What would you build a lighthouse out of?

Sounds a strange question, but this is what I’m asking Manchester University engineering students.

I’m in the middle of teaching engineering students how to identify different sorts of rocks and asking them to think about how they might use them, based on their properties. This is a key part of their studies and will be helpful throughout their future careers.

 
First of all, I ask the students to describe ten different rock samples using terms such as grain size, cement and the way they break. After that, they have to try and work out if the rock is sedimentary, igneous or metamorphic and then give the rock a name such as granite or sandstone. Then comes the fun bit!

Gneiss from the Museum's collection. Good lighthouse foundations!

They are given a map of an area of Scotland where they have to decide where to build their lighthouse (hopefully on strong foundations and somewhere near the coast) and then they have to decide which rocks they would use to make the lighthouse walls, floor, road and sea defenses.

We have run this session a couple of times now and the students seemed to have really enjoyed it. More complicated than you first imagine!