Dynamic Earth
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Dynamic Earth






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Dynamic Earth Dynamic Earth Presentation Transcript

  • The Earth’s Interior
  • The Earth’s Interior
    • Four Layers (see page 10 of Ref Tables)
    • Inner Core : solid, dense, 6,000 º C, Iron and Nickel
    • Outer Core : Liquid, dense, 3,700º-5,500ºC (increases with depth), Iron and Nickel
    • Mantle : Solid, minerals rich in Fe, Si, Ma, 1,500º - 3,200º C
    • Crust : upper layer, rigid, lighter rock, <1,000ºC
  • The Earth’s Interior
    • Some terms to know:
    • Asthenosphere : Upper layer of the mantle, may act in a semi-fluid (plastic) manner
    • Moho (Mohorovicic Discontinuity): The boundary between the mantle and the crust
    • Lithosphere : Consists of the crust and the rigid upper mantle
  • The Earth’s Interior
    • Where is the crust thickest?
    • Mountain Ranges.
    • Where is the crust thinnest?
    • The Ocean Floor.
  • The Earth’s Interior
    • Why is the core so hot?
    • Still retains heat from original formation.
    • Radioactive materials releasing energy as they decay.
    • Increased pressure from above.
  • The Earth’s Interior
    • What happens to rock density, going from the crust to the core?
    • It increases.
    • What happens to temperature, going from the crust to the core?
    • It increases.
    • What happens to pressure, going from the crust to the core?
    • It increases.
  • Continental Drift and the Origin of Plate Tectonics
  • Wegener’s Map showing the breakup of Pangea See Reference Table Page 9
  • Note how they fit together
  • I.The Theory of Plate Tectonics :
    • The Earth’s lithosphere is made of a number of solid pieces, called __________ which move in relation to each other.
  • These plates are “riding”on a more “plastic molten” layer below These plates are “riding”on a more “plastic molten” layer below
  • This plastic molten layer of magma is called the: asthenosphere
    • 1. Theory of Continental Drift
    • Proposed by _______ ________ in 1915. It stated that the earth’s continents separated and collided as they have moved over the surface of the Earth for millions of years.
    Alfred Wegener
  • Alfred Wegener (1880-1930) Geographer and Polar Explorer
    • B. Wegener’s evidence for his
    • his theory:
    • 1. When you line up __________
    • and _________
    • they fit like a puzzle.
    S.America Africa
  • 2. __________ species have been found on widely separated parts of the earth. Fossil
  • 3. Permian fossils are very similar in widely separated continents
  • Cynognathus
  • Lystrosaurus
    • Mt. Sirus
    • Antarctica
    • Lystrosaurus beds
  • Mesosaurus
  • 3. _____________ and ______________ have a good match of ancient continental rocks and tectonic _________ and _________ structures. S. America Africa fault fold
  • 4. Some mountain chains appear to be continuous from ____________ to______________ continent continent
  • 5. Evidence of _________ climates different from present. ancient Ex . Finding coal beds which indicate tropical climates
  • Technology developed during WWII
    • Sonar - image the deep ocean using reflected sound.
    • Magnetometer - detect faint magnetic fields.
    • Developed to search for U-boats
  • World War II Submarine warfare
  • Harry Hess
    • Geologist at Princeton U.
    • 1962 publishes “geopoetry.”
    • Sea floor spreading hypothesis.
    • Suggested that the ocean floor itself might be moving.
  • Cold War Nuclear Submarines
    • SSN Nautilus
    • 1st nuclear powered submarine
  • Mid-ocean ridge
  • 6 . Rocks of the ocean basins are _________ than continental rocks. younger
  • II. Ocean Floor Spreading:
    • Further evidence of horizontal movement of earth’s crust:
    • A. The ocean floor has a system of submerged mountain ranges called ______________________
    Mid-Ocean Ridges
  • Material from deep within the earth comes to the surface at the ___________________ where it spreads apart to make ________________. Ocean ridges New ocean crust
  • Sea floor spreading
  • B. The two major pieces of evidence are: Age of igneous ocean material 1. 2. Reversal of magnetic polarity
  • When rock hardened it kept the alignment forming a permanent record of the ___________________ of the earth at that time. Magnetic field
  • N S
  • N S
  • N S Magnetic polarity reversal
  • Rocks found farther from the ridges have a _____________ magnetic polarity. Parallel stripes of ________________ on either side of these ridges preserve the record of many ____________ of the earth’s magnetic field. reversed magnetism reversals
  • Measuring the Age of the Ocean Floor
    • 1968, establishment of the Deep Sea Drilling Project (DSDP).
    • Specially outfitted ship for drilling into the ocean floor and retrieving rock samples.
    • Sediment layers and igneous rock dated to reveal the age of the ocean floor in different places.
  • Deep Sea Drilling Project ship - Glomar Challenger
  • C. The _______ _________ (basaltic) igneous rocks of the crust near the ocean ridges are covered with a thin layer of ____________. dark dense sediment
  • This is evidence that the earth’s crust is very ___________ near the ridges. young
  • The oldest parts of the ocean crust are found far from the ___________ ridges and near the _______________ ocean continents
  • Acceptance of Sea Floor Spreading (Plate Tectonics)
    • 1970’s - rapid confirmation of remaining predictions and acceptance of the basic theory by most geologists.
    • 1980’s - Plate Tectonics becomes the dominant paradigm in geology.
    • 1990’s - Development of a detailed plate tectonic history of the last 700 million years.
    • Lesson 2
  • Lithospheric Plates ___________ in size and are made up of a combination of ___________ crust and ______________ crust vary oceanic continental
  • Three kinds of plate motion occur at plate boundaries:
    • 1. _____________________
    • 2. _____________________
    • 3. _____________________
    convergent divergent transform
  • Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo. (Photograph by Robert E. Wallace, USGS.)
      • 1a.When ocean collides with continent the_________ ocean plate dives down under or ____________ into the mantle forming a
      • ___________________
    denser subducts Subduction zone
  • Oceanic-Continental Convergence Ex. Andes in S.America
  • 1b.When two ocean plates converge the _______ ___________ocean plate will __________ forming an ____________ ________ older subduct island arc denser
  • Oceanic-Oceanic Convergence Ex. Indonesia, Phillippines,Japan & Aleutians
    • Called SUBDUCTION
    Continent-Oceanic Crust Collision
  • 1c.When two continental plates converge the edges of _______ are crumpled up forming _________ ________________ both mountains folded
  • Continental-Continental Convergence Ex. Himalayas
  • Himalayas
  • 2.At ____________ plate boundaries, the plates move ___________ and ________ flows up forming parallel ridges made of _______ __________ __________ divergent magma new igneous apart rock
  • Divergent Plate Boundary Ex. Mid-Atlantic Ridge
    • Iceland has a divergent plate boundary running through its middle
    Iceland: An example of continental rifting
  • 3. At ____________ plate boundaries, the plates move ________ each other causing shallow _____________ _______________ transform earth past quakes
  • Transform Plate Boundary Ex. San Andreas Fault of California
  • These plates are “riding”on a more “plastic molten” layer below III. MANTLE CONVECTION CELLS:
  • The evidence shows that approximately _______ million years ago, the major continents were _______________ 200 connected
  • And since that time they have been __ _________ separating
  • A convection cell is a stream of heated material that is moving because of _________ DENSITY DIFFERENCES
  • These convection cells exist in part of the mantle called the _______________ ASTHENOSPHERE
  • asthenosphere
  • The two sources of this heat are: 1. 2. Residual (leftover) heat from the formation of the Earth Heat generated from radioactive decay from the core of the earth
  • Hot Spots:
    • Places on the Earth’s surface where plumes of __________ are rising up from the mantle not located along ________ _________ ________
    magma active Plate boundaries
  • As a plate passes over a hot spot, a _______________ _______________ forms CHAIN OF VOLCANIC MOUNTAINS
  • The tectonic plate moves over a fixed hotspot forming a chain of volcanoes. The volcanoes get younger from one end to the other.
  • The only mountain that _______ ________ is the mountain located directly over the _____ ______ remains active hot spot