Geology 101 Week 1
Geology 101 Week 1 GEO 101
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This 0 page Class Notes was uploaded by Kayla Corbett on Wednesday January 20, 2016. The Class Notes belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Dr. Natasha T. Dimova in Fall 2016. Since its upload, it has received 63 views. For similar materials see The Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 01/20/16
Welcome to GEO 101002 The Dynamic Earth Lecture 1 The Earth in Context An introduction Chapter 1 What is Science Science is the human effort to understand or to better understand the natural world and how it works by observing physical evidence Science is done through observation of natural phenomena andor through experimentation that tries to simulate natural processes under controlled conditions What is Earth Science Geoloav The study of the Earth focusing on its composition behavior and history including these subsystems Atmosphere Biosphere Hydrosphere Lithosphere Mantle Core Geology SpecialtiesDisciplines Structural geology distribution of rock units Stratigraphy rock layering Petrology origin and formation of rocks Mineralogy structure and properties of minerals Geochronology age of rocks fossils and sediments Paleontology fossils and prehistoric life Geochemistry chemistry of Earth s crust Planetary Geology geology of celestial bodies Environ Geology human interaction with environment Oceanography physicalchemicalbiologica1 aspects of oceans Hydrogeology water systems Geophysics Earth properties and physical principals Seismology earthquakes and seismic waves What does a Geologist Do Minerals exploration Oil and gas industry Environmental policy cleanup hydro coastal Civil engineering 0 Research 0 Teaching and academia How does geology effect our everyday lives 0 Natural Events 0 Economics and Politics 0 Our role as decisionmakers 0 Consumers and Citizens 0 Sustainable Development 2015 United Nations Climate Change Conference 0 The Paris climate summit yielded a pact to reduce air pollutants that contribute to global warming Interesting Statistic 0 Over twothirds 66 of the working geoscientists now have over 20 year s experience 0 Most of these people are going to retire in the next 510 years Who are going to fill these vacant positions Scientific Exploration 0 Science assumes the natural world is consistent and predictable 0 Goal discover patterns in nature and use knowledge to make predictions 0 Collect data through observation and measurementsexperimentation Hypothesis tentative untested explanation Theory welltested widely accepted view that scientific community agrees best explains certain observable facts Algae Blooms Example 0 Blooms of certain plankton called dino agellates may give the water red color and be harmful for people and other marine organisms Upwelling ocean water rich in nutrients causes the plankton to bloom Dino agellate Bloom red tide Example A Natural Phenomenon Red Tide in coastal areas QuestionWhat does cause red tide HypothesisGroundwater discharge in coastal areas ExperimentLab and field experiments Results of ExperimentResults ConclusionsConclusions The Comerstones of the Studv of Earth 0 Plate Tectonics Theory 0 The Rock Cycle 0 Hydrological Cycle 0 Climate change through geological times These theories supported by extensive research are the cornerstones of the study of Earth science and help explain many seemingly unrelated observations Plate Tectonic Theorv The Earth s lithosphere is divided into rigid plates of various sizes that move Plate Tectonics is responsible for most of the features of our planet The Rock Cvcle 0 Relates different types of rocks igneous metamorphic and sedimentary to one another and to the processes which recycle earth materials 0 Provides a way to examine the relationships between internal and external processes 0 Illustrates the different processes and paths as Earth materials change both on the surface and inside the Earth Three Tvpes of Rocks 0 Igneous Rocks basalt granite 0 Sedimentary Rocks limestone conglomerate 0 Metamorphic Rocks gneiss quartzite Plate Tectonics and the Rock Cvcle 0 How are the Rock Cycle and Plate Tectonics related 0 Processes controlled by plate tectonics result in the formation of certain rock types in particular areas The Blue planet 0 30 land 0 70 water Why do we need to know past climate 0 The Earth has experienced climate changes in the past that are similar to recent days 0 Therefore by studying the mechanisms the Earth has used to cope with this changes we can make prediction for the future Lecture 2 Deep Time How Old is Old Chapter 10 What is Geologic Time Geologic time the time of the physical formation and development of the earth Often geologic time is measured in millions 106 or even billions 109 of years and the comprehension of numbers that large is quite different from our daily concept of time Background James Hutton 17261797 Scottish farmer founder of modern geology At that time Earth was thought to be 6000 years old based on scholarly analysis of the Bible Hutton concluded that the processes we see today must also have been going on in the past Sir Charles Lyell 17971875 Lawyer and geologist Published Principles of Geology which really popularized Hutton s ideas Also close in uential friend of Charles Darwin who developed many of the key ideas regarding evolution of life How is Geologic Time measured 0 Relative time age of features is described in relation to one another ie feature A is older than feature B 0 Absolute time age of features is reported by a numerical value ie number of years Relative Time the age of one feature with respect to another When we determine the age we consider the following principles 1 Principle of uniformitarianism 2 Principle of superposition 3 Principle of original horizontality 4 Principle of original continuity 5 Principle of crosscutting relations 6 Principle of inclusions 7 Principle of baked contacts 1Principle of uniformitarianism 0 Physical processes occurring today also operated at comparable rates in the past the present is the key to the past 0 Modern ripple marks 0 Fossil ripple marks 140 million years old 2Principle of superposition 0 In an undeformed sequence of rocks oldest rocks are on the bottom and the youngest are on top 3 Principle of Original Horizontality 0 Sediments settle and accumulate on fairly horizontal surfaces 0 Geologic layers with fold or tilts were deformed after deposition 4 Principle of original continuity 0 Sediments accumulate in continuous layerssheets 0 Any breaks are result of erosion or deformation after deposition 5Principle of crosscutting relations 0 If one geologic feature cuts across another the feature that has been cut is older 6Principle of inclusions Inclusions are pieces of rock enclosed within another rock 0 The fragmentinclusion must be older than the surrounding rock 7 Principle of baked contacts 0 Molten rock magma can heat or bake surrounding rock 0 The baked rock must be older Other evidence fossil succession 0 Fossil species that disappear in certain layer would not reappear in a higher layer e g disappearing extinction is forever 0 Remains of once lived organisms plants and animals Paleontoloav Study of Fossils 0 Aid in interpretation of past environments 0 Important time indicators 0 Correlation matching of rocks of similar ages in different regions Unconformity 0 Definition a break in the rock record resulting from erosion andor nondeposition of rock sediment does not accumulate 1Angular Unconformitv 0 Tilted or folded rocks overlain by atlying rocks 0 Indicates deformation took place some time in between 1 Layers undergo folding 2 Erosion produces a at surface 3 Sea level rises and new layers of sediment accumulate 2 Nonconformitv When rocks that form in very different environments are found next to each other One could not have formed immediately following the other Sandstone amp shale sedimentary Granite igneous Nonconformity 1 A pluton intrudes 2 Erosion clears down to the crystalline rock 3 Sea level rises and new layers of sediment accumulate A pluton is an intrusive igneous rock we ll talk about this type of rock later 3DisconformitV 0 A break in the rock record between similar type rock units Can be hard to spot unless can see evidence of erosion or have some other marker like fossils that make it clear 1 Layers of sediment accumulate 2 Sea level dropsexposure and erosion occurs 3 Sea level rises and new layers of sediment accumulate 0 Grand Canyon 2 billion years of Geologic History 0 The earth is very old46 billion years Absolute numerical age 0 Definition the age of the formations is given in years exact number The method geologist use is called isotopic dating Radioactivity 0 Henry Becquerel Marie Curie and others recognized that some elements that are in the composition of rocks are unstable and breakdown Radioactivity occurs through different types of decay alpha beta and gamma decay Natural Radioactivity Radioactive atomsisotopes decay break down to other elements or isotopes The decaying atomisotope is called parent Ra226 The new formed atomisotope is called daughter Rn222 The rate of decay how fast is called halflife 1712 Ra2261600 yrs it s the time half of the parent s atoms will decay to daughter39s What is an isotope Example uranium U 0 238U uranium23 8 Chemical element uranium 92 in the periodic table Number of protons 92 Number of neutrons 23892146 0 234U uranium234 Chemical element uranium 92 in the periodic table Number of protons 92 Number of neutrons 23492142 0 235U uranium235 Chemical element uranium 92 in the periodic table Number of protons 92 Number of neutrons 23592143 0 Isotopes are atoms of the same chemical element with different number of neutrons Example carbon C 14C radio carbon14 1712 5730 years 0 Chemical element carbon 6 in the periodic table 0 Number of protons 6 0 Number of neutrons 14 68 12C carbon12 stable 0 Chemical element carbon 6 in the periodic table 0 Number of protons 6 0 Number of neutrons 12 66 Carbon14 dating 1So we can calculate how much 14Cpast was in the tree in the past 2We can also measure how much 14Ctodaywe have today 3We know how fast it decays from its halflife 1712 4We can calculate how long does it take to end up with today s 14C Or we can determine how old is the wood we have found Radioactive decay main law NN0exp7tt 7t06931712 N the number of atoms after some time t has passed No the number of atoms we start with at time t0 min Carbon 14 dating calculation t1n14Cpast14Ctoday 9quot Geologic Time Scale Calendar of Earth s historV 0 SubdiVides geologic history 0 Created by assigning absolute dates to relative features
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