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BELLWORK

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BELLWORK Name the 3 types of plate boundaries and an example of each. Uplift and Subsidence Uplift is the rising of regions of the Earth s crust to higher elevations. – PowerPoint PPT presentation

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Title: BELLWORK


1
BELLWORK
  • Name the 3 types of plate boundaries and an
    example of each.

2
Deforming the Earths Crust
3
Moving Continents
  • http//www.suu.edu/faculty/colberg/hazards/platete
    ctonics/18_Pangaea.html

4
Tracking Tectonic Plates
Scientists use GPS to track plate movement. Radio
waves are beamed from satellites to GPS ground
stations which record their position.
5
3 Possible Driving Forces
  • Convection Currents
  • Ridge Push and Slab Pull
  • Ridge Push At mid-ocean ridges, the oceanic
    lithosphere is higher than it is where it sinks
    into the asthenosphere. Because of ridge push,
    the oceanic lithosphere slides downhill under the
    force of gravity.
  • Slab Pull Because oceanic lithosphere is denser
    than the asthenosphere, the edge of the tectonic
    plate that contains oceanic lithosphere sinks and
    pulls the rest of the tectonic plate with it in a
    process called slab pull.

6
  • Plate movement causes geological events such as
    mountain formation, volcanic eruptions, and
    earthquakes.

7
Deformation
  • The process by which the shape of a rock changes
    because of stress.
  • Stress is the amount of force per unit area on a
    given material.
  • Different things happen to rock when different
    types of stress are applied.
  • Rock layers bend when stress is placed on them.
  • When enough stress is placed on rocks, they can
    reach their elastic limit and break.

8
Compression
  • The type of stress that occurs when an object is
    squeezed, such as when two tectonic plates
    collide.
  • When compression occurs at a convergent boundary,
    large mountain ranges can form.

9
Tension
  • Stress that occurs when forces act to stretch an
    object
  • Tension occurs at divergent plate boundaries,
    such as mid-ocean ridges, when two tectonic
    plates pull away from each other.

10
Folding
  • The bending of rock layers because of stress in
    the Earths crust.
  • Types of Folds depends on how the rock layers
    deform
  • Anticlines
  • Synclines
  • Monoclines

11
Anticline
  • Upward-arching folds.
  • Caused by horizontal stress.

12
Syncline
  • Downward, troughlike folds.
  • Caused by horizontal stress.

13
Monocline
  • Fold where both ends are horizontal.
  • Cause by vertical stress.

14
Faulting
  • The surface along which rocks break and slide
    past each other.
  • Some rock layers break when stress is applied
  • The blocks of crust on each side of the fault are
    called fault blocks.

15
Footwall Hanging Wall
  • When a fault is not vertical, its two sides are
    either a hanging wall or a footwall.

16
Normal Fault
  • When a normal fault moves, it causes the hanging
    wall to move down relative to the footwall.
  • Caused by rocks being pulled apart (tension).

17
Normal Fault
18
Reverse Fault
  • When a reverse fault moves, it causes the hanging
    wall to move up relative to the footwall.
  • Caused when rocks are pushed together
    (compression).

19
Reverse Fault
20
Strike-Slip Fault
  • When opposing forces cause rock to break and move
    horizontally.

21
Mountain Building
  • When tectonic plates undergo compression or
    tension, they can form mountain ranges in several
    ways.

22
Folded Mountains
  • The highest mountains in the world are formed
    when rock layers are squeezed together and pushed
    upwards to form folds.
  • This occurs at convergent
  • boundaries where plates collide.
  • The plates buckle and thicken.
  • The continental crust is pushed
  • upward, forming mountains.

23
Examples of Folded Mountains
  • Himalayas

24
  • Alps
  • In central
  • Europe

25
  • Ural Mountains
  • in Russia

26
  • Great Smoky Mountains

27
Fault-Block Mountains
  • Form when large blocks of the Earths crust drop
    down relative to other blocks.
  • Tension produces mountains that have sharp,
    jagged peaks.

28
Examples of Fault-Block Mountains
  • Teton Range in Wyoming.

29
  • Sierra Nevada mountain range in California

30
  • Harz Mountains in Germany

31
Volcanic Mountains
  • Form when magma rises to the Earths surface and
    erupts.

32
Examples of Volcanic Mountains
  • Mount St. Helens in Washington

33
  • Mount Pinatubo in the Phillipines

34
Uplift and Subsidence
  • Uplift is the rising of regions of the Earths
    crust to higher elevations.
  • Rebound When the crust slowing springs back to
    its previous elevation, as when a glacier melts.
  • Subsidence is the sinking of regions of the
    Earths crust to lower elevations.
  • Rocks that are hot take up more space than cooler
    rocks.

35
Tectonic Letdown
  • Subsidence can also occur when the lithosphere
    becomes stretched in rift zones.

36
Quiz
  1. Name the 3 types of faults.
  2. Name the 3 types of folds.
  3. What is compression?
  4. What is tension?
  5. Would you find a folded mountain at a mid-ocean
    ridge? Why or why not?
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