760:. Many such arguments were based on an apparent periodicity in the rate of reversals, but more careful analyses show that the reversal record is not periodic. It may be that the ends of superchrons have caused vigorous convection leading to widespread volcanism, and that the subsequent airborne ash caused extinctions. Tests of correlations between extinctions and reversals are difficult for several reasons. Larger animals are too scarce in the fossil record for good statistics, so paleontologists have analyzed microfossil extinctions. Even microfossil data can be unreliable if there are hiatuses in the fossil record. It can appear that the extinction occurs at the end of a polarity interval when the rest of that polarity interval was simply eroded away. Statistical analysis shows no evidence for a correlation between reversals and extinctions.
212:
740:. Supporters of this hypothesis hold that any of these events could lead to a large scale disruption of the dynamo, effectively turning off the geomagnetic field. Because the magnetic field is stable in either the present north–south orientation or a reversed orientation, they propose that when the field recovers from such a disruption it spontaneously chooses one state or the other, such that half the recoveries become reversals. This proposed mechanism does not appear to work in a quantitative model, and the evidence from
45:
593:. A Poisson process would have, on average, a constant reversal rate, so it is common to use a non-stationary Poisson process. However, compared to a Poisson process, there is a reduced probability of reversal for tens of thousands of years after a reversal. This could be due to an inhibition in the underlying mechanism, or it could just mean that some shorter polarity intervals have been missed. A random reversal pattern with inhibition can be represented by a
293:
113:, occurred 780,000 years ago with widely varying estimates of how quickly it happened. Other sources estimate that the time that it takes for a reversal to complete is on average around 7,000 years for the four most recent reversals. Clement (2004) suggests that this duration is dependent on latitude, with shorter durations at low latitudes and longer durations at mid and high latitudes. The duration of a full reversal varies between 2,000 and 12,000 years.
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161:. Although it was discovered that some rocks would reverse their magnetic field while cooling, it became apparent that most magnetized volcanic rocks preserved traces of the Earth's magnetic field at the time the rocks had cooled. In the absence of reliable methods for obtaining absolute ages for rocks, it was thought that reversals occurred approximately every million years.
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120:) for several hundred years, these events are classified as excursions rather than full geomagnetic reversals. Stable polarity chrons often show large, rapid directional excursions, which occur more often than reversals, and could be seen as failed reversals. During such an excursion, the field reverses in the liquid
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particular, the pattern of reversals is random. There is no correlation between the lengths of polarity intervals. There is no preference for either normal or reversed polarity, and no statistical difference between the distributions of these polarities. This lack of bias is also a robust prediction of
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Several studies have analyzed the statistical properties of reversals in the hope of learning something about their underlying mechanism. The discriminating power of statistical tests is limited by the small number of polarity intervals. Nevertheless, some general features are well established. In
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Most estimates for the duration of a polarity transition are between 1,000 and 10,000 years, but some estimates are as quick as a human lifetime. During a transition, the magnetic field will not vanish completely, but many poles might form chaotically in different places during reversal, until it
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could be liberated and bombard the Earth. Detailed calculations confirm that if the Earth's dipole field disappeared entirely (leaving the quadrupole and higher components), most of the atmosphere would become accessible to high-energy particles but would act as a barrier to them, and cosmic ray
693:
ran a numerical model of the coupling between electromagnetism and fluid dynamics in the Earth's interior. Their simulation reproduced key features of the magnetic field over more than 40,000 years of simulated time, and the computer-generated field reversed itself. Global field reversals at
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of reversals, as they are statistically random. The randomness of the reversals is inconsistent with periodicity, but several authors have claimed to find periodicity. However, these results are probably artifacts of an analysis using sliding windows to attempt to determine reversal rates.
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535:
million years ago). Thus far, this possible superchron has only been found in the Moyero river section north of the polar circle in
Siberia. Moreover, the best data from elsewhere in the world do not show evidence for this superchron. Certain regions of ocean floor, older than
346:) has been useful in estimating the age of geologic sections elsewhere. While not an independent dating method, it depends on "absolute" age dating methods like radioisotopic systems to derive numeric ages. It has become especially useful when studying
630:, Oregon, indicate that the Earth's magnetic field is capable of shifting at a rate of up to 6 degrees per day. This was initially met with skepticism from paleomagnetists. Even if changes occur that quickly in the core, the mantle—which is a
338:
Because Earth's magnetic field is a global phenomenon, similar patterns of magnetic variations at different sites may be used to help calculate age in different locations. The past four decades of paleomagnetic data about seafloor ages (up to
543:, have low-amplitude magnetic anomalies that are hard to interpret. They are found off the east coast of North America, the northwest coast of Africa, and the western Pacific. They were once thought to represent a superchron called the
234:
with the known time scale of reversals: sea floor rock is magnetized in the direction of the field when it is formed. Thus, sea floor spreading from a central ridge will produce pairs of magnetic stripes parallel to the ridge. Canadian
486:. The frequency of magnetic reversals steadily decreased prior to the period, reaching its low point (no reversals) during the period. Between the Cretaceous Normal and the present, the frequency has generally increased slowly.
203:
During the 1950s and 1960s information about variations in the Earth's magnetic field was gathered largely by means of research vessels, but the complex routes of ocean cruises rendered the association of navigational data with
156:
was better understood, theories were advanced suggesting that the Earth's field might have reversed in the remote past. Most paleomagnetic research in the late 1950s included an examination of the wandering of the poles and
1892:
Mankinen, Edward A.; Prévot, Michel; Grommé, C. Sherman; Coe, Robert S. (1 January 1985). "The Steens
Mountain (Oregon) Geomagnetic Polarity Transition 1. Directional History, Duration of Episodes, and Rock Magnetism".
763:
Most proposals tying reversals to extinction events assume that the Earth's magnetic field would be much weaker during reversals. Possibly the first such hypothesis was that high-energy particles trapped in the
3099:
Okada, Makoto; Niitsuma, Nobuaki (July 1989). "Detailed paleomagnetic records during the
Brunhes-Matuyama geomagnetic reversal, and a direct determination of depth lag for magnetization in marine sediments".
808:
is still estimated to have been at about three Earth radii during the
Brunhes–Matuyama reversal. Even if the internal magnetic field did disappear, the solar wind can induce a magnetic field in the Earth's
140:
first noticed that some volcanic rocks were magnetized opposite to the direction of the local Earth's field. The first systematic evidence for and time-scale estimate of the magnetic reversals were made by
451:
and the Kiaman. A third candidate, the Moyero, is more controversial. The
Jurassic Quiet Zone in ocean magnetic anomalies was once thought to represent a superchron but is now attributed to other causes.
709:
every 9–12 years. With the Sun it is observed that the solar magnetic intensity greatly increases during a reversal, whereas reversals on Earth seem to occur during periods of low field strength.
701:
In some simulations, this leads to an instability in which the magnetic field spontaneously flips over into the opposite orientation. This scenario is supported by observations of the
673:, blue when the field points towards the center and yellow when away. The rotation axis of the Earth is centered and vertical. The dense clusters of lines are within the Earth's core.
1856:
Prévot, M.; Mankinen, E.; Coe, R.; Grommé, C. (1985). "The Steens
Mountain (Oregon) Geomagnetic Polarity Transition 2. Field Intensity Variations and Discussion of Reversal Models".
431:. Two reversals occurred during a span of 50,000 years. These eras of frequent reversals have been counterbalanced by a few "superchrons": long periods when no reversals took place.
184:
to join their group. They produced the first magnetic-polarity time scale in 1959. As they accumulated data, they continued to refine this scale in competition with Don
Tarling and
716:, think that geomagnetic reversals are not spontaneous processes but rather are triggered by external events that directly disrupt the flow in the Earth's core. Proposals include
657:
million years ago. In 2018, researchers reported a reversal lasting only 200 years. A 2019 paper estimates that the most recent reversal, 780,000 years ago, lasted 22,000 years.
649:) contains a series of reversals and excursions. In addition, geologists Scott Bogue of Occidental College and Jonathan Glen of the US Geological Survey, sampling lava flows in
1239:
331:, whose orientation is influenced by the ambient magnetic field at the time at which they formed. These rocks can preserve a record of the field if it is not later erased by
109:
Reversal occurrences are statistically random. There have been at least 183 reversals over the last 83 million years (on average once every ~450,000 years). The latest, the
653:, found evidence for a brief, several-year-long interval during a reversal when the field direction changed by over 50 degrees. The reversal was dated to approximately 15
1594:
Carbone, V.; Sorriso-Valvo, L.; Vecchio, A.; Lepreti, F.; Veltri, P.; Harabaglia, P.; Guerra, I. (2006). "Clustering of
Polarity Reversals of the Geomagnetic Field".
208:
readings difficult. Only when data were plotted on a map did it become apparent that remarkably regular and continuous magnetic stripes appeared on the ocean floors.
2791:
Raisbeck, G. M.; Yiou, F.; Cattani, O.; Jouzel, J. (2 November 2006). "10Be evidence for the
Matuyama–Brunhes geomagnetic reversal in the EPICA Dome C ice core".
2382:
1741:
1663:
745:
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mechanisms were proposed that would lead to a false signal. That said, paleomagnetic studies of other sections from the same region (the Oregon
Plateau
689:
of planetary dynamos, reversals often emerge spontaneously from the underlying dynamics. For example, Gary Glatzmaier and collaborator Paul Roberts of
785:, which led to the magnetic field strength dropping to an estimated 5% of normal during the reversal. There is evidence that this occurs both during
756:
Shortly after the first geomagnetic polarity time scales were produced, scientists began exploring the possibility that reversals could be linked to
258:
2241:
Coe, Robert S.; Hongré, Lionel; Glatzmaier, Gary A. (2000). "An Examination of Simulated Geomagnetic Reversals from a Palaeomagnetic Perspective".
744:
for a correlation between reversals and impact events is weak. There is no evidence for a reversal connected with the impact event that caused the
3234:
300:. Dark areas denote periods where the polarity matches today's polarity, while light areas denote periods where that polarity is reversed. The
1785:
Coe, R. S.; Prévot, M.; Camps, P. (20 April 1995). "New evidence for extraordinarily rapid change of the geomagnetic field during a reversal".
1700:
Leonardo Sagnotti; Giancarlo Scardia; Biagio Giaccio; Joseph C. Liddicoat; Sebastien Nomade; Paul R. Renne; Courtney J. Sprain (21 July 2014).
969:
Nowaczyk, N.R.; Arz, H.W.; Frank, U.; Kind, J.; Plessen, B. (2012). "Dynamics of the Laschamp geomagnetic excursion from Black Sea sediments".
1840:
1341:
1301:
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measurements show that the magnetic field has not disappeared during reversals. Based on paleointensity data for the last 800,000 years, the
561:, and these sections of ocean floor are especially deep, causing the geomagnetic signal to be attenuated between the seabed and the surface.
197:
60:). Dark areas denote periods where the polarity matches today's normal polarity; light areas denote periods where that polarity is reversed.
2224:; Marie, L.; Ravelet, F.; Bourgoin, M.; Odier, P.; Pinton, J.-F.; Volk, R. "Magnetic field reversals in an experimental turbulent dynamo".
1202:
849:"The last magnetic pole flip saw 22,000 years of weirdness – When the Earth's magnetic poles trade places, they take a while to get sorted"
3148:
2157:
Glatzmaier, Gary A.; Roberts, Paul H. (1995). "A three dimensional self-consistent computer simulation of a geomagnetic field reversal".
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because it had no magnetic field to protect it. They predict that ions would be stripped away from Earth's atmosphere above 100 km.
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3138:
3089:
3070:
954:
3177:
3013:
1934:
1569:
1429:
1407:
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Cande, S. C.; Kent, D. V. (1995). "Revised calibration of the geomagnetic polarity timescale for the late Cretaceous and Cenozoic".
1098:
1054:
848:
2634:"Ice age polarity reversal was global event: Extremely brief reversal of geomagnetic field, climate variability, and super volcano"
547:, but magnetic anomalies are found on land during this period. The geomagnetic field is known to have low intensity between about
372:
Through analysis of seafloor magnetic anomalies and dating of reversal sequences on land, paleomagnetists have been developing a
609:
with long-ranging correlations between events in time. The data are also consistent with a deterministic, but chaotic, process.
149:
age or older. At the time, the Earth's polarity was poorly understood, and the possibility of reversal aroused little interest.
128:. Diffusion in the outer core is on timescales of 500 years or less while that of the inner core is longer, around 3,000 years.
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flows on land. Beginning in 1966, Lamont–Doherty Geological Observatory scientists found that the magnetic profiles across the
247:
177:
2664:"Geomagnetic modulation of the late Pleistocene cosmic-ray flux as determined by 10Be from Blake Outer Ridge marine sediments"
1990:
Bogue, S.W. (10 November 2010). "Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow".
189:
38:
792:
A hypothesis by McCormac and Evans assumes that the Earth's field disappears entirely during reversals. They argue that the
110:
3397:
822:
786:
253:
280:. The same magnetic anomalies were found over most of the world's oceans, which permitted estimates for when most of the
3080:
Ogg, J. G. (2012). "Geomagnetic polarity time scale". In Gradstein, F. M.; Ogg, J. G.; Schmitz, Mark; Ogg, Gabi (eds.).
2333:
2292:
2195:
642:) give consistent results. It appears that the reversed-to-normal polarity transition that marks the end of Chron C5Cr (
3227:
2034:
3033:
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1329:
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independently proposed a similar explanation in January 1963, but his work was rejected by the scientific journals
2468:
Courtillot, V.; Olson, P. (2007). "Mantle plumes link magnetic superchrons to phanerozoic mass depletion events".
1745:
3375:
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185:
153:
89:
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of molten iron in the planetary core generates electric currents which in turn give rise to magnetic fields. In
2701:
Baumgartner, S. (27 February 1998). "Geomagnetic Modulation of the 36Cl Flux in the GRIP Ice Core, Greenland".
1194:
765:
211:
2221:
1930:"Evidence from lava flows for complex polarity transitions: the new composite Steens Mountain reversal record"
878:
Clement, Bradford M. (2004). "Dependence of the duration of geomagnetic polarity reversals on site latitude".
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Glassmeier, Karl-Heinz; Vogt, Joachim (29 May 2010). "Magnetic Polarity Transitions and Biospheric Effects".
2526:
3402:
3351:
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Birk, G. T.; Lesch, H.; Konz, C. (2004). "Solar wind induced magnetic field around the unmagnetized Earth".
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Plotnick, Roy E. (1 January 1980). "Relationship between biological extinctions and geomagnetic reversals".
1596:
650:
273:
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2350:
598:
513:
2668:
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
3363:
3277:
686:
2588:
Uffen, Robert J. (13 April 1963). "Influence of the Earth's Core on the Origin and Evolution of Life".
2380:
McFadden, P. L.; Merrill, R. T. (1986). "Geodynamo energy source constraints from paleomagnetic data".
448:
424:, 13 reversals occurred. No fewer than 51 reversals occurred in a 12-million-year period, centering on
125:
121:
44:
2129:
2063:"Synchronizing volcanic, sedimentary, and ice core records of Earth's last magnetic polarity reversal"
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polarity, in which the predominant direction of the field was the same as the present direction, and
3203:
2355:
665:
3407:
3272:
2417:
Merrill, R. T.; McFadden, P. L. (20 April 1990). "Paleomagnetism and the Nature of the Geodynamo".
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367:
180:, wanted to know whether reversals occurred at regular intervals, and they invited geochronologist
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Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
512:. The magnetic field had reversed polarity. The name "Kiaman" derives from the Australian town of
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2015:
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The magnetic field of the Earth, and of other planets that have magnetic fields, is generated by
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17:
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Berhanu, M.; Monchaux, R.; Fauve, S.; Mordant, N.; Petrelis, F.; Chiffaudel, A.; Daviaud, F.;
2110:
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2007:
1951:
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1371:
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1013:
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978:
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634:—is thought to remove variations with periods less than a few months. A variety of possible
347:
324:
241:
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McHargue, L.R; Donahue, D; Damon, P.E; Sonett, C.P; Biddulph, D; Burr, G (1 October 2000).
1114:
Vine, Frederick J.; Drummond H. Matthews (1963). "Magnetic Anomalies over Oceanic Ridges".
3317:
1702:"Extremely rapid directional change during Matuyama-Brunhes geomagnetic polarity reversal"
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superchron is visible as the broad, uninterrupted black band near the middle of the image.
277:
236:
181:
137:
2061:
Singer, Brad S.; Jicha, Brian R.; Mochizuki, Nobutatsu; Coe, Robert S. (August 7, 2019).
261:
was the first key scientific test of the seafloor spreading theory of continental drift.
200:
showed that the same pattern of reversals was recorded in sediments from deep-sea cores.
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NASA computer simulation using the model of Glatzmaier and Roberts. The tubes represent
395:, the field reversed 5 times in a million years. In a 4-million-year period centered on
388:
The rate of reversals in the Earth's magnetic field has varied widely over time. Around
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North Pole, South Pole: The epic quest to solve the great mystery of Earth's magnetism
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2019:
1956:
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173:
69:
31:
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2895:"Global changes in intensity of the Earth's magnetic field during the past 800 kyr"
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770:
741:
733:
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516:, where some of the first geological evidence of the superchron was found in 1925.
355:
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205:
169:
116:
Although there have been periods in which the field reversed globally (such as the
57:
2722:
1627:
1247:
720:
or internal events such as the arrival of continental slabs carried down into the
2986:
2438:
1228:
Banerjee, Subir K. (2001-03-02). "When the Compass Stopped Reversing Its Poles".
251:, and remained unpublished until 1967, when it appeared in the literary magazine
145:
in the late 1920s; he observed that rocks with reversed fields were all of early
3332:
3307:
774:
706:
146:
2491:
986:
937:
Glatzmaier, G.A.; Coe, R.S. (2015), "Magnetic Polarity Reversals in the Core",
3297:
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1290:
The magnetic field of the earth: paleomagnetism, the core, and the deep mantle
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682:
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85:
81:
53:
2199:
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907:
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2313:
1914:
1878:
483:
320:
2820:
2746:"Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal"
2446:
2264:
2114:
2087:
1771:
1635:
1498:
1469:
Raup, David M. (28 March 1985). "Magnetic reversals and mass extinctions".
1255:
915:
164:
The next major advance in understanding reversals came when techniques for
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2730:
2969:
2365:
2328:
2039:
2011:
1726:
1701:
778:
507:
297:
49:
2812:
1610:
1288:
Merrill, Ronald T.; McElhinny, Michael W.; McFadden, Phillip L. (1998).
1085:
The Road to Jaramillo: Critical Years of the Revolution in Earth Science
899:
469:
3287:
3282:
1049:. San Francisco, California: W. H. Freeman. pp. 138–145, 222–228.
498:
376:. The current time scale contains 184 polarity intervals in the last 83
328:
323:) old, other methods are necessary for detecting older reversals. Most
269:
3049:
2870:
2843:
1180:
644:
585:
Most statistical models of reversals have analyzed them in terms of a
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1546:
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1135:
556:
549:
538:
479:
341:
314:
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1523:
Lutz, T. M. (1985). "The magnetic reversal record is not periodic".
1206:
426:
419:
404:
397:
390:
2744:
Raisbeck, G. M.; Yiou, F.; Bourles, D.; Kent, D. V. (23 May 1985).
30:"Magnetic reversal" redirects here. For switching of a magnet, see
2921:
2130:"Earth's Last Magnetic-Pole Flip Took Much Longer Than We Thought"
291:
210:
43:
1928:
Jarboe, Nicholas A.; Coe, Robert S.; Glen, Jonathan M.G. (2011).
1659:"Analysis of scaling in the geomagnetic polarity reversal record"
276:
were symmetrical and matched the pattern in the north Atlantic's
100:
polarity, in which it was the opposite. These periods are called
3212:
690:
3216:
447:
million years. There are two well-established superchrons, the
37:"Polarity reversal" redirects here. For a seismic anomaly, see
1002:"The distinction between geomagnetic excursions and reversals"
694:
irregular intervals have also been observed in the laboratory
3195:
Is it true that the Earth's magnetic field is about to flip?
3034:"How Are Geomagnetic Reversals Related to Field Intensity?"
813:
sufficient to shield the surface from energetic particles.
523:
is suspected to have hosted another superchron, called the
1324:
Evolutionary Catastrophes: the Science of Mass Extinctions
2842:
McCormac, Billy M.; Evans, John E. (20 September 1969).
2527:
10.1130/0091-7613(1980)8<578:RBBEAG>2.0.CO;2
1370:(2). International Union of Geological Sciences: 78–84.
268:
minerals of consolidated sedimentary deposits or cooled
2844:"Consequences of Very Small Planetary Magnetic Moments"
1425:"Spectral analysis of geomagnetic reversal time scales"
2035:"Researchers find fast flip in Earth's magnetic field"
781:
showed a peak of beryllium-10 during a brief complete
48:
Geomagnetic polarity during the last 5 million years (
1833:
Our magnetic Earth : the science of geomagnetism
1430:
Geophysical Journal of the Royal Astronomical Society
3014:"Ships' logs give clues to Earth's magnetic decline"
1394:
McElhinny, Michael W.; McFadden, Phillip L. (2000).
264:
Past field reversals are recorded in the solidified
1240:
American Association for the Advancement of Science
1321:
1082:
2893:Guyodo, Yohan; Valet, Jean-Pierre (20 May 1999).
2540:
2538:
2536:
2288:"Geomagnetic reversals from impacts on the Earth"
2152:
2150:
769:collisions would produce secondary radiation of
1360:"A third superchron during the Early Paleozoic"
626:Studies of 16.7-million-year-old lava flows on
226:provided a simple explanation by combining the
27:Reversal of direction of Earth's magnetic field
2286:Muller, Richard A.; Morris, Donald E. (1986).
1826:
1824:
1570:"Geomagnetic flip may not be random after all"
308:Because no existing unsubducted sea floor (or
136:In the early 20th century, geologists such as
3228:
3204:Pole Reversal Happens All The (Geologic) Time
1765:
1763:
380:million years (and therefore 183 reversals).
8:
3102:Physics of the Earth and Planetary Interiors
3065:(2nd ed.). Cambridge University Press.
2383:Physics of the Earth and Planetary Interiors
1835:. Chicago: The University of Chicago Press.
1664:Physics of the Earth and Planetary Interiors
1389:
1387:
1348:Translated from the French by Joe McClinton.
3084:(1st ed.). Elsevier. pp. 85–114.
1464:
1462:
601:found that the reversals also conform to a
3235:
3221:
3213:
2128:Science, Passant; Rabie (August 7, 2019).
1973:"Earth's Magnetic Field Flipped Superfast"
1283:
1281:
1279:
1277:
1275:
1273:
443:is a polarity interval lasting at least 10
409:, 17 reversals took place in the span of 3
80:are interchanged (not to be confused with
2968:
2929:
2869:
2364:
2354:
2104:
2086:
1955:
1725:
1684:
1609:
1450:
1375:
1037:
1035:
1033:
1031:
1029:
1017:
2329:"Avalanches at the core-mantle boundary"
1047:Plate tectonics and geomagnetic reversal
664:
327:incorporate minute amounts of iron-rich
310:sea floor thrust onto continental plates
3063:Reversals of the Earth's magnetic field
1518:
1516:
839:
597:. In 2006, a team of physicists at the
333:chemical, physical or biological change
3082:The geologic time scale 2012. Volume 2
1971:Witze, Alexandra (September 2, 2010).
1076:
1074:
1072:
1070:
1068:
1066:
296:Geomagnetic polarity since the middle
1396:Paleomagnetism: Continents and Oceans
746:Cretaceous–Paleogene extinction event
402:, there were 10 reversals; at around
7:
3370:
3032:Hoffman, Kenneth A. (18 July 1995).
1203:Woods Hole Oceanographic Institution
1199:Ocean Bottom Magnetometry Laboratory
873:
871:
847:Johnson, Scott K. (11 August 2019).
2471:Earth and Planetary Science Letters
1742:"Earth's Inconstant Magnetic Field"
971:Earth and Planetary Science Letters
777:. A 2012 German study of Greenland
493:lasted from approximately the late
1452:10.1111/j.1365-246X.1976.tb00311.x
947:10.1016/b978-0-444-53802-4.00146-9
92:has alternated between periods of
25:
2194:Glatzmaier, Gary; Roberts, Paul.
1935:Geophysical Journal International
1423:Phillips, J. D.; Cox, A. (1976).
1006:Geophysical Journal International
796:may have been eroded away by the
3369:
3357:
3346:
3345:
3172:. New York, NY: The Experiment.
2033:Byrd, Deborah (21 August 2018).
1957:10.1111/j.1365-246X.2011.05086.x
1195:"Geomagnetic Polarity Timescale"
1019:10.1046/j.1365-246x.1999.00810.x
198:Lamont–Doherty Earth Observatory
3149:"Look down, look up, look out!"
1895:Journal of Geophysical Research
1377:10.18814/epiiugs/2005/v28i2/001
1358:Pavlov, V.; Gallet, Y. (2005).
1160:Journal of Geophysical Research
413:million years. In a period of 3
374:Geomagnetic Polarity Time Scale
362:Geomagnetic polarity time scale
259:Morley–Vine–Matthews hypothesis
248:Journal of Geophysical Research
178:United States Geological Survey
18:Geomagnetic polarity time scale
3012:Barry, Patrick (11 May 2006).
2230:. Vol. 77. p. 59001.
1568:Dumé, Belle (March 21, 2006).
941:, Elsevier, pp. 279–295,
705:, which undergoes spontaneous
190:Australian National University
39:Polarity reversal (seismology)
1:
2723:10.1126/science.279.5355.1330
2688:10.1016/S0168-583X(00)00092-6
1628:10.1103/PhysRevLett.96.128501
1248:10.1126/science.291.5509.1714
823:List of geomagnetic reversals
3122:10.1016/0031-9201(89)90043-5
2956:Astronomy & Astrophysics
2439:10.1126/science.248.4953.345
2404:10.1016/0031-9201(86)90118-4
2334:Geophysical Research Letters
2293:Geophysical Research Letters
1686:10.1016/0031-9201(89)90117-9
463:or C34) lasted for almost 40
384:Changing frequency over time
168:were improved in the 1950s.
1831:Merrill, Ronald T. (2010).
505:million years, from around
417:million years centering on
72:such that the positions of
3424:
2987:10.1051/0004-6361:20040154
2492:10.1016/j.epsl.2007.06.003
1330:Cambridge University Press
987:10.1016/j.epsl.2012.06.050
474:, including stages of the
467:million years, from about
365:
152:Three decades later, when
68:is a change in a planet's
36:
29:
3341:
3268:
3250:
3200:, accessed 8 January 2019
2567:10.1007/s11214-010-9659-6
1091:Stanford University Press
783:reversal 41,000 years ago
732:or the initiation of new
712:Some scientists, such as
531:million years (485 to 463
525:Moyero Reverse Superchron
491:Kiaman Reverse Superchron
111:Brunhes–Matuyama reversal
3168:Turner, Gillian (2011).
3129:Opdyke, Neil D. (1996).
766:Van Allen radiation belt
613:Character of transitions
3209:, accessed 1 March 2022
2979:2004A&A...420L..15B
2484:2007E&PSL.260..495C
2314:10.1029/GL013i011p01177
2196:"When North goes South"
1915:10.1029/JB090iB12p10393
1879:10.1029/JB090iB12p10417
1597:Physical Review Letters
1000:Gubbins, David (1999).
979:2012E&PSL.351...54N
651:Battle Mountain, Nevada
647: million years ago
274:Pacific-Antarctic Ridge
3061:Jacobs, J. A. (1994).
2265:10.1098/rsta.2000.0578
2088:10.1126/sciadv.aaw4621
1081:Glen, William (1982).
939:Treatise on Geophysics
789:and during reversals.
674:
599:University of Calabria
565:Statistical properties
527:, lasting more than 20
358:are seldom available.
305:
215:
154:Earth's magnetic field
90:Earth's magnetic field
61:
32:Magnetization reversal
3278:Environmental science
3131:Magnetic stratigraphy
2547:Space Science Reviews
668:
501:, or for more than 50
461:Cretaceous Superchron
366:Further information:
312:) is more than about
295:
288:Observing past fields
214:
124:but not in the solid
70:dipole magnetic field
47:
3398:Geomagnetic reversal
2366:10.1029/2002GL015938
2327:Muller, RA. (2002).
2012:10.1029/2010GL044286
1865:(B12): 10417–10448.
752:Effects on biosphere
738:core-mantle boundary
703:solar magnetic field
671:magnetic field lines
607:stochastic processes
508:312 to 262
66:geomagnetic reversal
3273:Atmospheric science
3114:1989PEPI...56..133O
2914:1999Natur.399..249G
2862:1969Natur.223.1255M
2813:10.1038/nature05266
2805:2006Natur.444...82R
2762:1985Natur.315..315R
2715:1998Sci...279.1330B
2709:(5355): 1330–1332.
2680:2000NIMPB.172..555M
2604:1963Natur.198..143U
2559:2010SSRv..155..387G
2519:1980Geo.....8..578P
2431:1990Sci...248..345M
2396:1986PEPI...43...22M
2347:2002GeoRL..29.1935M
2306:1986GeoRL..13.1177M
2257:2000RSPTA.358.1141C
2251:(1768): 1141–1170.
2173:1995Natur.377..203G
2079:2019SciA....5.4621S
2004:2010GeoRL..3721308B
1948:2011GeoJI.186..580J
1907:1985JGR....9010393M
1871:1985JGR....9010417P
1799:1995Natur.374..687C
1718:2014GeoJI.199.1110S
1677:1989PEPI...57..284G
1657:Gaffin, S. (1989).
1620:2006PhRvL..96l8501C
1539:1985Natur.317..404L
1483:1985Natur.314..341R
1443:1976GeoJ...45...19P
1318:Courtillot, Vincent
1173:1995JGR...100.6093C
1128:1963Natur.199..947V
900:10.1038/nature02459
892:2004Natur.428..637C
698:experiment "VKS2".
545:Jurassic Quiet Zone
470:120 to 83
368:Magnetostratigraphy
3323:Physical geography
3133:. Academic Press.
1992:Geophys. Res. Lett
1770:Glatzmaier, Gary.
1748:on 1 November 2022
1727:10.1093/gji/ggu287
973:. 351–352: 54–69.
794:atmosphere of Mars
675:
623:stabilizes again.
605:, which describes
589:or other kinds of
306:
228:seafloor spreading
216:
166:radiometric dating
118:Laschamp excursion
62:
3385:
3384:
3056:on 16 March 2009.
3050:10.1029/95EO00172
2908:(6733): 249–252.
2871:10.1038/2231255a0
2756:(6017): 315–317.
2598:(4876): 143–144.
2425:(4953): 345–350.
2300:(11): 1177–1180.
2167:(6546): 203–209.
1842:978-0-226-52050-6
1533:(6036): 404–407.
1477:(6009): 341–343.
1343:978-0-521-58392-3
1303:978-0-12-491246-5
1209:on August 9, 2016
1181:10.1029/94JB03098
1167:(B4): 6093–6095.
1122:(4897): 947–949.
886:(6983): 637–640.
787:secular variation
758:extinction events
724:by the action of
714:Richard A. Muller
603:LĂ©vy distribution
510:million years ago
472:million years ago
459:(also called the
457:Cretaceous Normal
449:Cretaceous Normal
354:formations where
325:sedimentary rocks
302:Cretaceous Normal
224:Drummond Matthews
192:. A group led by
159:continental drift
143:Motonori Matuyama
16:(Redirected from
3415:
3373:
3372:
3361:
3349:
3348:
3237:
3230:
3223:
3214:
3183:
3164:
3162:
3160:
3144:
3125:
3108:(1–2): 133–150.
3095:
3076:
3057:
3052:. Archived from
3028:
3026:
3024:
2999:
2998:
2972:
2970:astro-ph/0404580
2950:
2944:
2943:
2933:
2899:
2890:
2884:
2883:
2873:
2839:
2833:
2832:
2788:
2782:
2781:
2770:10.1038/315315a0
2741:
2735:
2734:
2698:
2692:
2691:
2674:(1–4): 555–561.
2659:
2653:
2652:
2650:
2649:
2638:Sciencedaily.com
2630:
2624:
2623:
2612:10.1038/198143b0
2585:
2579:
2578:
2553:(1–4): 387–410.
2542:
2531:
2530:
2502:
2496:
2495:
2478:(3–4): 495–504.
2465:
2459:
2458:
2414:
2408:
2407:
2377:
2371:
2370:
2368:
2358:
2324:
2318:
2317:
2283:
2277:
2276:
2238:
2232:
2231:
2217:
2211:
2210:
2208:
2207:
2198:. Archived from
2191:
2185:
2184:
2181:10.1038/377203a0
2154:
2145:
2144:
2142:
2140:
2125:
2119:
2118:
2108:
2090:
2067:Science Advances
2058:
2052:
2051:
2049:
2047:
2030:
2024:
2023:
1987:
1981:
1980:
1968:
1962:
1961:
1959:
1925:
1919:
1918:
1889:
1883:
1882:
1859:J. Geophys. Res.
1853:
1847:
1846:
1828:
1819:
1818:
1807:10.1038/374687a0
1782:
1776:
1775:
1767:
1758:
1757:
1755:
1753:
1744:. Archived from
1738:
1732:
1731:
1729:
1712:(2): 1110–1124.
1697:
1691:
1690:
1688:
1671:(3–4): 284–289.
1654:
1648:
1647:
1613:
1591:
1585:
1584:
1582:
1580:
1574:physicsworld.com
1565:
1559:
1558:
1547:10.1038/317404a0
1520:
1511:
1510:
1491:10.1038/314341a0
1466:
1457:
1456:
1454:
1420:
1414:
1413:
1391:
1382:
1381:
1379:
1355:
1349:
1347:
1327:
1314:
1308:
1307:
1285:
1268:
1267:
1225:
1219:
1218:
1216:
1214:
1205:. Archived from
1191:
1185:
1184:
1154:
1148:
1147:
1136:10.1038/199947a0
1111:
1105:
1104:
1088:
1078:
1061:
1060:
1039:
1024:
1023:
1021:
997:
991:
990:
966:
960:
959:
934:
928:
927:
875:
866:
865:
863:
861:
844:
829:Magnetic anomaly
825:, including ages
730:subduction zones
656:
648:
560:
553:
542:
534:
530:
511:
504:
478:period from the
473:
466:
446:
430:
423:
416:
412:
408:
401:
394:
379:
345:
318:
86:geographic south
82:geographic north
21:
3423:
3422:
3418:
3417:
3416:
3414:
3413:
3412:
3388:
3387:
3386:
3381:
3337:
3318:Paleogeoscience
3264:
3246:
3241:
3191:
3186:
3180:
3167:
3158:
3156:
3147:
3141:
3128:
3098:
3092:
3079:
3073:
3060:
3031:
3022:
3020:
3011:
3007:
3005:Further reading
3002:
2952:
2951:
2947:
2897:
2892:
2891:
2887:
2841:
2840:
2836:
2799:(7115): 82–84.
2790:
2789:
2785:
2743:
2742:
2738:
2700:
2699:
2695:
2661:
2660:
2656:
2647:
2645:
2632:
2631:
2627:
2587:
2586:
2582:
2544:
2543:
2534:
2504:
2503:
2499:
2467:
2466:
2462:
2416:
2415:
2411:
2379:
2378:
2374:
2356:10.1.1.508.8308
2326:
2325:
2321:
2285:
2284:
2280:
2240:
2239:
2235:
2219:
2218:
2214:
2205:
2203:
2193:
2192:
2188:
2156:
2155:
2148:
2138:
2136:
2127:
2126:
2122:
2073:(8): eaaw4621.
2060:
2059:
2055:
2045:
2043:
2032:
2031:
2027:
1989:
1988:
1984:
1970:
1969:
1965:
1927:
1926:
1922:
1891:
1890:
1886:
1855:
1854:
1850:
1843:
1830:
1829:
1822:
1784:
1783:
1779:
1772:"The Geodynamo"
1769:
1768:
1761:
1751:
1749:
1740:
1739:
1735:
1706:Geophys. J. Int
1699:
1698:
1694:
1656:
1655:
1651:
1611:physics/0603086
1593:
1592:
1588:
1578:
1576:
1567:
1566:
1562:
1522:
1521:
1514:
1468:
1467:
1460:
1422:
1421:
1417:
1410:
1393:
1392:
1385:
1357:
1356:
1352:
1344:
1316:
1315:
1311:
1304:
1287:
1286:
1271:
1227:
1226:
1222:
1212:
1210:
1193:
1192:
1188:
1156:
1155:
1151:
1113:
1112:
1108:
1101:
1080:
1079:
1064:
1057:
1041:
1040:
1027:
999:
998:
994:
968:
967:
963:
957:
936:
935:
931:
877:
876:
869:
859:
857:
846:
845:
841:
837:
819:
754:
726:plate tectonics
663:
654:
643:
628:Steens Mountain
620:
615:
591:renewal process
587:Poisson process
567:
555:
548:
537:
532:
528:
506:
502:
468:
464:
444:
437:
425:
418:
414:
410:
403:
396:
389:
386:
377:
370:
364:
340:
313:
290:
284:had developed.
278:Reykjanes ridge
254:Saturday Review
182:Brent Dalrymple
138:Bernard Brunhes
134:
42:
35:
28:
23:
22:
15:
12:
11:
5:
3421:
3419:
3411:
3410:
3405:
3403:Paleomagnetism
3400:
3390:
3389:
3383:
3382:
3380:
3379:
3367:
3355:
3342:
3339:
3338:
3336:
3335:
3330:
3325:
3320:
3315:
3310:
3305:
3300:
3295:
3290:
3285:
3280:
3275:
3269:
3266:
3265:
3263:
3262:
3257:
3251:
3248:
3247:
3242:
3240:
3239:
3232:
3225:
3217:
3211:
3210:
3201:
3190:
3189:External links
3187:
3185:
3184:
3178:
3165:
3145:
3140:978-0080535722
3139:
3126:
3096:
3091:978-0444594259
3090:
3077:
3072:978-0521450720
3071:
3058:
3029:
3008:
3006:
3003:
3001:
3000:
2963:(2): L15–L18.
2945:
2885:
2856:(5212): 1255.
2834:
2783:
2736:
2693:
2654:
2625:
2580:
2532:
2497:
2460:
2409:
2372:
2319:
2278:
2233:
2212:
2186:
2146:
2120:
2053:
2025:
1998:(21): L21308.
1982:
1963:
1942:(2): 580–602.
1920:
1901:(B12): 10393.
1884:
1848:
1841:
1820:
1777:
1759:
1733:
1692:
1649:
1604:(12): 128501.
1586:
1560:
1512:
1458:
1415:
1408:
1400:Academic Press
1383:
1350:
1342:
1309:
1302:
1294:Academic Press
1269:
1220:
1186:
1149:
1106:
1099:
1062:
1055:
1025:
992:
961:
956:978-0444538031
955:
929:
867:
838:
836:
833:
832:
831:
826:
818:
815:
802:Paleointensity
753:
750:
662:
659:
619:
616:
614:
611:
566:
563:
436:
433:
385:
382:
363:
360:
289:
286:
220:Frederick Vine
133:
130:
78:magnetic south
74:magnetic north
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
3420:
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3406:
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3329:
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3309:
3306:
3304:
3301:
3299:
3296:
3294:
3291:
3289:
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3284:
3281:
3279:
3276:
3274:
3271:
3270:
3267:
3261:
3258:
3256:
3253:
3252:
3249:
3245:
3244:Earth science
3238:
3233:
3231:
3226:
3224:
3219:
3218:
3215:
3208:
3205:
3202:
3199:
3196:
3193:
3192:
3188:
3181:
3179:9781615190317
3175:
3171:
3166:
3155:. 10 May 2007
3154:
3153:The Economist
3150:
3146:
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3136:
3132:
3127:
3123:
3119:
3115:
3111:
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3103:
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3093:
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3083:
3078:
3074:
3068:
3064:
3059:
3055:
3051:
3047:
3043:
3039:
3035:
3030:
3019:
3018:New Scientist
3015:
3010:
3009:
3004:
2996:
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2966:
2962:
2958:
2957:
2949:
2946:
2941:
2937:
2932:
2927:
2923:
2922:10.1038/20420
2919:
2915:
2911:
2907:
2903:
2896:
2889:
2886:
2881:
2877:
2872:
2867:
2863:
2859:
2855:
2851:
2850:
2845:
2838:
2835:
2830:
2826:
2822:
2818:
2814:
2810:
2806:
2802:
2798:
2794:
2787:
2784:
2779:
2775:
2771:
2767:
2763:
2759:
2755:
2751:
2747:
2740:
2737:
2732:
2728:
2724:
2720:
2716:
2712:
2708:
2704:
2697:
2694:
2689:
2685:
2681:
2677:
2673:
2669:
2665:
2658:
2655:
2643:
2642:Science Daily
2639:
2635:
2629:
2626:
2621:
2617:
2613:
2609:
2605:
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3054:the original
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2644:. 2012-10-16
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2133:
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2038:
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1976:
1966:
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1746:the original
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1579:December 27,
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1207:the original
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858:. Retrieved
854:Ars Technica
852:
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806:magnetopause
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771:beryllium-10
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3308:Meteorology
3198:physics.org
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687:simulations
435:Superchrons
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147:Pleistocene
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3293:Geophysics
2648:2013-07-28
2206:2006-04-09
1043:Cox, Allan
835:References
811:ionosphere
798:solar wind
683:convection
521:Ordovician
476:Cretaceous
441:superchron
232:Harry Hess
230:theory of
126:inner core
122:outer core
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3303:Hydrology
3159:8 January
3023:8 January
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860:11 August
779:ice cores
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484:Santonian
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176:, at the
170:Allan Cox
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2995:15352610
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1256:11253196
1238:(5509).
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817:See also
618:Duration
329:minerals
298:Jurassic
270:volcanic
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3283:Geodesy
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242:Nature
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2991:S2CID
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2016:S2CID
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1640:S2CID
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920:S2CID
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3207:NASA
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3161:2019
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3067:ISBN
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2817:PMID
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