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NIU GEOL 120 - Exam 1 Study Guide

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GEOL 120 1st EditionExam # 1 Study Guide Lectures: 1 - 8Lecture 1 (Juanuary 13)Introduction to Geol 120.Lecture 2 (January 15) What is the Doppler Effect? Closer waves mean? Spread out waves mean?The Doppler Effect is the frequency of the wave that is affected by the speed of their source. The closer the Wave crests the higher the frequency. The further spread apartthe waves crests he lower the frequency.What is the Red shift? Blue lights mean? Red lights mean?Colors of light are created by light waves of different frequency. Light coming to earth from all galaxies is redder than expected. Blue light reflects a higher frequency and red light reflects a lower frequency.What is the Evolution of the Earth? What are the earth’s layers? The evolution of the earth consists of Compositional segregation. Heavier materials sink and lighter materials rise. Suggesting that the earth has layers. Earths’ layers consist of the:Atmosphere, troposphere, tropopause, stratosphere, stratopause, mesosphere, mesospause, and the thermosphere.What is the difference of the meaning of the composition and mechanics of the earth? What is the composition of the earth? What is the Mechanics of the earth?The composition is what the layers are made up of and the mechanics of the earth is the strength of each layer. The composition of the earth consists of the crust, the mantle and the core.The mechanics of the earth consist of the lithosphere (brittle) the asthenosphere and the mesosphere.Lecture 3 (January 20)Who is Alfred Wegner? What was his theory? Why did it fail?Alfred Wegner is the scientist who proposed continental drift. He observed that there is Glacial Deposits Distribution explaining that they formed on Pangaea. To support his theory that one day there was a super continent called Pangea he began making observations from the different continents. He found that there are specific rock types that are found on more than one continent that make more sense if continents were in positions different from today when they formed. He found Fossil distribution for animals that could not have crossed oceans are found on different continents. He observed unique plants are found on all southern continents and he also observed matching rock assemblages these rocks comprising discontinuous mountain belts align when continents are moved to earlier positions.Although Wegener had all these observations that made sense his theory failed because he could not explain how or why continents would have drifted apart from Pangea to what theyare now.Who is Harry Hess? What was his theory? How did his theory save geology?Harry Hess was a Geologist and United States Navy officer in World War II. As a professor at Princeton he revisited the idea of Pangea and Introduced key elements previously missing like Seafloor spreading n Subduction n 1968 – model of Earth’s 20 plates n Plate Tectonics. His theory was widely accepted and one of the most influential theories of how the Earth works n Explains many phenomena (i.e. earthquakes, volcanism )Putting It all TogetherWegener proposed Pangea hypothesis using observationFit of continents Locations of past glaciationsClimate belt distributionsFossil distributions Matiching geologic units Harry Hess proposed seafloor spreading as a mechanism to explain Wegener's observations n Bathymetric observations gave clues to physical processes that may be responsible for seafloor spreading n Ocean-ridges n Deep ocean trenches adjacent to volcanic arcs n Seamounts with active volcanism and a trail of inactive volcanic islands (remember Hawaii!) n Paleo magnetism documents seafloor spreading n The result of a spreading seafloor is continental drift! n BUT THIS IS STILL INCOMPLETE! n How do these observations and hypothesis interact with the lithospheric mantle and asthenosphere? Lecture 4 ( January 22)What is a plate tectonic? How are plates distributed? What types of continental margins are there? What are divergent and convergent plate boundaries? What is a subduction zone? What causes earthquakes? What is a hotspot?A plate tectonic is comprised of crust and uppermost mantle. They are found in the lithosphere and the thickness of each plate tectonic varies.Plates are distributed by the location of plate boundaries and they are defined by thedistribution of earthquakes. Plate boundaries may or may not occur and continental margins.A continental margin can be active meaning it is near a boundary or passive meaningit is far from a plate boundary which is where continental crus transitions to oceanic crust.Lecture 5 What are Mineral Characteristics, what is a polymorph? What are crystals? What are some mineral properties?Mineral CharacteristicsMinerals are naturally occurring have an Inorganic slid with a few exceptions here.They Do not contain carbon. They have a definable chemical composition which varies within limits.Graphite and diamond do have Carbon but inorganic. Minerals have an orderly arrangement of atoms which are crystalline. Glass is not a mineralPolymorphPolymorph is minerals with the same composition, but different structureEx:Diamond & Graphite are pure carbonall diamond bonds are covalentgraphite forms sheetscovalent bond within sheetsCrystalsCrystals are uninterrupted piece of crystalline solid they typically have crystal faces (typically). Crystals Shape is natural, it’s not cut and polishedAlthough they look that wayThey come in a wide variety of shapescube hexagonal prismdouble tetrahedronTrapezoidalMineral properties colorcolor results from light waves not absorbed by the mineralstreakhardnessLuster2 primary subdivisionmetallic (looks like metal)non-metallicvitreous (glassy)Earthy (dull)Lecture 6Define Magma? Lava? And viscosity?MagmaMolten (liquid state) rock beneath the earth’s surfaceLavaMolten (liquid state) rock that has flowed onto the earth’s surfaceViscosity (noun)Liquid state resistance to flowExHoney has a high viscosityWater has a low viscosityLook up flaux meltingLecture 7What is Viscosity in more detail?Viscosity describes resistance flow. It is primarily controlled by compositionIf it is Felsic (light) that means it has High viscosity. If it is Mafic (dark) that means it has Low viscosity. Lec 8Describe Volcanic Architecture?Volcanoes have characteristics features like a Magma chamber located in the upper crust. It’s usually an open cavity or area of highly fractured rock. May contain a large quantity of magma, and it may inflate and


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