Nov 4, 2021
I've heard this before, but in a different scenario; where the magnetic field itself flipped into reverse. It made more sense. Polarity can reverse itself in a molten global rotating glob of high concentrate metal... surely. If that is not possible, pls enlighten me. Also any change in magnetic normal over a long period over millions of years, is surely going to alter the status quo of the magnetite fossils..everything moves constantly... I am very interested in all this.
Lastly, pls explain how oxygen was a major aerial ignitor during a period when it was constantly being drowned by volcanis spume?
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Nile, first of all, let's look at what's known as paleomagnetism.

The record of Earth’s magnetic field is recorded in specific minerals, which are found in specific types of rock, especially igneous (volcanic) rocks extruded during volcanic activity. These minerals are rich in iron, and whilst the lava is still fluid, they align themselves with the Earth’s magnetic field just like a compass needle while they cool. Once the lava has cooled to form rock, those minerals are a direct record of the strength and orientation of the Earth’s magnetic field at that time they were laid down.

Geologists have collated this record of Earth’s palaeomagnetism, stretching back further than a billion years. In as early as the 1920s, geologists who were studying this record noticed something strange. Some of the magnetic minerals were aligned in the opposite direction to today’s magnetic field, suggesting that at points during Earth’s past history, the north and south pole of Earth’s dipole have swapped. The Earth’s magnetic field has therefore been undergoing both large and small changes throughout its history; these changes over time are known as palaeosecular variation.

Dr Franco* and his team including graduate students Wellington Paulo de Oliveira and Felipe Barbosa Venâncio de Freitas, are using complex numerical models to understand more about the changes in Earth’s palaeomagnetic field and why they might occur. They investigated a geological interval where there are an unusually high number of palaeomagnetic reversals (this high rate of reversal is about 6 reversals per million years). The Illwarra Hyperzone of Mixed Polarity occurred between 267 and 229 million years ago, and the team gathered an in-depth dataset of palaeomagnetic information including the magnetic field polarity (the orientation of the north and south poles of Earth’s axial dipolar field) and paleosecular variation (the long term temporal variations of the Earth’s magnetic field on local, regional, and global scales) throughout that period.

Complex convection currents in the Earth’s core create a vast magnetic field around the Earth, protecting us from the charged solar particles that emanate from the Sun. However, the Earth’s magnetic field has not always been quite the same. Earth’s rocks provide a record of geomagnetic reversals and variations through time in the geomagnetic field. Dr Daniel Franco and his team at the National Observatory of Brazil use complex numerical models to better understand the structure of Earth’s magnetic field and what might cause these changes over geological timescales.

Earth is surrounded by an invisible yet powerful shield: its magnetic field. This is what causes the aurora to dance in the skies around the North and South Pole, and protects life on Earth from the intense stream of solar particles racing across the solar system from our Sun. But how can we understand something we cannot even see?

Humans have been using the Earth’s magnetic field to navigate for hundreds of years using compasses, and this remains the easiest way for us to see Earth’s magnetic field in action. Scientists can also measure its intensity at points around the Earth’s surface, as well as its orientation, and satellites play a vital role in its continued monitoring.

The stability of today’s magnetic field is not only important for protecting life on Earth, it is vital for our technology. Mobile phones depend upon it to correctly identify their location. Increases in the solar wind (geomagnetic storms) can disrupt power grids, communications, satellites and navigation systems, and without a stable magnetic field to protect Earth we would be incredibly vulnerable to solar storm events.

Understanding how the magnetic field has changed through time will hopefully give us clues as to how it might fluctuate in the future. Earth’s rocks hold clues about its magnetic field in the past (the palaeomagnetic record), which geophysicists like Dr Daniel Franco at the National Observatory of Brazil, can bring together to understand how the palaeomagnetic field might have behaved.

To understand why Earth’s magnetic field changes through time, we first must understand how it is formed. A magnetic field can be created by a magnet, a piece of permanently magnetised metal that can attract or repel other materials. A magnet creates an invisible magnetic field, which describes the area of influence around a magnet. Magnets have two poles, generally termed a north and south pole, and the magnetic field flows from the north pole, around the outside of the magnet to the south pole. Earth’s magnetic field is well known to have a north pole and a south pole (we call this type of magnetic field an axial dipole), and when you stand on the Earth’s surface with a compass, the needle will align itself to the field pointing towards the north pole. However, it is something much more complex than a metal magnet generating Earth’s magnetic field.

A magnetic field can also be generated by a dynamo. This is when a flowing electrical current creates a magnetic field. Deep inside the Earth, fluid with the capacity to conduct electrical currents is constantly moving. Earth’s inner core is extremely hot, over 5000 °C, and this heat drives convection currents in the Earth’s fluid, metallic outer core. As the planet rotates, these convection currents are forced into columns along which move electrical currents, generating a huge magnetic field that extends out into the space around the Earth.

earth's magnetic field.jpeg
Dr Franco uses complex numerical models to better understand Earth’s magnetic field structure, the dynamo that drives geomagnetism and palaeosecular variation.

* Dr Daniel R. Franco (Observatório Nacional, Brazil) completed his MSc in Solid State Physics (2002) and his PhD in Geophysics (2007) from the University of São Paulo. He undertook post-doctoral training at the Department of Earth and Planetary Sciences, John Hopkins University. He is a researcher and associate professor of the Graduate Program in Geophysics and coordinator of the Laboratory of Paleomagnetism and Magnetic Mineralogy (under construction) of the National Observatory (Brazil). He is Associated Editor of the Geoscience Data Journal (Royal Meteorological Society, UK) and Revista Brasileira de Geofísica (RBGf).

Daniel Franco has expertise in rock magnetism, paleomagnetism and magnetostratigraphy, signal processing and analysis of high-resolution sequences of enviromagnetic data.

CAPES – Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior FAPERJ – Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (grant # E-26/203.302/2017) CNPq – Conselho Nacional de Desenvolvimento Científico e Tecnológico (grant # 313253/2017-0)

  • Dr Jean-Marie Flexor (National Observatory, Brazil) – In Memorian​
  • Dr Marcia Ernesto and Daniele Brandt (University of São Paulo, Brazil)​
  • Ricardo Sant’Anna Martins (State University of Rio de Janeiro, Brazil)​

Hopefully, Nile, you can see the importance of paleomagnetism found in igneous rocks which, when they cool, lock in the location of magnetic North due to the arrangement of the iron atoms and the molecules containing iron, like iron oxide, within the rocks. This can then be used today to point to the magnetic North at the time the igneous deposits were deposited.

Niles, on your second question about oxygen becoming an aerial ignitor I'm not quite sure, especially when combined with volcanism.

It is so hot, deep within the Earth due to disintegration of natural radioactive elements – like uranium, for example that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in large voids called magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava.

Some volcanic eruptions are explosive and others are not. The explosivity of an eruption depends on the composition of the magma. If magma is thin and runny, gases can escape easily from it. When this type of magma erupts, it flows out of the volcano. A good example is the eruptions at Hawaii’s volcanoes. Lava flows rarely kill people because they move slowly enough for people to get out of their way. If the magma is thick and gooey, gases cannot escape easily. Incredible pressure builds up until the gases escape violently and explode. A good example is the eruption of Washington’s Mount St. Helens. In this type of eruption, the magma blasts high into the air and breaks apart into pieces called tephra. Tephra can range in size from tiny particles of ash to house-size boulders. At Mt. St. Helens, the entirety of Spirit Lake was filled in with the pyroclastic flow.

Explosive volcanic eruptions can be dangerous and deadly. They can blast out clouds of hot tephra from the side or top of a volcano. These fiery clouds race down mountainsides destroying almost everything in their path. Ash erupted into the sky falls back to Earth like powdery snow. If thick enough, blankets of ash can suffocate plants, animals, and humans. When hot volcanic materials mix with water from streams or melted snow and ice, mudflows form. Mudflows have buried entire communities located near erupting volcanoes.

However, Nile, atmospheric oxygen has never been known to undergo combustion.

Even when the asteroid the size of Mt. Everest slammed into the Yucatan Peninsula and created the Chicxulub impact event was a ~100 million megaton blast that devastated the Gulf of Mexico region.

The blast generated a core of superheated plasma in excess of 10,000 degrees. Although that thermal pulse would have been relatively short-lived, a handful of minutes, it would have been lethal for nearby life.

The Chicxulub Impact event produced a shock wave and air blast that radiated across the seas, over coastlines, and deep into the continental interior. Winds far in excess of 1000 kilometers per hour were possible near the impact site, although they decreased with distance from the impact site. The pressure pulse and winds would have scoured soils and shredded vegetation and any animals living in nearby ecosystems. An initial estimate of the area damaged by an air blast was a radius 1500 kilometers. There are several factors that can affect this estimate, so the uncertainty might be better reflected in a range of radii from ~900 to ~1800 km. The travel times are quite short, so this effect would have occurred in advance of any falling debris ejected from the Chicxulub crater, debris which was thrown above the atmosphere.

Impact shock waves radiating across the surface are trailed by very high velocity winds called an airblast. The phenomenon was observed around nuclear weapon test explosions during the Cold War. The damage would have been severe across southern and central North America. This type of airblast effect also occurs around smaller craters, such as Arizona’s Meteor Crater. For readers wanting to compare the dimensions of the airblast zone, we refer you to LPI’s guidebook to Meteor Crater.

Despite this incredible explosion, the largest planet Earth has undergone except for its collision with a Mars sized planet** which gave us the Moon and left the Earth with a fully molten surface, the oxygen did not combust.


** In a collision with Earth, the volatile materials could transfer from the Mars-sized planet to Earth’s surface, but wouldn’t permeate to its core, which does not interact with its outer layers. This model solves a mystery that has puzzled geologists for decades regarding why these vital elements exist in all layers of Earth except its molten core.

“The core doesn't interact with the rest of Earth, but everything above it, the mantle, the crust, the hydrosphere and the atmosphere, are all connected,” explained Damanveer Grewal, lead author of the study, which was published in Science Advances. “Material cycles between them.”

collision w earth.jpeg
© Rasjdeep Dasgupta

The collision theory resembles existing models in which a meteorite is responsible for seeding the volatile elements on Earth. Unfortunately, the carbon to nitrogen ratio in such meteorites (called carbonaceous chondrites) is much lower than the ratio found in Earth’s non-core material. Additionally, the collision theory explains why the moon and Earth have the same elemental composition – they were once part of the same sphere.


Such an overwhelming collision destroyed the entire surface of the Earth, but no mention is made of atmospheric Oxygen ignition. However, if at anytime it might occur, this planetary collision with Earth would certainly be the time.

I hope, Nile, that I have provided you with some food for thought on paleomagnetism and what I think you're aiming at with atmospheric Oxygen combustion. If not, please flesh out your question a bit further.
Mar 4, 2020
We have all been told that a molten iron core is what generates earth's magnetic field. I have never heard of an explanation of HOW molten iron can cause it. I would love to here the reasoning about that. But not interested in the mathematics of it. Math can prove or disprove anything. And does so for many.

Then, they said they had found evidence of magnetic reversal of the field. Are you sure? IF our M field is caused by rotation, then how does ones explain it's reversal? Did the spin of earth reverse one night? Or slowly stop and start in the opposite direction?

If we take a molten magnetic material and poor it on the ground, as it cools, the puddle M field should line up with earth's M field. All one has to do, is turn the cooled puddle, and we have evidence of a field reversal. As plates move on earth's surface, they rotate and move up and down.

Where is the evidence that earth's M poles have flipped?

If you still believe they flipped.........then what is the reversible source of the field? It could not be the earth's rotation. Unless you believe that the earth flipped 180 degrees.

It takes a net charge in rotation to cause an M field. Have you ever heard of Kelvin's Thunderstorm....or Kelvin's water dropper?

What if the induction of earth's field comes from external forces. Like the external doughnut shaped area of charge that surrounds the earth. This would align ionic water on the earth at the equatorial area.....and the aligned molecules are in rotation with the earth. This would cause M poles at the earth poles. And if the doughnut shaped charge field, changed polarity, it would reverse our field, without changing the earth's rotation.

There are other possibilities. At the very least, the surface and crust is saturated with water. Bore holes have shown this. There are + and - ions in water. If one polarity of those ions is capable of alignment, more than the other polarity, and since all are in rotation, a M field will be generated.

The proportionality of the aligned ions could select the polarity of the M field, without a change in rotation.

The center of the earth remains mysterious. It it really the source of our M field? Is the pressure, temp and gravity strongest at the center? Or is the gravity strongest in a shell at some radius?

Since the earth is in rotation, only a net charge alignment is needed for an M field, no current or voltage required.