Reversal magnetostratigraphy

Abstract

The geomagnetic field has been likened to a chronometer (Cox 1973). The magnetic clock, driven relentlessly by electric currents in the Earth’s liquid core, oscillates back and forth switching between its two stable modes of a ‘normal’ state in which the Earth’s magnetic field points north and a ‘reverse’ state in which the field points south. The geomagnetic chronometer lacks a regulator so it runs unevenly with switching intervals varying from a few thousand years to several tens of millions of years. The magnetic timing system of north-south flips, tags rocks as they form with its binary reversal code. Palaeomagnetists have unravelled the magnetic coding scheme so that palaeomagnetic remanence signatures can now be used to date sequences of lava flows and sediments.

“Footprints on the sands of time”

Longfellow

A psalm for life