Watch it for long enough, and the Earth roils. Tectonic plates grind together, their squeezed rock melting, new minerals precipitating themselves from the tortured fluids. Tectonic plates pull apart, with new crust welling up into the gash between them, sometimes escaping from its sea-bed origins and hoisting itself up into the sunshine.

It has all happened before. But it happens slightly differently each time, and its details are the size of mountains and seas. Rocks are enriched, distilled, eroded, melted, mixed, changed in every way. The world ends up odd, unequal, differentiated. The processing is so slow that these dispositions of material are, for humans, fixed. But the processing never stops.