The Giant's Causeway cools into columns
A thick basalt lava lake in Antrim contracts as it solidifies and cracks into forty thousand hexagons.
- When
- —
- Duration
- 2 million years
- Known to
- ± 1 million years
- Era
- Paleocene, Cenozoic
Part of the North Atlantic eruptions, the Antrim flood basalts include a lava flow that ponded thickly enough to cool slowly and evenly. Contraction on cooling propagated cracks down from the surface, and the geometry that relieves the most stress for the least new crack area is a hexagonal net — the same physics that patterns drying mud, only at the scale of a landscape. Irish tradition credited the result to the giant Finn MacCool building a road to Scotland, and the basalts on Staffa at the other end are the same eruption.