PLEASE NOTE:
*
Date sent: Thu, 22 Jan
1998 09:52:00 -0500 (EST)
From:
HUMBPEIS B.J.PEISER@livjm.ac.uk
Subject:
CC-DIGEST, 22/01/98
To:
cambridge-conference@livjm.ac.uk
Priority: NORMAL
CAMBRIDGE CONFERENCE DIGEST, 22 JANUARY 1998
--------------------------------------------
(1) NEW EVIDENCE FOR GLOBAL CLIMATE DISASTER IN 3rd MILLENNIUM BC
(2) DEMISE OF THE AUSTRALIAN NEO PROGRAM
(3) WHAT CAN WE DO TO CONVINCE THE AUSTRALIAN GOVERNMENT TO
RE-START
NEO SEARCH IN SOUTHERN HEMISPHERE?
(4) REPORTS ABOUT 1KM IMPACT CRATER CAUSED BY GREENLAND EVENT
NOT
SUBSTANTIATED
(5) THAT'S A NEW ONE: TECTONIC THEORY OF TUNGUSKA EVENT
==================================================================
(1) NEW EVIDENCE FOR GLOBAL CLIMATE DISASTER IN 3rd MILLENNIUM BC
From: Harvey Weiss harvey.weiss@yale.edu
From: SCIENCE, Volume 279, Number 5349, 16 January 1998, pp.325-326
SEA-FLOOR DUST SHOWS DROUGHT FELLED AKKADIAN EMPIRE
Richard A. Kerr
When civilizations collapse, the blame is often laid on the
culture
itself--leaders who overreached, armies that faltered, farmers
who
degraded the land. Such were the conventional explanations for
the
end of the world's first empire, forged by the Akkadians by 2300
B.C.
Their reign stretched 1300 kilometers from the Persian Gulf in
present-day Iraq to the headwaters of the Euphrates River in
Turkey.
They were the first to subsume independent societies into a
single
state, but the Akkadian empire splintered a century later, not to
be
reunited in such grandeur for 1000 years.
In 1993, however, archaeologist Harvey Weiss of Yale
University
proposed that the Akkadians were not to blame for their fate.
Instead, he argued that they were brought low by a wide-ranging,
centuries-long drought (Science, 20 August 1993, p. 985) that
toppled
other civilizations too, including those of early Greece, the
pyramid
builders in Egypt, and the Indus Valley in Pakistan. Many
archaeologists were skeptical because the timing of these
collapses
was imprecise, and purely social and political explanations
seemed to
suffice. But now Weiss's theory, at least as applied to the
Akkadians, is getting new support from a completely independent
source: an accurately dated, continuous climate record from the
Gulf
of Oman, 1800 kilometers from the heart of the Akkadian empire.
At the annual fall meeting last month of the American
Geophysical
Union here, paleoceanographers Heidi Cullen and Peter deMenocal
of
Lamont-Doherty Earth Observatory in Palisades, New York, and
their
colleagues reported that a sediment core retrieved from the
bottom of
the gulf matches Weiss's version of events: The worst dry spell
of
the past 10,000 years began just as the Akkadians' northern
stronghold of Tell Leilan was being abandoned, and the drought
lasted
a devastating 300 years. The new results illustrate, says Weiss,
that
climate change "is emerging as a new and powerful causal
agent" in
the evolution of civilization.
Some archaeologists aren't willing to accept that the same
drought
changed history across the Old World, however. That argument
"just
doesn't float," says archaeologist Carl Lamberg-Karlovsky of
Harvard
University. But he and others agree that the new marine record
lends
support to the climate-culture connection that Weiss identified
at
the ruined city of Tell Leilan in the northern part of
Mesopotamia, a
region that includes parts of present-day Syria, Iraq, and
Turkey.
Weiss began excavations there, on the Habur Plains of northeast
Syria, in 1978.
Tell Leilan was a major city covering 200 acres by the middle
of the
third millennium B.C., and its people thrived on the harvests of
the
plains' fertile fields. But, unlike the farmers of Sumer in
southern
Mesopotamia, who used irrigation from the Euphrates and Tigris
rivers
to ensure bountiful harvests, the farmers of Tell Leilan depended
on
plentiful rainfall to water their fields. Less than a century
after
the people of Akkad in central Mesopotamia extended their reach
into
the north, those rains began to fail, says Weiss.
When Weiss and Marie-Agnes Courty, a soil scientist and
archaeologist
at the National Center for Scientific Research in Paris, dug
through
the accumulated debris of Tell Leilan, they encountered an
interval
devoid of signs of human activity, containing only the clay of
deteriorating bricks. The abandonment began about 2200 B.C., as
determined by carbon-14 dating of cereal grains. Soil samples
from
that time showed abundant fine, windblown dust and few signs of
earthworm activity or the once-abundant rainfall. All this
suggested
that the people of Tell Leilan, and, presumably, its environs,
retreated in the face of a suddenly dry and windy environment,
triggering the collapse of the Akkadian empire's northern
provinces.
Only after the signs of dryness abated, about 300 years later,
was
Tell Leilan reoccupied.
Weiss went further, however, proposing that refugees from the
drought
went south, where irrigation helped protect crops. Droves of
immigrants would have further strained a sociopolitical system
already stressed by the same drought, he says, until the whole
system
collapsed under the strain. And he noted that the
pyramid-building
Old Kingdom of Egypt, the towns of Palestine, and the cities of
the
Indus Valley went into precipitous declines at about the same
time
and apparently also suffered unstable climates.
It's a neat story, but critics questioned whether the drying
really
was catastrophic enough to bring down all of Mesopotamian
civilization, where irrigation would have helped farmers cope
with
the drought. And they were even more skeptical that such a
drought
could have felled other cultures across the Old World. To test
these
ideas, deMenocal and Cullen decided to see just how big and bad
the
drought really was. They analyzed sediment from the Gulf of Oman,
reasoning that if all of Mesopotamia had become a dust bowl, the
hot
northwest summer wind called the Shamal would have blown that
dust
down the Tigris and Euphrates valley, over the Persian Gulf, and
finally into the Gulf of Oman, 2200 kilometers from Tell Leilan.
Cullen and deMenocal looked for this far-traveled dust in a
2-meter
sediment core spanning the past 14,000 years, which was retrieved
from the Gulf of Oman by paleoceanographer Frank Sirocko of the
University of Kiel in Germany. In samples taken every 2
centimeters
along the core, they measured the amounts of dolomite, quartz,
and
calcite--minerals that today dominate the dust blown from
Mesopotamia
by the Shamal. They found that wind-blown dust levels in the Gulf
of
Oman were high during the last ice age until about 11,000 years
ago,
then settled down to levels more typical of today. But in the
sample
from 2000 B.C. plus or minus 100 years, as dated by carbon-14,
the
abundance of dust minerals jumped to two to six times above
background, reaching levels not found at any other time in the
past
10,000 years.
The extreme dustiness--which suggests a wide-ranging area of
dryness--persisted through the next sample 140 years later but
faded
away by the third sample, indicating a duration of a few hundred
years. The team also tracked isotopes of strontium and neodymium,
which occur in different ratios in dust from different regions.
They
confirmed that during the dust pulse, the proportion of minerals
with
a composition similar to that of the soils of Mesopotamia and
Arabia
increased.
Given the uncertainties of carbon dating, the marine dust
pulse and
the abandonment of Tell Leilan could still have been several
centuries apart. But Cullen and deMenocal found in the core
another
time marker that makes a somewhat tighter connection. Less than
about
140 years before the dust pulse is a layer containing volcanic
ash.
And Weiss had already reported that a centimeter-thick ash layer
lies
just beneath the onset of aridity and abandonment at Tell Leilan.
The
strikingly similar elemental compositions of the two ashes imply
that
they stem from the same volcanic event. If so, then Tell Leilan
was
abandoned just after the start of a climatic change of
considerable
magnitude, geographical extent, and duration. "There's
something
going on, a shift of atmospheric circulation patterns over a
fairly
large region," says Cullen.
Some archaeologists agree that this climate shift did change
history
outside northern Mesopotamia. "Most people who work in this
range of
time don't pay much attention to climate," says
archaeologist Frank
Hole of Yale; "rather, it's political and social events
[that
matter]. ... But I think the evidence is overwhelming that we've
got
something going on here."
While conceding that climate and culture interact, a number of
archaeologists still think that Weiss is pushing the connection
too
far. Drought may well have driven people from farmland dependent
on
rainfall, like that around Tell Leilan, says Lamberg-Karlovsky,
but
Weiss "generalizes from his northern Mesopotamia scenario to
a global
problem. That's utterly wrong. ... Archaeologists fall in love
with
their archaeological sites, and they generalize [unjustifiably]
to a
larger perspective."
Even in Mesopotamia, "you do not have by any means a
universal
collapse of cultural complexity," says Lamberg-Karlovsky.
For
example, at 2100 B.C., in the midst of the drying, the highly
literate Ur III culture centered in far southern Mesopotamia was
at
its peak, he says, as was the Indus River civilization to the
east,
which thrived for another 200 years. Weiss counters that
cuneiform
records show that Ur III did in fact collapse 50 years later,
apparently under the weight of a swelling immigrant population
and
crop failures. That timing still fails to impress
Lamberg-Karlovsky,
who concludes that Weiss is "getting little support for the
global
aspect of it."
Such support may yet come from climate records being retrieved
from
around the world. In an enticing look at the postglacial climate
of
North America, Walter Dean of the U.S. Geological Survey in
Denver
found three sharp peaks in the amount of dust that settled to the
bottom of Elk Lake in Minnesota. Dust peaked at about 5800, 3800,
and
2100 B.C., plus or minus 200 years, according to the counting of
annual layers in the lake sediment. During the 2100 B.C. dust
pulse,
which lasted about a century, the lake received three times more
dust
each year than it did during the infamous Dust Bowl period in the
U.S. in the 1930s. But the archaeological record doesn't reveal
how
this drought affected early North Americans, who at that time
maintained no major population centers.
In another sign that the Mesopotamian drought was global,
Lonnie G.
Thompson of Ohio State University and his colleagues found a dust
spike preserved in a Peruvian mountain glacier that marks "a
major drought" in the Amazon Basin about 2200 B.C., give or
take 200
years. It is by far the largest such event of the past 17,000
years.
But it doesn't seem to have had entirely negative effects;
indeed, it
roughly coincides with a shift in population centers from coastal
areas of Peru, where the ocean provided subsistence, to higher
regions, where agriculture became important. As more such records
accumulate in the rapidly accelerating study of recent climate,
archaeologists will have a better idea of just how much history
can
be laid at the feet of climate change.
========================================================================
(2)
DEMISE OF THE AUSTRALIAN NEO PROGRAM
From: Duncan Steel dis@a011.aone.net.au
DEMISE OF THE AUSTRALIAN NEO PROGRAM
People might wonder whether the cessation of the Australian
NEO program
makes much difference to the overall effort. Certainly, the
discovery rate
of NEOs is now increasing with the advent in 1996/97 of the two
new US
search programs using USAF GEODSS systems (NEAT based at JPL
using the
GEODSS system at Haleakala, LINEAR using that at Socorro); they
join the
excellent Spacewatch program at the University of Arizona (which
will soon
be starting searching with a 1.8-m telescope, replacing the 0.9-m
which
which has performed so admirably since 1989 on the NEO search
task). The
problem is that it is easy to find a needle and then throw it
back into a
haystack: unless the orbit of a NEO is secured quickly, then it
will become
lost (meaning that it must await accidental re-discovery rather
than being
recovered on its next apparition).
The Australian NEO program was of especial significance
because, as the only
southern hemisphere program, there was a special responsibility
to track
objects discovered by the US search programs but not accessible
to them
later. I have just been looking at some statistics, as I write a
valedictory
paper for our program. For example, in 1994-95 we supplied to the
Minor
Planet Center about 30% of all NEO astrometry obtained worldwide.
But even
that figure can be misleading, since the shear volume of data is
not the
most important thing (getting hundreds of observations of a few
NEOs is no
use if at the same time a large number of NEOs are not being
observed at
all, and so are lost). An even better measure is this. From
when the Minor
Planet Electronic Circulars began publication in 1993 September
through to
the termination of our program at the end of 1996, of all
recoveries
(spottings of NEOs in new apparitions) announced, we made about
60% of them.
In the year since our program was cut-off, there will be a few
NEOs which
may have passed by without being observed, and these may be
considered lost,
but the real problem is this. With orbital periods of a few
years,
individual NEOs return to be observable with a few years between
times. This
means that many of the NEOs now (in 1996-98) being discovered by
the
productive US search programs may well turn out to be like those
needles in
the haystack. Without us to follow them, they soon get lost
again.
It is essential for the international effort that there be a
global,
coordinated system of NEO tracking. This does not need to be part
of
some huge and expensive bureaucracy: in the past we have shown
that
the people involved, being keen and energetic, are able to
self-organize the system. (Just look at the WWW pages of the
Minor
Planet Center). One absolutely essential component is missing
now:
any substantial southern hemisphere effort. Even if I personally
am
not involved for some reason, still there must be such a program.
I
urge you to do all that you can to assist this international
effort,
whether it be through writing to your own politicians, writing to
politicians elsewhere to tell them how you feel that the US
effort is
being let down by their inactivity, or through directly
contributing
to the effort in one way or another (for example, Spacewatch
survives
in part on voluntary donations).
My final point is this. So far as we know, only one planet in
the
universe is the domain of life. On that planet, we are the only
species which has the ability to ensure that life is spread
throughout the galaxy. That gives us a heady responsibility: we
are
looking, in the case of (say) an impact by a one-mile asteroid,
at
not only a global catastrophe killing billions, and the end of
civilization as we know it, but also the snuffing out of the
potential for life to spread between the planets, and eventually
the
stars. The probability of such an impact catastrophe occurring
soon
is small, but the stakes are too high to ignore: you should give
much
more consideration to a gamble which may cost you your life,
rather
than a dollar bet on a horse in the Kentucky Derby. Here
we're
talking about all of our lives, and memes, and genes.
Do all that you can to ensure that humankind, having realized
that the
hazard is there, metaphorically flexes its shoulders and says
"OK, we can
tackle this problem." We need to declare war on the
heavens, and intercede
so as to make this a safe planet. Our environment is not just our
terrestrial backyard; for life on Earth, environmental concerns
must
encompass our cosmic backyard, too. The dinosaurs were not smart
enough to
see their nemesis coming, but we are; the question is whether
we're going to
be too dumb to do anything about it.
Duncan Steel
dis@a011.aone.net.au
==================================================================
(3) WHAT CAN WE DO TO CONVINCE THE AUSTRALIAN GOVERNMENT TO
RE-START
NEO SEARCH IN SOUTHERN HEMISPHERE?
From: Victor D. Noto vnn2@phoenixat.com
Those interested in writing, calling by phone or fax, or
emailing
their protest to the Australian government can go to the
following
URL link for information:
----------------------------------------------------------------------------
The Australian Parliament WWW page provides various links:
http://www.aph.gov.au/
There is a http address for the Prime Minister of Australia at
The
Australian PM's home page is:
http://www.pm.gov.au/
Duncan Steel says he will soon be taking a job at a bank doing
financial mathematics. This is an outrage to have all this
astronomical knowledge and talent go to waste. Duncan Steel who
in
1995 wrote the great book on the subject of the asteroid and
comet
threat called 'Rogue Asteroids and Doomsday Comets' (Wiley, NY,
1995)
trying to warn his country and the world of about the threat.
A recent article of Duncan Steel which appears in the journal
'New
Scientist' will be appearing on "Bigrock' soon with Duncan's
approval.
Victor Noto - Kissimmee, Florida USA
vnn2@phoenixat.com
http://www.phoenixat.com/~vnn2/BIGROCK.htm
====================================================================
(4) REPORTS ABOUT 1KM IMPACT CRATER CAUSED BY GREENLAND EVENT NOT
SUBSTANTIATED
From: Robert Matthews rajm@compuserve.com
Dear dr. Matthews
The report on a 1 km crater on the Greenland Ice Sheet has not
been
substantiated. The position has been overflown Jan 4 by the SAR
mission and
nothing particular was seen. The "crater" was an
observations from a SAS
plane from 27000 feet. A more likely explanation is a melt water
lake on the
ice that has been unplugged, emtied and leaving a depression
behind. We dont
put any significance this observation. There are no seismic
observations
from the event. There are reports on tremors and violent sound
effects from
Fiskenaesset, followed by violent wind effects.( see below)
Yours Sincerely
Torben Risbo
Coordinator of the Greenland Meteorite Search
Niels Bohr Institute AFG, Geophysical Department,
Juliane Maries Vej 30, DK 2100 Copenhagen O, Denmark
tr@gfy.ku.dk +45 35320585, +45 35320602 (sekr.)
----------------------------------------------------------------
The Greenland meteorite event:
Update Jan 9 1998.
----------------------------------------------------------------
The event occurred on Dec 9 1997 08.11 UTC (+-2 min) 05.11
local time.
Observations are visual sightings from the SW coast of Greenland
from the
Disco Bay area to the Julianehaabs District, trawlers in the
waters off the
coast SE of Greenland, the Bay of Julianehaab and W of Greenland
off
Fiskenaesset, a video recording in Nuuk and sounds, tremors and
wind effects
observed in Fiskenaesset.
The target area is obtained by a shallow angle intersection
between the
video camera view and two visual sightings from trawlers in the
waters off
the SE coast of Greenland. Accordingly some uncertainty is
connected with
the positioning of the endpoint epicenter of the track. We are
fairly sure
that the track ended on a position over land.
The best position of the impact/explosion site is now at the
Greenland ice
sheet near the Frederikshaab Isblink at the West Coast between
Fiskenaesset
and Frederikshaab (Pamiut).
There has been a discussion and an evaluation of seismic
signals
observed by NORSAR, Kjeller, Norway on the array stations in
Finmarka
and Svalbard. (ARCES & SPITS). The signals were at about the
expected
arrival times for a seismic event in Southern Greenland. The
times were not
consistent with the arrival of signals from an explosive event in
Greenland,
but they were apparently arriving from about that direction.
NORSAR cannot
identify seismic phases in the signals. Also the frequency (10
Hz) is high
for a teleseismic event.
We and NORSAR do not relate the seismic signals at ARCES and
SPITS to
the meteorite event in Greenland.
Erik Hjortenberg, Kort og Matrikel Styrelsen (KMS) reports
that the SFJ
(Soendre Stroemfjord) seismic station was not in operation on the
time of
the event. This is most regrettable since this station is near
(300 km) the
target area and records seismic signals to high frequency.
Seismic signals
were not seen at the seismic station Danmarkshavn (DAG) in NE
Greenland.
Violent sounds and shakings of houses have been reported in
Fiskenaesset 110 km south of Nuuk. This was followed some minutes
later by wind effects of short duration in an otherwise quiet
weather.
The meteorite event was recorded by a video surveillance
camera placed in a
private house in Nuuk. For about 1 second the meteorite track was
in the
field of view of the camera, the camera was saturated for a
moment in a near
white out in an explosive flash of light while the track was in
the field of
view. Daylight conditions reigned during a fraction of a second.
A terminal
light flash was clearly seen on the video but the origin was
below the
horizon of the camera, the field of view was restricted by the
nearby
mountain Store Malene SE of Nuuk. The flash gave a diffuse light
from the
sky (cirrus clouds) as seen from the camera site. The afterglow
on the sky
from the track indicates an angle of the track of 50 dgr. with
the horizon
as seen from Nuuk. Analysis of the video sequence is in progress.
We are fairly sure that the track ended on a position over land.
The best position of the impact/explosion site is now at the
Greenland ice
sheet near the Frederikshaab Isblink at the West Coast between
Fiskenaesset
and Frederikshaab (Pamiut).
A joint SAR mission by the Royal Danish Air Force and the
Danish Center for
Remote Sensing (DCRS) at the Technical University of Denmark is
completed on
Jan 4 over the target area. An area of 10000 km**2 were covered
in 6 flight
tracks extending from the ice border zone and inland. Two
additional tracks
were covering the Frederikshaab Isblink.
Since the the surface topography is rough the detection of an
impact
feature may be difficult. Data processing in progress at DCRS and
is
expected to go on for 3-4 weeks.
The target area is obtained by a shallow angle intersection
between the
camera view and two visual sightings from trawlers in the waters
off the SE
coast of Greenland. Accordingly it has moved about on the ice
sheet now to
end in the coastal region following a critical evaluation and
dismissal of
some conflicting trawler observations.
No microbarograph detections are seen by an array in Los Alamos.
A log of aircraft positions in the airspace of Greenland (>
19000 feet) has
been obtained from the control in Gander, Canada. Only 3 aircraft
were in
the area and none were judged to be in a position and on a course
at the
moment to give useful information.
Some 30 reports of visual observations have been obtained by
telephone
interviews with authorities, people in Greenland and trawlers
operating in
the waters off Greenland. Most visual observations do not allow
useful
bearing determination, but support the picture. Two trawler
observations
have delivered accurate and reliable information.
The magnitude of the light flash is cautiously estimated to be
m=-21 as seen
from the trawlers off the SE coast 400 km away. This certainly
indicate a
light effect comparable to a nuclear discharge in the atmosphere.
The owner
of the Nuuk camera claims that the light was comparable to full
sunlight
conditions as seen in Nuuk (m=-26) at a distance of 150 km. By
comparison
with published data from satellite observations of light flashes
from
meteorite events in the atmosphere (ref) it is estimated that the
flash
equals the light emission from a 10 ktons nuclear discharge.
Running updates on the Greenland meteorite event can be
obtained at
http://www.astro.ku.dk/~holger/
and http://www.dcrs.dtu.dk
Ref.
J. Kelly Beatty, Sky and Telescope Feb 1994, 26-27 "Impacts
Revealed".
Torben Risbo
Coordinator of the Greenland Meteorite Search
Niels Bohr Institute AFG, Geophysical Department,
Juliane Maries Vej 30, DK 2100 Copenhagen O, Denmark
tr@gfy.ku.dk +45 35320585, +45 35320602 (sekr.)
===========================================================================
(5) THAT'S A NEW ONE: TECTONIC THEORY OF TUNGUSKA EVENT
From: Joel Schiff schiff@math.auckland.ac.nz
Benny,
For a "tectonic explanation" of the Tunguska Event
check out the new
website:
http://www.tm.ru/tunguska/tunguska.htm
Cheers,
Joel