GEOL1011_Major_AS2_Nov92020

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Thompson Rivers University *

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Geology

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Oct 30, 2023

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GEOL 1011: Introduction to Geoscience 1 Jordy Major T00532765 GEOL 1011 Assignment 2 Nov 9, 2020 Assignment 2 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. This assignment includes two field exercises. You are expected to go out into an area close to where you live, take some photographs, and describe what you see. 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). Please type your answers into the grey boxes. 1. Explain why the presence of carbon-dioxide in the atmosphere is important to weathering. ( 2 points ) The presence of carbon-dioxide in the atmosphere is important to weathering because it produces weak carbonic acid when combined with water which breaks down the rocks. 2. What are the main products of weathering of igneous rocks? ( 2 points ) Typical weathering products of igneous rocks are quartz as sand grains, clay minerals, serpentine, chlorite, calcium, and iron oxide minerals. 3. Describe some of the ways that soil can be degraded if we don’t take care to look after it. ( 2 points ) Forestry and agriculture can degrade soil because when vegetation is removed, the soil is no longer held in place and it is now exposed to water and wind. The water and win subject the soil to erosion. 4. How does the velocity of moving water affect the transportation of sedimentary particles? ( 2 points ) The speed at which the sedimentary particles move and the size of the particles is dependent on the velocity of water – the faster the water flows, the larger the particles it can move. 5. What is chert made of, and what is the typical source of that material? ( 1 point ) Chert is a chemical sedimentary rock that is made from ions that were TRU Open Learning

2 Assignment 2 transported in solution and converted into minerals. The source of chert is usually from deep-oceans sedimentary rocks. 6. Describe the tectonic origins of rift basins and forearc basins. ( 2 points ) A rift basin is formed where the continental crust is pulled apart and the crust on both sides of the rift subsides. A forearc basin is located between the subduction zone and the volcanic arc. It is formed by friction between the subducting plate and the overriding plate, which pulls down part of the overriding plate. 7. What is the typical origin and depositional environment of normal (i.e., fining upward) graded bedding? ( 2 points ) Many graded beds form in a submarine-fan environment. The sediment flows down from a shallow marine shelf onto the deeper sea floor. 8. With respect to sedimentary rocks, what are the criteria for defining a “formation”? ( 1 point ) A formation is distinct bed (from the beds above and below) that is thick enough to be shown on geological maps. 9. Explain why mineral stability is important to metamorphism. ( 2 points ) Mineral stability is important because when a rock is subjected to increased temperatures, some minerals could become unstable and start to recrystalize into new minerals. 10. Describe the nature of foliation in gneiss. ( 1 point ) The nature of foliation in gneiss is for the mineral to separate into bands of different colours. 11. Describe the rock “skarn” and the conditions under which it forms. ( 2 points ) Skarn is a type of metamorphism where a hot pluton intrudes into carbonate rock and the magmatic fluids flowing through change the chemistry resulting in the deposition of minerals that would not normally exist in the igneous rock. 12. Provide the names and age ranges for the Periods of the Cenozoic. ( 1 point ) The periods of the Cenozoic are the Paleogene (66-23mil years ago), the Neogene (23-2.6mil years ago), and the Quaternary (2.6mil years ago - present). Part B: Exercises ( 45 points in total ) B1: Observe and document weathering ( 15 points ) Weathering is happening all around us, although most of the time we don’t even notice it. For this exercise, you need to look around the region where you live, find some evidence of mechanical or chemical weathering, photograph it, and then TRU Open Learning

GEOL 1011: Introduction to Geoscience 3 describe what you see in the photo. Some examples are freeze-thaw weathering of a rock exposure, tree-roots pushing rocks apart, lichen growing on a rock, a rusty stain on a rock exposure, frost-heaving on a road, a crack in a building stone or sidewalk, dissolution or other weathering of a headstone or other old monument, and so on. Ask your Open Learning Faculty Member for help if you can’t think of a place to look. Include your photo with your response, and write a few sentences about the weathering effects that you can see in the photo. Provide some evidence in the photo that you were there when it was taken (e.g., a piece of paper with your name on it, or your hand with three fingers showing). The photo is an example of lichen growing on a rock. This is a type of chemical weathering. The lichen creates chemicals produced by colonies of algae and fungi that break down the rock. B2: Photograph and describe a depositional environment ( 15 points ) Sediments are also being deposited all around us, and for this exercise you need to go and find and photograph a depositional environment. Some examples might be a section of a stream, lake, wetland, beach, delta, bay of the ocean, and so on. Don’t hesitate to ask your Open Learning Faculty Member for help. Include a photo with your response. Describe what type of sediments (clay, silt, sand, pebbles etc.) you think are being deposited (based on what you can see or what you think should be there), and speculate about how long this particular sedimentary basin has existed. Do you think it’s likely that these sediments will be turned into rock at some time in the future, or is it more likely that they will be re-eroded and deposited elsewhere? Again, provide some evidence in the photo that you were there when it was taken. Examples of sedimentary basin photos are provided below. TRU Open Learning

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