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1.0 Processes within Earth’s crust cause natural events. Plate Tectonics. Earth’s plates. Facts. Rocks that form the plates under the continents are lighter than those found under the ocean The ocean floor is made up of ridges (mountains) and trenches (valleys). Theory of Plate Tectonics. - PowerPoint PPT Presentation
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PLATE TECTONICS1.0 Processes within Earth’s crust cause natural events
Earth’s plates
Facts
Rocks that form the plates under the continents are lighter than those found under the ocean
The ocean floor is made up of ridges (mountains) and trenches (valleys)
Theory of Plate Tectonics
The lithosphere (crust + mantle) are made up of large areas called plates Earthquakes and volcanoes tend to more
common where plates meet
Convection and Earth’s plates What makes the Earth’s plates
move? CONVECTION
Where would the required heat come from??
What happens when they meet? Edges of the plates are called
‘boundaries’ Diverging Boundary
When plates are moving apart. At these boundaries lava flows from the ridge and forms new crust Sometimes these are big enough to be
seen from the ocean’s surface, like those that formed Iceland
Converging boundary Plates come together This causes earthquakes and volcanoes
or mountains typically form nearby and trenches form at the boundary
Another kind is where the plates crush together to form mountain ranges (SK mountains 1.8 b.y.a)
You find………………
1. What is an earthquake?2. Why does it to happen?3. Where do they occur?4. How are earthquakes measured?5. Who predicts earthquakes (and what
do they do with this information?)With remaining time?? Discover a past earthquake- where was it, how strong, what was the damage?
What?
May 15, 1909, the largest earthquake in SK was recorded at 5.5 on the richter scale
Terminology
Faults- cracks in the Earth’s surface where movement occurs (different from boundaries)
Focus- place that rocks break under the surface in an earthquake
Seismic waves- earthquake waves Epicenter- point on the surface above the
focus Richter Scale- measures earthquakes Seismograph- measures and records motion
made by earthquakes
Mountains
Mountain ranges are a series of mountains
A mountain is part of the Earth’s crust that is much higher than the rest of the land Most are formed by folding or faulting
Folding
Folding can only happen when rocks were softened by heat and pressure within the crust
Think back to where mountains tended to form, what forces here would have caused the rocks to soften?
Activity/ Demo
Folded Mountains
Building Mountains Mountains are formed by folding,
faulting and volcanic activity Folding- colliding plates cause heat and
pressure, softening the rock and making it ‘wrinkle’. This forces the rock to be pushed upwards forming mountains
Fault- made by the shifting of faults in the crust
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