Thread: Can Geology explain...

...how long it takes for the Earth's magnetic field to invert? I heard in some places it can instantly swap but in some places it takes far longer. Is there any geological evidence for this phenomena?

The record tells us when the poles have switched in the past but we cannot predict when they will switch in the future. At times the switch has been rapid (although rapid does not mean instantly in my understanding).

Google magnetic stratigraphy.

Originally Posted by svwillmer

...how long it takes for the Earth's magnetic field to invert? I heard in some places it can instantly swap but in some places it takes far longer. Is there any geological evidence for this phenomena?

The process takes a few thousand years. In geological terms this is instantaneous. That may account for why you have heard both versions.

There is a vast amount of evidence for this phenomena. Magnetic minerals in magma align themselves with the Earth's magnetic field. When the magma solidifies this alignment is 'frozen' in the rock. We can then measure it and determine the orientation and direction of the poles at the time the rock solidified.
Observations of the alternating stripes of magnetic alignment on the ocean floor provied the evidence for sea floor spreading, a key component of plate tectonics. Observation of the alignment of continental materials alllowed the paths of the continents to be traced back through geological time.

Originally Posted by svwillmer

...how long it takes for the Earth's magnetic field to invert? I heard in some places it can instantly swap but in some places it takes far longer. Is there any geological evidence for this phenomena?

This will help:
Geomagnetic Reversal

Originally Posted by Wikipedia

Evidence of geomagnetic reversals can be seen at mid-ocean ridges where tectonic plates move apart and the sea bed is filled in with magma. As the magma seeps out of the mantle the magnetic particles contained within it are oriented in the direction of the magnetic field at the time.