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New Method Confirms Magnetic Field Switch 10 Million Years Ago
The Hague - Nov 26, 2001 NWO researchers have developed an improved method of identifying the magnetic signals in old geological strata. The researchers used the new method to show that the earth's magnetic field really did reverse itself ten million years ago. Particles of iron in sediments orient themselves in accordance with the local magnetic field of the earth. As the sediment consolidates and lithifies over the course of several decades, the particles of iron continue to lie in the direction of the original magnetic field. They thus preserve data on the state of the magnetic field when the sediment was being deposited. This data is used world-wide to date geological strata. The researchers developed a method which provides information on the carriers of the magnetic signal in sediments. Carriers include the iron oxides magnetite and hematite. Using this method, the researchers were able to demonstrate that a short-lived change in the earth's magnetic field really did take place about ten million years ago. Hitherto, researchers had been unable to exclude the possibility that subsequent chemical or physical processes had altered the magnetic signal in the sediment.
Studies of the earth's past magnetic field are important for our understanding of the 'geodynamo'. Researchers use the term 'geodynamo' to refer to the idea that the geomagnetic field is generated in the centre of the earth. The hypothesis is that the electricity that runs through the molten iron of the earth's outer core causes the magnetic field. The earth's magnetic field now points south, meaning that a compass needle points north. Some 800,000 years ago, a compass needle would have pointed south, having previously pointed north. Changes in the direction of the earth's magnetic field are referred to as reversals. Community Email This Article Comment On This Article Related Links Netherlands Organization for Scientific Research SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express Dirt, rocks and all the stuff we stand on firmly
Magnetic Reconnection Region Larger Than 2.5 Million Km Found In The Solar Wind
Paris (ESA) Jan 12, 2006Using the ESA Cluster spacecraft and the NASA Wind and ACE satellites, a team of American and European scientists have discovered the largest jets of particles created between the Earth and the Sun by magnetic reconnection. This result makes the cover of this week's issue of Nature. |
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