Re: C-14 Dating

[Douglas.Minnema@dp.doe.gov]

Message authorized by:
    : enielsen@iw.edwpub.com_at_internet at x400PO
    Erik,
    
    From the last paragraph of the article, it would appear that they 
actually 
    carbon-dated the fossilized remains of earlier clones of the plant, 
which 
    were then shown to be genetically identical to the current growth.  This 

    then suggests that the remains and the current growth are the same plant,
 
    and not just 'related'.
    
    I agree that the current growth would have a current carbon ratio.
    
    Doug Minnema, CHP
    Defense Programs
    Dept. of Energy
    <Douglas.Minnema@dp.doe.gov>
    
    what few thoughts I have are truly my own/


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Subject: C-14 Dating
Author:  radsafe@romulus.ehs.uiuc.edu_at_internet at x400PO
Date:    7/9/97 1:08 AM


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RADSAFE/RADCHEM memebers with knowledge of C-14 dating. Please consider the 
following article (Reuters):
    
Australian botanists find 43,000-year-old plant
    
    
        HOBART, Australia (Reuter) - Australian botanists said Tuesday they
had discovered a naturally cloned shrub thought to be 43,000 years old, 
which would make it the world's oldest known living plant.
    
        Carbon-dating indicated the Lomatia tasmanica shrub,commonly called
King's Holly, found in the rugged wilderness of Australia's island state of 
Tasmania, was 43,000 years old, Tasmanian Parks and Wildlife Service chief 
botanist Stephen Harris said.
    
        Botanists previously thought the world's oldest living plant was a
13,000-year-old huckleberry in the United States.
    
        The plant, found in a 0.4 square mile patch of rainforest in
Tasmania's wild and thinly populated southwest, was originally found in the 
1930s but its age had not been suspected, Harris told reporters.
    
        The shrub was a self-propagating clone which did not produce seeds
but reproduced by shedding ``cuttings'' of itself onto the forest floor 
which grew into genetically-identical plants, he
said.
    
        The plant looked like several hundred individual shrubs but they
were all genetically identical, meaning they were essentially the same 
plant, he said.
    
        ``When people think of a 43,000-year-old plant they probably
visualize something gnarled and twisted. This just looks like an undershrub 
in the forest,'' he said.
    
        Cuttings from the plant were identical to fossilized remains in the
forest floor carbon-dated at 43,000 years, he said. The plant had glossy, 
pointed leaves resembling holly and flowered regularly, which was unusual 
for a plant that did not seed, Harris said.
         ^REUTER@
    
    
Where did I miss the boat?  Wouldn't a current cutting of a plant today 
reflect the current C-14 content of the atmosphere?  I suppose that if they 
sampled "old" trunk material of this plant it would be depleted in C-14 but 
would it reflect the age of that material?  Isn't there a 
substitution/equilibration factor for "new C-14" replacing C-12, C-13 and 
"old C-14".  I would think that any living material would reflect current 
C-14 material.  There are exceptions to C-14 dating...(modern deep sea 
shellfish that reflect the C-14 content of carbonate in the water around 
them...[fossil] vs. the atmospheric standard), is this one of them?
    
Erik Nielsen
    
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