Rapid True Polar Wander


by Andre
Tags: polar, rapid, wander
Andre
Andre is offline
#1
Apr12-03, 01:48 PM
PF Gold
Andre's Avatar
P: 5,450
Whenever the Frozen Mammoths emerge, the debate about a possible poleshift is revisited. Sine 100 years ago ideas of Hugh Auglingson Brown, Charles Hapgood, John White, Flavio Barbieri, etc, address some sort of poleshift.

However, nothing is more stable than a spinning axis and any attempt to disturb it, results in precession and or nutation wobbling. So physicists must deny the posibilitly of a spin axis change. But a fast spinning egg erects itselfs on the pointy end. It did not change the direction of the spin axis but the whole egg wandered around the spin axis to erect itself, a true polar wander.

Could Earth have done the same? Fast enough that a warm Steppe- Siberia loaded with mega fauna around 25.000 years ago gradually changed into a frozen tundra around 10.000 years ago? And how? Is it coincidence that this period is also known as the coldest part of the ice ages? Could it be that the evidence and signs of the "ice age" in fact were evidence and signs of the Rapid True Polar Wander instead?
Phys.Org News Partner Physics news on Phys.org
Better thermal-imaging lens from waste sulfur
Scientists observe quantum superconductor-metal transition and superconducting glass
New technique detects microscopic diabetes-related eye damage
Funkee
#2
Apr12-03, 08:01 PM
P: n/a
I don't know whether this has come up before, but it's definately an interesting possibility. We never had much time to measure much change, but I think the ice age, and where it occured depends on both that and the movement of the continents.

I'm coming down with a flu, or something bad, so I can't really think now. I'll get back to it later, but it's a good idea.
Hurkyl
Hurkyl is offline
#3
Apr12-03, 08:42 PM
Emeritus
Sci Advisor
PF Gold
Hurkyl's Avatar
P: 16,101
Well, the problem with the egg analogy is that the "wandering" occurs near the beginning of motion when the surface is not yet reached an equilibrium orientation.

It's hard to imagine how the earth could have spent billions of years in unstable rotation until it started to right itself 25,000 years ago... so if polar wandering occured, it would have required some catastrophic cosmic event to knock the earth out of equilibrium spin, one that would surely leave its mark in some other fashion.

Hurkyl

Andre
Andre is offline
#4
Apr13-03, 04:06 AM
PF Gold
Andre's Avatar
P: 5,450

Rapid True Polar Wander


Thanks for the interest.

Yes a mechanism is intrigueing. The egg mechanism is nowhere near what the Earth is doing since the friction of the egg and the surface on which it is spinning is playing a major role. It was just an illustration that a polar wander is about migration of the earth mass over the poles while the direction of the spin axis itself is not affected.

So what do you want first, some compelling evidence for recent Polar wanders or a possible mechanism for it. The problem with the latter though that it is not provable at any given time. We just can't look inside the Earth.
Hurkyl
Hurkyl is offline
#5
Apr13-03, 09:35 AM
Emeritus
Sci Advisor
PF Gold
Hurkyl's Avatar
P: 16,101
My question is what sort of effects would a polar shift have. Would we expect, for instance, that a polar shift would have a profound affect on the magnetic field, thus leaving traces we could detect? Would such an event leave any long term traces on the orbit of the moon? Could, perhaps, the earth have captured the moon during the ice age which triggered a polar shift? (I imagine that 25000 years isn't long enough for the moon to have synchronized, though).


So, I guess, it's the compellnig evidence I want first. [:)]

Hurkyl
Andre
Andre is offline
#6
Apr13-03, 12:13 PM
PF Gold
Andre's Avatar
P: 5,450
OK, extraordinary claims need extraordinary substantiation. And that's available.

The hypothesis is that the Pleistocene (from 1,7 Million years ago till 10,000 years ago) is not about ice ages but about multiple rapid true polar wanders and instead of waxing ice sheets we have migrating ice sheets, following the poles, as they wander.

There must be big differences between wandering ice sheets and growing and shrinking ice sheets so we should be able to isolate them, at least that of the so called "Last Glacial Maximum" (LGM). The first outstanding evidence is the megafauna that proves that Siberia was a grass steppe at moderate temperatures during the last Glacial Maximum during which America suffered in ice conditions of the Winconsin Glaciation. See also the mammoth thread that wasn't considered too interesting since mammoths were out of fashion again.

I declare the Siberian mammoth steppe as first evidence for the Rapid True Polar Wander, your witness, counselor.

Next evidence: dating of the ice migrating during the last glacial maximum.
Hurkyl
Hurkyl is offline
#7
Apr13-03, 03:27 PM
Emeritus
Sci Advisor
PF Gold
Hurkyl's Avatar
P: 16,101
Seems I've inherited the job of providing counterpoint! I'll confess now to this not being one of my better subjects, but I'll give it a shot!



After some brief searching on google, it seems that there is pretty good evidence that the region really was colder and drier, a cross between a steppe and a tundra. http://www.soton.ac.uk/~tjms/eurasia.html seems to provide compelling reason to believe that western Sibera was a harsh cross between a tundra and a steppe...


Following the link you gave in the mammoth thread, even there they don't conclude a temperate climate, just that the environment was more of a steppe than a tundra with temperatures still hovering around freezing.

I don't really see how any of this could plausibly lead to evidence of polar shifting.

Hurkyl
Andre
Andre is offline
#8
Apr14-03, 07:01 AM
PF Gold
Andre's Avatar
P: 5,450
Thanks Hurkyl for playing counterpoint.

So the first thing is about a warm northerly Siberia during the coldest part of the ice age when the ice even decended below the great lakes.

As you may see, your link is based on elder references mostly pre 1995 but the former black box Siberia is opening rapidly. Have a few very recent reports:
PALEOECOLOGY OF NORTHWESTERN BERINGIA: RECONSTRCTION BASED ON MACROFOSSIL PLANT REMAINS FROM ZHOKHOV ISLAND, SIBERIA
AUTHORS

SMITH, LEDA . Center for Northern Studies / Middlebury College.

A buried peat deposit from Zhokhov Island (76. 06'N, 152.42'E, northeast of the New Siberian Islands chain, Russia) contains a variety of well preserved plant material. The calibrated radiocarbon dates for the
sample indicate that it was deposited about 14,000 to 15,000 years ago (average calibrated radiocarbon age of 14, 410 BP [Beta Analytic]). The sample thus represents a botanical assemblage from the Late Pleistocene of Northwestern Beringia. Identification and analysis of the plant macrofossils indicates that several vascular plant species occurred on Zhokhov at that time, but have since disappeared from the area. It is clear that the assemblage would be typical of a warmer environment than that which is current on Zhokhov Island....
(no link found at the moment)
YANA/RHS SITE: GEOLOGY, STRATIGRAPHY, DATING, AND ARCHAEOLOGY.
AUTHORS

PITULKO, VLADIMIR V. Institute for the History of Material Culture, RAS.
Anisimov, Mikhail A. Arctic and Antarctic Research Institute.
Basilyan, Alexander E. Institute for Geology, RAS.
Giria, Evgeny Yu. Institute for the History of Material Culture, RAS.
Nikolsky, Pavel A . Institute for Geolgoy, RAS.
Odess, Daniel . University of Alaska Museum.
Pavlova, Elena Yu. Arctic and Antarctic Research Institute, RAS.
Tumskoy, Vladimir E. Moscow State University.


During a recent survey by the ZHOKHOV 2000 project, a locality where geologist Mikhail Dashtseren found a foreshaft made of woolly rhinoceros horn in 1996 was revisited to assess its research potential. The site is located on the left bank of the Yana River about 100km south of its entrance into the Laptev Sea (73 NL). ....

At the Yana/RHS site the cultural material (fragmented/broken bones of Pleistocene animals and lithic artifacts) were located in several exposures along the riverbank. ....

...Although nearly 300 faunal specimens were collected at the site, only a few were found associated with the artifacts. Among the animal species represented by the bones were reindeer, horse, mammoth, bison, musk ox, polar fox, wolf, and birds....

....These dates are in agreement with the AMS date run on the foreshaft and suggest that the site is around 27,000 years old.

We stress that the significance of the Yana/RHS site is that this is the earliest evidence of human occupation north of 71 degrees NL, and the first evidence that humans inhabited the Eastern Siberian Arctic during the last interglacial.
http://www.colorado.edu/INSTAAR/Arct...str.html?id=75

A remarkable vivid area, so close to the North Pole, where there is now only an icy arctic tundra. Even Rhino's seemed to be roaming well North of the present day pole circle.

I don't want to post to be too long. How many more do you want?

What is the relationship with a true polar wander?
Anywhere from 60,000-25,000 years ago, Siberia was warm while America was freezing with a big polar ice sheet simultanously (Laurentian Ice Sheet). From 25,000 to 10,000 years ago this situation reversed gradually and NW Europe got some brief deep freezing as well in the proces.

It will be very hard to find a meteorological model that allows for deep freezing way down south in America while it allowed for a warm Siberia way up north. If we accept that poles can wander it is much more easy to assume that the pole is where the cold is. Obviously that was in Canada some 60-30,000 years ago.

So it looks like the Rapid True polar wander was from somewhere in Canada via a big curve over the Atlantic to the present position, It probable started between 40-30,000 years ago and ended 10,000 years ago.

The ultimate crackpot hypothesis? But it fits logically to the visible evidence.
Hurkyl
Hurkyl is offline
#9
Apr14-03, 04:17 PM
Emeritus
Sci Advisor
PF Gold
Hurkyl's Avatar
P: 16,101
Are you using "warm" in a relative sense? I.E. you're just saying that Siberia was warmer than North America, not that Sibera was actually somewhat warm with temperatures of 60 degrees farenheight or more?



And incidentally, do you know any web sites on the dynamics of glacial formation?

Hurkyl
elas
#10
Apr14-03, 04:54 PM
P: n/a
I cannot remrmber the details but there was a very popular and fairly comprehensive book published 30 to 40 years ago, in which the author used new charts of the cracks in the Earth's suface under the oceans, as the basis for claiming rapid pole reversal and related temperature change to magnetic pole reversal.
Andre
Andre is offline
#11
Apr15-03, 01:53 PM
PF Gold
Andre's Avatar
P: 5,450
Hurkyl, warm was meant as in grassy steppes with abundant wild life. Perhaps like the prairies. So certainly warmer as today. Of course harsh winters were possible, with the animals migrating. But certainly much warmer as the insolation energy allows for today.

Perhaps a useful link to ice age data in general:
http://college.hmco.com/geology/reso...c/topic17.html
but a lot is based on older data and may be obsolete due to the newer discoveries.

Perhaps next time I go into more detail about ice sheet dynamics and migration.

Elas the book you mention may be:

Cataclysm!: Cosmic Catastrophe in 9500 BC
aka When the Earth Nearly Died
by D.S Allan and J.B Delair

Some remarkeble catastropism but based on obsolete data. Some good practice in out of the box thinking though.
elas
#12
Apr15-03, 05:21 PM
P: n/a
That does not sound like the right book. The concept was about the upper layer of the Earth's structure (above the Moho?) storing up energy and then moving about five times faster than normal for a short period of years given rise to increase volcanic activity and a special type of surface cracking. The theory rapidly lost favour with the arrival of the comet theory, though why we should restrict a series of events to the same cause at each occurence is beyond me.
ObsessiveMathsFreak
ObsessiveMathsFreak is offline
#13
Apr15-03, 05:25 PM
P: 406
It could be possible that the entire solar system is wobbling on it's own axis, maybe the whole galaxy is. In this case, the magnetic fields would shift, i think, but the rotations of planets would remain unchanged.

I think perhaps it is possible that earths direction of spin could have changed. Mantle currents are very powerful. The killer is the earths solid crust, denser and much harder to shift. But look at uranus. A gas giant whose axis is perpendicular, almost, to every other planet. perhaps this was not always so.
Andre
Andre is offline
#14
Apr16-03, 07:15 AM
PF Gold
Andre's Avatar
P: 5,450
Elas, If thats not the right book, we have a few more:

Hamlet's Mill, Giorgio De Santillana & Hertha Von Dechend
Earth in Upheaval, Immanuel Velikovsky
Pole Shift, John White
Not by Fire, but by Ice, Robert W. Felix
Path of the Pole, Charles Hapgood
Earth's Changing Axis, Mac B. Strain

But these are all highly speculative works, based on little evidence and little substantiation. Most are plainly wrong. And that's the problem of course. If a pole shift has been debunked several times over and over again, why do you still think that yet another attempt can be succesfull. Well this time we do have the evidence that was not available even five years ago.

BTW Have a look at a shifting pole, the North Pole of Mars:

http://mars.jpl.nasa.gov/mgs/msss/ca...0_1_2_proj.jpg
and
http://mars.jpl.nasa.gov/mgs/msss/ca...001_15perc.gif

Pictures credit to Malin Space Science Systems/NASA

See the series of rings shifting to the pole position. As there seems not to be to much erosion, to me it appears that that pole wandering occurred quite recently.


why we should restrict a series of events to the same cause at each occurence is beyond me.
Firstly, One of the problems is regularity. According to the ice sheet and the deep sea sediment core the true polar wander occured roughly around every 100.000 years for the past 800.000 years but to pattern is too irregural to be attributed to fixed swarms of meteorites visiting with a very regular interval. On the other hand the pattern is too regular to be caused by random meteorite strikes for instance.

Secondly, Meterorites leave marks. Not only craters but also dust layers trapped in ice sheets. In the past 420,000 years record of the Antarctic Vostok ice core there has not been reported any prevailing indication of real catastrophic meteorite impacts. Furthermore there seem no recent iridium layers reported like that impact of 65 million years ago in Yucatan.

OMF,
I think perhaps it is possible that earths direction of spin could have changed. Mantle currents are very powerful. The killer is the earths solid crust, denser and much harder to shift.
From gyroscope behavior we note that changing directions of spinning axes is a though thing to do. Instead gyroscopes tend to wobble and precess if you push against them but the spin axis remains more or less fixed. We are thinking of wandering of the Earth body over the fixed spin axis as I posted in the start of the thread. The force for that is probably not external, where the crust has to push the mantle but from the inside, things that happen in the core and the mantle.

So what's next? More evidence first or more on that core mantle process?
elas
#15
Apr16-03, 09:05 AM
P: n/a
'Path of the Pole' by 'Hapgood' rings a bell, is the theory still regarded as valid?
Daminc
Daminc is offline
#16
Apr16-03, 10:32 AM
P: 157
We just can't look inside the Earth
Evidence for Internal Earth Structure and Composition

[snippet]
What Causes the Earth's Magnetic Field?
Early ideas about what caused the compass needle to point toward the north included some divine attraction to the polestar (North Star), or attraction to large masses of iron ore in the arctic. A more serious hypothesis considered the Earth or some solid layer within the Earth to be made of iron or other magnetic material forming a permanent magnet. There are two major problems with this hypothesis. First, it became apparent that the magnetic field drifts over time; the magnetic poles move. Second, magnetic minerals only retain a permanent magnetism below their Curie temperature (e.g., 580C for magnetite). Most of the Earth's interior is hotter than all known Curie temperatures and cooler crustal rocks just don't contain enough magnetic content to account for the magnetic field.

The discovery of the liquid outer core allowed another hypothesis: the geodynamo. Iron, whether liquid or solid, is a conductor or electricity. Electric currents would therefore flow in molten iron. Moving a flowing electric current generates a magnetic field at a right angle to the electric current direction (basic physics of electromagnetism). The molten outer core convects as a means of releasing heat. This convective motion would displace the flowing electric currents thereby generating magnetic fields. The magnetic field is oriented around the axis of rotation of the Earth because the effects of the rotation on the moving fluid (coriolis force).
[/snippet]
Andre
Andre is offline
#17
Apr16-03, 12:37 PM
PF Gold
Andre's Avatar
P: 5,450
Elas, about Charles Hapgood's "Path of the pole". It is not valid. Hapgood poses that the Earth crust could slide over the mantle due to imbalance (the pole ice sheets initially but abandonned later). Hapgood has been utterly despiced like this:
http://www.talkorigins.org/faqs/mom/atlantis.html
and this:
http://www.intersurf.com/~chalcedony/wildside.shtml

What we surely can say now, is that his mechanism is wrong. The volcanic hot spots that originate deep in the Mantle like Hawaii, La Palma and Iceland for instance have been aligned with the crust for millions of years. If the crust had slipped over that, this alignment would be disrupted. Apart from that there is more solid geologic evidence.

Furthermore Hapgood used too much debatable evidence like the Piri Reis map for instance. When one piece of evidence can be debunked, so is the whole hypothesis.

One thing we believe, that he was right about, is in the original position of the North Pole, being in Canada, presumably the Hudson bay. One nice piece of evidence, for instance, are the locations of the found Mammoth remains, namely almost everywhere in the Northern hemisphere except for NE Canada and perhaps North Scandinavia.


Thanks for that link Daminc. Unfortunately it does not detract from the sad notion that we cannot look inside the Earth. We only can measure anything that there is to measure and then speculate on the possible causes. We may become very good at that, but never good enough.
Hurkyl
Hurkyl is offline
#18
Apr16-03, 04:47 PM
Emeritus
Sci Advisor
PF Gold
Hurkyl's Avatar
P: 16,101
How does the timing of magnetic inversions coincide with the alledged polar shifts?

Hurkyl


Register to reply

Related Discussions
rapid adiabatic compression - puzzle Classical Physics 14
Waking reflexive rapid eye movement Biology 19
Rapid Analysis Introductory Physics Homework 0
Can rapid acceleration have momentum? General Physics 3
Rapid Healing General Discussion 61