scombrid

I read page 1 of this thread and have skipped the rest. My answer to initial zzang trolling follows:

zzang says that extrapolating observed microevolution to macroevolution given time is no more plausible than creationists extrapolating 100yrs of observed magnetic field trends back in time.

Your analogy sucks. If evolution simply extrapolated observed microevolution, you'd be correct. However, you forget to add microevolution+fossils+morphological and molecular synapomorphies etc... Likewise our current understanding of the magnetic field is not simply based on 100years of observed field but also on paleo-magnetic data. Striping of igneous rock at mid-ocean ridges is really telling.

Wait, no, I've got it. We've all been wrong.

The earth really is young. A strong magnetic field balances the human energy. That's why those Old T people lived so long. The Fall is the cause of the decaying magnetic field. Now we have a way to counteract The Fall, MAGNETIC BRACELETS. They counteract earth's decaying magnetic field by creating your own personnal magnetic field to balance your energy. So buy one now and live as long as those OT folks.

zzang

Well electromagnetic storms would be too severe and that would greatly affect life. Then theres all the organisms that depend on the magnetic field for mating, migration,...etc. They would be greatly affected as well. If you want sources try the journal of Electromagnetic Biology and Medicine. Also there was a recent article in Science about the magnetic field being 3 times stronger in the past.

zzang

Interesting, you jump from this:

To this:
<strong> I think I can safely assume you weren't sincere in the rest of your post.

zzang

Thats correct.

zzang

No I'm not.

<strong> I think its cause I disagree with the position of the people here (as if a belief concerning origins was something so important to get so worked up about).

<strong> Its no more arrogant than asserting the conclusions of ufo experts, psychic experts, or ghost experts as invalid.

<strong> Uhm my reason is that the evidence isnt compelling. But I also gave a short list of points.

ps418

I'm not talking about polarity reversals, I'm talking about changes in field intensity over time as they are recorded as remanant magnetiism in igneous and sedimentary rocks. You seem to (finally) understand this point when you say:

Ah, I take it that you did not bother to read any of the papers I provided links to, which describe some of the details about how the paleointensity is determined and remnant magnetization seperated from magnetic overprints?

Here are several arguments that support the reliability of paleointensity data determined by Thellier-Thellier analyses of sedimentary and igneous rocks, and/or falsify the decaying-field model you are defending. Perhaps you could explain how these data fit better with a decaying field model.

1. For very recent samples, paleointensity estimates can be compared with magnetic observatory data for the same time period. An example of this is presented in Cottrell and Tarduno (1999), where paleointensity derived from T-T analyses of single plagioclase crystals in a 1955 basalt flow yields an estimate of 33+/_ microteslas, which agrees within error with the magnetic observatory data. See: Geomagnetic paleointensity derived from single plagioclase crystals, Earth and Planetary Science Letters 169, pp. 1-5.

2. Because of the shielding effect of the geomagnetic field, the production rates of cosmogenic nuclides in the atmosphere, such as 10Be and 36Cl, are inversely related to the intensity of the geomagnetic field. These nuclides are incorporated into sediments in the ocean, and therefore can serve as a proxy for field strength. The stronger the field, the slower the production rate, and vice versa. Therefore, fluctuations in the concentration of these nuclides in deep-sea sediments should be correlated with fluctuations in paleointensity determined from Thellier-Thellier analyses. This is what is found. See:

Frank et al., 1997. A 200 kyr record of cosmogenic radionucluide production rate and geomagnetic field intensity from 10Be in globally stacked deep-sea sediments. Earth and Planetary Science Letters 149, pp. 121-129.

Baumgartner et al., 1998. Geomagnetic Modulation of the 36Cl Flux in the GRIP Ice Core, Greenland. Science 279, pp. 1330-1333.

3. The production rate of in situ terrestrial cosmogenic nuclides (in minerals such as quartz and olivine) is also inversely related to the intensity of the geomagnetic field. These production rates can be measured experimentally, over exposure times of only a few years. They can also be deduced from geologic calibration. For instance, find a surface of known age, and measure the amount of cosmogenic nuclides which have been produced, and divide by the age in years (glossing over the details for now).

The point here is that if the average field strength has remained relatively constant, then the production rates determined from geologic calibration should match those derivered from modern, experimental measurements in controlled targets. If the field strength has been declining with a half-life ~1500 yrs as YECs suppose, then these two procedures should yield totally different estimates.

The actual results strongly support the hypothesis that the average field strength has remained relatively constant, though not ruling out some variation.

For instance, the production rate of 21Ne in quartz derived from geologic calibration using a 13ka surface is 19±3.7 atoms/gms/yr (Niedermann, 2000), compared with a experimental production rates of 16.3 derived from only a few years of data (Graf et al., 1996). Similarly, the production rate of 10Be in quartz derived from geologic calibration are ~5.1 ±0.3 (Stone, 1999), which agrees remarkably well with the modern production-rate value of 5.21±0.278 determined through the use of water targets (Nishiizumi et al., 1996).

By the same logic, if the intensity of the field has been decling, then production rates should be smaller when they are averaged over longer periods of time, and larger when averaged over shorter periods of time. This is not supported by the data. The production rates determined from geologic calibration agree well whether averaged over 10 thousand years or over a million years (e.g. Dunai and Wijbrans, 2000).

Dunai, T.J., and Wijbrans, J.R., 2000. Long-term cosmogenic 3He production rates (152 ka-1.35 Ma) from 40Ar/39Ar dated basalt flows at 29°N latitude, Earth and Planetary Science Letters 176, pp. 147-156.

Graf, T., Marti, K. and Wiens, R.C., 1996. The 21Ne production rate in a Si target at mountain altitudes. Radiocarbon 38(1), p. 155.

Niedermann, S., 2000. The 21Ne production rate in quartz revisited. Earth and Planetary Science Letters 183, pp. 361 - 364.

Nishiizumi, K., Finkel, R.C., Klein, J. and Kohl, C.P., 1996. Cosmogenic production of 7Be and 10Be in water targets. Journal of Geophysical Research 101, pp. 22225-22232.

Stone, J.O., 1999. A consistent Be-10 production rate in quartz - muons and altitude scaling. AMS-8 Proceedings Abstract Volume, Vienna, Austria.

Here are a few more papers on paleointensity research I found with about five minutes of searching:

<a href="http://www.elsevier.com/gej-ng/10/35/40/131/49/28/abstract.html" target="_blank">A detailed palaeointensity and inclination record from drill core SOH1 on Hawaii. Physics of the Earth and Planetary Interiors, Vol. 131 (2) (2002) pp. 101-140</a>

<a href="http://www.elsevier.com/gej-ng/10/35/40/103/27/42/abstract.html" target="_blank">Geomagnetic palaeointensity just prior to the Cretaceous normal superchron. Physics of the Earth and Planetary Interiors, Vol. 128 (1-4) (2001) pp. 207-222</a>

<a href="http://www.elsevier.com/gej-ng/10/35/40/66/22/31/abstract.html" target="_blank">Paleointensity of the geomagnetic field recovered on archaeomagnetic sites from France. Physics of the Earth and Planetary Interiors, Vol. 120 (1-2) (2000) pp. 111-136</a>

<a href="http://www.elsevier.com/gej-ng/10/35/40/104/31/28/abstract.html" target="_blank">Geomagnetic intensity and inclination variations at Hawaii for the past 98kyr from core SOH-4 (Big Island): a new study and a comparison with existing contemporary data. Physics of the Earth and Planetary Interiors, Vol. 129 (3-4) (2002) pp. 205-243</a>

<a href="http://www.elsevier.com/gej-ng/10/18/23/90/27/30/abstract.html" target="_blank">Paleointensity record in zero-age submarine basalt glasses: testing a new dating technique for recent MORBs. Earth and Planetary Science Letters, Vol. 183 (3-4) (2000) pp. 389-401</a>

<a href="http://www.elsevier.com/gej-ng/10/35/40/131/50/31/abstract.html" target="_blank">The variation of intensity of earth's magnetic field with time. Physics of the Earth and Planetary Interiors, Vol. 131 (3-4) (2002) pp. 237-249</a>

Patrick

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Albion

So are you a devotee of the "radiometric dating is a fatally flawed method" school of thought (if "thought" is the right word), or what is the basis of your rejection of the results of radiometric dating?

Jesus Tap-Dancin' Christ

What, is OJ innocent too?

ps418

Ah hah! You must mean this paper:

This paper reports on --Thellier-Thellier analyses of plagioclase crystals in mid-Cretaceous (113-116 mya) basalts formed during of normal polarity during the mid-Cretacous (the Cretaceous Normal Polarity Superchron).

Their results show that the interval covered by their data was characterized by high field stength, with a dipole moment of about 12.5 ± 1.4 × 10^22 amperes per square meter.

First, this is less than twice the current dipole moment (which is about 7-8), not three times as you erroneously imply. What the authors do say is that the dipole moment during the interval were "three times greater than mean Cenozoic and Early Cretaceous-Late Jurassic dipole moments when geomagnetic reversals were frequent." That is, the mean as determined from numerous other Thellier-Thellier analyses of Jurassic, Cretaceous and Cenozoic rocks.

As the authors note, this was an expected result -- that times of low reversal frequency are characterized by high field intensity.

Oddly enough, you just asserted that you didnt think such analyses were reliable. Yet you are now appealing to it as evidence for a declining field? Which is it? If you accept the validity of this method, then your model is instantly falsified, because the same type of Thellier-Thellier analyses show that there has been no long-term decay in the field strength.

Patrick

[ October 08, 2002: Message edited by: ps418 ]</p>

Dark Jedi

*boggle*

Do you happen to know what oscillating means?

This is akin to saying "We know that AC current reverses itself, but this does not support the oscillating amplitude theory."

Edited to clarify:

For a force to reverse itself, it will need to go from a value, past zero, to an opposite value.

How, exactly, do you propose something repeatedly reverse itself without oscillating?

[ October 08, 2002: Message edited by: Dark Jedi ]</p>