GEOL 101 Test Study Guide UPDATED
GEOL 101 Test Study Guide UPDATED GEOL 101
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This 9 page Study Guide was uploaded by Victoria Williams on Monday March 14, 2016. The Study Guide belongs to GEOL 101 at George Mason University taught by Mark Uhen in Fall 2016. Since its upload, it has received 69 views. For similar materials see Introductory Geology in Geology at George Mason University.
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Date Created: 03/14/16
1 Test 2 Study Guide Sedimentary Rocks Most common rock is _______ Formed from material derived from ________ rocks Three classes of these rocks, define each: o Detrital o Chemical o Organic Detrital Sedimentary Rocks o Texture – Sizes of particles within the rock. Put the following particle sizes into order from biggest to smallest: Silt Sand Clay Gravel o Also name one rock for each of these particle sizes. o Poorly sorted rocks have a wide range of ______ sizes. o Angularity and Sphericity, defining the difference in shape in particles. An angular rock has sharp particles, spherical rocks have rounded particles. Chemical Sedimentary Rocks o Formed from a solution like water. Like in Limestone, water carries the minerals and it settles/crystals form when ___________ escapes the water droplet. o Name other chemical sedimentary rocks and the process they are made by. o Another process in which chemical rocks are formed is evaporation, Halite and Gypsum are created through the evaporation of sea water. Organic Sedimentary Rocks o Primarily made of _______ matter o When this material is compressed without much oxygen, it will rot and become Peat. o When you remove more water and compress more, Peat becomes _______. o Name the next two organic rocks formed from through the process of pressure. Lithification – Creation of these sedimentary rocks – Define the two methods of creation o Compaction o Cementation Environments where these rocks form – There are twelve, name the others. o Sand Dunes o Stream o Lakes o Caves 2 o Glaciers Sedimentary Structures – Define each term o Strata o CrossBedding o Graded Bedding o Ripple Marks o Mud Cracks o Organic Structures Metamorphic Rocks Which state in the U.S. has no metamorphic rocks? Metamorphic rocks are produced from preexisting rocks by applications of _______ and________. Metamorphism – The process that leads to changes in minerology, texture, and sometimes ________ composition. Different amounts of _______ and ________ affect the outcome. These rocks are in part composed of their parent rock, like slate’s parent rock is shale but it changes with the application of outside factors. Metamorphic Grade o Slight changes ______ Grade (Low heat and pressure) o Dramatic changes ______ Grade (High heat and pressure) Metamorphic Agents o Heat can cause recrystallization of minerals to a point where some mineral is no longer stable, these ‘switch out’ for a different mineral/crystal as compositions change. o Pressure that is equal on all sides causes metamorphic change, pressure that is not equal on all sides is called __________ stress. o Brittle rocks on the surface become more ductile (moldable) under pressure and heat. Imagine silly putty. o Geothermal Gradient – Change in temp. based on depth and relative closeness to active magma chambers. Metamorphic Fluids o Contact with heated fluids (most often water) can cause metasomatism. Water around a magma chamber can create a metamorphic ______ in the rock around the chamber. If the water is squeezed out, a ________ will form. Metamorphic Foliated Textures – Define Each o Slatey Cleavage 3 o Schistosity o Gneissic o Porphyroblastic o **Foliation does not occur with a rock made up of one type of rock. Ex. Marble. Types of Metamorphism o Hydrothermal ______ pressure, ______ heat o Contact Metamorphism ______ pressure, ______ heat o Regional ______ pressure, ______ heat o Subduction Zone metamorphism ______ pressure, ______ heat o Please write a basic explanation on what happens for each of these. o Bonus: Impact Metamorphism Metamorphic Mineralogy – Chart in Book o Low > Intermediate > High Graded o Forming first to last, Chlorite, Muscovite, Biotite, Garnet (only Int. and high), staurolite (mainly int. but some high), and sillimanite forms mainly in high grade. Quartz is found in all grades. Volcanism Components of Magma Magma Viscosity o What are the three factors? o Low viscosity magma have _________ eruptions o High viscosity magma have __________ eruptions Types of Volcanoes (What shape are they, how are they formed, and generally what type of eruptions do they have?) o Shield o Composite o Cinder Cone Lava Flows o What is the most common type of lava? o Define: Aa (ahah) Pohoehoe Define the following terms o Lava Tubes o Volcanic Gases (composition, origin) o Pyroclastic Material o Pyroclastic Flows o Lahars o Calderas o Fissure Eruptions 4 o Lava Domes o Plutons (Sills and Dikes) Weathering and Soils Where is weathering most intense? Weathering – Physical and Chemical alteration of existing rocks at or near the earth’s surface. Physical changes appearance, Chemical changes composition. o Process: Erosion Types of Physical/Mechanical Weathering o Frost Wedging o Unloading o Fractures and Joints o Thermal Expansion o Biological Activity Chemical Weathering o Process: Dissolution Types of Chemical Weathering o Oxidation o Hydrolysis o Spheroidal Weathering Rates of Weathering o Composition Bowen’s Reaction Series Which end of the BRS is least resistant to chem. weathering? Which is most resistant? o Climate Freezethaw cycles, frost wedging Temperature Cycles Precipitation Vegetation Cover o Differential Weathering – Capstones in the Midwest deserts, what causes these? Soil – Combination of mineral and organic matter Variables of Soil Formation: o Parent Material o Time o Climate o Biological Components o Topography Soil Formation – What happens to the soil in each of these places? o Steep Slopes o Flat Terrain o Streams and Rivers 5 Soil Terminology – Please define the following terms o Humus o Leaching o Eluviation o Solum O A E B C Distribution of Soil – Different types of soil develop in different bands based on climate around the globe. Earthquakes Where did the biggest earthquake in the US occur? What is an earthquake? They are vibrations of the Earth produced by a rapid release of energy. Important vocabulary: o Faults o Focus o Stress o Strain o Foreshocks o Aftershocks o Seismology o Seismic Waves (effect on the surface and speeds) P Waves S Waves Surface Waves Deep Earthquakes occur farther from trenches and shallow earthquakes happen closer to trenches. Why does this happen? What is an intraplate earthquake? (Hint, there was one in Virginia a few years ago!) Earthquake Size Scales o Intensity Scale o Magnitude Scale (most common) o Mercalli Intensity Scale Richter Magnitude Scale is a scale based on amplitude, each unit is a tenfold increase in wave amplitude. Each unit of Richter scale represents 32 fold increase of energy released (different than wave amplitude). Earthquake destruction occurs differently on different types of land. 6 o Unconsolidated Deposits – Most Destruction, explain why o Solid Bedrock – Less Destruction, explain why Effects of Earthquakes o Liquefaction o Tsunami o Landslides Prediction o Short Range – None o Long Range – Seismic Gaps in a large timeline, S. California has a large seismic gap while Alaska has a very small seismic gap. Earth’s Layered Structure From outside in: Crust, Lower Mantle/Inner Mantle, Outer Core, and the Inner Core. How do earthquakes help us figure out the composition of the earth? How does each type of wave travel through the earth? o S Waves o P Waves The Moho – boundary between crust and mantle The Mantle – In Order from Upper to Lower o Upper – Part of stiff lithosphere, mainly Peridotite o Below the upper, mantle is a part of weaker asthenosphere o Transition Zone between upper and lower (same composition as upper mantle, but the pressure causes the peridotite to turn into beta spinel) o Lower Mantle – Made of olivine and pyroxene to take the form of mineral perovskite. Slabs of oceanic crust are pulled through the mantle and melt in the D” layer (varying thickness, just above the core/mantle boundary). CoreMantle Boundary o What types of waves can pass through the core? Which cannot? o How these waves help us define the structure of the earth? o The core is mainly comprised of three components: iron, nickel, and ___% of lighter elements. o The change in density between the mantle and core is comparable to the difference between ______ and _______. o The core is completely solid, but the outer core is still moveable. Imagine a marble in the middle of JellO as a comparison. Source of Earth’s Heat o There are four ways that Earth has gotten its heat, using the hints below write out what each one is! 7 Planetesimals – The Beginning The Moon ShortTerm Decay Long TermDecay Conduction and Convection o Conduction is heat transferring through a solid material, write an example. o Convection is heat transferring through a fluid material (gas or liquid), write an example. Earth’s Gravity o Where is gravity the strongest and weakest on the planet? (Hint: think of weight) o See the map below, write a brief explanation for the differences in gravity all across North America. Earth’s Magnetic Field o The core of the earth is electrically charged, fluid metal. This causes the core to become like a ____________. o Define Geodynomo o Are the magnetic poles moving? If so, why? Oceanic Composition Mapping the Sea Floor – Two types of sonars are used o Basic Sonar o SideScan Sonar Seismic Profiles _____ frequency sound waves that pass through the sediment to map out a rough sketch of _______________. Sea Surface Anomalies o What causes water to ‘pile’ up in certain areas of the ocean? Continental Margins 8 o Passive Margins – No Tectonic Activity – East Coast of U.S. Continental Shelf Shelf Break Continental Slope Abyssal Plane o Active Margins – Tectonic Activity – West Coast of U.S. Subducting lithosphere Accretionary Wedge What gathers in the accretionary wedge? Where does it come from? Deep Ocean Basins: Trenches o Long, narrow, and extremely deep. They represent the area between _________ plates. o Above these trenches are the abyssal planes, mainly comprised of sediment and what else? Seamounts (guyots) o Submarine Volcanoes o As the crust moves the volcano away from the hotspot, it cools. The volcano then sinks. o As it is sinking (over thousands of years), ______ begins to form on it. o Eventually these seamounts will subduct under a plate. Oceanic Plateaus o Raised areas on the ocean floor composed of thick layers of ______ magma spilling out. Oceanic Ridges o Elevated linear features at the boundary of two areas of oceanic lithosphere. o There are three main ridges on the planet. The one South of Asia and part of Africa, the Atlantic ridge, and the Pacific ridge. Which one of these creates new oceanic crust the fastest? How about the slowest one? Oceanic Ridge Topography o Slow forming oceanic crust creates a __________ rift valley o Fast forming oceanic crust does not create a valley, but _______ in the crust. Ophiolite Complex – Crosssection adjacent to a midocean ridge. Using the image, try to write the process in which each layer is formed. Ex. How are Pillow Basalts formed? 9 Continental Rifts o Where is there a continental rift right now? o This rift has three ‘prongs’ to it, creating three definitive formations. Name each one. Mantle Plume and Gravity Sliding o A mantle plume creates a bulge under a continent, initiating continental rifting. o When Pangea was together, which two modernday continents had a mantle plume split them apart? Where is that plume now? Slab Subduction/Death of a Plate o Rollback of the trench flow of the asthenosphere o When the continental crust is moving over the oceanic crust and ‘eating’ it up at a faster pace. o Name one place on earth where this is happening right now.
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