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