From: hyde@cs.dal.ca (Bill Hyde)
Subject: Re: Back to "Bales Scales"
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada
Date: Sun, 27 Sep 1992 00:47:17 GMT

In article <7081@tekig7.PEN.TEK.COM>, bobb@tekig1.PEN.TEK.COM (Robert W Bales) writes:
|> 
|> Sue Bishop writes:
|> 
|> >Hey, Bob, are you EVER going to discuss ice core dating?
|> 
|> >Apologies if you do discuss it in your posting.
|> 
|> Actually, I did mention it.  Since Sue didn't read the article, I'll repeat the
|> appropriate section:
|> 
|> ----------
|> Having said this, and having been asked about varves and ice cores without
|> answering, let me address these briefly, to show I'm not purposely avoiding
|> the subject.  After this brief detour, I don't intend to discuss them further
|> while the other topics I'm discussing are still current.  I have no objection
|> to discussing them as part of later discussions.
|> 
|> a. I don't know the cause of varves and ice cores which appear to give an age
|>    of > 50,000 years for the earth.
|> 
|> b. These dating techniques rely on counting layers.  If a layer is produced in
|>    a period of other than a year, the count of layers will not give the age in
|>    years.
|> 
|> c. Ice cores and varves, even if accurate, only go back a tiny fraction of the
|>    accepted age of the earth. (200,000+ years if I remember right.) They do
|>    not establish the earth is 4.5 bllion years old.



	See below.


|> 
|> d. All the evidence must be considered.  While the simplest explanation for
|>    varves is that the earth is 200,000 years old, there is other evidence (as
|>    I have pointed out before) for which the simplest explanation is that the
|>    earth is < 50,000 years old.  Obviously, one of the "simplest explanations"
|>    must be false.  It is not correct, logically or scientifically, to chose to
|>    believe some evidence and ingore other evidence.  Both possibilities
|>    should  be considered.



	Both possibilities have been considered, and the reasoning
	posted here many times.  I think Matt Brinckman has a FAQ
	on the subject.  As to varves, here is a post I have addressed
	to you at least twice.  Care to explain how the spectral
	peaks from the New Jersey core can match the astronomical
	periods if the varves are not annual layers?


In article <5650@tekfdi.FDI.TEK.COM>, bobb@tekfdi.FDI.TEK.COM (Robert Bales) writes:
> 
> 2) The citing of rocks which date to 3.9 billion years as evidence that the
>    earth is actually at least that old.  The problem here is that no
                                                                    ^^
>    verification of the accuracy of the dating method was given, while I had
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^     
>    shown cases in which the same types of measurment methods (determination of
>    isotope ratios) had given wrong results.


	With regard to dating, bob, you never answered this post.
	I have not been wise enough to keep track of the dates when
	you have been asked to address these points, but after each
	previous posting you left Talk.origins for some months.

	[original post begins]

	Bob, while you're at it, you can try to explain the
	similar dataset from the Antarctic ice sheet (they've drilled
	a little deeper there, 160,000 + years).  Curiously, isotope
	ratios in these cores vary with periodicities which exactly match
	(within fairly narrow error bars) the periodicities of certain
	astronomical parameters (such as the obliquity of the earth's
	orbit, with  a periodicity of 41,000 years, and the precessional
	periods of about 19,000 and 23,000 years.

	Now, there are good theoretical reasons to expect such a match,
	(these orbital wobbles affect received sunlight)
	and indeed it is observed both in ice and sea-bottom cores.

	[insert july 91]  

	These sea bottom cores now go back
	several million years and the astronomical periodicities
	are still there, and K-Ar dates are still in reasonable
	agreement (better than 10%) with astronomical dates.
	
	[original post resumed]

	The question for you, Bob, is this: Since the astronomical
	periods do *not* depend in any way on radiometric dating, and
	since these same periods show up in cores dated *by* radiometric
	dating (the dreaded K-Ar and uranium series dating) is this not
	an *independent* test of radiometric dating?  If not, why?

	The predictions as to time made by calculation of planetary
	orbits and by K-Ar dating agree very well - for a long time you've
	complained that K-Ar is not calibrated - well here it is.


	[july 91 insert]

	In recent months a 25 million year long record from the
	triassic (about 200 million years ago, for those of us
	who believe such things) has been obtained.  The rock
	is banded, and the bands form quite regular groupings.
	The smallest bands contain about 20,000 varves (annual
	layers) - and the precession cycle at that time was
	about 20,000 years long.  Coincidence?  Well, the
	precession cycle is modulated by the 100,000 year
	eccentricity cycle so the bands should occur in groups
	of five, with slightly different characteristics within
	the group.  They do.  Not enough?  There is also a
	400,000 year eccentricity cycle, so the large bands
	should be bunched in groups of four.  And they are.

	So K-Ar dating and varve count give the same spectral
	dependence, and both agree with astronomical calculations.

	Well before this result was obtained (it hasn't even
	been published yet) a simple climate model was used
	to estimate the power spectrum of maximum annual
	temperature at a similar site [see ref].  The low
	frequency end of this model's output agrees
	entirely with the observations.  The cores
	have not yet been measured accurately enough to
	compare the high frequencies.

	This is quite clear evidence that these bands are
	astronomical in origin, and thus *astronomy*, not
	radiometric dating, tells us that this sample of
	rock was laid down over 25,000,000 years.
	So the earth is at least that old.  Furthermore, since
	K-Ar dating gives the same length to this record we
	have no reason for not trusting within a few percent the
	K-Ar absolute age for this stratum, which is about
	200 million years.

	Well, Bob?


						Bill Hyde


	References

	The geological evidence was presented by Paul Olsen of
	Lamont-Doherty at a recent workshop at Johns Hopkins.
	Preprints should exist in a few months.  The theoretical
	paper is


Short, D. A., J. G. Mengel, T. J. Crowley, W. T. Hyde and G. R. North 1991:
Filtering of Milankovitch Cycles by Earth's Geography.
Quaternary Research. 35, 157--173.
Newsgroups: talk.origins