GeographyGeography
Plate tectonicsPlate tectonics
Why have all the mountains not
worn away by now?
Earth StructureEarth Structure
• Radius 6300-6400km
• Thin crust
• Mantle extends
almost halfway to the
centre
• The core ...
CompositionComposition
• Low density solid crust
floating on an almost
solid mantle
• But overall the Earth is
dense
• The...
Rock CycleRock Cycle
• Weathering breaks down the rocks
• Erosion wears them into smaller pieces as they are
transported t...
Deposition of sedimentsDeposition of sediments
• Most sediments settle
in water
• Currents and waves
form ripple marks
• E...
Sedimentary rocksSedimentary rocks
• Grand Canyon
• Youngest rocks at the
top
• Rocks and fossils
older as you go down
Unstable EarthUnstable Earth
• The Earths crust is
subjected to huge
forces
• Very large forces can
fracture the rock
• Th...
Tilted and FoldedTilted and Folded
• Sedimentary rocks
are often found tilted
• They can also be
folded by the huge
forces...
Alfred WegenerAlfred Wegener
• Some people thought the
Earth was shrinking and
cracking
• Wegener thought whole
sections o...
Tectonic platesTectonic plates
EvidenceEvidence
• Same fossils and
rocks found in
different parts of the
world
• Africa and South
America look like
piece...
EarthquakesEarthquakes
• Plates moving in any
direction causes
earthquakes
• The worst are caused
by plates rubbing past
e...
Sea floor spreadingSea floor spreading
• Large continents
begin to crack and
split apart
• The gaps fill with
water
• Smal...
Why spread?Why spread?
• Why is the Atlantic still
getting wider
• The plates are pulled
apart by convection
currents in t...
More evidenceMore evidence
• More evidence has
been found for
Wegeners theory
• The Earths North and
South pole have
flipp...
So the Earth must be growing?So the Earth must be growing?
• Dense heavy oceanic
crust can be subducted
below less denser
...
Continents CollideContinents Collide
• Eventually when plates
move together the
continental crust collides
• The heat and ...
Upcoming SlideShare
Loading in...5
×

Plate tectonics gcse geography

1,669

Published on

gcse geography revision.

Published in: Education, Technology, Spiritual
0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,669
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
34
Comments
0
Likes
4
Embeds 0
No embeds

No notes for slide

Plate tectonics gcse geography

  1. 1. GeographyGeography Plate tectonicsPlate tectonics Why have all the mountains not worn away by now?
  2. 2. Earth StructureEarth Structure • Radius 6300-6400km • Thin crust • Mantle extends almost halfway to the centre • The core makes up the rest
  3. 3. CompositionComposition • Low density solid crust floating on an almost solid mantle • But overall the Earth is dense • The core must be very dense • Probably made of dense metals nickel and iron • Hot liquid outer core and solid inner core
  4. 4. Rock CycleRock Cycle • Weathering breaks down the rocks • Erosion wears them into smaller pieces as they are transported towards the sea
  5. 5. Deposition of sedimentsDeposition of sediments • Most sediments settle in water • Currents and waves form ripple marks • Evidence can be found for this in the rock • Ripple marks can be preserved in the rock
  6. 6. Sedimentary rocksSedimentary rocks • Grand Canyon • Youngest rocks at the top • Rocks and fossils older as you go down
  7. 7. Unstable EarthUnstable Earth • The Earths crust is subjected to huge forces • Very large forces can fracture the rock • This can be seen as fault lines in the rock layers
  8. 8. Tilted and FoldedTilted and Folded • Sedimentary rocks are often found tilted • They can also be folded by the huge forces • This has happened at Lulworth cove • Sometimes the rock layers can even be turned upside down
  9. 9. Alfred WegenerAlfred Wegener • Some people thought the Earth was shrinking and cracking • Wegener thought whole sections of the crust moved (plate tectonics) • Some people did not understand and thought the continents floated around in the oceans (continental drift) • He died before people accepted his ideas
  10. 10. Tectonic platesTectonic plates
  11. 11. EvidenceEvidence • Same fossils and rocks found in different parts of the world • Africa and South America look like pieces of a jigsaw
  12. 12. EarthquakesEarthquakes • Plates moving in any direction causes earthquakes • The worst are caused by plates rubbing past each other as in C • This happens along the Californian coast
  13. 13. Sea floor spreadingSea floor spreading • Large continents begin to crack and split apart • The gaps fill with water • Small seas become oceans • The mid ocean ridge continues to produce new crust
  14. 14. Why spread?Why spread? • Why is the Atlantic still getting wider • The plates are pulled apart by convection currents in the mantle below • Caused by heat released from natural radioactive processes • At the mid Atlantic ridge molten rock from below rises up to fill the gap with new basaltic rock
  15. 15. More evidenceMore evidence • More evidence has been found for Wegeners theory • The Earths North and South pole have flipped many times • These leaves magnetic ‘stripes’ in rock containing iron minerals
  16. 16. So the Earth must be growing?So the Earth must be growing? • Dense heavy oceanic crust can be subducted below less denser continental crust. • The friction melts rock • This magma rises through the crust to form new volcanoes • This is happening in South America (The Andes)
  17. 17. Continents CollideContinents Collide • Eventually when plates move together the continental crust collides • The heat and pressure make metamorphic rock • It also pushes and folds the rocks into high mountains • The Himalayas rise to 8848m and are still growing today

×