Re: Geology Question (KRS related)
On Thu, 2 Feb 2006 01:21:58 +0100, "Peter Alaca" <P.Alaca@xxxxxx>
wrote:
>Steve Marcus wrote:
>> "Hayabusa" wrote
>>> , "Steve Marcus" wrote:
>>>> Steve Marcus wrote:
>
>>>>> And, of course, Wolter's Maine-tombstone-to-KRS comparison
>>>>> depends upon a fundamental assumption, that
>>>>> the KRS has not experienced any factors which might
>>>>> "accelerate the weathering rate of biotite mica".
>>>>> In suggesting that weathering rate of the Maine tombstone biotite
>>>>> might have been accelerated, Wolter is treating the KRS
>>>>> as if it were the control sample in the comparison
>>>>> (which is not the way to do the comparison),
>
>>> I think that' a fair assumption. Biotite doesn't weather easily. -
>>> Take into account that I know little about weathering, but I am a
>>> hardrocker. I have seen biotite bleached by acidic soils - swamps and
>>> bogs; these conditions are usually much stronger than any rain can
>>> provide, and the bleaching was caused over 10.000 years or so. If you
>>> leave biotite in a jar of humous acid for 100 years I would be
>>> surprised if you get any observable effect.
>
>> Interesting. The authors state that at least some of the Maine
>> tombstones (although they don't positively state it for the three
>> samples they used in their dating of the KRS) had lichens on them
>> and that acid produced by these lichens would
>> "accelerate the weathering rate of biotite mica."
>>
>> The KRS was discovered buried in soil that one might safely predicate
>> was a bit "swampy" or "boggy"; that condition was used to support
>> consideration of Runestone Hill as fitting the term "island" which
>> appears on the KRS. Do I conclude from your post that burying a
>> stone in swampy or boggy conditions would not accelerate the
>> weathering of biotite so as to impart a "200 year old appearance" to,
>> let's say, a 100 year old inscription that had been buried for 50
>> years?
>
>For the effect of lichens and more, see
>"Biodegradation of Cultural Heritage:
>"Decay Mechanisms and Control Methods"
>http://www.arcchip.cz/w09/w09_tiano.pdf
>[300 kb]
>(Lichens on page 6)
I'm not quite sure that this is entirely relevant to the KRS which is
made of greywacke which is not mentioned at all. Basalt is mentioned
only once and then only in reference [103]. There is no mention of
granite or slate. The materials of primary interest are sandstone,
limestone and marble..
>
>And also, with an other view:
>Irish Stone Monuments study
>http://www.heritagecouncil.ie/publications/stone/conc.html
>
> " Patinas of biological origin were studied on
> limestone and sandstone. Microscopic study
> showed evidence of carbonate and quartz
> particles being removed by the lichen and
> incorporated into biological tissue in limestone
> and sandstone respectively.
> ...
> However, biological coats also provide protection
> against rainfall dissolution, wind abrasion,
> atmospheric pollution and salt weathering. The
> rate of particle removal by lichen can be lower
> than the rate of material loss through the above
> decay processes and agents, especially in the
> exposed environments of the west coast. ..."
This too seems to primarily focus on sandstone and limestone.
Eric Stevens
.
Relevant Pages
- Re: Geology Question (KRS related)
... In suggesting that weathering rate of the Maine tombstone biotite might have been accelerated, Wolter is treating the KRS as if it were the control sample in the comparison, ...
(sci.archaeology) - Re: Geology Question (KRS related)
... "accelerate the weathering rate of biotite mica". ... In suggesting that weathering rate of the Maine tombstone biotite ... Wolter is treating the KRS ...
(sci.archaeology) - Re: Geology Question (KRS related)
... In suggesting that weathering rate of the Maine tombstone biotite ... Wolter is treating the KRS ...
(sci.archaeology) - Re: Geology Question (KRS related)
... "accelerate the weathering rate of biotite mica". ... In suggesting that weathering rate of the Maine tombstone ... Wolter is treating the KRS ...
(sci.archaeology) - Re: Geology Question (KRS related)
... "accelerate the weathering rate of biotite mica". ... In suggesting that weathering rate of the Maine tombstone biotite ... Wolter is treating the KRS ...
(sci.archaeology) |
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