Do any mass extinctions correlate with magnetic reversals?

No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals.

Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million years or so--compared to mass extinctions, which occur every hundred million years or so.

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Why measure the magnetic field at the Earth's surface? Wouldn't satellites be better suited for space-weather studies?

Satellites and ground-based magnetometers are important for making measurements of the Earth’s magnetic field. They are not redundant but are instead complementary. Satellites provide good geographical coverage for data collection. Ground-based magnetometers are much less expensive and much easier to install than satellites. An array of...

Does the Earth's magnetic field affect human health?

Not directly. High-altitude pilots and astronauts can experience higher levels of radiation during magnetic storms, but the hazard is due to the radiation, not the magnetic field itself. Direct effects on human health from the magnetic field at the Earth's surface are insignificant. Geomagnetism can impact the electrically-based technology that we...

Are we about to have a magnetic reversal?

Almost certainly not. Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those...

How does the Earth's core generate a magnetic field?

The Earth's outer core is in a state of turbulent convection as the result of radioactive heating and chemical differentiation. This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic energy is converted to electrical and magnetic energy. Basically, the motion of the electrically...

Do animals use the magnetic field for orientation?

Yes. There is evidence that some animals, like sea turtles and salmon, have the ability to sense the Earth's magnetic field (although probably not consciously) and to use this sense for navigation.

Is the Earth a magnet?

In a sense, yes. The Earth is composed of layers having different chemical compositions and different physical properties. The crust of the Earth has some permanent magnetization, and the Earth’s core generates its own magnetic field, sustaining the main part of the field we measure at the surface. So we could say that the Earth is, therefore, a "...

Could magnetic reversals be caused by meteorite or comet impacts?

Although extremely unlikely, it might be possible for a reversal of the Earth's magnetic field to be triggered by a meteorite or comet impact, or even for it to be caused by something more "gentle," such as the melting of the polar ice caps. But self-contained dynamic systems like Earth’s dynamo can do this without any outside influence. Reversals...

Is it true that Earth's magnetic field occasionally reverses its polarity?

Yes. We can see evidence of magnetic polarity reversals by examining the geologic record. When lavas or sediments solidify, they often preserve a signature of the ambient magnetic field at the time of deposition. Incredible as it may seem, the magnetic field occasionally flips over! The geomagnetic poles are currently roughly coincident with the...
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Date published: July 31, 2017

Subsurface Magma Triggers Earth’s Most Severe Extinction

Subsurface magma intrusions (sills), rather than surface lava flows, may have triggered the Earth’s most catastrophic extinction event approximately 252 million years ago.

Date published: September 12, 2016

Mapping a Space-Weather Menace to Electric-Power Grids

New strides have been made toward quantifying how geomagnetic storms can interfere with the nation’s electric-power grid systems.  

Date published: March 21, 2016

EarthWord – Tertiary

The Tertiary is a system of rocks, above the Cretaceous and below the Quaternary, that defines the Tertiary Period of geologic time. T

Date published: August 31, 2015

"Mutant" Fossils Reveal Toxic Metals May Have Contributed to World’s Largest Extinctions

Toxic metals such as iron, lead and arsenic may have helped cause mass extinctions in the world’s oceans millions of years ago, according to recent research from the U.S. Geological Survey, the National Center for Scientific Research, France; and Ghent University, Belgium.

Date published: December 18, 2013

A Modern Compass Improves Oil Production

By using the Earth's magnetic field, combined with new innovative technology, oil and gas drilling companies are increasing oilfield productivity while reducing development costs and environmental impacts.

Date published: May 23, 2006

USGS, NOAA Mark 50 Years of Geomagnetic Research at Corbin, Va.

 

On May 23, 1956, a research center and observatory opened at Corbin, Va. to continuously monitor the Earth's magnetic field. It was charged by Congress "to enhance geomagnetic field studies and monitoring programs in support of scientific, general public, basic and national security needs of the United States."

Date published: March 20, 1998

Comet that triggered mass extinction was much larger than originally thought...

Minuscule fossil animal teeth, known as conodonts, indicate that a 370-million-year-old comet that slammed into Nevada could be as much as five times larger than scientists initially suspected.

Filter Total Items: 12
December 16, 2013

Hazards: Geomagnetic Storms

Space weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation. It is also during magnetic storms that beautiful aurora

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Attribution: Geomagnetism
Image: Trilobite Fossil (Phacops rana africana)
February 20, 2008

Trilobite Fossil (Phacops rana africana)

A fossilized Trilobite, Phacops rana africana, an extinct marine invertebrate. Item originally from Alnif, Morocco.

USGS
October 16, 2007

Earth Science Week, Continued: Geomagnetism and the Self-Sustaining Dynamo Called Earth

USGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.

March 22, 2007

PubTalk 3/2007 — Impact!

Piecing together the story of a giant meteorite crater beneath the Atlantic coast

By David S. Powars, Geologist, and R.D. Catchings, Geophysicist

  • Buried under Chesapeake Bay is a very well preserved impact structure 56 miles across and more than 2 miles deep
  • Following clues from drill holes and seismic imagery, careful
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July 29, 2004

PubTalk 7/2004 — Secrets in Stone

The Role of Paleomagnetism in the Evolution of Plate Tectonic Theory Video Presentation

Presentation of the award-winning USGS video "Secrets in Stone" (35 minutes), introduced by Jack Hillhouse, Research Geophysicist, and followed by a tour of the USGS Paleomagnetics Laboratory

  • Crucial discoveries in the early 1960.s were made
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Image: Rubens coil in the Rock Magnetics Laboratory in Menlo Park, California
December 1, 1995

Rubens coil in the Rock Magnetics Laboratory in Menlo Park, California

Rubens coil inside the Rock Magnetics Laboratory on the USGS Menlo Park campus. The function of the Rubens coil is to cancel the earth's magnetic field for thermal demagnetization of core samples. It is constructed of nonmagnetic materials and the control unit is place far enough away from the instrument to avoid interference from its metal components.

During the

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What is Space weather

Space weather

Attribution:
The geomagnetic polarity timescale.

The geomagnetic polarity timescale

The geomagnetic polarity timescale.

Chart showing the Earth’s magnetic feild

Chart showing the Earth’s magnetic feild

This is one of five world charts showing the declination, inclination, horizontal intensity, vertical component, and total intensity of the Earth’s magnetic field at mean sea level at the beginning of 2005. The charts are based on the International Geomagnetic Reference Field (IGRF) main model for 2005 and secular change model for 2005-2010. The IGRF is referenced to the

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Image: Interior of Rock Magnetics Laboratory in the Tarpaper Shack (room 40)

Interior of Rock Magnetics Laboratory in the Tarpaper Shack (room 40)

Interior of room 40 inside the tarpaper shacks on the USGS Menlo Park campus, circa 1965. During the early 1960s, three of the key scientists working on the theory of magnetic reversals operated in the Rock Magnetics Laboratory that was housed in these shacks. The Rock Magnetics Laboratory was designated a National Historic Landmark on October 12, 1994.

For more

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