Actually, it just occurred to me that what would be really cool would be a geology version of the Star Walk app - you point it at the ground/hill/mountain and it shows you what its made up of.

Explaining the history of features would be even cooler :-)

And imagine if you had a game that generated terrain by erosion + tectonic plate movement, and you got to see a visualisation of that as it was generating :) 2 billion years of geological activity, simulated in a minute-scale.

42!