Re: Geology Question (KRS related)

Steve Marcus wrote:
> "Daryl Krupa" <icycalmca@xxxxxxxxx> wrote in message
> news:1138600323.430523.90870@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > Steve Marcus wrote:
> > <snip>
> >> What I've learned, so far, about
> >> the geology of the dating method employed
> >> is that a weathering comparison was used to date the inscription
> >> by comparing the KRS (which is
> >> greywacke, a meta-sedimentary rock
> >
> > Steve:
> > Just a point of clarification:
> > graywacke (American spelling) is a sedimentary rock;
> > metagraywacke is a metamorphic rock,
> > which could be called meta-sedimentary.
>
> Which is why I asked you for help. I couldn't tell whether the name
> metagraywacke implied that the rock was sedimentary graywacke produced by
> metamorphism, as slate is produced from shale.

Steve:
Just to be perfectly clear, yes, "metagraywacke" implies that
the rock was sedimentary graywacke
produced by metamorphism,
much
as slate is produced from shale.

> > The KRS is best described as metagraywacke,
> > in that it is graywacke that shows signs of
> > having undergone metamorphosis
> > (i.e., changes resulting from heating, pressing,
> > and crystal growth and substitution, etc.).
> > What does Wolter call it?
>
> Metagraywacke.
> >
> >> bearing these micas: biotite, chlorite and muscovite)
> >
> > Chlorite is a flat *** silicate, like the micas,
> > but it is not generally called a mica, though some would see it as
> > related. From:
> >
> > http://www.eos.ubc.ca/personal/groat/claymanual.htm
>
> I was working from this site, which gives "the most common"
> micas, and does not list chlorite (but, of course, does not
> exclude chlorite as a member of the mica grouping):
>
> http://www.galleries.com/minerals/silicate/micas.htm

If you go to another page associated with that site, you will
see that they have a separate "chlorite group", which they
put under a larger "clay group", which they put at the same
classification level as a "mica group"; thus, they do indeed
exclude chlorite as a member of the mica grouping:

http://www.galleries.com/minerals/silicate/phyllosi.htm

> lass.htm#phyllo

I do not know what this fragment is intended to denote.

> > See also this description of the metamorphic
> > origins of mica and chlorite:
> >
> > http://csmres.jmu.edu/geollab/Fichter/MetaRx/Metatexture.html
> >
> > Does Wolter say that chlorite is a type of mica?
>
> Nielsen and Wolter's book, at page 34, discusses
> the mineralogy of the KRS and states:
> "The elongated grains
> exhibit a preferred orientation
> that is sub-parallel (nearly parallel) with
> the foliation
> composed of various mica minerals (muscovite, chlorite and biotite)
> that comprise the matrix."

Aaarrgghh. How are we supposed to parse this sentence?
I can't tell what is supposed to be composed of mica.
It's not the foliation, because that is
a physical property of the rock indicating
a significant direction of stress on the rock during metamorphosis.
It's not the preferred orientation, because that is also
a physical property of the rock, also indicating
a significant direction of stress on the rock during metamorphosis.
It might be the elongated grains, but then we have to guess at
what words are missing to connect
"The elongated grains" to
"composed of various mica minerals".
Of course, I assume that there is a connection, rather than
that the writing above should actually have been printed as
two separate sentences.
As quoted above, the sentence is unclear as to its meaning.
This would be an example of a style of writing that
is not indicative of scientific thought processes;
it also does not qualify for technical writing standards.

Did you quote the book word-for-word, i.e. verbatim, above?
If so, that quotation might be evidence that Wolter's writing
has not been submitted to other geologically-minded types
for commentary, review, or analysis.
Alternatively, it's just evidence of sloppiness.

> >> with three slate (a metamorphic rock) tombstones
> >> from Augusta Maine
> >> that were selected from a much larger number of tombstones
> >> because the mica grain size in samples of those three tombstones
> >> was comparable to the grain size of the KRS micas.
> >> The authors only discuss biotite,
> >> leading me to believe that the tombstones
> >> did not have the other KRS micas.
> >
> > I wouldn't go that far. Absent a detailed description
> > of the Augusta tombstones, we don't know that.
> >
> > Did Wolter say which formation the tombstone slate
> > was quarried from?
>
> Not that I've been able to see in the material that I've read so far.
> (I've reached the end of the "tombstone comparison" material,
> but that doesn't mean that more info re the tombstones won't
> crop up later in the book.)
> The tombstones were from Hallowell Cemetary in Hallowell, ME.

According to the City of Hallowell, Maine, it is called something
similar, but yet different: the
Hallowell Calvary Cemetery (note the lack of an "a" in "cemetery):

http://tinyurl.com/a7cdh

That is, of course, south of Augusta, Maine, proper,
(which originated as the upper and middle parts of Hallowell),
but still within the Augusta Metropolitan area:

http://www.epodunk.com/cgi-bin/genInfo.php?locIndex=114202

OR

http://tinyurl.com/c4s87

> Another tidbit: Nielsen/Wolter include
> a photo of lichens from one of the tombstones
> (although it isn't stated whether it is from one of the three
> tombstones from which samples were used to date the KRS).
> They state that acid produced by these lichens would
> "accelerate the weathering rate of biotite mica."
> (page 44, and Fig. 51 on page 46).
> No comment is made regarding the possibility that
> given the similar climates of Augusta, ME
> (evidently as close as to Hallowell, ME as they could gather data for)
> and Kensington, whether it would have been likely that
> lichen would have grown on the KRS
> (obviously any such material would have been removed in the various
> cleanings that the stone received subsequent to its discovery).

That might well be true, about acid prodiced by
such lichen(s) accelerating biotite weathering,
but as you mention above,
it is not clear whether or not such lichen actually
colonised one of the tombstones they sampled,
and so it is not clear whether or not
acid produced by such lichen(s) ever had
an opportunity to accelerate the weathering rate of biotite
in the sampled tombstones.
But that might be considered to be a moot point;
there are several factors which might tend to
cause biotite weathering to have proceeded at
a faster rate in the Maine tombstones than in the KRS.
Any or all of these factors might indicate that
whatever biotite weathering is seen in the Maine tombstones
took less time to accomplish than
an equivalent appearance of biotite weathering in the KRS.
That would indicate that
whatever biotite weathering is seen in the KRS
took longer to accomplish than
the equivalent amount of weathering in the Maine tombstones,
and so
Maine tombstone weathering-rate observations give
minimal ages for equivalent weathering on the KRS.
I.e., Maine tombstones are younger than they look,
so the KRS is older than it looks.
Fine. That would mean that the KRS stood out in the open,
exposed to weather, for longer than
those sampled Maine tombstones have stood out in the weather.
But that is just an educated guess. It is not a proven fact.
Weathering of KRS biotite might have proceeded more rapidly
than weathering of Hellowell Calvary Cemetery tombstone biotite
(as you mention above, possibly by the action of
acid produced by lichen).
Weathering of Hellowell Calvary Cemetery tombstone biotite
might be unusually slow.

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),
or,
he is implicitly acknowledging that
Maine tombstones should not be considered to be reliable
control samples regarding the rate of biotite weathering,
until more is known about rates of biotite weathering and
the various influences that may accelerate or decelerate that rate.
In either case, such a rudimentary sampling and testing procedure
can only produce preliminary results, useful for designing further,
more extensive or intensive research on more samples, but
the sampling and testing procedure utilised so far cannot produce
reliable and definitive results.
There are too many variables, too many unknown values, and
too few known constants to allow Wolter's extrapolation from his
preliminary results from observation of Maine tombstones to be
an accurate description of the state of the KRS.

> > Yet the specific type of biotite was not given.
> > I am not a petrology or mineralogy wizard, but
> > I have seen descriptions of a single rock type
> > with four phases of biotite, with different chemical
> > makeup in each.
> > The longer a rock is metamorphosed,
> > the more the biotite that it contains changes;
> > e.g., garnet can grow at the expense of biotite.
> > I have also seen analyses of biotite weathering that distinguished
> > between different types.
> > This might be a case of comparing apples and
> > oranges, WRT weathering characteristics of biotite.
>
> >> The tentative dating for the KRS is
> >> "older than 200 years" because
> >> all of the mica minerals on
> >> the "man-made surfaces" of the KRS
> >> have weathered away
> >> (it's not present in either the inscription or
> >> the surfaces bearing the inscription),

I didn't want to bring this into my critical treatment re: geology,
but
does Wolter indicate that
the surface of the KRS that bears the larger part of the inscription,
aka the "front face",
is a "man-made surface"?
I had thought, from the list of named surfaces of the KRS
that Alan had quoted, that there was only one "man-made surface"
bearing an inscription, i.e.
the one bearing the lesser part of the inscription,
aka the "split side".
It seemed to me that if Wolter has denoted the "front face" as
being "glacial", then that would preclude the "front face" from
being a "man-made surface".
Does Wolter explain which are these inscription-bearing
"man-made surfaces"?
I ask because I have seen several interpretations of which
surfaces of the KRS are "man-made", and I want confirmation
of Wolter's classification scheme.

> >> while the biotite on the tombstones
> >> (average age 194 + or - 5 years)
>
> > Hmmm? I had thought that that was
> > about the age of the oldest tombstone sampled.
>
> "The average age of weathering of the three samples was
> 194 years, plus or minus 5 years."
> The three sample tombstones had "death dates" of 1806, 1805
> and 1815, yielding 197 years, 198 years, and 188 years of
> weathering in 2003.

That average figure, of course, assumes that the tombstones
were erected during the years of their respective death dates,
and ignores the possibility that they
were erected at some time or times after their death dates.
But that average figure also assumes that
the reader cannot do simple arithmetic:
194 + 5 = 199. (Fine, that includes 197 and 198.)
194 - 5 = 189. (That does not include 188.)
The average age of weathering was
194 years, plus or minus
six years, not five years.
The average you quoted is an inaccurate representation of
the values of 197, 198, and 188.
If one is going to round off one's tolerance range to
the nearest half-decade, then
one must also round off one's average value, so that
if a range of plus or minus five years is to be used, then
the average should be stated as being
195 years, plus or minus 5 years
(which is also inaccurate).

> >> is still present,
> >> although it is severly weathered.
> >
> > If the weathering characteristics of the biotites
> > in the Augusta tombstones and the KRS were similar,
> > then that 200-year-plus age estimate might be
> > a fair assumption.
> > But it is as yet only an assumption, as
> > the congruency of the two materials' weathering
> > characteristics has not been proven.
>
> Or, at least, haven't been stated by Nielsen/Wolter.
> I figured as much;
> quite possibly, an apples/bananas comparison,
> all tricked out with some "8 x 10 color glossy photos",
> to borrow a nicely turned phrase from Arlo Guthrie.

And to extend that quasi-literary allusion, those photos
ultimately proved to be useless in determining the facts
of the matter.
From "Alice's Restaurant", * in which ** Officer Obie ***
intends to prove that Arlo and friends had deposited
an inscribed artifact on a low hill:

"We walked in, sat down, Obie came in with the twenty-seven
eight-by-ten colour glossy pictures with circles and arrows and
a paragraph on the back of each one, sat down. Man came in
said, "All rise." We all stood up, and Obie stood up with the
twenty-seven eight-by-ten colour glossy pictures, and the judge
walked in sat down with a seeing eye dog, and he sat down, we
sat down. Obie looked at the seeing eye dog, and then at the
twenty seven eight-by-ten colour glossy pictures with circles and
arrows and a paragraph on the back of each one, and looked at
the seeing eye dog. And then at twenty seven eight-by-ten colour
glossy pictures with circles and arrows and a paragraph on the
back of each one and began to cry, 'cause Obie came to the
Realization that it was a typical case of American Blind Justice,
and there wasn't nothing he could do about it, and the judge
wasn't going to look at the twenty seven eight-by-ten colour glossy
pictures with the circles and arrows and a paragraph on the back
of each one explaining what each one was to be used as evidence
against us."

> >> It is noted that the tombstones are from
> >> a geographical area stated in the text to
> >> average 17 inches of rain per year more than
> >> falls in Kensington (although tabular data
> >> in the book states that the average is
> >> 17 inches of *precipitation*,
> >
> > A minor flaw, perhaps resulting from
> > an assumption that precipitation in Maine
> > is mainly plain rain.
>
> You would have thought that; I certainly did, until
> the authors noted that they hadn't obtained any
> below ground samples from the tombstones because
> the ground was frozen and covered in a foot of snow.

Yeah, you'd think that someone who had been thinking
about rates of weathering would have made a distinction
between low-energy solid precipitation which would tend
to fall off or blow off of a tombstone's surfaces and higher-
energy liquid precipitation which would tend to coat the
surfaces of a tombstone with a continuous film. Or not,
depending on how much actual thinking had been done.

> >> and although it is stated that both above and
> >> below grade samples should have been compared,
> >> only above-grade samples were collected from
> >> the tombstones because the ground was frozen
> >> and covered with a foot of snow.
> >
> > If we knew the burial history of the KRS, and
> > how long any one side had buried, under what
> > conditions, and for what amount of time, that
> > might be a significant problem.
> > But we don't, so I am content to limit the
> > discussion to sub-aerial weathering (i.e.,
> > that which comes about during exposure to weather).
> >
> >> Leaving aside the issue of differences in
> >> average temperatures between Augusta ME and
> >> Kensington, MN, as well as acid rain issues,
> >> I'm wondering whether the comparison made by
> >> the authors is geologically sound in the
> >> sense of comparing apples to apples.
> >> I don't know enough geology to know whether
> >> the fact that the two rocks are of different
> >> types, and the micas on the two different types
> >> of rocks also being different different
> >> (the rocks are reported as having only biotite
> >> in common) amounts to comparing apples to bananas.
> >
> > I would be surprised to find that the only common
> > mica between the KRS and the Augusta tombstone slate
> > was biotite.
> > A mention of the tombstones' parent formation
> > would have been useful in that regard, or even
> > the location of the quarry or quarries that
> > supplied the cemetary.
> >
> > From an ancient tome on American slate quarrying,
> > WRT Maine slate:
> >
> > 1906
> > Slate Deposits and Slate Industry of the United States
> >
> > http://www.cagenweb.com/quarries/states/me-slate_1906.html
> >
> > "
> > The constituents of this slate, arranged in
> > the order of their decreasing abundance,
> > appear to be muscovite (sericite), quartz,
> > chlorite, biotite, pyrite, carbonaceous or
> > graphitic matter, magnetite, rutile, and apatite.
> > "
> >
> > Two types of mica there,
> > the most important constituent of the rock (i.e.,
> > the matrix that the other minerals occur within)
> > being
> > the mica known as muscovite.
> >
> > Similarly from 1914:
> > Excerpts From
> > Slate in The United States
> >
> > http://www.cagenweb.com/quarries/states/me-slate_1914.html
> >
> > That Maine slate seems to be made mainly of
> > another type of mica than biotite seems
> > to have been known for a century. Or more.
> >
> >> Any light you could shed on these points
> >> would be appreciated.
> >
> > Hoping that this has been a start on answering,
> > Daryl Krupa
> >
>
> Daryl, your time and your expertise are greatly appreciated.
> I'm trying to approach the Nielsen/Wolter book objectively,
> looking for evidence that solidly supports the logic of the
> authors and their conclusion. So far, through about 60 pages,
> I haven't found a great deal of solid logic.
> Your input seems to be that their "tombstone evidence" may
> be nothing more than suggestive, but inconclusive.

That is a correct appreciation of the gist of my submission,
Your Worship. ****

Spending far too much time on this nonsense ***** ,
Daryl Krupa

* Let Me Make One Thing Perfectly Clear: This song is called
Alice's Restaurant, and it's about Alice, and the restaurant, but
Alice's Restaurant is not the name of the restaurant, that's
just the name of the song, and that's why he called the song
Alice's Restaurant. Thank you, and God Bless America.

** If you've never been there, you should go:
http://www.arlo.net/lyrics/alices.shtml

*** An archetypal Interested Amateur.

**** The original form used in The King's Justice;
besides, the American "Your Honor" is mis-spelled.
Hah. Hah. Hah.

***** <yawn> <thunk> <a'plkzdfhgnnnnnnnnnnnn>

.

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