Draw a cross section of the earth and
label it with the correct names and
characteristics
crust - relatively thin and rocky (Oceanic 30-50km and continental 6-8km) - LITHOSPHERE!
mantle - has the properties of a solid, but can flow very slowly 35 - 2900 km, 900-1600 oC –
ASTHENOSPHERE
outer core - made from liquid nickel and iron 2900-5270km, 4000-5000 oC
inner core - made from solid nickel and iron
How is the earth heated?
Where does the heat come for
the convection currents?
Radioactive decay of uranium in the core raises the temperature to over 5000oC
Heat moves from the core to the surface in plumes. These bring magma to the
surface
Magnetic field
The Earth also has a
magnetic field as a
result of the outer
core – the liquid iron
acts as an electric
dynamo and produces
the field
This field protects us
from the sun’s harmful
radiation
Plate boundaries
Typical exam question: (4Marks)
Explain why earthquakes happen on
destructive plate margins. You may draw a
diagram to help your answer.
What are the
commands in
this question?
A Destructive margin is where 2 plates collide.
One plate is sub-ducted under the other one.
Usually a oceanic plate is sub-ducted under a
continental plate. There is friction between
the two plates. The pressure builds and
eventually gives way, The energy release is the
land shaking, called an earthquake.
Constructive Plate Boundary
Name this plate boundary.
A
G
B
E
C
F
D
Match the labels to the letters
Earthquakes occur due to friction
The oceanic crust sinks under
the less dense continental crust
Oceanic plate
Continental crust
Explosive volcanoes
The oceanic crust
melts and rises
Mantle
• Named Continents
• Named Plates
• Use of Keywords
• Clear Descriptions
• Clear Explanations
Volcano types
• Watch the video and sketch the different
types of volcano with their characteristics
• http://www.youtube.com/watch?v=sl5Id6wRS
eU&NR=1
• There are 3 different types of volcanoes:
• Active - eruptions can be anytime and often.
• Dormant - has been a while since it has
erupted, but could at anytime.
• Extinct, meaning it hasn't erupted in a very
long, long time so it probably won't ever
again.
Pyroclastic flow
• fast-moving current of superheated gas
• can reach temperatures of about 1,000 °C
• rock which reaches speeds moving away from a
volcano of up to 700 km/h
Lava flow
• Lava is molten rock that flows out of a volcano
• Depending on its composition and
temperature, lava can be very fluid or very
sticky (viscous).
• Fluid flows are hotter and move the fastest;
they can form streams or rivers
Cinder cone volcanoes
Cinder cones
build from lava that is blown violently into the air and breaks into
fragments.
As the lava pieces fall back to the ground, they cool and harden into
cinders (lava fragments about ½ inch in diameter) that pile up
around the volcano's vent.
Cinder cones are the smallest volcanoes and are cone-shaped.
• Where are volcanoes located?
Volcanoes are found along destructive (subducting) plate
boundaries, constructive (divergent) plate boundaries and at hot
spots in the earth's surface.
• What is the Ring of Fire?
A volcanic chain surrounding the Pacific Ocean. It is formed along a
destructive (subducting) plate boundary.
• What are lahars and pyroclastic flows?
The most destructive aspect of volcanoes are lahars and pyroclastic
flows.
• Lahars are volcanic mudflows created when water (from rain or
melt water from glaciers) and ash mix. This deadly combination can
have devastating results on the surrounding area. When lahars
settle they can be metres thick and as hard as cement. Lahars can
occur long after a volcanic eruption.
•
Pyroclastic flows are avalanches containing hot volcanic gases, ash
and volcanic bombs. On steep volcanoes pyroclastic flows can reach
speeds of over 100 miles per hour.