Tectonic plates with golden syrup…

On Monday in class I ran a demonstration on the movement of tectonic plates. I like to visually show things using experimental material. So to demonstrate this I used a Bunsen burner, some golden syrup and a biscuit. You may now sound confused but trust me it will all come together.

Tectonic plates with golden syrup and a biscuit

  1. Take a 500 ml beaker with about 1/3 of it Golden Syrup and place it in a freezer for about one hour (this increases the viscosity).
  2. Break a biscuit in half and place together on top of the syrup.
  3. Place the beaker on a tripod (I used a gauze at this point) and heat with a Bunsen burner on high
  4. As the syrup heats, you should look side on, you will see convection currents forming
  5. Slowly the biscuits will start to move apart (in my demo one sank under another too).
  6. Be careful not to let it boil over – this could be dangerous (and what happened in my test – see video below) – and misses the point.
  7. When it cools they should move towards each other.

So what have we modelled? The core is represented by the Bunsen burner; the mantle (and flowing magma) is the golden syrup and the biscuit is the crust. This is a great chance to raise questions about how the model doesn’t really work. My students came up with some great answers, from the crust is too think and the density of syrup isn’t correct to the move ludicrous “but Sir magma isn’t sticky”.

So you have now gotten to this point… I think its time you saw my test demonstration (note: the end of the world-esq ending and me having to drop the camera to turn the Bunsen off):

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2 responses to “Tectonic plates with golden syrup…”

  1. Neil Tarrant says :

    Magma is sticky!

    [Well, it can be – isn’t that essentially one way in which we characterize magma, by it’s stickiness? So different magma can produce somewhat different rocks at the surface?]

    • samuel says :

      Yeah – you are right but that’s really not how they meant it. I wasn’t clear above. They were talking about touching it with there hands. I had to go back and discuss temperature and there was a realisation of – oh no hand.

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