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
 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………………
What is an earthquake?
Why does it to happen?
Where do they occur?
How are earthquakes measured?
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?
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5.
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
 https://ees.as.uky.edu/sites/default/files/elearning
/module10swf.swf