UPDATE 17 June 2015
The illusory Settled Science of Palaeomagnetism morphs into the realm of Super Surreal Science [a brand new category] simply because they forgot all about Photomagnetism.
On the Magnetising Power of the Solar Rays
Professor Barlocci found that an armed natural loadstone, which could carry l.5 Roman pounds, had its power nearly doubled by twenty-four hours’ exposure to the strong light of the sun.
M. Zantedeschi found that an artificial horse-shoe loadstone, which carried 13.5 oz., carried 3.5 more by three days’ exposure, and at last supported 31 oz., by continuing it in the sun’s light.
He found, that while the strength increased in oxidated magnets, it diminished in those which were not oxidated, the diminution becoming insensible when the loadstone was highly polished.
He now concentrated the solar rays upon the loadstone by means of a lens; and he found that, both in oxidated and polished magnets, they acquire strength when their north pole is exposed to the sun’s rays, and lose strength when the south pole is exposed.
He found likewise that the augmentation in the first case exceeded the diminution in the second.
A Treatise on Optics – David Brewster – 1838
Simply put for the benefit of Earth Scientists:
Surface magnetism can be determined by exposure to sunlight and surface exposure to sunlight over thousands, millions or billions of years will determine surface magnetism because iron and magnetite are ubiquitous in surface rocks.
Magnetite is a mineral, one of the three common naturally occurring iron oxides (chemical formula Fe3O4) and a member of the spinel group.
Magnetite is the most magnetic of all the naturally occurring minerals on Earth.
Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, and this was how ancient people first noticed the property of magnetism.
Small grains of magnetite occur in almost all igneous and metamorphic rocks.
END of UPDATE 17 June 2015
Palaeomagnetism details a history of the Earth that is littered with Magnetic Reversals.
A geomagnetic reversal is a change in the Earth’s magnetic field such that the positions of magnetic north and magnetic south are interchanged.
The Earth’s field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was the opposite.
These periods are called chrons.
The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years with an average of 450,000 years.
Most reversals are estimated to take between 1,000 and 10,000 years.
The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago.
Unfortunately, nobody knows why the Earth’s repeatedly flips into reversed polarity.
Unfortunately, nobody knows why the Earth’s repeatedly flips back to normal polarity.
Unfortunately, nobody has actually observed the Earth perform a polarity flip of any sort.
Observationally, Magnetic Reversals are on a par with Ice Ages and the Tooth Fairy.
The “scientific” literature is littered with hypothetical magnetic poles, hypothetical geomagnetic dipoles, hypothetical geo-dynamos, hypothetical magnetic reversals and very little of scientific substance.
Theoretically, Magnetic Reversals are as credible as Enid Blyton and the brothers Grimm.
Therefore, it is advisable to review the “science” of Palaeomagnetism to ensure Magnetic Reversals are not simply expensive Logic Reversals.
Unfortunately, the interpretation of Palaeomagnetic “data” is not straightforward.
Firstly, the intensity and location of the Earth’s magnetic poles is continually changing.
These changes can be very rapid [and significant] and NOAA [for example] has only modelled the Earth’s magnetic field back to 1,590 CE based upon “ship log data”.
Basically, it is impossible to model the Earth’s magnetic field prior to 1,590 CE.
Secondly, the location of the geologic sample is continually moving [according to both the Plate Tectonics and Expanding Earth theories] in a geologic timeframe.
Thirdly, even if you can establish the configuration of the Earth’s magnetic field [for a specific date] and the specific geographic location of the Palaeomagnetic specimen then you have to determine which Magnetic Poles [or combination of Magnetic Poles] determined the orientation of the magnetic “data” contained within the rock.
This is especially difficult when [as is currently the case] the Earth has four Magnetic Poles or when there is [or was] local magnetic interference.
As early as the 18th century it was noticed that compass needles deviated near strongly magnetized outcrops.
Fundamentally, the problem is that the direction of the North [or South] Magnetic Pole cannot be determined from the magnetic data contained within a geologic sample because the configuration of the Earth’s magnetic field [when the specimen was originally magnetised] is unknown.
The same fundamental problem applies to a compass because it aligns to “the local direction of the Earth’s magnetic field”.
However, the compass reading must be corrected for two effects.
The first is magnetic declination, the angular difference between magnetic North (the local direction of the Earth’s magnetic field) and true North.
The second is magnetic deviation, the angular difference between magnetic North and the compass needle due to nearby sources of iron.
The Earth’s magnetic field is modified by local magnetic anomalies.
These include variations of the magnetization in the Earth’s crust caused by geomagnetic reversals as well as nearby mountains and iron ore deposits.
Generally, these are indicated on maps as part of the declination.
Because the Earth’s field changes over time, the maps must be kept up to date for accurate navigation.
Short term errors in compass readings are also caused by fields generated in the Earth’s magnetosphere, particularly during geomagnetic storms.
The geographical change in variation in some parts of the world is sufficiently rapid to need consideration. For instance, in approaching Halifax from Newfoundland the variation changes by 10° in less than 500 miles, and in the English Channel by about 5° in 400 miles.
Finally, even if the all the previous problems have been resolved you still have to assume that the geological specimen has remained undisturbed [since it was originally magnetised] and that the embedded magnetic data has not be compromised by geothermal heating, weathering, leaching, impacts, compression, buckling, lightning or any other form of electromagnetic activity.
In 1797, Von Humboldt attributed this magnetization to lightning strikes (and lightning strikes do often magnetize surface rocks).
The risk of electromagnetic contamination is particularly high in volcanic rocks because “short duration sparks, recently documented near newly extruded magma, attest to the material being highly charged”.
In the early 20th century geologists first noticed that some volcanic rocks were magnetized opposite to the direction of the local Earth’s field.
Volcanic activity produces lightning-friendly conditions in multiple ways.
The enormous quantity of pulverized material and gases ejected into the atmosphere with explosive power, creates a dense plume of highly charged particles, which establishes the perfect conditions for lightning.
The ash density and constant motion within the volcanic plume, continually produces electrostatic ionization, resulting in very powerful and very frequent flashes attempting to neutralize itself.
Powerful and frequent flashes have been witnessed in the volcanic plume as far back as the 79 AD eruption of Vesuvius by Pliny The Younger.
Likewise, vapors and ash originating from vents on the volcano’s flanks may produce more localized and smaller flashes upwards of 2.9 km long.
Small, short duration sparks, recently documented near newly extruded magma, attest to the material being highly charged prior to even entering the atmosphere.
However, the overall risk of electromagnetic contamination by lighting is truly staggering because, on average, each square metre of the Earth’s surface will be struck by lightning 2.78 times every million years.
Lightning occurs approximately 40–50 times a second worldwide, resulting in nearly 1.4 billion flashes per year.
Overall, the Palaeomagnetic narrative for continental rocks is extremely suspect because of lightning strikes and volcanic activity.
However, the Palaeomagnetic bandwagon initially gathered momentum 50 years ago when astatic magnetometers detected magnetic anomalies on the ocean floor.
The British physicist P.M.S. Blackett provided a major impetus to paleomagnetism by inventing a sensitive astatic magnetometer in 1956. His intent was to test his theory that the geomagnetic field was related to the Earth’s rotation, a theory that he ultimately rejected; but the astatic magnetometer became the basic tool of paleomagnetism and led to a revival of the theory of continental drift.
Alfred Wegener first proposed in 1912 that continents had once been joined together and had since moved apart. Although he produced an abundance of circumstantial evidence, his theory met with little acceptance for two reasons:
(1) no mechanism for continental drift was known, and
(2) there was no way to reconstruct the movements of the continents over time.
Keith Runcorn and Edward A. Irving constructed apparent polar wander paths for Europe and North America. These curves diverged, but could be reconciled if it was assumed that the continents had been in contact up to 200 million years ago. This provided the first clear geophysical evidence for continental drift.
Then in 1963, Morley, Vine and Matthews showed that marine magnetic anomalies provided evidence for seafloor spreading.
However, it is important to note that astatic magnetometers do not detect magnetic polarity.
Astatic magnetometers do detect “magnetic anomalies” by measuring the “magnetic gradient”.
A magnetometer for determining the gradient of a magnetic field by measuring the difference in reading from two magnetometers placed at different positions.
Magnetic gradiometers are pairs of magnetometers with their sensors separated, usually horizontally, by a fixed distance. The readings are subtracted in order to measure the difference between the sensed magnetic fields, which gives the field gradients caused by magnetic anomalies. This is one way of compensating both for the variability in time of the Earth’s magnetic field and for other sources of electromagnetic interference, thus allowing for more sensitive detection of anomalies. Because nearly equal values are being subtracted, the noise performance requirements for the magnetometers is more extreme.
Gradiometers enhance shallow magnetic anomalies and are thus good for archaeological and site investigation work. They are also good for real-time work such as unexploded ordnance location. It is twice as efficient to run a base station and use two (or more) mobile sensors to read parallel lines simultaneously (assuming data is stored and post-processed). In this manner, both along-line and cross-line gradients can be calculated.
The 1963 Vine and Matthews paper indicates that magnetic anomalies can be associated with topographical features on the ocean floor.
The trough of negative anomalies corresponds to a general depression in the bottom topography which represents the median valley of the Ridge.
The positive anomalies correspond to mountains on either side of the valley.
However, Vine and Matthews were earlier pioneers in computer modelling [although they did have the decency to call theirs a “computer programme”] who modelled two “isolated volcano-like structures” which demonstrated opposite magnetic anomalies.
Vine and Matthews concluded that their computer model “results suggested that whole blocks of the survey area might be reversely magnetized” and, as they say, the rest is history.
Thus, Palaeomagnetism gathered momentum without a single oceanic Magnetic Reversals actually being observed [because they were only ever modelled].
Fast forward 50 years and Palaeomagnetism has produced the EMAG2 magnetic anomaly grid.
Interestingly, the EMAG2 map only displays the “total intensity anomaly”.
However, for those individuals that are still convinced these magnetic anomalies represent Magnetic Reversals, there is one other very significant observation that has to be considered.
Wherever the Earth’s surface is fractured [or cracked because of expansion, contraction or faulting] then [as on the planet Mars] “the edges of the cracks will automatically have opposite polarities, because nature does not allow there to be a positive pole without a negative counterpart”.
MAGNETIC STRIPES PRESERVE RECORD OF ANCIENT MARS
Alternate explanations for the banded structure may involve the fracturing and breakup of an ancient, uniformly magnetized crust due to volcanic activity or tectonic stresses from the rise and fall of neighboring terrain.
“Imagine a thin coat of dried paint on a balloon, where the paint is the crust of Mars,” explained Dr. Mario Acuna of Goddard, principal investigator on the Global Surveyor magnetometer. “If we inflate the balloon further, cracks can develop in the paint, and the edges of the cracks will automatically have opposite polarities, because nature does not allow there to be a positive pole without a negative counterpart.”
Image Credit: NASA, Jack Connerney, Mario Acuna, Carol Ladd
Ultimately, the “science” of Magnetic Reversals is just pattern matching.
Sadly, the matches are of different durations and are from different periods.
After 50 years of “study” this is truly pitiful.
After 50 years they still haven’t realised these bands are the “stretch marks” of an Inflating Earth.
Michigan State University – Magnetism Activity