Reversals in the Earth’s magnetic field are believed to result from instability that develops within the outer core geodynamo. To understand this process and to predict how the Earth system would respond to a future reversal, it is critical to map out a detailed description of the global geomagnetic field that occurs during the transition between long-lived, relatively stable, polarity states.
Continue reading “Synchronizing records of reversal”Rapid reversal creates no record
During the past 50 years, field measurements of sea-floor magnetic anomalies combined with paleomagnetic studies of volcanic and sedimentary sequences have yielded the construction of the geomagnetic polarity time scale. Excursions represent periods during which the magnetic pole deviates by more than 40° away from the geographic pole.
Continue reading “Rapid reversal creates no record”Antarctic melt triggers Ice ages
The melting of Antarctic icebergs could be the key to the activation of a series of mechanisms that cause the Earth to suffer prolonged periods of cooling according to Francisco J. Jiménez-Espejo, a researcher at the Andalusian Earth Sciences Institute (CSIC-UGR).
Continue reading “Antarctic melt triggers Ice ages”Geomagnetic field pointers
The earth has a large-scale dipolar magnetic field. The magnetic North and South poles are commonly understood as positions on the Earth where the geomagnetic field is vertical (i.e., perpendicular) to the ellipsoid. The Earth’s magnetic field shields us against high-energy particles from the Sun and outer space, thereby protecting our atmosphere and the life that it supports.
Continue reading “Geomagnetic field pointers”Source of intraplate volcanism
The asthenosphere – which is derived from the Greek asthenes, meaning weak – is the uppermost part of the Earth’s mantle, right below the tectonic plates that make up the solid lithosphere. Traditionally, the asthenosphere has been viewed as a passive region that separates the moving tectonic plates from the mantle.
Continue reading “Source of intraplate volcanism”A Core-Mantle link
Researchers at a number of institutions around the globe have stumbled on a hint that the mantle does leave its mark on magnetic reversals. They have found that as the poles wander from north to south or vice versa during successive reversals, they show a startling tendency to trace out the same paths across the surface of the planet.
Continue reading “A Core-Mantle link”Steens Mountain shocker
Geological processes tend to be slow. But in 1995 a discovery by a group of scientists shocked the world when they announced they had found evidence of a rapid geomagnetic reversal. Before then, geophysicists believed that a complete flip would take around 5000 years.
Continue reading “Steens Mountain shocker”