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PLATE TECTONICS

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PLATE TECTONICS AND CONTINENTAL DRIFT GEOLOGY Geology is the science and study of the solid Earth and the processes by which it is shaped and changed. – PowerPoint PPT presentation

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Title: PLATE TECTONICS


1
  • PLATE TECTONICS
  • AND
  • CONTINENTAL DRIFT

2
GEOLOGY
  • Geology is the science and study of the solid
    Earth and the processes by which it is shaped and
    changed.
  • Geologists are scientists who study the forces
    that make and shape the planet Earth.

3
Theory of continental drift
  • Alfred Wegener first proposed the theory of
    continental drift in 1912.
  • Continental drift is Wegeners theory that all
    continents had once been joined together in a
    single landmass and have drifted apart since.
  • Wegener named this supercontinent Pangaea.
  • Wegeners theory was rejected by scientists
    because he could not explain what force pushes
    or pulls continents.

4
PANGEA
5
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6
Evidence to support continental drift theory
  • Sequence of Rocks
  • Same rock patterns found in South America, India,
    Africa, Antarctica and Australia
  • Ancient Climates
  • Tropical plant remains found in Antarctica
  • Glaciations in Africa, South America, India, and
    Australia during the same time

7
Evidence to support continental drift theory
  • Distribution of Fossils
  • Plant and animal fossils found on the coastlines
    of different continents
  • Puzzle Pieces
  • Continents look like they could be part of a
    giant jigsaw puzzle

8
Sea-Floor Spreading
  • In the early 1960s, Princeton geologist Harry
    Hess proposed the hypothesis of sea-floor
    spreading, in which magma from the mantle rises
    to create new ocean floor at mid-ocean ridges.
  • The mid-ocean ridge is the longest chain of
    mountains found deep below the oceans surface .

9
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10
SUBDUCTION
  • The ocean floor plunges into deep underwater
    canyons called deep-ocean trenches.
  • Subduction takes place in deep-ocean trenches.
  • Subduction is the process by which the ocean
    floor sinks beneath a deep-ocean trench and back
    into the mantle.

11
PLATE TECTONICS
  • The Earths crust is divided into 12-13 major
    plates which are moved in various directions.

12
Plate Movement
  • Plates of lithosphere are moved around by the
    underlying hot mantle convection cells

13
3 types of plate boundaries
  • Divergent
  • Convergent
  • Transform

14
DIVERGENT BOUNDARY
  • At divergent boundaries, two plates move apart
    from each other and the space that this creates
    is filled with new crustal material sourced from
    molten magma that forms below.

15
CONVERGENT BOUNDARY
  • A tectonic boundary where two plates are moving
    toward each other. If the two plates are of equal
    density, they usually push up against each other,
    forming a mountain chain. If they are of unequal
    density, one plate usually sinks beneath the
    other in a subduction zone.

16
There are 3 types of convergent plate boundaries
  • Continent Continent When two continents meet
    head-on, neither is subducted because the
    continental rocks are relatively light. (forms
    mountains)
  • Ocean Continent When an oceanic plate pushes
    into and subducts under a continental plate (
    creates volcanoes)
  • Ocean Ocean When two oceanic plates converge
    one is usually subducted under the other. (forms
    trenches)

17
Oceanic-continental
  • Continental-continental
  • Oceanic-oceanic

18
TRANSFORM FAULT BOUNDARY
  • Transform Plate Boundaries are locations where
    two plates slide past one another. The fracture
    zone that forms a transform plate boundary is
    known as a transform fault.

19
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