lab3
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York University *
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1012
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Geography
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Apr 3, 2024
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11
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LE/ESSE 1012 Lab 3 ©NTandon Page 1
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LE/ESSE 1012 3.0 The Earth Environment
Winter 2024 Lab. Section: 3 Name: Tahman Ahmed Student Number: 220825071 LAB 3: WEATHERING Due February 16, 2024, 10:00 PM ET IMPORTANT: This is a hands-on lab. You must attend the lab session in person in order to receive credit for this lab. Unless otherwise indicated, show your work for all problems. You can either enter your answers into this document electronically using a computer or tablet, or you can print this document, handwrite your answers in the spaces provided, and scan the pages. If you need additional space, you can insert additional pages or you can add additional space within the Word document. For all numerical answers, the units should be indicated. Students can discuss this lab with each other, but copying from each other or copying from other sources is cheating and is not permitted. You should not share your answer sheets with other students or look at the answer sheets of other students. You should understand the concepts well enough to explain your answers in your own words. Your answers for hands-on portions of the lab should be based on work that you yourself performed in the lab location. If the lab procedure indicates that you can form groups to complete particular tasks, then you should still be physically present in the lab location contributing to the completion of those tasks, you should write the names of other group members on your answer sheets and show your work in your own words for all questions unless otherwise indicated. If your work relies on information that is obtained from a legitimate source other than ESSE 1012 course materials, please indicate the source of that information with enough detail so that someone else can locate the source. Please see the course outline for detailed policies.
This lab requires you to find three different examples of weathering outside near the lab location, explain the physical processes responsible and the possible impact of climate change. You should review your notes, lecture slides and text chapter on weathering prior to the lab session. Dress warmly if the weather is cold. In addition to this procedure either in paper or electronic form, you will need the following materials: •
A phone, fully charged, with camera and location feature turned on. (Or you should have other devices with equivalent capabilities.) •
Any helpful reference materials (e.g. lecture notes, lecture slides, text)
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Procedure Once your lab session starts, please do the following 1. Go to the lab location, sign in with the TA and leave any belongings there that you do not wish or need to bring with you outside. The TA will remain in the lab to supervise. 2. Exit the lab and do the following: a. Photograph an example of physical weathering on either a natural or man-made structure and take a screenshot of Google Maps indicating the location of the weathering. Zoom into the map enough so that your location relative to familiar York landmarks (e.g. the Petrie building) is clear. If your phone is not able to determine your location, explain why. You should be able to find such weathering easily around Petrie or the neighbouring buildings. You should definitely not need to take risks, like stopping in the middle of a street or entering restricted areas. Do not go anywhere alone, especially after dark. The TAs will be available in the lab if you require assistance. b. If the weathering you photographed in step 2a is located in a location with a slope, take a picture of the slope to help assess possible slope instability. c. Repeat steps 2a-b, but for an example of chemical weathering on either a natural or man-made structure. The location you choose should be different from the locations you chose in the previous steps. d. Repeat step 2a, but for an example of biological weathering on either a natural or man-
made structure. The location you choose should be different from the locations you chose in the previous steps. 3. Return to the lab within 40 minutes of the start of the lab period and answer the questions below. 4. Since you are not allowed to copy from each other or from other sources, your pictures should be distinct from those of other students. While you can photograph the same site as another student, no two students should have all three weathering examples in common.
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Question 1: Physical Weathering For your example of frost wedging, respond to the following: a. Insert a photo of the weathering in the space below. (2 points) b. In the space below, insert a screenshot of the Google Maps location where you found the weathering. (2 points)
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c. What type of physical weathering is occurring in the location that you photographed? What evidence do you see for this type of weathering? (5 points) Frost-wedging. Cracks appeared on the sidewalks where most ice/snow settle after a storm. d. Are there any additional types of weathering occurring at the photographed location? If so, what are they? Do the different weathering processes interact with each other, and if so, how? If the weathering is in a sloped location and would potentially contribute to slope instability, please insert a photo of the slope and comment on that as well. (9 points) Yes, biological weathering. They do, since the surrounding plants around it grow underneath and around the sidewalk and hence, push against the sidewalk, making it more susceptible to cracking. A very slight slo
pe, no it wouldn’t contribute to any slope instability.
e. Assume that, under climate change, Toronto will get warmer but continue to experience freeze-thaw cycles, and there will also be an increase in precipitation. How do you expect the physical weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (8 points) Higher temperatures contribute to increased thermal expansion and contraction of pavement materials. During warmer periods, the pavement materials expand, and during cooler periods, they contract. This expansion and contraction put stress on the pavement, leading to cracks. Despite the overall warming trend, freeze-thaw cycles are expected to persist. During these cycles, water penetrates the cracks in the pavement. When the water freezes, it expands, exerting pressure on the pavement and widening existing cracks or creating new ones. Higher precipitation levels mean more water infiltrating into pavement cracks. As mentioned earlier, water penetration into cracks is a significant factor in pavement deterioration, particularly in freeze-thaw climates. The combination of warmer temperatures, continued freeze-thaw cycles, and increased precipitation will likely lead to more rapid physical weathering and pavement cracking compared to present weathering rates in Toronto. The collaborative effects of these climate change factors will amplify the stress on pavement materials, hastening their deterioration and necessitating more frequent maintenance and repair efforts.
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f. Assume that under climate change, Toronto will warm so much that it no longer experiences freeze-thaw cycles, and there will also be an increase in precipitation. How do you expect the physical weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (7 points) Without freeze-thaw cycles, which are a significant contributor to pavement cracking due to the expansion and contraction of pavement materials, one major mechanism of pavement deterioration is removed. However, the increase in precipitation could still have an impact on pavement cracking. While it may not directly contribute to freeze-thaw cycles, water infiltration into pavement cracks weakens the pavement structure and makes it more susceptible to cracking over time. Under the described scenario, the weathering rate of pavement cracking would likely become less rapid compared to the present rate due to the elimination of freeze-thaw cycles, despite the increase in precipitation.
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Question 2: Chemical Weathering For your example of chemical weathering respond to the following: a. Insert a photo of the weathering in the space below. (2 points) b. In the space below, insert a screenshot of the Google Maps location where you found the weathering. (2 points)
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c. What type of chemical weathering is occurring in this location? What evidence do you see of this type of weathering? (6 points) Oxidation. Rusted off metal, that has lost its structural integrity, broken pieces of rusted material, rust-colored water dripping from the wall it was attached to. d. Are there any additional types of weathering occurring at the photographed location? If so what are they? Do the different weathering processes interact with each other, and if so, how? If the weathering is in a sloped location and would potentially contribute to slope instability, please insert a photo of the slope and comment on that as well. (9 points) Yes, very slight physical weathering. Yes, they do, where the rusted railing has been bolted to the wall, as the metal loses its rigidity, the wall that is it connected to forms very slight cracks from the joints being moved from it. There is no slope in this particular location. e. Assume that, under climate change, Toronto will get warmer but continue to experience freeze-thaw cycles, and there will also be an increase in precipitation and carbon dioxide concentration in the atmosphere. How do you expect the chemical weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (8 points) Higher temperatures can accelerate chemical reactions, including the oxidation process responsible for rust formation. Freeze-thaw cycles can intensify rusting by promoting the formation of cracks and crevices in railings, which provide pathways for oxygen and moisture to reach the underlying metal surface. These cycles can accelerate the corrosion process by exposing fresh metal surfaces to oxidizing agents. Higher levels of precipitation can enhance rusting by providing more moisture for the oxidation reaction to occur. Elevated levels of carbon dioxide in the atmosphere can indirectly affect rust formation by contributing to the acidification of rainwater. Acidic rainwater can accelerate the corrosion of metal surfaces by providing hydrogen ions that react with metal ions to form soluble salts, which can further corrode the metal. To summarize, the rusting rate of railings would likely increase due to warmer temperatures, freeze-thaw cycles, higher precipitation, and elevated atmospheric CO2.
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f. Assume that under climate change, Toronto will warm so much that it no longer experiences freeze-thaw cycles, and there will also be an increase in precipitation and atmospheric carbon dioxide concentration. How do you expect the chemical weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (7 points) As said on the previous page, higher temperatures can accelerate chemical reactions. However, if freeze-thaw cycles cease, the expansion and contraction stress on railings decreases, potentially slowing down the development of cracks and crevices where rust can form. Considering the factors mentioned in the previous page, it's plausible that the overall effect on the chemical weathering rate of rust formation in railings would depend on the balance between the positive effects of increased precipitation and carbon dioxide concentration and the negative effect of the cessation of freeze-thaw cycles. However, since freeze-thaw cycles are no longer present to introduce additional stress on the railings, it's likely that the rate of rust formation could either remain like the present rate or even decrease slightly, depending on the magnitude of the other factors.
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Question 3: Biological Weathering For your example of biological weathering respond to the following: a. Insert a photo of the weathering in the space below. (2 points) b. In the space below, insert a screenshot of the Google Maps location where you found the weathering. (2 points)
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c. Explain the biological weathering process occurring in the location that you photographed. Specifically, what is the life form that is causing the weathering, and how is it causing the weathering? (5 points.) Macroscopic processes. The roots of the tree, and the weathering is caused by the growth of said roots penetrating and hence, pushing up on the pavement from the ground underneath it, displacing a few bricks. d. Are there any additional types of weathering occurring at the photographed location? If so what are they? Do the different weathering processes interact with each other, and if so, how? If the weathering is in a sloped location and would potentially contribute to slope instability, please insert a photo of the slope and comment on that as well. (9 points) No, there are no other additional weathering occurring in this photographed location. There is no slope in this particular location. e. Assume that, under climate change, Toronto will get warmer but continue to experience freeze-thaw cycles, and there will also be an increase in precipitation. How do you expect the biological weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (8 points) Higher temperatures can stimulate the growth of vegetation, including tree roots. Warmer conditions may lead to more vigorous root growth, increasing the likelihood of roots overgrowing and pushing against pavement bricks. Freeze-thaw cycles can worsen pavement damage caused by tree roots. When water penetrates pavement cracks and freezes, it expands, causing additional stress on the pavement and making it more susceptible to root-induced displacement. Higher levels of precipitation can promote the growth of vegetation, including trees, by providing more moisture and nutrients. This could lead to more extensive root systems, increasing the potential for roots to overgrow and damage pavement. The biological weathering rate of tree roots pushing pavement bricks would likely become more rapid compared to the present rate due to the combined effects of warmer temperatures, continued freeze-thaw cycles, and increased precipitation.
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f. Assume that under climate change, Toronto will warm so much that it no longer experiences freeze-thaw cycles, and there will also be an increase in precipitation. How do you expect the biological weathering that you photographed to be affected? Specifically, compared to the present weathering rate, will the weathering become more rapid or less rapid and why? (7 points) Higher temperatures can stimulate the growth of vegetation, including tree roots. However, if freeze-thaw cycles cease, the pavement may become more stable, reducing the likelihood of displacement by tree roots. Taking all these factors into consideration, it's plausible that the overall effect on the biological weathering rate of tree roots pushing pavement bricks would depend on the balance between the positive effect of increased precipitation promoting root growth and the negative effect of the cessation of freeze-thaw cycles stabilizing the pavement. Without the disruptive force of freeze-thaw cycles, the pavement may be less prone to displacement by tree roots. However, the increased precipitation could still lead to more extensive root growth, potentially offsetting the stabilizing effect of the absence of freeze-thaw cycles.