The Taconic orogeny
Island arcs slam into North America, raising mountains whose erosion cools the whole planet.
- When
- —
- Duration
- 27 million years
- Known to
- ± 10 million years
- Era
- Ordovician, Paleozoic
As the Iapetus Ocean closes, volcanic arcs collide with the eastern margin of Laurentia, building a mountain chain whose eroded remnants form the Appalachians. Weathering of the freshly exposed silicate rock consumes atmospheric carbon dioxide on a scale large enough to cool global climate. It is one of the clearest cases of mountain building driving a change in world climate.