Organization: Mitre Corporation
From: jmeritt@ajax.mitre.org (James W. Meritt)
Message-ID: <2boh26$iad@newsflash.mitre.org>
Newsgroups: talk.origins
In article schumach@convex.com
(Richard A. Schumacher) writes:
}The Teen Mission conveniently ignores the fact that you don't
}need a single live tree to get a continuous record, just an
}overlapping sequence. The existing overlapping records of
}(mostly dead) trees go back about 20,000 years.
Here are tree rings for 11,000 years, 5000 years, 7272 years, 8000 years,
9000 years, 9400 years,
....................................................................
"Detailed records of atmospheric 14C/12C have been obtained for the last
11,000 years from the measurements of carbon in wood, where annual tree
rings provide an independent chronology for the establishment of
variations in the atmospheric 14C/12C ratio (2-4)."
2. M Stuiver and R S Kra, Eds., Radiocarbon 28, 805 (1986).
3. B Becker and B Kromer, ibid. p 961.
4 ___, P Trimborn, Nature 353, 647 (1991).
(For older samples, carbonates for example, the 14C/12C ratio can be
measured and the 230Th dating used to determine age.)
All of the above from Science, Vol 260, 14 May 1993, 962.
..................................................................
Scientists Hope Tree Rings Will Answer Questions About Past
BY: CATHERINE DRESSLER
DATELINE: PITTSBURGH PRIORITY: WEEKDAY ADVANCE WORD COUNT: 571
THE ASSOCIATED PRESS DATE: June 16, 1988 12:44EDT
Experts hope a boat found near a pharoah's pyramid will answer questions
about ancient Egypt, but they're not studying the way it was built -
they're looking at the wood it's made of.
''There are 2 1/2 centuries of information in one piece of wood from that
boat,'' says Peter I. Kuniholm, a Cornell University archaeologist and
tree- ring expert who is studying pencil-like cores drilled out of the
planks of the 30-foot-long boat probably buried more than 3,800 years ago
in Dashur.
It and three similar boats were buried near the pyramid complex of
Senwosret III so he could use them in the afterlife, says Diana Craig
Patch, the Carnegie Museum of Natural History Egyptologist.
Industrialist Andrew Carnegie bought the boat in 1901 and shipped it from
Egypt to Pittsburgh. Two of the others are at the Egyptian Museum in Cairo
and the third is at the Field Museum of Natural History in Chicago.
Kuniholm hopes rings in the samples will pinpoint the boat's age and create
a framework to help date Egyptian objects and determine when events
occurred.
Dendrochronology, the science of tree ring dating, was established in 1930
when Andrew E. Douglass of the University of Arizona studied rings in
wooden artifacts to determine the age of a prehistoric Indian site.
Though the technology has existed for decades, scientists have been limited
by a lack of old wood samples from certain parts of the world, Kuniholm
says.
Only in recent years have scientists collected enough wood from medieval
ruins, ice layers, artifacts and other sources to date objects more than
5,000 years old, said Michael G.L. Baillie of Queen's University in
Belfast, Ireland.
Archaeologists first studied tree rings only to determine the age of
objects, but the science increasingly is revealing more useful information
about the past, like the weather or environment 5,000 years ago.
''The trees are recording some form of environmental information,'' Baillie
said in a telephone interview from Kuniholm's laboratory in Ithaca, N.Y.
''The trick is going to be to try and get some of that back.''
The spacing of rings represents time intervals when trees were alive and
growing. The width of each ring reflects the weather each growing season,
and comparison of many samples from one region gives a climate pattern.
Scientists can check ring patterns against radiocarbon analysis, which is
used to calculate the age of once-living objects. Living things absorb
carbon from the environment, some of it radioactive carbon-14. When a plant
or animal dies, carbon-14 decays at a measurable rate.
To determine the age of ancient wood, scientists must build chronologies
dating back for thousands of years in unbroken sequences. One, finished in
1984 in Ireland, established an unbroken record of tree rings in oak trees
from the present to 7,272 years ago, Baille said.
''You take living trees of a particular species in a particular area, and
you measure the pattern of wide and narrow rings,'' he said. ''You can then
go back to ancient timbers from buildings, for example, and measure the
ring patterns, and if they overlap in time, you should be able to link
those patterns together.
''You're basically piecing together this master pattern, which is anchored
at the present day.''
..................................................................
And provided from Chris:
The oldest trees are bristlecone pines, between 4500 and 5000 years in
age. Dead trees have been matched with live ones, extending the scale
of bristlecone pine tree rings of known age back about 8000 years before
the present.
[_Scientists Confront Creationism_, L. Godfrey, Ed.;
New York: Norton, 1983. p. 35]
Contains no references to additional literature.
The dendrochronological scale of bristlecone pines extends back nearly
9000 years. Trees in the same area share bountiful and lean years which
result in wide or narrow rings, respectively. Two important applications
of dendrochronology are calibration of the [14]C dating method and study
of past changes in climate in the locality.
[_Timescale_, N. Calder;
New York: Viking, 1983. pp. 28-29, 224, 271-273]
Contains references to several articles and a few books.
Use of fossil fuels lowered the [14]C balance of the atmosphere by about
2% (this is called the "Suess effect"). Explosion of nuclear devices in
the atmosphere, operation of reactors, and particle accelerators have
increased the [14]C balance of the atmosphere since about 1945. The
variation of [14]C level of the atmosphere in past years can be measured
by dendrochronology. Dendrochronology is useful to about 8000 years
before the present. For years previous to that, one must rely on varve
chronologies (varves are annual layers deposited in glacial lakes).
[_Principles of Isotope Geology_, G. Faure;
New York: Wiley, 1986. pp. 390-393]
Contains many references of a more technical nature.
Trunks of dead bristlecone pines have been matched to live ones, creating
a scale which extends back about 9000 years before the present. A graph
of dendrochronological age versus [14]C age shows that the [14]C balance
of the atmosphere has changed over time, which causes [14]C dates to be
wrong if calculated from today's level of atmospheric [14]C. From this
chart, corrections to [14]C dating have been obtained.
[_Science and Earth History_, A. N. Strahler;
New York: Prometheus, 1987. pp. 155-158]
Contains several references.
Variations in the [14]C level of the atmosphere have been measured by
dating tree rings of known age. Both giant sequoias and bristlecone pines
are used, having a dendrochronology which extends to about 5400 BC.
Creationists argue that trees can grow multiple rings - or none at all.
Dendrochronologists insure reliability by limiting scales to about three
dozen genera of trees (which do not produce multiple rings) and certain
geographical areas. "Tree ring dating is complicated but very reliable
when properly done."
[_Radiometric Dating, Geologic Time, And The Age Of The Earth:
A Reply To "Scientific" Creationism_, Dalrymple, G. B.;
USGS Open-File Report 86-110, 1986. pp. 39-41]
Contains several references.
................................................................
provided from Bill Hyde:
Recently a dendrochronological record in subfossil german
oak has been established going back 9928 years (Nature,
vol 353, page 647). The authors also have a 1600 year
old pine chronology which overlaps the end of the oak
chronology. As interspecies comparison is difficult they
have not yet fixed an absolute age for the pine chronology.
If they are able to we will probably have a chronology
going back 11,500 years. This will cover the whole
of the Younger Dryas with even better resolution than
provided by ice cores.
A good reference to Dendrochonology and Dendroclimatology
is "Quaternary Paleoclimatology", by R.S. Bradley
(Unwin Hyman, 1985).
.....................................................................
No mention of a flood....
