GEOL1011_Major_AS4_Jan14,2021

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GEOL 1011, Major, Too532765, AS4, Jan 14, 2021 Assignment 4 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. Identify the forces that drive the hydrological cycle. ( 1 point ) Solar energy evaporates water from bodies of water, the surface of land, and plants. Air then moves it through the atmosphere where it forms clouds of water droplets or ice that fall back down. 2. Building dykes to prevent river flooding is useful, but there are some drawbacks. Describe some of the negative consequences. ( 2 points ) Some of the consequences of building dykes are that it is expensive, dyking in one area can lead to flooding in other areas, and flooding is what makes valet land fertile. 3. Explain why clay, which is typically highly porous, is also normally quite impermeable. ( 2 points ) Despite being highly porous, the particles of clay are very small and closely packed and held together tightly so that the particles cannot move easily within the clay deposit. Because of how tightly it is packed together, it is impermeable. 4. Describe the difference between a confined aquifer and an unconfined aquifer. ( 2 points ) An unconfined aquifer is open to the surface and can be easily recharged by rain while a confined aquifer is covered by a layer of impermeable material and can be recharged by a body of surface water or surface runoff. 5. Explain how over-pumping in one well could lead to another nearby well going dry. ( 2 points ) Over-pumping in one area could lead to another well going dry because the pumping lowers groundwater near the well, creating a flow towards it. It creates a cone of depression around the well and can pull all the water towards it and deplete the available ground water for other wells. 6. During the Pleistocene, what was the approximate difference in mean global temperature between a glacial period and an interglacial period; and what is the origin of the Pleistocene glacial fluctuations? ( 2 points ) The origin of the Pleistocene glacial fluctuations is attributed to the subtle changes TRU Open Learning

2 Assignment 4 in Earth’s orbital parameters. The approximate difference in mean global temperature between a glacial period and interglacial period is about 4 degrees. 7. The following diagram is a copy of Figure 16.13 from the textbook. Explain why the rate of ice motion (blue arrows) increases up to a certain point, and then remains the same from there to the surface of a glacier. ( 2 points ) The rate of motion of the blue arrows increases in the areas where stress is greater than 100 kilopascals while the ice velocity increases upwards. The deformation motion in the lower ice is transmitted to the upper ice (above the red dashed line) where it does not flow but it pushed along with the lower ice at a faster rate, because the lower ice is slowed by the overlying ice. © Steven Earle. Data Source: Environment Canada 8. What are the textural characteristics of lodgement till? ( 2 points ) Lodgement till has elongated particles with rounded edges. It is unsorted and does not typically show layering. 9. Describe how weaknesses within a body of rock (fractures, bedding, foliation, etc.) can contribute to mass wasting. ( 2 points ) If planes of weakness within a body of rock are parallel to a slope, gravity pulls rock or unconsolidated material down, causing mass wasting. The type of material is an important factor. For example, sandstone and mudstone are more likely to have weaknesses and become unstable. 10. Explain how the motion of a slide (either translational or rotational) differs from that of a flow. ( 2 points ) A translational slide’s motion moves as a unit along a planar surface at a typically slow rate of motion. A flow has a fast rate of motion and moves down a channel. TRU Open Learning

GEOL 1011, Major, Too532765, AS4, Jan 14, 2021 11. From the perspective of not contributing to mass wasting, what should be the primary consideration when constructing a building near to the top of a potentially unstable slope? ( 1 point ) When building a house near the top of a potentially unstable slope, the changes the building will have on drainage in the surrounding area should be the primary consideration. TRU Open Learning

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4 Assignment 4 Part B: Exercises ( 45 points in total ) B1: Interpreting a river hydrograph ( 10 points ) Figure A4-1 shows the variations in the daily discharge during 1957 for the Elaho River, north of Squamish, BC. 1. Discuss the origins of the variations in discharge over the year by focussing on the following: (a) the long period of low discharge in January, February, and March, (b) the increasing flows in early spring, (c) the high flows in summer, and (d) the pronounced high flows in late September and in November and December. a) The cold weather keeps melting to a minimum. Freezing conditions are throughout most of the drainage basin. b) As the climate begins to warm, melting is nearing its peak. c) The snow from the winter melts in the warmer weather. d) The high flows in September could be from the rainfall. 2. The Elaho River is a popular destination for white-water kayaking. Based on the information in the graph, which month should you pick if you want to book your holidays so as to maximize the likelihood of high discharges and lots of white water? Based on the graph, the best month for white-water kayaking would be early July, which has consistently higher levels of discharge. September has some of the highest days of discharge, but overall is lower than July. Figure A4-1. Daily flows on the Elaho River during 1957. © Steven Earle. Data Source: Environment Canada http://wateroffice.ec.gc.ca/report/report_e.html?type=h2oArc&stn=08GA041 . B2: Groundwater flow paths and rates ( 15 points ) The following diagram (Figure A4-2) shows a cross-section of a sandy aquifer. The black line is the land surface. The dashed blue line is the water table, and the dashed TRU Open Learning

GEOL 1011, Major, Too532765, AS4, Jan 14, 2021 red lines are lines of equal hydraulic potential, with pressure levels shown in red numbers. The hatched area at the bottom represents impermeable unfractured granite. 1. Following the example given in Figure 14.8 in the textbook, draw several flow lines depicting the likely overall nature of groundwater flow in this region. (You can draw in the Word document itself if you are familiar its drawing tools. If not, you could print the diagram, draw the lines in pen or pencil, take a photograph, and insert that into your Word document.) Figure A4-2. Groundwater flow example for Exercise B2. © Steven Earle. Used with permission. 2. The elevation of the water table at the top of the hill (point A) on the right- hand side of the diagram is 43 m, and the elevation of the stream at the valley bottom (point B) is 8 m. The horizontal distance from the hilltop to the stream is 125 m. The sandy sediment has a permeability of 10 -5 m/s (0.00001 m/s). What is the likely average flow velocity between points A and B? V = K * i V = (0.00001 m/s) * (35/125) V = (0.00001 m/s) * 0.28 V = 0.0000028 m/s B3: Field trip to observe evidence of mass wasting or glaciation ( 20 points ) Take a field trip somewhere in your region to look for evidence of mass wasting or glaciation, and take a photograph. You may be thinking that no such features are accessible in your region, but that’s very unlikely. If you need some help deciding TRU Open Learning

6 Assignment 4 what to look for and where, contact your Open Learning Faculty Member. If you already have a good photo that illustrates either glacial or mass wasting features, you could use that, but please include the date when it was taken. Whatever photo you use, you must have been there when it was taken. If mountains are nearby, you should be able to find some glacial erosion features, such as a U-shaped valley or a glacial lake. You might be able to find close-up evidence of glaciation, such as a streamlined glacial feature (roche moutonée or drumlin) or glacial grooves (also known as glacial striae). Or you might be able to find some glacial deposits nearby, such as unsorted glacial till or thick deposits of glaciofluvial sediments. In addition, you may find some kind of mass wasting feature nearby, such as evidence of a slump, debris flow or rock fall, or tilted gravestones or trees on a steep slope. Road cuts are good places to look for mass wasting, especially where it was necessary to cut steep banks into one or both sides of the road. Mass wasting also is common along lake or ocean shorelines or where stream water has eroded steep slopes. Take a photograph, making sure to provide some context in the background. It might be a good idea to take a couple of photographs, so you can include more than one perspective or get a close-up of some important features. In a few sentences, describe where you went (and when). Include the names of roads, mountains, rivers, lakes, beaches, etc., so your Open Learning Faculty Member can figure out where it is (or else provide a map), and—most important of all—write a description of what you saw and how you think it formed. The following photos were taken on January 4 th , 2021 on Campbell Creek Road in Kamloops. The slope is on Sunrise Mountain. TRU Open Learning

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GEOL 1011, Major, Too532765, AS4, Jan 14, 2021 TRU Open Learning

8 Assignment 4 These photos are an example of debris flow. The mass of sediment becomes saturated with water from snowmelt and the nearby stream, causing the material to flow. Picture three is the stream located a few meters from the mass wasting. The type of debris includes gravel and some fallen trees. There are some larger particles at the bottom (photo 2). Some of the flow could be from human activity, since locals collect rocks from the area for landscaping – people usually go after the snowmelt once new rocks have flowed down. TRU Open Learning

GEOL 1011, Major, Too532765, AS4, Jan 14, 2021 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, but if you use any outside sources provide in-text citations. Use any referencing style that you are comfortable with. 1. Investigate the source of the water that flows out of your tap. Where does it come from, how is it treated, and how does it get to you? Briefly describe some potential risks to the quality and quantity of that water. Suggest some steps that you and your neighbours can take to ensure that your source of water does not become contaminated, and that the supply continues to be adequate for your community. ( 10 points ) In Kamloops, our water source is the South Thompson River. Intake pumps bring in raw water that is filtered and treated with chlorine. Distribution pumps then send the water to 45 reservoirs throughout the city. During flooding season in the spring and summer, the levels of particulates and pathogens can increase which can be a risk. Yet Kamloops’ water treatment facility has the highest-level certification recognised in BC, so there are not huge risks to the quality. Kamloops has a backup plan to pump from the North Thompson if there is an issue with quantity. We can assure we maintain out supply by being mindful of our water usage and reporting any changes we may notice in quality to the city. 2. Complete the following table by describing the characteristics and origins (how they form) of these five different features of alpine glaciation. ( 10 points ) Glacial feature Description and Origins U-shaped valley - Wide valleys, relatively flat bottom, steep sides - Formed through glacial erosion - Erode more at the base than the sides Arete - Sharp ridges between U-shaped valleys - Formed between valleys Horn - Steep peaks - Glacially and freeze thaw eroded on three or more sides Truncated spur - steep triangle-shaped cliffs - The end of aretes that have been eroded by the glacier in the corresponding main valley Hanging valley - U-shaped valets of tributary glaciers that hang above the main valley TRU Open Learning

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10 Assignment 4 - Formed from the larger main valley glacier eroding more deeply into the terrain - Exist where the two glaciers meet 3. British Columbia’s Sea-to-Sky Highway (Highway 99), between Horseshoe Bay and Pemberton, is prone to relatively frequent and dangerous mass wasting events. Based on the information in the textbook, the Course Units, and any other sources that you can access, describe the various types of slope failures that have occurred in recent decades along this route, and some of the steps that have been taken to mitigate the risks. ( 15 points ) Types of slope failure: - Debris flow (most common): a flow of sand gravel, and larger fragments. - Rock fall: rock fragments falling vertically - Rockslide: A large rock body moving as a unit across a planar surface Steps to mitigate risks: - Debris-flow defense structures in several drainage basins - Allow debris to flow quickly through the ocean along a smooth channel - Capture debris with constructed basin that allows excess water to continue through - Geological studies to predict unsafe areas TRU Open Learning