n
The liquid iron
and solid iron core of the earth, work together to create the Earth’s Magnetic Field.
The currents and movement of the liquid iron, against or along the solid iron, generate the Earth’s magnetism. The field is created or enforced by the electricity of the electric ions and currents
in the liquid core (U.S. Geological Survey 2007). It is likely
that a disturbance within this dynamo will cause the Magnetic Field to reverse.
o The disturbance
may be that the liquid core slows down or becomes cooler, causing the Earth’s Magnetic field to weaken, but it will
eventually heat up again or start moving more fluidly, causing a new field to be formed in the opposite direction (Geological
Survey of Canada 2007).
n
“Reversals only take 5,000 years to occur, but it takes 15,000 years
for the Magnetic Field to decay” (Geological Survey of Canada 2007).
n
During the number of years that it takes for the Magnetic Field to reverse,
people in the Arctic regions may see “changes that wouldn’t match what Tropical regions would note across the
generations” (Britt 2004).
n
“Sometimes lava flows occur frequently enough, or sediment deposit
is fast enough, that we can actually determine the change in direction and field intensity during the reversal itself. These occurrences are relatively rare” (Geological Survey
of Canada 2007).
n Geophysists Allan Cox and Richard Doell, as well as geochemist Brent Dalrymple developed the method of potassium-argon
dating to provide evidence of magnetic striping along the ocean floor, which in turn helped the development of the seafloor-spreading
hypothesis. They also took their findings and used them “to measure the
magnetic orientation of continental and oceanic rocks, allowing them to assign ages to the Earth’s recent magnetic reversals”
(2 Watson 1999).
n “Eventually scientists were able to date and correlate the magnetic striping patterns for nearly all of the
ocean floor, parts of which are as old as 180 million years old” (2 Watson 1999).
n The Magnetic Field may sometimes only play out a partial transition as opposed to a full reversal, wherein there
is a large decrease in the strength of the magnetic field, but it then “regenerates itself with the same polarity”
(British Geological Survey 2007).
- “Although
extremely unlikely,… it might be possible for a reversal… to be triggered by a meteorite or cometary impact, or
even for it to be caused by something more ‘gentle’, such as the melting of the polar ice caps” (U.S. Geological
Survey 2007).
