Geomagnetic field reverses in a flash

2 Sep 10 – Rocks just north of a truck stop along I-80 in Battle Mountain, Nevada, provide new evidence of super-fast reversals of Earth’s magnetic polarity.

Geomagnetic reversals – times when a compass would have pointed toward Antarctica instead of toward the Arctic – have occurred more often than is generally known.
Polarity reversals occur every couple hundred thousand years, and (supposedly) take about 4,000 years to make the change, says this article in Science News.

The Nevada rocks suggest that this particular reversal happened at the amazing rate of one degree per week — a flash in geologic time.

Flipping in record time (Image: G. Glatzmaier/Los Alamos National Laboratory/P. Roberts/UCLA/SPL)

A paper describing the discovery is slated to appear in Geophysical Research Letters.

Scott Bogue, a geologist at Occidental College in Los Angeles and his colleague, Jonathan Glen of the U.S. Geological Survey in Menlo Park, California, went to Nevada to study a series of well-preserved lava flows. As each flow had cooled into solid rock, it preserved the orientation of the magnetic field at the time.

The two geologists found that the rocks in one particular lava flow had reoriented themselves a whopping 53 degrees in one year, suggesting that the magnetic field had changed direction at approximately one degree per week.

This is only the second report of such a speedy reversal. The first report, published in 1985, was based on a study of rocks formed from ancient lava flows at Steens Mountain, Oregon. That report, which indicated a change of three to six degrees per day, has never gained widespread acceptance.

Although this article says the first report was published in 1995, I mention a report published in 1985 by Prévot, Mankinen, Coe and Grommé in both “Not by Fire but by Ice” ( p.191) and “Magnetic Reversals and Evolutionary Leaps” ( p. 95).

Regardless of when that first report was published, this new discovery bolsters the theory that reversals can happen very quickly, over a matter of years instead of millennia.

I’ve received a lot of flack over my assertions that magnetic reversals can occur in as little as 30 days. I cited the rapid reversals in the lava flows on Steens Mountain as part of my proof, so I’m glad to see this new discovery in Nevada.

“We’re trying to make the case that [the new work] is another record of a superfast magnetic change,” says Bogue, lead author of the paper.

As might be expected, not all experts are convinced.

“The last stable reversal occurred 780,000 years ago,” the article continues. “Some geologists argue the Earth is overdue for a reversal and might even be entering one now, as the geomagnetic field has been getting weaker over the past 150 years or more.”

Did you catch that?

“The Earth is overdue for a reversal and might even be entering one now, as the geomagnetic field has been getting weaker over the past 150 years or more.”

But nobody should worry about waking up one morning to geomagnetic havoc, says Bogue. “If you were alive when it was happening, it probably wouldn’t be that big a deal.”

Not a big deal?

I think it would be a Big deal, with a capital “B.” That’s if you think that evolutionary leaps, huge floods, huge earthquakes, huge snowstorms (triggering an ice age), huge explosions in the sky, and carbon raining onto the earth would be a big deal.

And that’s just for starters.

When they say that the last magnetic reversal occurred 780,000 years ago, they’re ignoring magnetic excursions, times when the earth’s magnetic field moved south and then moved back north in perhaps as short a time as 500 years.

Consider the Gothenburg magnetic reversal/excursion of about 12,000 years ago, when some 40 percent of all of the larger mammals in North America, such as the mammoth, mastodon, sabre-toothed cat and great dire wolf, went extinct. That’s when the Carolina Bays were blasted into the ground. That’s when carbon rained from the sky. That’s when radiation levels in the soil measured up to 2,000 times higher than normal. Not a big deal?

Or consider the Mono Lake magnetic reversal of 23,000 years ago when the European forest elephant went extinct, the mammoths were hammered, and we descended into catastrophic glaciation. Not a big deal?

Or look at the Lake Mungo magnetic reversal of 33,500 years ago, when the Neanderthal went extinct. Not a big deal?

What about the Blake magnetic reversal of 115,000 years ago, which marked the abrupt end of a period of warmth even warmer than today (the Eemian Period), and the earth descended into yet another catastrophic glaciation in less than 100 years, perhaps in less than 20 years. Not a big deal?

See entire article:

See also:

Thanks to Michael Gershman, Craig Adkins, Keith Phillips and Laurel in Australia for this link

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