11-03 Notes GEOL 1200 - 003
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GEOL 1200 - 003
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This 4 page Class Notes was uploaded by Keely Haggar on Thursday November 12, 2015. The Class Notes belongs to GEOL 1200 - 003 at University of North Carolina - Charlotte taught by Jake Armour in Summer 2015. Since its upload, it has received 37 views. For similar materials see Physical Geology (no lab) in Geology at University of North Carolina - Charlotte.
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Date Created: 11/12/15
Geology 1200 11-‐03 Ancient River Channels Ø Is there life on Mars? o Liquid is flowing through channels o Water on mars § Ripple marks on mars – some point it had oceans on it What kind of rock is this? a. Metamorphic b. Sedimentary c. Igneous d. Sediment e. Soil Ans: b. Sedimentary Ø At the beach we have a lot of sediment, pieces of broken up rock. It has not yet been compacted into a sedimentary rock. 2 Types of Weathering Ø Mechanical Weathering o No change in composition o Once you weather it, you increase the speed in weathering. It increases the amount of surface area enabling it to weather faster. o Ø Chemical Weathering o Dissolve things § Dissolution and precipitation of a solid • Monuments made of calcium carbonate, reacts to rainwater due to the pH of it being 6.5, dissolves these monuments. • Oxidation; ex. aluminum-‐oxide. Ø Physical and Chemical work together. o Ex. Spheroidal Weathering § There is a lot of water soaking into the ground, slightly acidic water, which is dissolving the rock at our feet. o Both operate in all environments. In a more wet environment you’ll have more chemical. In a drier environment you’ll have more mechanical. Differential Weathering Ø Some of the sandstones are stronger and more resistant to erosion as some of the mudstone. **pic* Ø Crowder's Mountain NC – differential weathering, this rock is stronger than the softer stuff around it. Ø Stone Mountain NC – intrusion of granite, rock around it was softer thus was removed. What type of wreathing process preserves this dome shape of Stone Mountain? a. Oxidation b. Wedging c. Dissolution d. Exfoliation Ans: D. Exfoliation Types of Mechanical Weathering Why does this exfoliation happen? Ø A mechanical weathering type called: Pressure Release o Because of that expansion rate that is equal in all directions, it becomes a nice dome shape and exfoliates sheets. A release of pressure creates that exfoliation. Wedging: Ø Frost Wedging: Water gets in between rock and freezes. When it freezes it expands, causing parts of rock to break off. Ø Root Wedging: Plants roots pursue water, which is in these fractures. So as these roots locate those areas they then grow and expand these cracks. Other Mechanical Weathering Types: Ø Diurnal o Repetitive expansion and contraction Ø Daytime Temperature Differential If the sun rises in the East and sets in the West, in what orientation should a crack form in a rock? a. N-‐S b. E-‐W c. N45E d. N45W e. Randomly Ans: A. N-‐S Why? Ø When it’s the morning, part of the rock is expanding on one side. Then the other side, it is cooling. There are tensional forces that are set up. Then once the sun is setting, the other side of the rock is even hotter, say 140 degrees and the other side that was once heated has come down to 70. It creates a major tension that creates that break. Which direction would there be a crack on mars? Ø Similar day length and similar sun path, get the same data as Earth. When stuff is weathered away, this is creating sediment. Once it is weathered to the point where it can be carried away, that is erosion. Review: 1. Physical Weathering a. Sand, boulders, clay, pebbles 2. Chemical Weathering a. Salts 3. Organic Weathering a. Shells, humus Ø Coal is an organic sedimentary rock composed exclusively of plant material. o A swampy environment will eventually have enough material to produce new coal. o How old is the coal we are burning right now? § Most of it is coming from PA, very old – produced during Cretaceous time period (a couple hundred million years old) § Why we call it a non-‐renewable resource? • It can be re-‐made, it just takes LOTS of time. • Sedimentologists: Ø Studies sediment, but fluctuate with the price of oil. Ø $60-‐90,000 average starting salary with BS How would you describe this material? a. Sediment b. Sedimentary Rock c. Igneous Rock d. Metamorphic Rock Ans: b. Sedimentary Rock Talus (Talus Slope): Large broken off rocks, caused by freeze-‐thaw or root wedging. Glacial environments move a tremendous amount of this. As they reach rivers they become rounded, and you get down to the beach and you have sand. Ø Sand can pile up into huge dunes because of wind. Concluding that wind can only move smaller particles. Ø Sand is not a material, sand is a size, the maximum size wind can move. Deposition: • Once a sand particle has stopped moving it has been deposited. Where is deposition occurring in this satellite image? a. b. c. d. ans: B