ps418

I've pretty much finished the article I've been working on. The article discusses cosmogenic nuclide exposure dating, its application to various geologic questions, and why it rules out an earth only a few thousands years old.

<a href="http://www.geocities.com/earthhistory/tcn.htm" target="_blank">Cosmogenic nuclides and the Age of the Earth</a>


Patrick

Coragyps

Thanks once again, Patrick! <img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />

Kevin Dorner

Good article: well-referenced and informative. A keeper!

I wonder how a YEC would respond...

/creationist_hat_on (as we seem to be short on YEC's these days around here)

Clearly the amount of cosmogenic isotope production in situ is due to c-decay. Radionuclide emissions (alpha particles, beta particles, gamma rays) were able to travel much faster just after Creation as relativistic velocity-limiting effects occurred at a much higher value of c, and thus radiation flux was much higher, producing the appearance of greater age. So-called glacial moraine was deposited by the Flood, so it would still be expected to have a correspondingly lower occurrence of cosmogenic isotopes. The higher radiation flux accounts for the vastly higher mutation rate and corresponding rate of microevolution that occurred among the various created kinds after the Flood.

/creationist_hat_off

Geez, I could do this for a living... if I had no ethics. That hat is kinda tight though, like it was designed to restrict cranial bloodflow. I won't wear it too often.

[Edit: Hey, 666th post... I really was playing Devil's Advocate!]

[ August 25, 2002: Message edited by: Kevin Dorner ]</p>

ps418

The problem with 'explanations' like that are fatal, although I didnt point them out very clearly.

First, cosmogenic production rates derived from geologic calibration agree pretty closely with modern, experimentally-determined production rates. As I pointed out, this is good evidence that changes in production rates have not been profound.

Second, you can use the concentration of atmospheric 10Be and 14C in lake deposits, in ice, and tree rings, for instance, as proxy measurements for in situ production rates. Under the assumption that production rates have declined, you'd expect 10Be and 14C concentrations measured by these proxies to decline. Instead the variation that does exist looks more like variation around a mean.

Third, the YECs have argued that geomagnetic field strength has declined since creation. Well, the GMF acts like a force field against cosmic radiation, except at the poles, where field strength has essentially no affect on production rates. A very strong field in the past would have greatly reduced the surface flux, resulting in greatly underestimated exposure ages.

Fourth, the declining production hypothesis could be easily tested by determining concentrations of TCNs in surfaces of known (calender) age, such as granite or limestone monuments (providing they were shielded prior to quarrying). I don't know if this has been done, except in the case of some historical glacial moraines.

[ August 25, 2002: Message edited by: ps418 ]</p>

Kevin Dorner

You did now... nice rebuttals, Patrick. If any of this will assist your article, happy to have helped.

Dr.GH

Vey good article. Thanks.

One editorial commnt: First paragraph, last sentence,
This seems a little awkward, and has a typo ‘eexisted.’ Might I suggest, “Such analyses show that many landform surfaces have been exposed to cosmic radiation for at least 10^5 -10^6 years, far older than Genesis based chronologies.”

[ August 25, 2002: Message edited by: Dr.GH ]

[ August 25, 2002: Message edited by: Dr.GH ]</p>

ps418

Thanks Coragyps, Kevin and Gary. I changed the awkward sentence to:

EDIT: That should be &lt;10k, not &gt;10k.

[ August 25, 2002: Message edited by: ps418 ]</p>

Dr.GH

Good. I haven't noticed any other typos.
Again, Thanks for the effort.

KeithHarwood

There is a `recieved' in there somewhere.

&lt;Creationist hat&gt;
It's well known that increased solar activity causes a decrease in galactic cosmic ray exposures (it's called a Forbush decrease IIRC) so the sun was much more active just after the fall therefore the exposure is greater.
&lt;/Creationist hat&gt;

But that's the wrong way. The rocks would be older than they appear and you want them to be younger.

&lt;Creationist hat&gt;
All right, solar activity changes galactic cosmic ray exposure, therefore the rocks are younger than they appear.
&lt;/Creationist hat&gt;

Boy, you are right, it's a very tight hat.