Lesson 12 overview
==================
This week we will be introduced to the equations that govern the flow of viscous materials.
At depths greater than those where rocks deform in a brittle manner, crustal and mantle rocks can be treated as viscous fluids with very high viscosities.
Ice also behaves as a viscous fluid in glaciers, which will be further explored in `this week’s exercise <https://github.com/IntroQG-2017/Exercise-12>`__.
Like the previous two weeks, we will start with a `short lecture <../../_static/slides/L12/Rock-and-ice-as-viscous-materials.pdf>`__ about the equations of viscous flow and its application to modelling river erosion.
There are also :doc:`some notes <viscous-flows>` posted about viscous flow down an incline.
These are not required reading, but may be of interest for the exercise this week.
As usual we will finish with the `exercise for this week <https://github.com/IntroQG-2017/Exercise-12>`__.

1. `Rock and ice as viscous materials lecture slides <../../_static/slides/L12/Rock-and-ice-as-viscous-materials.pdf>`__
2. `Gemmer et al., 2004 - Modelling salt tectonics <https://dx.doi.org/10.1111/j.1365-2117.2004.00229.x>`__ *(optional)*
3. :doc:`Notes on viscous flow down an incline <viscous-flows>` *(optional)*
4. :doc:`Theory for Exercise 12 <exercise-12-theory>`
5. :doc:`Exercise 12 <ex-12>`
6. :doc:`Exercise 12 hints <exercise-12-hints>`

Learning objectives
-------------------
After completing this week's lesson you should be able to:

- State what a fluid is and how its flow is related to its viscosity
- Explain why geological fluids deform in a nonlinear fashion
- Model the flow of ice in valley glaciers using viscous flow equations