Deep-sea sediment records of the Laschamp geomagnetic field excursion (41kya)

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In summary, the conversation discusses the paper which concludes that magnetic field excursions, specifically the Laschamps excursion event, are not necessarily related to magnetic field reversal. The effects of a 10% magnetic field for 2000 years on plant and animal life are also mentioned, but it is stated that discussions about speculative ideas, such as the "Rogue Moon" hypothesis, are not allowed on the site. Overall, the conversation focuses on the scientific understanding of geomagnetic excursions and their potential effects on life.
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aspergers@40
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This paper http://www.agu.org/pubs/crossref/2005/2003JB002943.shtml concludes that the narrow Laschamps excursion event, or class I excursions in general, are more closely related to normal secular variation and are not necessarily a prelude to magnetic field reversal. So what are they and what causes them? The geomagnetic field suffered for some time and so one would imagine that life did as well: "magnetic field intensities less than 10% of normal that persisted for almost 2000 years". How relevant is this event to the megafaunal extinctions for example?
Wikipedia Geomagnetic Excursions
[URL [Broken] Earth's Magnetic Field[/url]

.
 
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  • #2
aspergers@40 said:
This paper http://www.agu.org/pubs/crossref/2005/2003JB002943.shtml concludes that the narrow Laschamps excursion event, or class I excursions in general, are more closely related to normal secular variation and are not necessarily a prelude to magnetic field reversal. So what are they and what causes them? The geomagnetic field suffered for some time and so one would imagine that life did as well: "magnetic field intensities less than 10% of normal that persisted for almost 2000 years". How relevant is this event to the megafaunal extinctions for example?
Wikipedia Geomagnetic Excursions
[URL [Broken] Earth's Magnetic Field[/url]

.

We should not be bothering with alleged relevance to megafaunal extinctions unless that association appears somewhere in the scientific literature, and I am pretty confident it doesn't.

Discussion of the ideas in the paper, which are to do with physical causes of magnetic field excursions, are fine.

Cheers -- sylas
 
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  • #3
Okay, but I'm interested in the effects of a 10% magnetic field for 2000 years on the plant and animal life. I'll google some more papers I guess..
 
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Am I allowed to speculate on a 'Rogue Moon' hypothesis (or any 0.5 moon object), whose flyby exerted a gravitational influence which disrupted the dynamics of the Earth's core some 41,000 years ago?
 
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Check the Guidelines. Speculations about a rogue moon would be against this section, because they have not been published in the scientific literature (and never will be, frankly).
Greg Bernhardt said:
Overly Speculative Posts:
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1. What is the Laschamp geomagnetic field excursion?

The Laschamp geomagnetic field excursion refers to a period of time approximately 41,000 years ago when the Earth's magnetic field experienced a significant weakening and reversal. This event is named after the location where it was first discovered, the Laschamp lava flows in France.

2. How do scientists study the Laschamp geomagnetic field excursion?

Scientists study the Laschamp geomagnetic field excursion by examining deep-sea sediment records. These sediments, which have accumulated over thousands of years, contain magnetic particles that align with the Earth's magnetic field at the time they were deposited. By analyzing the orientation of these particles, scientists can reconstruct the strength and direction of the Earth's magnetic field during the Laschamp excursion.

3. What caused the Laschamp geomagnetic field excursion?

The exact cause of the Laschamp geomagnetic field excursion is still being debated by scientists. Some hypotheses include interactions between the Earth's core and mantle, changes in the Earth's rotation, or external factors such as solar activity or cosmic rays. However, the exact cause is still not fully understood.

4. What impact did the Laschamp geomagnetic field excursion have on the Earth?

The Laschamp geomagnetic field excursion had minimal impact on the Earth itself, as the reversal process took place over thousands of years. However, it may have had some effects on the Earth's climate and biosphere. Some studies suggest that the weakening of the magnetic field during the Laschamp excursion may have allowed more cosmic rays to reach the Earth's surface, potentially affecting climate and possibly even human evolution.

5. Are there any other known geomagnetic field excursions?

Yes, there have been other known geomagnetic field excursions throughout Earth's history. The Laschamp excursion is one of the most recent, but other notable events include the Blake excursion (about 115,000 years ago) and the Matuyama-Brunhes reversal (about 780,000 years ago). These events are important for understanding the long-term behavior and stability of the Earth's magnetic field.

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