GEO 101-007 Exam 3 Study Guide
GEO 101-007 Exam 3 Study Guide GEO 101-007
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This 13 page Study Guide was uploaded by Jennifer Gintovt on Monday October 19, 2015. The Study Guide belongs to GEO 101-007 at University of Alabama - Tuscaloosa taught by Dr. William Lambert in Summer 2015. Since its upload, it has received 199 views. For similar materials see The Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 10/19/15
GEO 101007 Exam 3 Study Guide Chapter 8 Earthquake 0 an episode of ground shaking Q How many seismograph locations do you need to determine where an earthquake originated 0 Causes of Earthquakes I Sudden fracture on which sliding occurs Sudden Sudden change in the arrangement of atoms in the minerals of a rock Movement of magma in a volcano Explosion of a volcano Giant landslide Meteorite impact And underground nuclearbomb test Hypocenter the place underground where rock breaks and generates earthquake waves point on the surface of Earth directly above the focus where the earthquake originates A fracture crack in the Earth s surface on which sliding movement occurs Fault basics Match the definition with the type of fault 1 Normal faults A One block literally slides past another no vertical displacement 2 Reverse faults B Form during shortening of the crust steep 3 Thrust faults C Form during extension of the crust 4 Strikeslip fault D Also form during shortening gentle 1 slope 1 v 3917 o 392 8 39z 3 39I SIaMsuv the amount of movement or slip across a fault plane a small step on the ground surface where one side of a fault has moved vertically with respect to another New Fault Formation Stress a push pull or shear applied to a material Elastic Strain a change in shape of a material that disappears instantly when stress is removed Existing Fault Friction the force that resists sliding on a surface Fault terms Stickslip behavior stopstart movement along a fault plane caused by friction stick which prevents movement displacement until stress builds up sufficiently slip Elasticrebound theory the concept that earthquakes occur when rock elastically bends until it fractures the fracturing generates earthquake energy and decreases the elastic energy stored in the rock Foreshocks and aftershocks Foreshock the series of smaller earthquakes that precede a major earthquake Aftershock the series of smaller earthquakes that follow a major earthquake Seismic Waves Match the correct term with the definition 1 Body Waves A Seismic waves that travel along the Earth s surface 2 Surface Waves B Compressional move through Earth s interior fast velocity nondestructive travel through both liquids and solids 3 Pwaves C Seismic waves that pass through the interior of Earth 4 Swaves D Destructive cause ground to ripple up and down 5 L waves E Most destructive waves cause ground to ripple back and forth 6 R waves F Shear pass through Earth s interior 2 moderately fast velocity nondestructive travels through only solids o 399 a 399 d 3917 a 39E v 392 393391 SJaMsuv Body Wave Velocities Pwaves travel faster than swaves and are the rst to be recorded on seismographs Velocity of waves varies and depends on the type rock sediment through which they are passing Surface Wave Velocities L waves travel faster than Rwaves but surface waves travel much slower than body PampS waves Surface waves are last to be recorded by a seismograph Seismograph Instrument that can record the ground motion of an earthquake 0 Can tell us an earthquake is occurring 0 Provides data to determine earthquake epicenter 0 Provides data to determine intensity of earthquake Defining the size of an earthquake Mercalli Intensity Scale 0 Italian scientist Giuseppe Mercalli Richter Scale magnitude scale 0 American Scientist Charles Richter I Quantative measurements but works best with shallow earthquakes close to seismograph Momentmagnitude scale a numerical representation of the size of an earthquake that takes into account the area of the fault that slipped the amount of slip and the strength of the rock that broke Where do earthquakes occur Plate boundaries 0 Divergent I Shallow earthquakes o Convergent I Shallow intermediate and deep earthquakes o Transform I Shallow earthquakes Continental rifts 0 Shallow earthquakes similar to divergent plate boundaries but quakes occur near populated areas since on land Collision zones Intraplate earthquakes We make longterm predictions for example San Francisco will experience a major earthquake within the next 100 years We make shortterm predictions for example we cannot say a major earthquake will hit San Francisco on July 29 2016 0 Its not a matter of quotifquot but rather when Chapter 9 Principles Superposition the principle that younger layers of sediment are deposited on older layers of sediment thus a sequence of strata the oldest layer is at the base Original Horizontality the principle that sediments are deposited in nearly horizontal layers 0 Rocks found may include sandstone shale etc Tilted rock Foliated Rock 0 May include quartzite slate etc o Metamorphic rocks Q In a normal fault is the hanging wall moving up or down A Hanging wall moves Orogen orogenic belt a linear range of mountains Orogeny a mountain building event may last tens of millions of years Match the key words with the proper definitions 1 Uplift A A bend or wrinkle of rock layers folds form from a consequence of ductile 2 Deformation deformation B The upward vertical movement of the 3 Joints ground surface that occurs during mountain building 4 Faults C A change in the shape position or orientation of a material by bending 5 Folds breaking or owing 3 D Naturally formed cracks fractures in rocks E A fracture on which one body of rock slides past another V 399 El 3917 Cl 398 I 39Z quotcl 391 ism SUV Strain The change in shape of an object in response to deformation ie 1 Stretching a Rock becomes longer 2 Shortening a Rock becomes shorter 3 Shear a Rock becomes tilted with change in angular relationships Brittle vs Ductile Deformation Brittle deformation the cracking and fracturing of a material subjected to stress chemical bonds break ceramic plate Ductile plastic deformation the bending and owing of a material without cracking or breaking subjected to a stress dough 0 New chemical bonds are quickly formed when old bonds break Factors Controlling Deformation Type Temperature warm rocks tend to deform ductilely while cold rocks tend to deform brittlely Pressure increased pressure causes more ductile deformation Higher pressure makes it harder for rock to separate into segments Deformation rate slow deformation rate allows for ductile deformation A sudden rate of deformation will act brittlely Composition some rocks are softer than others and are more capable of deforming ductilely Brittleductile transition Rocks at the Earth s surface 1015 km tend to have brittle behavior Rocks below this depth tend to have ductile behavior Boundary between brittle and ductile material is known as the brittleductile transition Stress Stress Force applied per unit area Compression takes place when a rock is squeezed Tension occurs when a rock is pulled apart Shear stress develops when one side of a rock body moves sideways past the other side Pressure refers to a special stress condition in which the same push acts on all sides of an object Stress i Strain Stress causes strain change in shape Shear causes shear strain joint i Fault Both joints and faults are cracks or fractures in rock but movement does not occur along a joint All faults are joints but not all joints are faults Faults Surfaces of Slip more cartoons Faults Surfaces of Slip Thrust Reverse thrust and normal faults quotdipslip faultsquot 39 Transform Faults quotstrikeslip faultsquot 0 Right or left lateral displacement Left Lateral Right Lateral Axial plane Fold Terminology Hinge Line portion of fold where curvature is greatest m sides of folds show less curvature Axial plane surface imaginary surface that cuts through hinges of multiple layers splits fold down the middle Anticline fold with archlike shape limbs dip away from hinge think quotAquot for anticline 0 Rock farthest out is youngest Hinge line Axial plane Syncline Fold with throughlike shape limbs dip toward hinge think quotSquot for smile syncline Youngest rock is at the center Anticlines and Synclines happen together Monocline 0 Fold with stairstep shape only one dipping limb Dome 0 Fold with overturned bowl shape limbs dip away from center 0 Youngest rock is outer edge Basin 0 Fold with bowl shape limbs dip toward center Youngest rock is at the center Plunging Anticline 0 If the hinge is horizontal the fold is called a nonplunging fold but if the hinge is tilted the fold is called a plunging fold anticline syncline Symmetrical vs Asymmetrical Folds Symmetrical folds go straight up and down 0 Asymmetrical folds have a more diagonal shape Overturned folds have an extreme diagonal shape Measuring Dip The angle of inclination of a rock unit or fault measured from a horizontal plane Includes both a angle measurement ie how much its tilted and a direction ie which direction is it tilted Line of Horizontal plane strike Measuring Strike Perpendicular to dip The compass direction of the line produced by the intersection of a rock layer or fault with a horizontal plane Generally expressed as an angle relative to north measured clockwise Number typically is not shown quot I 39 3 guts Chapter 10 Relative vs Numerical Age Relative The age of one geologic feature with respect to another older than younger than Numerical The age of a rock or structure as specified in years referred to as absolute agequot in older literature Original continuity 0 Sediments generally accumulate in continuous sheets they will either pinch outquot or run into a preexisting feature 0 Layers that are cut are due to subsequent erosion Crosscutting relationships 0 The relative age of rock can be determined by looking at which rock or structure cuts another the feature that has been cut is older Baked contacts 0 An igneous intrusion bakes metamorphoses surrounding rocks The rock that has been baked must be older than intrusions Inclusions o The rock containing inclusions must be younger The rock that makes up the inclusions must be older Unconformities Gaps in the Record A boundary between two different rock sequences representing an interval of time during which new strata were not deposited and or were eroded missing timequot o mular unconformity I An unconformity in which strata blow were tilted or folded before the unconformity developed strata below the unconformity therefore have a different tilt than the strata above 0 Nonconformity I A type of unconformity at which sedimentary rocks overlie basement older intrusive igneous rocks and or metamorphic rocks 0 Disconformity I An unconformity parallel to the two sedimentary sequences it separates Q Is there a single location on Earth that contains a complete record of Earth history A No How do geologists describe strata Stratigraphic strat Column a crosssection diagram of a sequence of strata summarizing information about the sequence Stratigraphic formations a sequence of beds of a specific rock type or group of rock types that can be traced over a fairly large region The Redwall Limestone is a formation mainly limestone The Supai Group is a formation consisting of multiple rock types Contact the boundary surface between two formations this is one of many types of geological contacts Lithologic Correlation Correlation matching of formations to other nearby formations based on similarities in rock types Fossil Correlation Correlation matching of formations to other distant formations based on similarities in fossil type age The Geologic Column The geologic column has been pieced together using information from millions of local stratigraphic columns The column is divided into segments each of which represents a specific interval of time The largest subdivisions break earth history into m which include the Hadean Archean Proterozoic and Phanerozoic Phanerozoic means visible life V r quot gtm39 V w A mpyai F it A A 1 11 kv a 39 The Phanerozoic Eon visible life is divided into eras o Cenozoic era recent life o Mesozoic era middle life 0 Paleozoic era early life m are divided into E Eras are divided into periods 0 Period names come from area where rocks of that age are well represented Devonian Devon England or an important characteristic of thmat time Carboniferous period contain a lot of coal Periods are divided into Epochs Numerical Age Study of rocks ages is called geochronology The process of determining the numerical age of rocks is called radiometric dating isotope dating Isotope different versions of a given element carbon that have the same atomic number but different atomic weights same number of protons but different number of neutrons Stable they will always retain the same number of protons and neutrons essentially forever Unstable radioactive they change with time to a different element Radioactive Decay Radioactive Decay the process by which a radioactive atom undergoes fission or releases particles thereby transforming into a new element Parent isotope the original isotope that undergoes decay Daughter isotope the product of the decay of a parent isotope Halflife the time it takes for half of a group of radioactive element s isotopes to decay example 5000 years Parent Daughter b The ratio of parenttodaughter isotopes changes with the passage of each successive halflife Toda 5000 s 10000 s 15000 s 20 000 Chapter 1 1 Slow StartActionpacked Ending Based on our current scientific understanding the first part of Earth s history was devoid of life and an extremely hostile environment About 542 million years ago there was an explosion in the diversity of living organisms Many mass extinctionsquot have helped to shape the history of life on earth The Hadean Eon 4570 3850 million years ago Spans Earth formation to first appearance of continental crust Hell on Earthquot Moon formation questions still remain about the environment The Archean Eon 3850 2500 million years ago Begins with the first appearance of continental crust First life thought to be present 3800 3500 0 Chemical molecular fossils or biomarkers o Isotope signatures 0 Fossil forms fossilized bacteria Stromatolites distinctive mounds of sediment produced by mats of cyanobacteria Atmosphere high in carbon dioxide and nitrogen little oxygen Proterozoic Eon 2500 524 million years ago Spans almost half of Earth s history Larger plates and continents formed 90 of continental crust Atmosphere became oxygenrich Shields formed broad lowlying region of exposed Precambrian rock Cratonic platforms formed strata burying shield Rodinia an early supercontinent Ediacaran fauna first multicellular organisms Great oxygenation event dramatic increase in atmospheric oxygen around 2400 million years ago due to photosynthetic organisms producing oxygen and other environments not be able to absorb oxygen Snowball Earth a proposed state of Earth in which Glacial conditions were found globally 0 Many organisms went extinct 0 C02 from volcanic activity is thought to have warmed earth enough to melt 1ce Phanerozoic Eon 524 million years ago to present Diverse organisms with shells or skeletons Supercontinents formed and broke apart Mountain ranges formed happening today Subdivided into 3 Eras o Paleozoic o Mesozoic o Cenezoic The Early Paleozoic Era Cambrian Ordovician Periods 542 444 million years ago Epicontinental seas shallow seas that may have supported many organisms 20 million year period of dramatic diversification of life based on fossil record Conodonts resemble tiny jaws may have belonged to tube like animals 0 Trilobites The Middle Paleozoic Era Silurian Devonian Periods 444 359 million years ago On land vascular plants with woods tissues seeds and veins for transporting food and water rooted for the first time 0 Plants were able to grow to larger sizes than previously T iktaalik first amphibian to crawl onto land and inhale air with lungs The Late Paleozoic Era Carboniferous Permian Periods 359 251 million years ago Relatively cooler sea level dropped land exposed and high amounts of organic material produced eventually coal 0 Pangea formed First reptiles appear 0 gt95 of all marine life went extinct The Early and Middle Mesozoic Era Triassic Iurassic Periods 251 145 million years ago Pangea starts to break apart was together for 100 million years Iurassic period dinosaurs TRex lived during the Cretaceous Period not Iurassic The Late Mesozoic Era Cretaceous Period 145 65 million years ago Sea level rose dramatically ooding much of the continents Atmosphere was very warm A shallow sea divided presentday North America Very active west coast Not just dinosaurs 0 Giant turtles 0 Larger animals 0 quotmodernquot fish appear The KT boundary event 0 K Cretaceous Period T Tertiary Period 0 150million year long rein of dinosaurs ended instantly o 90 of plankton species and 75 of plant species went extinct Chicxulub Crater The last ice age 0 Ended about 11000 years ago
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