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The Changing Earth
Chapter 1: Plate Tectonics
Section 1.1
Earth Has Several Layers
Earth is made up of materials
with different densities.
 Theory: Earth began as a spinning mass of rocks
and dust 5 (16?)...
See Page 10
See Page 11
Earth’s layers have different
properties.
Earth’s Layers
Layer Composition Temperature Thickness
Inner Core solid metals 7...
Continued
 Earth’s crust and the top of the
mantle form the lithosphere.
 The lithosphere sits on a layer of
hotter, sof...
The lithosphere is made up of
many plates.
Continued
 The lithosphere is split into large and
small slabs of rocks called tectonic
plates, which fit together like a...
See Page 13
Section 1.2
Continents Change
Position Over Time.
Continents join together
and split apart.
 Alfred Wegener proposed the theory
of continental drift in early 1900’s
 All ...
Wegner’s theorized that all the continents
were once a single landmass.
See Page 16
Wegner used fossil evidence to support
his continental drift theory.
See Page 15
The theory of plate tectonics
explains how plates and their
continents move.
 Wegener’s theory and sea floor maps
were us...
Continued: Mid Ocean Ridge at Spreading Center
Continued
 Old crust gets pushed aside and the
sea floor slowly spreads apart.
 Earth DOESN’T get larger because
oceanic...
See Page 18
See Page 19
Section 1.3
Plates Move Apart
Tectonic plates have different
boundaries.
 Plate boundary: where the edges of
two plates meet
 Divergent Boundary: occu...
Divergent Boundary
Convergent Boundary
Transform Boundary
The sea floor spreads apart at
divergent boundaries.
 Mid-ocean ridges and rift valleys
occur at divergent boundaries in ...
See Page 23
Continued
 Earth’s magnetic poles have switched
places several times.
See Page 24
These magnetic reversals are caused by changes in Earth’s
magnetic fields. Bands of rock record periods of magnetic
revers...
Continents split apart at
divergent boundaries.
 Divergent boundaries on continents
produce rift valleys.
 Magma rises t...
See Page 26
Hot spots can be used to track
plate movements.
 Hot Spot: an area of volcanic activity
that develops above where magma
r...
The Hawaiian islands are located in the middle
of the Pacific Plate. The largest island, Hawaii,
is still over the hot spo...
When the plate moves on, it carries the first volcano away
from the hot spot. Heat from the mantle plume will then
melt th...
Section 1.4
Plates
Converge or
Scrape
Past Each
Other.
Tectonic plates push together
and form three types of
convergent boundaries.
Continental-
continental collision:
Two conti...
Continued
Oceanic-oceanic subductions: two oceanic
plates collide and the older, denser plate sinks
beneath the top plate,...
Continued
Oceanic-continental subductions: an oceanic
plate sinks beneath a continental plate, forming
a deep-ocean trench...
See Page 32
Tectonic plates scrape past each
other at transform boundaries.
 Two plates move
past each other in
opposite directions.
...
The San Andreas Fault is a transform
boundary and moves about 1 inch per year.
Boundaries are
formed when
tectonic plates
move. The
direction of the
movement
determines the
type of
boundary.
See Page 35
Comparing Boundaries
Divergent *plates move apart *in ocean and on
land *produce mid-ocean ridges, rift
valleys, volcanoes...
The theory of plate tectonics
helps geologists today.
 The plate tectonics
theory enables
geologists to
understand how
Ea...
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Chapter 1 Plate Tectonics Power Point

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Chapter 1 Plate Tectonics Power Point

  1. 1. The Changing Earth Chapter 1: Plate Tectonics
  2. 2. Section 1.1 Earth Has Several Layers
  3. 3. Earth is made up of materials with different densities.  Theory: Earth began as a spinning mass of rocks and dust 5 (16?) billion years ago.  Explosions from comets and asteroids, and pressure of Earth’s gravity, produce enough heat to melt materials inside Earth.  Dense material sank to the Earth’s center, less dense material moved toward the surface, forming Earth’s layers.
  4. 4. See Page 10
  5. 5. See Page 11
  6. 6. Earth’s layers have different properties. Earth’s Layers Layer Composition Temperature Thickness Inner Core solid metals 7000-8000°C 2400 km diameter Outer Core liquid metals 4400-6100 °C 2300 km thick Mantle heated rock 870-4400 °C 2900 km thick Crust Cooler rock 0-700 °C 6-70 km thick
  7. 7. Continued  Earth’s crust and the top of the mantle form the lithosphere.  The lithosphere sits on a layer of hotter, softer rock in the upper mantle called the asthenosphere.
  8. 8. The lithosphere is made up of many plates.
  9. 9. Continued  The lithosphere is split into large and small slabs of rocks called tectonic plates, which fit together like a jigsaw puzzle.  Most large plates contain both continental and oceanic crust.  Tectonic plates provide evidence of continental movement that supports the theory of Pangaea.
  10. 10. See Page 13
  11. 11. Section 1.2 Continents Change Position Over Time.
  12. 12. Continents join together and split apart.  Alfred Wegener proposed the theory of continental drift in early 1900’s  All continents were once joined and gradually moved apart (still moving).  Fossils, studies of ancient climates, and rock formations provide evidence.  Africa and Brazil have matching rock formations indicating they were once joined.
  13. 13. Wegner’s theorized that all the continents were once a single landmass. See Page 16
  14. 14. Wegner used fossil evidence to support his continental drift theory. See Page 15
  15. 15. The theory of plate tectonics explains how plates and their continents move.  Wegener’s theory and sea floor maps were used to develop the theory of plate tectonics.  Along spreading centers in the sea floor, melted rock rises through cracks, cools, and forms new crust that builds up mid-ocean ridges.
  16. 16. Continued: Mid Ocean Ridge at Spreading Center
  17. 17. Continued  Old crust gets pushed aside and the sea floor slowly spreads apart.  Earth DOESN’T get larger because oceanic crust is destroyed along deep-ocean trenches, where the oceanic plates sink into the asthenosphere.
  18. 18. See Page 18
  19. 19. See Page 19
  20. 20. Section 1.3 Plates Move Apart
  21. 21. Tectonic plates have different boundaries.  Plate boundary: where the edges of two plates meet  Divergent Boundary: occurs where plates move apart, usually found in the ocean  Convergent Boundary: occurs when plates push together.  Transform Boundary: occur when plates scrape past each other.
  22. 22. Divergent Boundary Convergent Boundary Transform Boundary
  23. 23. The sea floor spreads apart at divergent boundaries.  Mid-ocean ridges and rift valleys occur at divergent boundaries in the ocean.  Mid-ocean ridges form the longest mountain ranges on earth.  Most contain a rift valley along their center.
  24. 24. See Page 23
  25. 25. Continued  Earth’s magnetic poles have switched places several times. See Page 24
  26. 26. These magnetic reversals are caused by changes in Earth’s magnetic fields. Bands of rock record periods of magnetic reversals. As molten material cools, magnetic minerals line up with the magnetic field. When it hardens, the minerals act like tiny compass needles. See Page 24
  27. 27. Continents split apart at divergent boundaries.  Divergent boundaries on continents produce rift valleys.  Magma rises through cracks and forms volcanoes.  As rift valleys grow wider, continents split apart.  If the valley continues to widen, the thinned floor sinks below sea level.  It may fill with water to form a sea or lake.
  28. 28. See Page 26
  29. 29. Hot spots can be used to track plate movements.  Hot Spot: an area of volcanic activity that develops above where magma rises in a plume from the mantle.  Can be used to measure plate movement because it generally stays in one place as the tectonic plate above it moves.  Can provide a fixed point for measuring the speed and direction of plate movements.
  30. 30. The Hawaiian islands are located in the middle of the Pacific Plate. The largest island, Hawaii, is still over the hot spot.
  31. 31. When the plate moves on, it carries the first volcano away from the hot spot. Heat from the mantle plume will then melt the rock at a new site, forming a new volcano. See Page 28
  32. 32. Section 1.4 Plates Converge or Scrape Past Each Other.
  33. 33. Tectonic plates push together and form three types of convergent boundaries. Continental- continental collision: Two continental plates collide, crumpling and folding the rock between them. Mountains could form.
  34. 34. Continued Oceanic-oceanic subductions: two oceanic plates collide and the older, denser plate sinks beneath the top plate, forming deep-ocean trenches and island arcs.
  35. 35. Continued Oceanic-continental subductions: an oceanic plate sinks beneath a continental plate, forming a deep-ocean trench and volcanic coastal mountains.
  36. 36. See Page 32
  37. 37. Tectonic plates scrape past each other at transform boundaries.  Two plates move past each other in opposite directions.  No crust is formed or destroyed.  Occurs on the sea floor and on land.
  38. 38. The San Andreas Fault is a transform boundary and moves about 1 inch per year.
  39. 39. Boundaries are formed when tectonic plates move. The direction of the movement determines the type of boundary. See Page 35
  40. 40. Comparing Boundaries Divergent *plates move apart *in ocean and on land *produce mid-ocean ridges, rift valleys, volcanoes, earthquakes Transform *plates move past each other in opposite directions *in ocean and on land Convergent C-C Collision *crumples and folds crust * produces mountains, earthquakes Convergent O-O Subduction *older, denser plate sinks *produce deep-ocean trenches, island arcs Convergent O-C Subduction *oceanic plate sinks under continental plate * forms deep-ocean trench, volcanic coastal mountains
  41. 41. The theory of plate tectonics helps geologists today.  The plate tectonics theory enables geologists to understand how Earth’s continents and ocean basins formed.  Helps scientists predict earthquakes and volcanic activity.

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