EVPP 110 Lecture - Physical Environment - Earth Origin Age Structure - Student - Fall 2010

EVPP 110 Lecture - Physical Environment - Earth Origin Age Structure - Student - Fall 2010

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Unformatted text preview: Physical Environment: Earth Origin, Age & Structure EVPP 110 Lecture Instructor: Dr. Largen 1 Topics brief history of universe & earth earth in context of solar system age of earth early ideas about physical features of earth nature and origin of rocks geologic time/dating rock & fossil record components of earth system structure of earth 2 Brief History of Universe & Earth Universe • Origin Various theories http://www.youtube.c om/watch?v=a8MguIMmCI a8MguIMmCI • Age 13.75 billion years, +/­ 170 million years • 3/1/10, in Astrophysical Journal, using data from Hubble Space Telescope, using technique called gravitational lensing 3 Brief History of Universe & Earth Universe • Size Expanding ~93 billion light years in ~93 diameter diameter • 1 light ≈ 10 trllion km 4 Brief History of Universe & Earth Universe • dynamic adolescence 5 Earth in context of our solar system 6 Earth in context of our solar system Origin of solar system • solar nebula theory • sun Nebula collapsed under its own gravity • Nebula = giant, swirling cloud of gas and dust formed in center of collapsed nebula • planets • temperature & density were high enough for nuclear fusion to begin formed from rest of swirling disk 7 Animation of origin of solar system at http://www.classzone.com/books/earth_science/terc/cont 8 Earth in context of our solar system planets of solar system • grouped as terrestrial Jovian (non-terrestrial) Jovian (non-terrestrial) Pluto = dwarf planet Pluto dwarf 9 Earth in context of our solar system Earth 10 10 Age of the Earth 11 11 Age of the Earth Early ideas • James Ussher (1581-1656) Protestant Archbishop of Armagh (Anglican Primate of All Ireland) volume 4 of his Annals of the World (1650) • Earth was formed on Sunday, October 23, 4004 BC (Julian) 12 12 Age of the Earth Current estimate • ≈4.6 billion years 13 13 iiClicker Question Clicker The current estimate of the age of the earth is ~ • • • • A. 4.6 million years B. 4.6 billion years C. 10 billion years D. 20 billion years 14 14 iClicker Question 2 Is the earth older or younger than the universe? • A. older • B. younger 15 15 Early ideas about Early physical features of the Earth Earth 16 16 Early ideas about physical Early features of the Earth features Early ideas • unchanging 17 17 Early ideas about physical Early features of the Earth features Catastrophism • Earth’s surface is modified only by period, violent disasters • enabled explanation of observations of early geologists within framework of a “young” earth attributed by some to divine origin 18 18 Early ideas about physical Early features of the Earth features fundamental principles of modern geology • principle of superposition • principle of original horizontality • principle of uniformitarianism 19 19 Early ideas about physical Early features of the Earth features Nicolaus Steno (Danish, 1636­1686, anatomist, geologist, and bishop) • Formulated principles of Superposition Original Original Horizontality Horizontality Original Lateral Original Continuity Continuity 20 20 Early ideas about physical features of Early the Earth the principle of superposition Oldest Youngest 21 21 Early ideas about physical features Early of the Earth of principle of original horizontality 22 22 Early ideas about physical features of Early the Earth the principle of original lateral continuity 23 23 Early ideas about physical features of Early the Earth the James Hutton (Scottish, 1726­ 1797) • formulated in 1785 principle of principle uniformitarianism uniformitarianism • "the present is the key to the past“ • processes occurring in the present were the same processes that had operated in the past 24 24 Uniformitarianism Uniformitarianism Present Past (fossilized/lithified/petrified) Ripples in sand at water shore Sand dunes Glacial deposits 25 Uniformitarianism Uniformitarianism Present Past (fossilized/lithified/petrified) Cracked mud Impact crater Alluvial fan (aka river delta) 26 iClicker Question 3 In this diagram of unaltered layers In of sedimentary rock, rock found in layer C would be ____________ than rock found in layer E according to the principle of superposition. superposition. • A. older • B. younger 27 27 iClicker Question 4 According to the principle of original horizontality, According if you discovered rock in which the layers were vertical you would conclude that the layers ______________. ______________. • A. were deposited in this manner and that the rock is A. unaltered unaltered • B. were deposited horizontally and the layers were B. altered (tilted) some time after their formation altered 28 28 Nature and Origin of Nature Rocks Rocks 29 29 Nature and Origin of Rocks mineral • uncombined elements or compounds (made up of different elements) • has a definite atomic structure and chemical composition rock • made up of minerals usually several, but sometimes only one or two 30 30 Nature and Origin of Rocks three basic types •Igneous •Sedimentary •Metamorphic 31 31 Nature and Origin of Rocks Rock cycle 32 32 Animation of sediment deposition at Animation http://www.classzone.com/books/earth_sc http://www.classzone.com/books/earth_sc 33 33 Animation of formation of Animation metamorphic rock at http://www.classzone.com/books/earth_sc http://www.classzone.com/books/earth_sc 34 34 Geologic Time & Dating the Rock & Fossil Record Record 35 35 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil geologic time • expressed as relative time (relative age) absolute time (absolute age) 36 36 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil geologic time • expressed as relative time (relative age) absolute time (absolute age) 37 37 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Determined via evidence from Principle of intrusive relationships Principle of cross-cutting relationships Principle of inclusions Unconformities Principle of faunal succession Geologic correlation 38 38 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Principle of intrusive relationships 39 39 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Principle of cross-cutting relationships 40 40 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Principle of inclusions 41 41 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil Unconformity • surface with very large time loss • types angular unconformity disconformity nonconformity 42 42 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Unconformities angular unconformity • sedimentary over tilted sedimentary folded/ 43 43 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Unconformities disconformity • Sedimentary over eroded sedimentary 44 44 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Unconformities nonconformity • sedimentary over eroded igneous or metamorphic 45 45 Plate tectonics Plate Animation of formation of unconformity Animation boundary at http://www.classzone.com/books/earth_science http://www.classzone.com/books/earth_science Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Principle of faunal succession 47 47 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • Geologic correlation 48 48 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil relative time (relative age) • summary 49 49 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil geologic time • expressed as relative time (relative age) absolute time (absolute age) 50 50 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil absolute time (absolute age) • Role of radioactivity some elements have isotopes some isotopes are • radioactive • version of an element with a different number of neutrons than “normal” (=periodic table) unstable “decay” into other elements by emitting particles and 51 51 energy Geologic Time & Dating the Rock/Fossil Record Record Radioactive isotopes • radioactive decay original radioactive isotope (parent isotope) decays into daughter isotope • rate of decay unique to each radioactive isotope exponential determined by half-life • amount of time it takes for ½ of parent isotope to decay into daughter isotope Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil Radiometric dating • Method for determining the age of an object based on the ratio of the amount of a particular radioactive isotope relative to the amount of its decay products 53 53 Half Lives of Some Radiometric Half Isotopes Isotopes Radioactive isotope Rubidium 87 Thorium 232 Uranium 238 Uranium 235 Carbon 14 ~Half life in Product of years decay 48.6 billion Strontium 87 14.0 billion 4.5 billion 0.7 billion 5730 Lead 208 Lead 206 Lead 207 54 54 Nitrogen 14 Iclicker question 5 Iclicker Half­life is… • A. the amount of time it takes for one half of your life to pass • B. the amount of time it takes for all of a given quantity of radioactive isotope to decay • C. the amount of time it takes for ½ of a given quantity of radioactive isotope to decay Iclicker question 6 Iclicker The larger the half­life, the _________ the amount of time it takes for a radioactive isotope to decay. • A. shorter • B. longer Iclicker question 7 Iclicker Assume you have a radioactive isotope with a half­ life of 1000 years and you start with 600g of the material. How much of the original material will you have after 3000 years? • A. 600g • B. 300g • C. 150g • D. 75g • E. 37.5g Geologic time Eons • largest divisions, 1st is Archean (4.6 to 3.8 billion years ago) • Eras (subdivisions of eons) defined by dominant life forms Periods (divisions of eras) • based on smaller scale changes • Epochs (divisions of periods) based on detailed, smaller scale changes 58 58 Geologic Time & Dating the Geologic Rock/Fossil Record Rock/Fossil Geologic Time Scale Archean Eon (4.6bya­2.5bya) Proterozoic Eon (2.5bya­543mya) Phanerozoic Eon (543mya­present) “interval of well­displayed life” • Paleozoic Era (543mya­251mya) “old life” 8 periods; Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvania, Permian • Mesozoic Era (251mya­65mya) “middle life” 3 periods; Triassic, Jurassic, Cretaceous • Cenozoic Era (65mya­present) “modern life” Paleogene Period (65mya­24mya) • 3 epochs; Paleocene, Eocene, Oligocene Neogene Period (24mya­present) • 4 epochs; Miocene, Pliocene, Pleistocene, Holocene 59 59 Geologic Time 60 60 Components of the Components Earth System - or “Ecosphere” “Ecosphere” 61 61 Components of the Earth Components System System Ecosphere or Earth System Lithosphere Atmosphere Biosphere Hydrosphere 62 62 Animation of spheres at http://www.classzone.com/books/earth_science/terc/cont 63 Components of the Earth System Ecosphere Lithosphere Hydrosphere Hydrosphere Atmosphere Biosphere Ecosphere 64 64 Earth’s Structure 65 65 Earth’s Structure formally described two ways • chemical-based description • mechanical-based description 66 66 Earth’s Structure continental chemical-based description • Crust •Continental •Oceanic • Mantle • Core 67 67 Earth’s Structure Mechanical-based description • Lithosphere • Asthenosphere • Mesosphere • Outer core • Inner core 68 68 Chemical-based description Earth’s Structure Mechanical-based description 69 69 Earth’s Structure Interior of earth • trends in temperature pressure density 70 70 The End 71 71 ...
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This note was uploaded on 01/21/2011 for the course EVPP 110 taught by Professor All during the Winter '08 term at George Mason.

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