1: Interpreting waves (15 points)
Figure A5-1 is an aerial view of waves approaching Long Beach on Vancouver Island.
1. Using the drawing tools in Word1 draw in a few lines to show the
predominant orientation of the crests of un-refracted waves approaching this
coast. (4 points)
The red lines show the direction of crest and for the un-refracted waves crest
would be aligned orthogonally to the shores.
2. What is the approximate wavelength (in metres) of the un-refracted waves?
(2 points)
This would be 100m. I have taken the approximate length of the wave forms from
the image.
3. If the amplitude to wavelength ratio is 0.02, what is the amplitude of these
waves? (2 points)
amplitude / wavelength = 0.02
amplitude = wavelength x 0.02 m = 100 x 0.02 = 2m
1 Inside word, click on the drawing itself, and then under the Insert tab, click Shapes. If you are
unable to use the drawing tools in Word, print the image, draw on it by hand, take a photograph,
and insert it in your Word document.
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4 Assignment 5
4. Point out some locations where the waves are being refracted, and describe
how they are changing. (4 points)
The bends on the blue lines show the location where the waves are refracted
which is caused by the change in the shore geometry.
5. Describe in words, or show with an arrow, the likely direction of the
longshore current under these conditions. (3 points)
The green arrow indicates the most likely direction of longshore current. This
current occurs when refracted waters start moving parallel to the coast.
Image © Digital Globe Data SIO, NOAA, U.S. Navy, NGA, GEBCO, © Google, © Terametres
Figure A5-1. Waves approaching Long Beach, Vancouver Island, June 2012.
B2: Measuring rates of atmospheric CO2 increase (15 points)
Figure A5-2 is similar to Figure 5-6 in Unit 5, except that a trend line (black) has been
fitted to the data. The levels of CO2 in 1960 and 1970 are shown (316 and 325 ppm,
respectively), and this 9-ppm difference equates to an average increase in CO2
concentration of 0.9 ppm/year over that period.
1. Using the same method, determine the annual rates of CO2 increase between
1985 and 1995 and between 2005 and 2015. (6 points)
In 1985 CO2- 347 ppm
1995-. 359 ppm
so, the annual rate of CO2 increases between 1985 and 1995
= (359-347)/10
= 1.2 ppm per year (1985-1995)
Now the CO2 in 2005= 378 ppm
in 2015= 400 ppm
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