Episodically, the Earth erupts large quantities of basaltic magma in geologically short periods of time. This results in the formation of large igneous provinces, which include continental flood basalt provinces, volcanic rifted margins, and giant oceanic plateaus. These fluctuations in the Earth's system are still poorly understood. Do they owe their origin to mantle plumes, meteorite impacts, or lithosphere-controlled processes? Whatever their origin they correlate closely with major changes in oceanic and atmospheric chemistry and may trigger global mass extinctions.