Exam 2 Study Guide
Exam 2 Study Guide GEO 101
Popular in Dynamic Earth
Popular in Geology
This 11 page Study Guide was uploaded by Jamie Bynum on Friday September 23, 2016. The Study Guide belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Dr. Keene in Fall 2016. Since its upload, it has received 19 views. For similar materials see Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 09/23/16
Geo 101 – The Dynamic Earth Exam 2 Study Guide THIS IS NOTALLINCLUSIVE – especially if you don’t fill it out fully. 1.You must know all the terminology we covered in order to answer the questions. 2. Where do magma and lava come from? - The upper mantle 3.What are the ways magma forms, and how does each work? 1. Decrease in pressure - Heat + decrease in pressure allows rock to melt 2.Adding volatiles -Adding volatiles to rock decreases melting temperature 3. Heat transfer - Exactly how it sounds: heat rises up and melts rock 4. What are the major types of magma and how/why are their compositions different? 1. Felsic: has the most silica and least iron and magnesium 2. Intermediate: has slightly less silica and slightly more iron and magnesium 3. Mafic: has even less silica and even more iron and magnesium 4. Ultramafic: has the least silica and the most iron and magnesium 5. What does Bowen’s reaction series tell us about magma formation? - Different minerals (such as the ones in magma) form at different temperatures based on chemical composition 6. Why does magma flow and what affects viscosity? - Magma flows because it is less dense than solid rock and is squeezed upwards by pressure - Heat, volatiles, and silica affect viscosity 7. What are the differences between intrusive and extrusive rocks? (formation, cooling, deposits) - Intrusive rocks are formed inside the Earth 1. Magma in a magma chamber solidifies; called pluton or batholith 2. Magma gets stuck under the surface as a magma blister and solidifies; called a laccolith 3. Magma travels up a long tunnel and solidifies; called a dike or dam 4. Magma travels sideways and cools; called a sill 8. How do geologists classify igneous rocks? - Composition (felsic, intermediate, mafic, or ultramafic) - Texture (aphanitic [fine grained], phaneritic [coarse grained], porphyritic [large crystals with smaller background crystals], glassy [no crystals], and pyroclastic [volcanic; contains pieces of rock] 9. In what areas are igneous rocks formed? 1. Hot spots 2. Subduction zone 3. Continental rift zone 4. Mid-ocean ridge 10.Which rock type makes up most continental crust? Most ocean crust? - Most continental crust: granite (felsic) -Most ocean crust: basalt (mafic) 11.What are the products of volcanic eruptions? What are their characteristics? 1. Lava: has three major types 2. Pyroclastic Materials: depends on the type of eruption 3. Gases: contains water vapor (highest %), carbon dioxide, sulfur dioxide, hydrogen sulfide, and the remainder is variable 4. Geological Deposits/Rocks: Tephra is loose pyroclastic grains; tuff is lithified tephra 12.What are the main types (and subtypes) of lava and why are they different from one another? 1. Basaltic lava (mafic): very runny due to low silica content 2.Andesitic lava (intermediate): thicker than basaltic; flows, but slowly 3. Rhyolitic lava (felsic): doesn’t flow, but mounds up into lava dome 13.What are the differences between the types of eruptions we studied? - Effusive eruption: lots of low viscosity lava (basaltic) - Explosive eruption: lots of pyroclastic debris 14.What are the main features of a volcano? - Magma chamber: filled with molten rock (source) - Crater: hole - Fissure: crack * Volcanoes usually have either a crater or fissure at the top* - Main vent: tunnel to crater or fissure - Flank vent: vent on side of volcano - Fumarole: gas vent - Caldera: collapsed magma chamber 15.What are the major types of volcanoes? What are their main characteristics? 1. Shield volcano: low to the ground; low viscosity lavas 2. Scoria cone: basaltic lapilli pile; geologically short-lived 3. Stratovolcano: large, steep sides; alternating layers of lava and pyroclastic material 16.Where do volcanoes occur? - Mid-ocean ridges - Subduction zones - Continental rift zones - Hot spots - Flood basalt 17.Where are specific types of volcanoes most likely to occur? - Stratovolcanoes: contiental rift zone - Shield volcanoes: oceanic hot spots - Scoria cone: most likely on land (literal pile of lapilli) 18.What are the volcanic hazards we covered? What are their characteristics? How do we protect ourselves? 1. Lava: extremely hot (obviously); evacuate or divert it 2. Pyroclastic flow: ash, air, and pyroclastic material; 100-300 km/h; full of poison gas 3.Ash and lapilli: toxic glass shards; blunt trauma; evacuate 4. The blast itself: high forces 5. Landslides: moves up to 250 km/h; billions of tons of materials 6. Lahar: water (or snow) and ash; travels over 50 km/h 7. Earthquakes: damage to buildings can hurt or kill people 8. Poison gas: can occur with or without eruption 9. Tsunami: large volume of water - Determine the danger of each volcano: is it active, dormant, or extinct? 19.What factors help us to predict a volcanic eruption? - Earthquake activity - Heat flow - Volcano shape (bulge appears) - More gas and steam 20.How do volcanic eruptions affect climate? - High altitude dust may block sunlight and cause high temperature drop 21.Are there volcanoes elsewhere in the solar system? What are they like? - Yes, they are similar to Earth’s in that some are active while others are extinct 22.What are all the steps in the process of weathering and erosion? 1. Weathering 2. Erosion 3. Transport 4. Deposition 5. Lithification 23.What are the principal agents of erosion? - Liquid, ice, and wind 24.What are the major types of weathering and how are they different from one another? - Physical: no change to chemical or mineral composition - Chemical: chemical composition is altered or rock is dissolved 25.What are the subtypes of weathering and what do they do to rocks? - Physical: 1. Biological: plants and animals 2. Jointing: change in heat and/or pressure 3. Frost Wedging: ice wedges a crack open 4. Salt Wedging: water dissolves and ice crystals wedge a crack open 5.Abrasions: wind, glaciers, or water break rock - Chemical: 1. Dissolution: water and acids within dissolve rock 2. Hydrolysis: chemical reaction between water and a mineral where a new mineral forms 3. Oxidation: minerals combine with oxygen and new minerals form 4. Hydration: water is absorbed into a mineral 5. Biological: fungi, lichen, and plants secrete acid 26.What factors affect weathering rates? Why? 1. Whether there is both physical and chemical weathering or just one type; they can be complimentary 2. What form water is in; ice weathers slowly, while water weathers quickly 27.How do different size grains act during entrainment, transportation, and deposition? Why? - Entrainment: Some particles take less energy to get moving than other particles; van der Waals forces - Transportation: Larger particles take more energy to keep moving than smaller particles - Deposition: Larger particles land sooner than smaller particles 28.What are the products of weathering? - Sediments and soil 29.Why are there different types of soil? - Soil types are controlled by: 1. Parent rocks and minerals 2. Water content 3. Climate 4. Local vegetation 5.Age 30.How do geologists classify sedimentary rocks? - Clastic, chemical, and biochemical 31.How are bed, strata, and formation related to one another? -Abed is a layer of sedimentary rocks -Astrata is a group of beds -Aformation is several strata together 32.Know the common stratigraphic structures we covered in class and what they tell us about the rocks in which they are found. 1. Ripple Marks and Dunes: indicate moving water or air 2. Cross-Bedding: indicates change in wind direction 3. Desiccation Cracks: indicates water has evaporated 4. Graded Beds: indicates an underwater disruption 5. Trace Fossils: indicates organisms 33.Know the environments of deposition we covered in class. What kinds of rocks would form in each environment? (Think about sediment deposition.) - Terrestrial: 1. Glacial: clastic 2. Mountain Stream: conglomerates 3.Alluvial Fan: Conglomerates 4. River: sandstone, siltstone, and mudstone 5. Lake: mudstones, clay stones 6. Sand Dunes: sandstone - Marine: 1. Marine Delta: many kinds of deposits 2. Costal Beach: well-sorted sandstone 3. Shallow Marine: fine-grained, well-rounded, well-sorted 4. Shallow-Water Carbonate: full of carbonate sand 5. Deep Marine: plankton skeletons 34.What is the significance of a sedimentary basin? - It is an extremely large, low area in the lithosphere where sediments collect 35.What do transgressions and regressions tell us? - They tell us if the continents and/or sea floor are rising 36.Why does sea level change? - Due to continents and/or sea floor rising I announced in class when we deviated from the textbook. Please remember, as stated in the syllabus, that when the lecture and textbook deviate from each other, the lecture is where you should get your information. Extra office hours for exam prep: Monday, September 26 from noon – 2:00pm. Email me for an appointment if these don’t work for you.
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