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The Earths tectonic plates

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					The Earth’s tectonic
plates
There are two types of crust: -
Oceanic crust – denser and about 5km thick.
Continental crust – lighter and about 30km thick.
Plate Boundaries
The crust is made up of individual
plates. These plates are constantly
moving due to the hot convection
currents that rise within the mantle.


The movement of the plates has a great
impact on the boundaries of the plates,
but the middle area of the plates are
relatively stable.




                               Convection Currents
                               Large convection systems in
                               the mantle may carry along
                               the plates of the lithosphere
                               like a conveyor belt.
Plates may move apart, move closer
together or slide past each other. This
may result in: -
•Fold mountains
•Volcanoes
•Earthquakes
•Rift valleys
•Deep ocean trenches
Exercise – name
the plates!!!




      Types of Plates
Compressional (destructive) plate
boundary

 •Plates move together
 •One plate sinks below the other
 •The plate melts in the subduction
 zone where there is great pressure
 •Energy may be released as an
 earthquake
 •The molten rock or magma may
 rise forming composite volcanoes
 •The lighter crust at the surface
 may crumple to form fold
 mountains
    Tensional (constructive) plate boundaries
•   Plates move apart
•   Gap filled by rising
    magma from the mantle
•   Rising magma forms
    shield volcanoes
•   Most common under
    oceans so submarine
    volcanoes or volcanic
    islands
•   Plates buckle to form
    ridges
   Passive (conservative) plate boundaries
• Plates slide past each
  other
• May slide past each
  other the same
  direction ( and
  different speeds) or
  the opposite direction.
• Pressure builds up
  until one plate gives
  way causing an
  earthquake
• Can cause land to be
  crumpled or ridged
• E.G. North American
  Plate/Pacific Plate –
  San Andreas Fault.
1. What is the likelihood of tectonic activity in the UK?


2. Tectonic activity in Europe is concentrated in Iceland
   and southern Italy. State one tectonic similarity and
   one difference between Iceland and Italy.

3.   Type of      Examples       Features      Example
     plate        of plates      produced      country/regi
     margin                                    on

				
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posted:3/18/2012
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