Stories
Slash Boxes
Comments

SoylentNews is people

posted by takyon on Friday July 31 2015, @12:11AM   Printer-friendly
from the flip-em dept.

The fiery demise of ancient huts in southern Africa 1,000 years ago left clues to understanding a bizarre weak spot in the Earth's magnetic field — and the role it plays in the magnetic poles' periodic reversals.

Patches of ground where huts were burned down in southern Africa contain a key mineral that recorded the magnetic field at the time of each ritual burning. Those mineral records teach researchers more about a weird, weak patch of Earth's magnetic field called the South Atlantic Anomaly and point the way toward a possible mechanism for sudden reversals of the field.

[...] "They had this ritualistic burning of villages," Tarduno told Space.com. "Particularly in times of drought, the conclusion would be that there might have been some offence in the village, so the solution was to have a burning down of the village." The process was intended to cleanse the village, their collaborator archaeologist Thomas Huffman, from Witwatersrand University in South Africa, said in the statement.

At the very least, it cleansed the ground: The burning villages would reach temperatures of over 1,800 degrees Fahrenheit (1,000 degrees Celsius), which would melt the magnetic compounds like magnetite in the clay floors. The magnetite would become remagnetized by the Earth's magnetic field at the precise instant it cooled, ready to be analyzed centuries later.

Interesting that an act of destruction would be the reason we can learn centuries later. It's reminiscent of how we can thank fire for preserving so many examples of Akkadian cuneiform, written on clay tablets and baked when their storage areas were burned.


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 1) by jdavidb on Friday July 31 2015, @01:42AM

    by jdavidb (5690) on Friday July 31 2015, @01:42AM (#216106) Homepage Journal

    The magnetite would become remagnetized by the Earth's magnetic field at the precise instant it cooled

    Wait, isn't cooling usually a gradual phenomenon?

    --
    ⓋⒶ☮✝🕊 Secession is the right of all sentient beings
  • (Score: 1) by Bogsnoticus on Friday July 31 2015, @02:56AM

    by Bogsnoticus (3982) on Friday July 31 2015, @02:56AM (#216129)

    It is a gradual phenomenom, but everyone knows the instant something cools. Its the very instant you touch it to see how hot it is, and your finger doesn't end up smelling and sounding like frying bacon.

    --
    Genius by birth. Evil by choice.
  • (Score: 1, Insightful) by Anonymous Coward on Friday July 31 2015, @03:20AM

    by Anonymous Coward on Friday July 31 2015, @03:20AM (#216138)

    Gradual on your time scale - virtually instantaneous on a geological time scale. The magnetic field won't change significantly over the time it takes to cool.

  • (Score: 0) by Anonymous Coward on Friday July 31 2015, @07:51AM

    by Anonymous Coward on Friday July 31 2015, @07:51AM (#216199)

    They're referring to the moment it passes the Curie Point on the way down, see:

    https://en.wikipedia.org/wiki/Curie_point [wikipedia.org]

    And, yes, it is named after THOSE Curies! They did other things before the radioactivity craze.