Gauss-Matuyama reversal

The Gauss-Matuyama Reversal was a geologic event approximately 2.588 million years ago when the Earth's magnetic field underwent reversal.

This event, which separates the Piacenzian from the Gelasian and marks the start of the Quaternary, is useful in dating sediments.

Biological effects
The event is marked by the extinction of calcareous nannofossils Discoaster pentaradiatus and D. surculus, among others.