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.
Self-contained dynamic systems like Earth’s dynamo can have reversals without any outside influence. Reversals of Earth's magnetic field can simply happen.
Learn more: USGS Geomagnetism Program
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The Chesapeake Bay impact structure
About 35 million years ago, during late Eocene time, a 2-mile-wide asteroid or comet smashed into Earth in what is now the lower Chesapeake Bay in Virginia. The oceanic impact vaporized, melted, fractured, and (or) displaced the target rocks and sediments and sent billions of tons of water, sediments, and rocks into the air. Glassy particles of...
Powars, David S.; Edwards, Lucy E.; Gohn, Gregory S.; Horton, J. Wright
The Boulder magnetic observatory
The Boulder magnetic observatory has, since 1963, been operated by the Geomagnetism Program of the U.S. Geological Survey in accordance with Bureau and national priorities. Data from the observatory are used for a wide variety of scientific purposes, both pure and applied. The observatory also supports developmental projects within the...
Love, Jeffrey J.; Finn, Carol A.; Pedrie, Kolby L.; Blum, Cletus C.
Monitoring the Earth's dynamic magnetic field
The mission of the U.S. Geological Survey's Geomagnetism Program is to monitor the Earth's magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research...
Love, Jeffrey J.; Applegate, David; Townshend, John B.
How to build a model illustrating sea-floor spreading and subduction
This report describes how to build a model of the outer 300 km (180 miles) of the Earth that can be used to develop a better understanding of the principal features of plate tectonics, including sea-floor spreading, the pattern of magnetic stripes frozen into the sea floor, transform faulting, thrust faulting, subduction, and volcanism. In...
Lahr, J.C.
Dinosaurs, facts and fiction
Litwin, Ronald J.; Weems, Robert E.; Holtz, Thomas R.
Chicxulub impact event; computer animations and paper models
Alpha, T.R.; Galloway, John P.; Starratt, S.W.
This dynamic earth: the story of plate tectonics
In the early 1960s, the emergence of the theory of plate tectonics started a revolution in the earth sciences. Since then, scientists have verified and refined this theory, and now have a much better understanding of how our planet has been shaped by plate-tectonic processes. We now know that, directly or indirectly, plate tectonics...
Kious, W. Jacquelyne; Tilling, Robert I.
Meteoroids and impact craters
On a clear night scores of meteoroids streak across the sky. they leave light paths we call meteors or shooting stars as the Earth is showered with debris from distant parts of the solar system. When these meteoroids hit the Earth (as meteorites) they range in size from pebbles to the 34 ton Ahnighito meteorite that the American explorer Admiral...
Spall, Henry
New 3D Measurements Improve Understanding of Geomagnetic Storm Hazards
Measurements of the three-dimensional structure of the earth, as opposed to the one-dimensional models typically used, can help scientists more accurately determine which areas of the United States are most vulnerable to blackouts during hazardous geomagnetic storms.
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.
Iowa Meteorite Crater Confirmed
USGS Airborne Surveys Back Up Previous Decorah Research
Evidence Presented in Toronto... Meteorite Impact Formed Chesapeake Bay Impact Crater Controls Region’s Groundwater Flow and Quality
A large meteorite plummeted into the western Atlantic Ocean about 35 million years ago, creating the 120-km wide Chesapeake Bay impact crater [Geology (Boulder), 22 (8), p. 691-694].
Tiny Teeth Forecast Ancient Comet Showers
Minuscule fossil animal teeth, known as conodonts, indicate that a 370-million-year-old comet that slammed into southern Nevada could be as much as five times larger than scientists initially suspected.
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.
Comet Struck Southern Nevada 370 Million Years Ago
An extraterrestrial object, theorized to be a comet at least one kilometer in diameter, impacted what is now southern Nevada about 370 million years ago.
Chesapeake Bay Impact Crater
Chesapeake Bay Impact Crater Boundaries Map
Gale crater
Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.
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
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.
Cratered cones near Hephaestus Fossae
Cratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape.
Cinder cones (otherwise known as scoria cones) are the most common type of volcano
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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
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
Chart showing the Earth’s magnetic field
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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