GEOL1011_Major_AS5_Jan182021

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GEOL 1011, Major, T00532765, Jan 18, 2021 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 ) The amplitude and wavelength of wind waves depends on the speed of the wind, the length of the fetch, and the size of the body of water. Whether or not the wave base interacts with the bottom of the ocean can also affect them. 2. Explain why waves get refracted in near-shore areas and describe some of the implications of this refraction. ( 3 points ) Waves get refracted in near shore areas because as waves come in at an angle, one part of the wave will hit the bottom sooner and slow down. This causes the wave to bend (becoming more parallel with the shore) and refract. An implication of this is rip currents, which can pull people into the open ocean. 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 ) Canada was a strongly glaciated area. Isostatic sea-level changes caused the land to be uplifted by post-glacial isostatic rebound. This is why areas along the coast are meters above previous sea levels. 4. Describe the property of greenhouse gases that enables them to trap heat within the atmosphere. ( 2 points ) Greenhouse gases vibrate at frequencies that match the frequencies of the infrared radiation emitted by surfaces of the earth that have been warmed by the sun. When the infrared radiation makes contact with a GHG molecule, the molecule vibrates more vigorously which heats the molecule, thus warming the atmosphere. 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 ) The earth has differing albedos (measurements of reflectivity of a surface). Snow and ice are some of the brightest surfaces, meaning areas with ice sheets and alpine glaciers reflect the solar energy so that it is not absorbed and does not heat the atmosphere and Earth’s climate. In areas where ice is melting (positive TRU Open Learning

2 Assignment 5 feedback), the water absorbs a much higher percentage of solar energy and contributes to warming climates. 6. Summarize the main human activities that contribute to climate change. ( 2 points ) Main human activities contributing to climate change: - Fossil fuels and CO2 emissions - Agriculture and landfills - World population growth - Clearing forests/forestry 7. Describe the geological origins of the Appalachian fold belt of eastern North America. ( 2 points ) Present day Africa collided with the eastern coast of North America. When this happened, volcanic islands and sedimentary layers were pushed inland to become the Appalachian fold belt. 8. Which of the individual terranes of the Intermontane Superterrane (listed in Figure 21.14 in your textbook) do you think might have reached North America first? Explain your answer. ( 2 points ) I think the Yukon-Tanana may have reached North America first because the Intermontane pushed sediments upwards and the Yukon is the farthest north. 9. Explain what makes the Queen Charlotte Fault a transform fault. ( 2 points ) The Queen Charlotte Fault is a transform fault because the ridges of the northern end of the Juan de Fuca and the Aleutian subduction zone have horizontal/ strike- slip motion. 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 Word 1 draw in a few lines to show the predominant orientation of the crests of un-refracted waves approaching this coast. (4 points) The white lines show orientation the un-refracted waves (yet to become parallel with the shore). 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. TRU Open Learning

GEOL 1011, Major, T00532765, Jan 18, 2021 3 2. What is the approximate wavelength (in metres) of the un-refracted waves? (2 points) The approximate wavelength of the un-refracted waves is close to 100 meters. 3. If the amplitude to wavelength ratio is 0.02, what is the amplitude of these waves? (2 points) 0.02 = amp/length 0.02 = amp/100 Amplitude = 2 m 4. Point out some locations where the waves are being refracted, and describe how they are changing. (4 points) As the waves approach the shore (depicted in red) they are refracted to become more parallel with the beach and their wavelength decreases. 5. Describe in words, or show with an arrow, the likely direction of the longshore current under these conditions. (3 points) The white arrows show the direction of the longshore current. Image © Digital Globe Data SIO, NOAA, U.S. Navy, NGA, GEBCO, © Google, © TerraMetrics Figure A5-1. Waves approaching Long Beach, Vancouver Island, June 2012. B2: Measuring rates of atmospheric CO 2 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 CO 2 in 1960 and 1970 are shown (316 and 325 ppm, respectively), and this 9 ppm difference equates to an average increase in CO 2 concentration of 0.9 ppm/year over that period. 1. Using the same method, determine the annual rates of CO 2 increase between 1985 and 1995 and between 2005 and 2015. ( 6 points ) TRU Open Learning

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4 Assignment 5 1985 to 1995: 360 – 342 = 18 = 1.8 ppm/year difference 2005 to 2015: 400 – 379 = 21 = 2.1 ppm/year difference by Steven Earle from data at https://scripps.ucsd.edu/programs/keelingcurve/ Figure A5-2. Atmospheric CO 2 concentrations as measured at the Keeling Lab on Mauna Loa, Hawaii 2. In 1992, countries around the world (including Canada) signed the Kyoto Protocol and committed to reducing their CO 2 emission levels. Comment on what the data in Figure A5-2 tells us about the collective success of these commitments. ( 4 points ) 1975 to 1985: 342 – 332 = 10 = 1 ppm 1985 to 1995: 360 – 342 = 18 = 1.8 ppm 1995 to 2005: 379 – 360 = 19 = 1.9 ppm 2005 to 2015: 400 – 379 = 21 = 2.1 ppm The collective results of the Kyoto Protocol do not appear to be effective. The amount of ppm/year continue to increase in each time period. TRU Open Learning

GEOL 1011, Major, T00532765, Jan 18, 2021 5 3. What accounts for the saw-tooth nature of the Earth’s CO 2 curve (the pink line on the graph)? It may help to refer to the inset showing the data for 1998 and 1999 in detail. ( 5 points ) During the winter, levels of CO2 increase in the atmosphere and reduce in the summer. This is why the pink line is saw-toothed. TRU Open Learning

6 Assignment 5 B3: Terranes and the Mt. Polley map ( 15 points ) As shown in Figure A5-3, the Mt. Polley map area is almost entirely underlain by Quesnel Terrane rocks, although small parts of two other terranes also are represented on the map—the Cache Creek Terrane in the southwest and the Kootenay Terrane in the northeast. Most of the Quesnel Terrane in this area is volcanic and sedimentary in origin. You should refer to this map when answering the questions below, but the answers can be found on the Mt. Polley map itself, and in the legend. © Steven Earle. Used with permission. Figure A5-3. Overview of the terranes represented on the Mt. Polley map. (The Quesnel and Cache Creek Terranes are part of the Intermontane Superterrane, and the Kootenay Terrane is part of ancestral North America.) 1. What type of rocks make up the Cache Creek Terrane in this area, and how old are they? ( 3 points ) The Cache Creek Terrane is of the Mississippian to Jurassic Cache Creek Group, made of ribbon chert, argillite, basalt, limestone, and greenstone. They are about 145 Ma. 2. What type of rocks make up the Kootenay Terrane in this area, and how old are they? ( 3 points ) TRU Open Learning

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GEOL 1011, Major, T00532765, Jan 18, 2021 7 The Kootenay Terrane is of the Proterozoic to Mississippian Snowshoe group, made of gneiss, schist, marble, amphibolite, conglomerate, and quartzite. They are about 540 Ma. 3. When the Quesnel Terrane was accreted onto North America in the early Jurassic (at around 185 Ma), it already included some intrusive igneous rocks, but other intrusions appeared later. Identify the post-accretion intrusive igneous rock(s) and indicate their age(s). ( 3 points ) The post-accretion intrusive rocks are K-spar metacystic syenite and augite porphyry. They are 205-200 Ma. 4. Some sedimentary and volcanic rocks and some still-unconsolidated sediments were deposited in this region after the early Jurassic terrane accretion event. Identify these units, and indicate their ages and the types of materials. ( 6 points ) LT MPic: Hydrothermal altered intrusive carapace holocrystalline monzonitic intrusion and volcaniclastic wall rock LT bx: Breccias They are 205-200 Ma. TRU Open Learning

8 Assignment 5 Part C: Longer Questions ( 35 points in total ) Please answer the following questions. Write as much as you think is necessary to address each question, but be as concise and clear as possible. Feel free to use point- form or a table rather than standard essay format. You do not need to reference the text or the material in the Course Units (excluding images and quotations), but if you use any outside sources, provide in-text citations. Use any referencing style that you are comfortable with. 1. Describe the various landforms of coastal erosion, including sea-cliffs, sea- caves, arches, stacks, and wave-cut platforms; and explain how they are related to one another. ( 10 points ) Sea cliffs Wave-eroded escarpments on the coast. Sea caves A result of the erosion of relatively non-resistant rock. Once the sides become eroded, it will become an arch Arches Formed when the relatively non-resistant rock of a sea cave erodes on the sides. Once the arch collapses, small stacks are left at the end of the points. Stacks Relatively resistant rocks that do not get completely eroded during the formation of a wave cut platform form a stack. Wave cut platforms Substrates are eroded into a flat surface, caused by the wave base impinging on the sea floor and where the waves are breaking in the surf zone. 2. Describe how changes in ocean currents have contributed to climate change in the past, and how climate change might contribute to changes in ocean currents in the future. ( 10 points ) Fluctuating ocean current cycles can change the thermohaline circulation system so that sea-surface temperatures are warmer than average. The sea-surface temperature heats the atmosphere and warms the overall climate. An example of this is the sea-surface temperature and surface pressure changes in the equatorial Pacific Ocean, called El Ninos. During a strong El Nino, sea-surface temperatures in the region are warmer than usually and heat the atmosphere to warmer than average global temperatures. In the future, climate change can warm the ocean temperatures and change wind patterns, thus impacting currents. Warmer water weakens ocean currents/circulation. 3. Western Canada’s two main mountain ranges are the Rocky Mountains and the Coast Range. Compare these two ranges from the perspective of their geological (tectonic) origins, major rock types, and age. Show the approximates extents of the Rocky Mountains and the Coast Range on the map below. ( 15 points ) TRU Open Learning

GEOL 1011, Major, T00532765, Jan 18, 2021 9 Rocky Mountains Origins: Small continents collided with the West Coast of North America and thrusted the sedimentary rocks inland. The later collision of more small continents created uplift of the Rockies. Rock Types: - Sedimentary: Ordovician, Devonian, Carboniferous, Permian - Cambrian rocks Age: ~200 Ma Coast Range Origins: Subduction of oceanic crust along the west coast and within accreted terranes. Rock Types: - Intrusive igneous rocks Age: ~100 Ma TRU Open Learning

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