"… if you look back into history, the way the world has divided up into, say, linguistic groups, cultural groups, is ultimately under the control of geology. So, for example, think of the differences between the peoples north and south of the Himalayas. It’s extremely hard for people to cross – even the individual valleys within the Himalayas have cultural differences. Their history has been controlled to a large extent by those barriers. That’s a great control. But even on a small scale, the way cities looked – you know, the kind of cities that could be built – was controlled by the rocks that underlay it. For example, you could build tower blocks in New York because you had that nice, firm metamorphic rock to drive your piles down into. And the particular building stones are what have given, well, let’s say the majority of French cities and towns their own peculiar and interesting flavor. So geology controls the character of the world to a large extent."