Exam 1 Study Guide
Exam 1 Study Guide Geology 101
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This 7 page Study Guide was uploaded by Gabrielle McDonald on Sunday September 20, 2015. The Study Guide belongs to Geology 101 at Washington State University taught by Wilkie in Fall 2015. Since its upload, it has received 124 views. For similar materials see Geology in Geology at Washington State University.
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Date Created: 09/20/15
Exam 1 Study Guide Answers Chapter 1 Earth in Context 1 Scientific method 1 Recognize the problem 2 Collect data 3 Propose a hypothesis 4 Test the hypothesis 2 The principle of uniformitarianism states that physical processes we observe operating today also operated in the past at roughly comparable rates I The present is the key to the past 3 The nebular hypothesis is an explanation for the origin of planets moons asteroids and comets The material from which the solar system was formed was once a slowly rotating cloud or nebula of extremely hot gas The gas cooled and the nebula began to shrink As the nebula became smaller it rotated more rapidly becoming somewhat attened at the poles A gravitational force from the mass of the nebula caused rings of gas to be left behind as the nebula shrank These rings condensed into planets and their satellites while the remaining part of the nebula formed the sun As the Sun began to form the inner part of the disk became hotter causing volatile elements to evaporate and drift to the outer portions of the disk Thus the inner part of the disk ended up consisting predominantly of refractory dust whereas the outer portions accumulated large quantities of volatile materials and ice As this was happening the protoplanetary disk evolved into a series of concentric rings in response to gravity Later the material of surrounding rings began to clump and bind together due to gravity and electrical attraction Eventually enough blocks condensed to form planetesimals which then exerted enough gravity due to their mass to attract and pull in other objects that were nearby Like vacuum cleaners Eventually they grew into protoplanets and once it succeeded in incorporating virtually all the debris within its orbit it became a full edged planet The protoplanetary disk is the outer part of the disk that is attened The planets moons etc are formed from the material in the attened protoplanetary disk Volatile materials such as hydrogen helium methane ammonia water and carbon dioxide are materials that can exist as gas at the Earth s surface In the pressure and temperature conditions of space all volatile materials remain in a gaseous state closer to the Sun but beyond the frost line some materials condense into ice Refractory materials are those that melt only at high temperatures and they condense to form solid sootsized particles of dust in the coldness of space 4 The moon was formed sometime during the late stages of accretion when a Marssized body impacted the Earth resulting in Ej ecta of debris into space Speed up of Earth s rotation 0 10 Tilting of Earth s orbital plane to 23 Formed our Moon The ecliptic plane is inclined at 235 0 with respect to the celestial equator because of the tilt of the Earth39s rotation axis with respect to the plane of its orbit around the sun The Earth is made up of different layers like the inner and outer core the lower and upper mantles and the crust Crust forms the outer most rigid layer of the lithosphere distinguished by composition continental or oceanic plates Lithosphere brittle stone Aesthenosphere weak moldable or ductile solid plastic Deep Mantle solid but hotter contains most of Earth s volume Outer core Liquid Inner core Solid The Earth is dated to be about 457 billion years old Continents were formed from the lighter molten materials that rose to the surface that solidified as it cooled The Oceans and Atmosphere were formed by two different hypotheses l Resulted in impact of volatilerich matter striking the Earth from space after it was formed such as comets 2 Resulted from volatile tied up in planetesimals which formed the Earth Volatiles were released later by volcanism Evidence shows that planets went through many of the same process They all have atmospheres and had water as well Internal heat powered by heat and energy trapped during planetesimal bombardment an heat generated by radioactive elements decay within the earth External heat solar energy from the sun is the driving force powering the water and climate conditions Solar energy affects the atmosphere hydrosphere and biosphere The concept that largescale movement of continents has been around since the 16th century There are 4 concepts 1 The outer portion of the earth39s lithosphere is not a continuous shell but is broken in units called plates2 The plates move Plates act as ridge unites that ride on the asthenosphere which is also in motion3 Most geologic activity such as earthquakes and volcanoes are concentrated near plate boundaries4 Plate interiors are relatively quite less active Chapter 2 The Way the Earth Works Plate Tectonics l l Continents fit 2 Patterns of animal life 3 Fossils 4 Related rocks 5 Ancient climates Not evaluated as a theory until 196039s because it was not widely accepted at first because no one knew what force could have moved the continents 6 Pangea is all of the continents that were once connected as a super continent Sea oor spreading new oceanic lithosphere is created where partially molten mantle materials rises to fill the gap in the rift Evidence of sea oor spreading was the recycling of ocean oor Magnetic stripping the magnetic patterns of the rocks on the ocean oor they go though changes over time called magnetic reversal where south becomes north and north becomes south This helps up to know how long the ocean was around The ring of fire is where a lot of volcanoes are around the edge of the continents and also where a lot of earthquakes have happened Around the Ring of Fire the Pacific Plate is colliding with and sliding underneath other plates This process is known as subduction Earthquakes occur at transform plate boundaries Oceanicoceanic convergence and continentcontinent convergence They generally occur near the edge of continents Volcanoes occur at convergent plate boundaries and Continental to oceanic convergences Divergent Boundarv tension move away from each other by rifting sea oor spreading new lithosphere decompression melting Rift a crack like valley which allows molten rock to erupt from below Examples midatlantic ridge Iceland Sea of Cortez Convergent Boundarv compression move towards each other collision or subduction occurs ContinentalOceanic OceanicOceanic ContinentContinent ContinentContinent Convergence Transform Boundarv Shear Stress Plates shift past each other laterally and generate earthquakes volcano present Fault fracture in the crust along which there has been movement Hot Spots Stationary result of a thermal plume burns a hole in the plate and erupts at the surface Hawaii and Yellowstone Convection at a divergent boundary is considered more of a passive upwelling Bulging of the continent due to mantle upwelling gives rise to ridge push gravity driven mechanism Slab pull by cold crust as it sinks into the mantle at a convergent boundary As the subducting slabs descends it induces mantle circulation slab suction pulling the plate towards the trench See 5 At oceanic plate boundaries 10 11 12 13 14 15 Due to sea oor spreading at divergent boundaries The density of a plate determines if it will subduct a plate with a higher density subducts under a lower density plate The type of crust that forms at subduction zones is Continental crust Flux melting occurs at subduction zones in convergent plate boundaries Flux melting is partial melting in a subduction zone and it forms new land volcanism Continental crust is created during accretion It is created at subduction zones Hot spots are stationary surface expression of volcanic activity They result from a thermal plume a localized source of rising heat energy from the mantlecore boundary You can tell the direction from youngest to oldest A portion of it is going to ride on the Pacific Plate northwestward eventually forming an island due to the San Andreas fault line which is a transform boundary 115 cmyr Chapter 3 Patterns in Nature Minerals 1 Naturally occurring Inorganic no organic carbon crystalline solid atoms are arranged in a particular structure ex cube specific chemical compound contains particular elements in a set ratio An isotope is when the number of neutrons change within an atom Isotopes are used to determine the age of rocks Ionic bonding is the transfer of electrons and they form when shells are nearly empty or nearly full Covalent bonding is the sharing of electrons forms when shells are half full Covalent bonding is the strongest bond where atoms combine by losing gaining or sharing electrons to fill their electron shells chemical bonding Minerals form by chemical reactions between elements of crystallization The conditions for minerals to form are 1 lower the temp for a liquid below its freezing point 2 Liquids evaporate from a solution forming a supersaturated solution and results in precipitate 3 hydrothermal uids created by the circulation of water through hot rock or near a magma chamber The water is heated and is able to dissolve elements forming a weak acid solution Mineral Properties Color least reliable depends on presence of ions Luster how the surface re ects light metallic v non metallic Streak color of mineral in its powdered state Cleavage the tendency of minerals to break along planes of weakness Fracture breaks randomly crumbles the structure of the mineral controls how it will break Hardness Moh s hardness scale a mineral s resistance to scratching and abrasion Things that affect hardness are atomic structure type of chemical bonds and type of atoms it is made of 0 Same chemical formula different crystal structure Ex diamonds and graphite 7 Silicates are the most abundant group of minerals in the crust Another group is non silicates 8 Only one of the six types of asbestos is linked to lung cancer 9 What makes a gem Beauty Transparency Brilliance Durability Rarity or perceived rarity 10 Diamonds are formed deep in the Earth through covalent bonding in the mantle and is a 10 on Moh s hardness scale It is a polymorph of carbon along With graphite and is brought to the surface through kimberlite pipes Chapter 4 Up from the Inferno Magma and Igneous Rocks 1 Three Main Rock Types Igneou form by the solidification of molten rock or melting Sedimentary Form by either cementing together fragments of preexisting rocks or by precipitation of mineral crystals out of water solutions at or near the earth39s surface Metamorphic form When preexisting rocks change character in the solid state as a response to a change in pressure and temperature conditions does not require melting 2 Igneous rocks make up the bulk of the earth39s crust The most abundant rock type we find on the surface are sedimentary rocks compaction and cementEatichn 4 The two types of igneous rocks are intrusive and extrusive Intrusive slow cooling large crystals Phaneritic all visible and pegmatitic very large Extrusive quick cooling tiny crystals or glassy also called volcanic 5 Textures Aphantic crystals are too fine to be distinguished without a microscope Pyroclastic fragments of material ejected explosively into the air pumice ash tuff Vesicular void spaces where gas bubbles were Pegmatitic very large Phanertic all visible Porphyrtic 2 distinct crystal sizes Phenocrysts big crystals slow cooling and matrix background is aphanitic fast cooling Glassy no minerals present 6 Generation of magma Divergent boundaries midocean ridge mafic composition because basalts dominate most of the ocean oor Partial melting of upper mantle Convergent boundaries continentaloceanic ocean island arcs and continental volcanic arcs Intermediate to felsic composition andesitediorites to rhyolites granites Partial melting form plate subduction 7 Rocks are composed of different mineralsMinerals melt at different temperaturesOnly a fraction of rock might melt depending on the temperature and pressure conditions 8 Do not need to know specific temperatures just order Felsic 600800 degrees C Intermediate 8001000 degrees C Mafic 10001200 degrees C Ultramafic greater than 1200 degrees C 9 Viscosity is resistance to ow Mafic higher melting temperature low viscosity Felsic lower melting temperature high viscosity 10 Magma Cools solidifies freezes and forms silicate minerals Fractional crystallization is the process of sequential crystal formation and settling Magma to igneous rock magma cools either above or below surface either way forms igneous rock Fractional crystallization early formed crystals prevented from reacting with remaining magma creates magma with evolving chemical composition 11 A piece of oceanic crust attached to the surface Gabbro would be found 12 Intrusions intrudes parallel to sedimentary bedding many are horizontal vertical or steeply inclined intrusion which cuts cross other rock types Batholith largest of intrusive igneous rocks bodies cuts VLin long regularly shaped occurrence in an ore filled with crystals and minerals Chapter 5 The Wrath of Vulcan Volcanic Eruptions 1 Mount Saint Helens Pyroclastic eruption which has violent eruptions lava high in silica intermediate to felsic high viscosity gas trapped occur at convergent boundaries and hot spots Mount Rainier Composite volcano stratovolcano primarily vent eruption steep slopes and up to 10km across Low temperature
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