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Introduction to Physical Geology

Introduction to Physical Geology. Earth. We live on a very active planet. Five things make our planet unique: It resides in the “Goldilocks Zone” H 2 O in all three phases Large moon-to-planet ratio Plate Tectonics Life. Summary of EQ events 2011/06/06 .

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Introduction to Physical Geology

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  1. Introduction to Physical Geology

  2. Earth • We live on a very active planet. • Five things make our planet unique: • It resides in the “Goldilocks Zone” • H2O in all three phases • Large moon-to-planet ratio • Plate Tectonics • Life

  3. Summary of EQ events 2011/06/06 4.9  2011/06/06 18:52:26   37.560   143.659 51.3  OFF THE EAST COAST OF HONSHU, JAPANMAP 2.6  2011/06/06 15:33:48   51.653  -178.306 50.0  ANDREANOF ISLANDS, ALEUTIAN IS., ALASKAMAP 3.0  2011/06/06 13:58:54   19.153   -65.192 47.0  PUERTO RICO REGIONMAP 2.7  2011/06/06 13:28:42   34.897  -120.396 2.3  CENTRAL CALIFORNIAMAP 4.4  2011/06/06 12:17:46  -15.133  -178.097 398.2  FIJI REGIONMAP 3.0  2011/06/06 09:49:35   18.956   -67.360 8.0  PUERTO RICO REGIONMAP 3.0  2011/06/06 08:45:00   18.167   -64.473 105.6  VIRGIN ISLANDS REGIONMAP 4.7  2011/06/06 07:50:20   36.318   142.609 20.1  OFF THE EAST COAST OF HONSHU, JAPANMAP 2.7  2011/06/06 07:40:37   18.723   -67.262 8.3  PUERTO RICO REGIONMAP 3.4  2011/06/06 07:09:11   33.915  -118.274 25.0  GREATER LOS ANGELES AREA, CALIFORNIAMAP 3.1  2011/06/06 07:00:42   19.076   -67.549 48.0  PUERTO RICO REGIONMAP 2.7  2011/06/06 06:31:58   18.888   -64.580 5.8  VIRGIN ISLANDS REGIONMAP 3.3  2011/06/06 05:24:50   40.400  -107.055 4.9  COLORADOMAP 4.8  2011/06/06 03:00:07   38.364   142.153 33.4  NEAR THE EAST COAST OF HONSHU, JAPANMAP 3.2  2011/06/06 02:48:39   19.634   -64.672 49.8  VIRGIN ISLANDS REGIONMAP 2.7  2011/06/06 02:35:16   47.760  -122.360 29.8  SEATTLE-TACOMA URBAN AREA, WASHINGTONMAP 3.4  2011/06/06 01:49:47   18.275   -68.917 29.3  DOMINICAN REPUBLIC REGIONMAP 4.8  2011/06/06 00:46:48   39.923   142.977 44.6  NEAR THE EAST COAST OF HONSHU, JAPANMAP 2.5  2011/06/06 00:31:32   17.661   -66.829 34.1  PUERTO RICO REGION

  4. 7-day summary of EQ eventsMagnitude > 4.5

  5. EQ swarm at Yellowstone Nat’l Park 2009

  6. EQ swarm at Yellowstone Nat’l Park2009 • As of January 8, 2009, the seismic activity has markedly decreased It is possible that the swarm has ended, although a return of activity may occur as previous Yellowstone swarms of this size have lasted for tens of days to many weeks. Swarms are common at Yellowstone. The last notable swarm occurred in 2004. • About 900 earthquakes occurred between Dec. 26, 2008 and Jan. 8, 2009 in the Yellowstone Lake area. There were 111 earthquakes with magnitudes greater than 2.0 (> M2.0) and 18 earthquakes > M3.0. The largest earthquake during the swarm was a magnitude 3.9 on Sunday, December 28, 2008. • Depths for shallow earthquake hypocenters are difficult to determine accurately unless the seismic stations are spaced much more closely than those in the Yellowstone Seismic Network. The best located earthquakes have hypocenters (depths) of 3 to 10 km (1.8 to 6.0 miles). From Dec. 26 through Jan 2, the hypocenters appear to have migrated northwards, starting southeast of near Stevenson Island, with many of the latest events occurring near Fishing Bridge.

  7. Physical Geology Definition : Geology – the scientific study of the Earth’s processes and materials.

  8. Why study geology? • Understand the natural world around us • Economic ore deposits • Location, quantity, quality, accessibility • Understand and predict catastrophic events • Where, when, why, mitigation, risk analysis • Where and how to build safe structures • Trace and catalog our historic past • Predict and interpret geologic processes on other planets

  9. Scientific Method • Begin with a question : • How did the Grand Canyon form? • Collect data, take measurements, describe and record phenomena, compile lab results : • Flow rates, stream capacity (load), geomorphic interpretation, elevation, fault movement, etc. • Propose a hypothesis : a logical but preliminary explanation that fits the data collected and may account for future findings : • Colorado River cut G.C. during uplift phase of C.P. •  Test, report, examine, change •  Theory : proven over time and accepted by peer review • Law : undeniable – gravity

  10. Origin of the Solar System • Nebula collapse • Existence of early (~5bya) nebula in Milky Way galaxy • Compositional segregation • Denser, hotter materials (Fe, Ni) in inner zone • Lighter, colder materials (H, He) in outer zone • Planetary accretion • Inner rocky planets (Mercury, Venus, Earth, Mars) • Iron, Nickel, silicate minerals (oxygen and silicon) • Outer gas bags (Jupiter, Saturn, Uranus, Neptune) • Present solar system

  11. Eagle Nebula Pillars These pillars composed of dusts & gasses are a “nursery” for star formation. New proto-stars are beginning to form at the apex of the stubby fingers found near the top of the pillars proper.

  12. Origin of the Solar System • Collapse of nebular cloud • Rotation and flattening of • circumstellar disk • Formation of Protostar • Accretion of material into • planetesimals, protoplanets, • planets and moons

  13. Development of the Earth • Differentiation • The separation of material through differences in density • Atmosphere/Hydrosphere/Biosphere • The outer lightest gases and liquids • Crust - Thin outer layer composed mostly of Si and O (silicate) rocks • Mantle - Thicker layer dominated by silicates but including heavier elements such as Fe and Mg • Layers based not on composition but strength • Lithosphere – crust and upper mantle composing strong, rocky layer • Asthenosphere – heat-softened, slow-flowing layer of still “solid” rock • Core - Small inner-most layer composed of Fe and Ni • Outer core is liquid – responsible for the Earth’s magnetic field • Inner core is solid

  14. Layered structure of the Earth

  15. Definitions • Element – smallest form of matter that cannot be broken down further by heating, cooling or chemical reactions • Mineral – naturally occurring solids consisting of one or more elements in specific proportions • Rock – naturally occurring solid composed of one or more minerals

  16. Rock Cycle(Figure 1.23) • Any type of preexisting rock can be transformed in to any other type • Igneous • Formed by the cooling and solidification of molten material at or below the Earth’s surface • Sedimentary • Formed by the erosion and breakdown of preexisting rocks • Metamorphic • Formed by compositional and textural changes caused by heat and/or pressure or chemical reactions

  17. Rock Cycle(Figure 1.23)

  18. Geologic Time Scale(Figure 1.8) • Cenozoic • 66mya – present • Includes the appearance of modern humans • Begins at time of extinction of the dinosaurs • Mesozoic • 245 – 66mya • Age of dinosaurs • First flowering plants • Appearance of mammals • Paleozoic • 545-245mya • Appearance of reptiles • Appearance of fish • Precambrian • 4.6bya-545mya • Simplest plant and animal life

  19. Geologic Time Scale(Figure 1.8)

  20. Geological Concepts • Catastrophism – the hypothesis that the Earth evolved through a series of sudden and violent upheavals •  Uniformitarianism - • James Hutton Scottish naturalist in 18th century • Proposed that the processes we see today can be used to interpret the rock record of past geological events • (“present is the key to the past”) • These are small, physical, chemical and biological processes working slowly over time and resulting in the world we see today

  21. Geological Concepts • Superposition/Horizontality – youngest or most recently deposited units are at the top / older previously deposited units are at the bottom • Crosscutting relationships – the cutting surface is younger than the cut surface • Inclusions – what is included within on material is older than the material itself • Fossil Succession – the progression of life • Simple to complex organisms • Once gone from fossil record, never returns

  22. Geological Concepts(continued) • Age Dating • Relative – events and/or products are placed in their proper sequence (space/time orientation) w/out knowing more precise age in years • Geochemical/Radiometric – uses knowledge of radioactive decay to more precisely assign age in years

  23. Geological Concepts(continued) • Plate Tectonics – • 1) Alfred Wegener – continental drift • 2) The upper crust and mantle (Lithosphere) are composed of rigid plates (7 major and 8 minor) • 3)      The plates move slowly relative to each other (centimeters/yr) • 4)      Most of Earth’s large-scale activity (earthquakes, volcanoes, etc) occurs along plate boundaries • 5)      The plate interiors are generally quiet.

  24. Continental DriftBreak-up of Pangaea during the last ~230my

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