PLEASE NOTE:
*
CCNet, 085/2000 - 8 September 2000
-----------------------------------
Chaos, Cosmos! Cosmos, Chaos!
Who can tell how all will end?
Read the wide world's annals, you,
and take their wisdom for your friend.
Forward then, but still remember how
the course of Time will swerve,
Crook and turn upon itself in many a
backward streaming curve.
--- Lord Alfred Tennyson
"The mass
extinction at the end of the Permian Period was
catastrophic and
sudden. The only thing we know of that can
cause an extinction
like this is a large impact of an asteroid
or comet. But we still
haven't found conclusive evidence that
an impact
occurred."
-- Michael Rampino, 7 September 2000
(1) WHERE'S THE SMOKING GUN OF THE END-PERMIAN MASS EXTINCTION?
Space.com, 7 September 2000
(2) U.S. GEOLOGICAL SURVEY TO 'CAT SCAN' IMPACT CRATER
Ron Baalke <baalke@jpl.nasa.gov>
(3) FUNDING DILEMMA SOLVED: KIDS WATCH OUT FOR SPACE ROCKS
Bob Kobres <bkobres@uga.edu>
(4) RARE SPACE ROCK IN BRITISH LAB
BBC News Online, 8 September, 2000
(5) TUNGUSKA 2001 INTERNATIONAL CONFERENCE
Andrei Ol'khovatov (olkhov@mail.ru)
(6) ASTEROID 2000 QW7
Jonathan Shanklin <jdsh@bas.ac.uk>
(7) NEW EVIDENCE FOR ABRUPT GLOBAL COOLING EVENT
Harvey Leifert <HLeifert@agu.org>
(8) GLOBAL WARMING TREND GOES BACK AT LEAST 150 YEARS
Andrew Yee <ayee@nova.astro.utoronto..ca>
==============
(1) WHERE'S THE SMOKING GUN OF THE END-PERMIAN MASS EXTINCTION?
From Space.com, 7 September 2000
http://www.space.com/scienceastronomy/planetearth/extinction_permian_000907.html
ROCKS REVEAL DETAILS OF MASS EXTINCTION
By Lee Siegel
Recent analysis of South African rocks reveals that rivers
suddenly
became clogged with sediments 251 million years ago, indicating
Earth's
worst mass extinction wiped out many trees and other plants that
held
soil in place.
Peter Ward, the study's first author, said he believes a huge
comet or
asteroid walloped Earth to cause the mass die-off at the end of
the
Permian Period and dawn of the Triassic - although his study does
not
say so. Another scientist estimates the object was 9 to 12 miles
(15 to
20 kilometers) wide.
Previous research showed the extinction wiped out nearly 90
percent of
sea species and 70 percent of vertebrate animal species on land.
That
made it far worse than the Cretaceous-Tertiary extinction of the
dinosaurs and many other creatures 65 million years ago - an
event
often blamed on the impact of a perhaps 6-mile- (10-kilometer-)
wide
asteroid.
In the September 8 issue of the journal Science, Ward and
colleagues
concluded the Permian-Triassic catastrophe also stripped Earth of
many
rooted plants, triggering severe erosion.
As a result, sedimentary rocks from that time show that large
meandering rivers throughout South Africa's Karoo Basin took on a
braided, multichannel appearance, resembling streams in areas
devastated by Mount St. Helens' big eruption or areas logged by
clear-cutting.
"When you remove all vegetation, that's what clear-cutting
is. The
Permian-Triassic extinction was the mother of all
clear-cutters," said
Ward, a geologist and paleontologist at the University of
Washington in
Seattle. "It was Armageddon."
Other recent studies have found similar abrupt changes from
meandering
to braided river deposits during Permian-Triassic time in
Australia,
Antarctica and Northern Europe. That supports the notion of a
global
die-off of land plants, including extinction of Glossopteris
trees and
bushes, which resembled modern ginkos. Ward said a variety of
ferns,
seed ferns and early pine trees also went extinct.
Until land plants evolved roughly 415 million years ago, Earth's
rivers
were typically braided rather than meandering, he said.
Braided rivers are common in Alaska and mountainous areas where
glaciers and streams erode rock quickly, filling streams with
sediments.
The Permian-Triassic switch from meandering to braided streams
once was
thought due to mountain-building uplift and subsequent erosion.
But
mountain-building episodes in the Karoo Basin do not coincide
with the
Permian-Triassic extinction, Ward said.
He conducted the new study with David Montgomery, a University of
Washington geomorphologist (landform researcher), and
sedimentologist
Roger Smith of the South African Museum in Cape Town.
Ward said the rocks indicate the rivers changed from meandering
to
braided within 50,000 years, then returned to normal meandering
courses
in another 50,000 to 100,000 years.
Ward said there could be a practical future benefit from his
study.
"Let's pretend we're looking for habitable planets from
space," he
said. "All you need to do is see a meandering river and you
know you
have higher plants, so go there."
The new study is the latest in a series showing the
Permian-Triassic
catastrophe was quick - at least in geological terms - and
extremely
nasty.
But it has not settled debate among those who advocate various
theories
of what caused the extinction: an object whacking Earth, floods
of lava
from the Siberian Traps, climate change, and/or deadly radiation
from a
nearby supernova or other cosmic explosion.
In July, Doug Erwin of the Smithsonian Institution's National
Museum of
Natural History published a study in Science in which marine
rocks from
China revealed the Permian-Triassic extinction happened in less
than
160,000 years.
And in July's issue of the journal Geology, a study of seafloor
rocks
now in the Austrian Alps concluded the extinction happened in
less than
60,000 years and perhaps in less than 8,000 years, said the main
author, planetary scientist Michael Rampino of New York
University.
Because the rock layers do not permit finer dissection of time,
the
findings are consistent with the extinction being triggered by an
impact that happened during "a single bad day," Erwin
said.
"The mass extinction at the end of the Permian Period was
catastrophic
and sudden," ravaging sea and land life, Rampino said.
"The only thing
we know of that can cause an extinction like this is a large
impact of
an asteroid or comet.. But we still haven't found conclusive
evidence
that an impact occurred."
Rampino said the object "would have to be bigger - one and a
half to
twice as big" - as the 6-mile- (10-kilometer-) wide asteroid
usually
blamed for the dinosaurs' extinction.
In 1997, University of Oregon paleontologist Gregory Retallack
reported
finding elevated iridium levels and shocked quartz crystals in
Permian-Triassic rocks - telltale signs of an impact.
"Unfortunately, we have not found a good candidate
crater," he said.
Ward said a comet made of ice "would be almost invisible
geologically."
Last April, Australian scientists said they found a 75-mile-
(120-kilometer-) wide crater in western Australia that might be
from an
impact that caused the Permian-Triassic extinction or a later
extinction at the end of the Triassic Period roughly 200 million
years
ago.
But Rampino said the age of that crater is so poorly known that
"it is
impossible to tie that impact to this [Permian-Triassic]
extinction."
Nevertheless, Retallack favors impact as the cause, perhaps with
the
impact triggering an undersea release of methane that robbed the
oceans
of life-sustaining oxygen. He says the impact also may have
triggered
massive eruptions from volcanic vents named the Siberian Traps.
"There is no evidence of an impact" at Permian-Triassic
time, Erwin
said. "So while the data are consistent with an impact,
there is
nothing that tells us it was an impact," and massive
volcanic eruptions
may be a more likely cause.
Rampino said the Siberian volcanic eruptions lasted hundreds of
thousands of years, so "if the extinctions were gradual over
a half
million years, we might suspect volcanism or changes in climate
caused
by volcanic eruptions. But the fact the extinctions were so
sudden and
catastrophic argues against a volcanic interpretation."
Copyright 2000, Space.com
=============
(2) U.S. GEOLOGICAL SURVEY TO 'CAT SCAN' IMPACT CRATER
From Ron Baalke <baalke@jpl.nasa.gov>
--------------------------------------------------------------------------
News Release
Address
U.S. Department of the
Interior
150 National Center
U.S. Geological
Survey
Reston, VA 20192
Release
Contact
Phone Fax
September 5, 2000 Marion Fisher
(USGS) 703-648-4538 703-648-4588
Chris Rink (NASA)
757-864-6786 757-864-6333
-------------------------------------------------------------------------
USGS Takes "Cat Scan" of Va. Crater
This summer the U.S. Geological Survey (USGS) has been drilling a
deep
hole inside the edge of a 56-mile-wide impact crater created 35
million
years ago when an asteroid or comet slammed into the ocean near
the
present-day mouth of the Chesapeake Bay. The USGS has been
conducting
the drilling project right in the backyard of the NASA Langley
Research
Center in Hampton, Va.
As part of the overall research project, USGS scientists also
plan to
set off firecracker-like blasts underground to perform a seismic
reflection survey across the crater's margin. The seismic survey
will
begin on or about September 6 and will be conducted from the
Langley
Research Center through Hampton and Newport News to a point near
the
James River. This survey will produce a "cat scan"
image of the
distribution of subsurface materials and structures inside,
outside,
and across the crater's margin.
The scientists working on this aspect of the USGS research
project will
produce the seismic waves by firing eight-gauge blank shotgun
shells in
the ground at a depth of approximately 12 to 18 inches below the
surface, or by detonating one-pound or smaller explosive charges
at a
depth of approximately 10-15 feet below the surface. Because of
the
small amount of explosives used, it is doubtful that anyone other
than
the scientists in the immediate area of the shot hole will hear
or feel
anything.
During the past 35 years, the USGS has conducted seismic
investigations
at many locations across the United States. Rufus Catchings, a
USGS
geophysicist who is coordinating the project, said, "the
objective of the
proposed work is to produce an image of the crater margin that
will
help scientists understand the formation and location of the
buried
impact crater."
Some of the data gathered by the scientists in the overall
Chesapeake
Bay Impact Crater Project will be incorporated into the regional
ground-water flow model that was developed by USGS water
resources
specialists in Virginia. Results of the project, which is
supported and
partially funded by the Hampton Roads Planning District
Commission and
the Virginia Department of Environmental Quality, will assist
local and
state water resources managers in making better decisions
concerning
the availability and use of ground water, an important water
supply in
southeastern Virginia.
As the nation's largest water, earth and biological science and
civilian mapping agency, the USGS works in cooperation with more
than
2000 organizations across the country to provide reliable,
impartial
scientific information to resource managers, planners and other
customers. This information is gathered in every state by USGS
scientists to minimize the loss of life and property from natural
disasters, to contribute to the conservation and the sound
economic and
physical development of the nation's natural resources, and to
enhance
the quality of life by monitoring water, biological, energy, and
mineral resources.
=============
(3) FUNDING DILEMMA SOLVED: KIDS WATCH OUT FOR SPACE ROCKS
From Bob Kobres <bkobres@uga.edu>
Thursday's Classroom for September 6, 2000
http://www.thursdaysclassroom.com
Last Friday, a small asteroid zoomed past Earth barely 12 times
farther
from our planet than the Moon. There was no danger of a
collision, but
astronomers are keeping a close eye on the space rock and many
others like
it. This episode of Thursday's Classroom features stories for
kids and
educational lesson plans about Near-Earth asteroids and NASA's
efforts to
discover and track them.
Activities include:
o Alphabet Soup for Rocket Scientists -- If NEA 2000 QW7 passes
0.03 AU
from NASA HQ, should we worry? Students find out in this
lesson about
acronyms and abbreviations.
o Oh Fudge, it's an Asteroid! -- Asteroids may look like
"flying
potatoes," but modeling their shapes is a lot more fun if
you use
fudge.
o Asteroid Angles -- This middle school and high school level
math
exercise helps students decide whether it's better to blow up an
Earth-threatening asteroid, or just to nudge it a bit.
o The Near-Earth Asteroid Coloring Book -- Students can color
original
art by Duane Hilton as they follow along with this week's
lessons.
...and more!
Please visit http://www.thursdaysclassroom.com
=============
(4) RARE SPACE ROCK IN BRITISH LAB
From BBC News Online, 8 September, 2000
http://news.bbc.co.uk/hi/english/in_depth/sci_tech/2000/festival_of_science/newsid_915000/915677.stm
By BBC news Online's Jonathan Amos
UK researchers have got hold of a fragment of one of the rarest
meteorites ever to have fallen to Earth.
The scientists from the Natural History Museum hope the little
chunk of
space rock will tell them about the early formation of the Solar
System
4.5 billion years ago.
The Tagish Lake meteorite came down in a remote area in
northwestern
America, between Atlin, British Columbia, and Carcross, Yukon
Territory, in January.
Several fragments were recovered and are now being studied in
different
labs.
Dr Sara Russell from the Natural History Museum told the British
Association's Festival of Science: "This meteorite is
extremely fragile
and can disintegrate quite easily."
FULL STORY at
http://news.bbc.co.uk/hi/english/in_depth/sci_tech/2000/festival_of_science/newsid_915000/915677.stm
================
(5) TUNGUSKA 2001 INTERNATIONAL CONFERENCE
From Ron Baalke <baalke@zagami.jpl.nasa.gov>
wrote:
Forwarded from Andrei Ol'khovatov (olkhov@mail.ru)
TUNGUSKA 2001 INTERNATIONAL CONFERENCE
CONTENTS
1. PRELIMINARY ANNOUNCEMENT
It seems that it is time to have a new conference of Tunguska,
and
Tunguska 2001 sounds rather good. I talked with several Tunguska
researchers, and they approved the idea. Similar situation was in
1995
when Tunguska researchers having no financial support (Russian
Min. of
Science and Technology gave some financial support at the last
moment),
were able to organize Tunguska 95 international conference.
Of course, the main topic will be Tunguska: factual data, as well
as
interpretations of Tunguska. Till now there are about a hundred
of
hypotheses - from an iron meteorite fall to poltergeist-like
(see, for
example, Abstracts of the Tunguska 98 conference). Maybe a new
one will
appear at the TUNGUSKA 2001 conference?
Besides Tunguska, topics of the conference include related items,
i.e
other similar (whatever origin, as we don't know Tunguska's
origin)
natural catastrophes.
The conference is to be held in Moscow, a capital of Russia, and
probably in one of the Siberian cities (Tomsk, Novosibirsk,
Krasnoyarsk
- to be established soon).
Date of the conference is preliminary scheduled on June 30 - July
1,
2001 in Moscow, and July 3 - July 5, 2001 in Siberia. The shift
can be
no more than 1-2 days.
We hope to organize a few days long trip/excursion to the
Tunguska
epicenter right after the conference, as were during Tunguska 95
and
Tunguska 98 conferences. The expenses depends on many factors,
but
expected to be about $700-1000 per person (from the Siberian city
to
the epicenter and back).
I ask everybody, who has a willing to take part in the excursion,
to
contact me olkhov@mail.ru
right now , as the expenses, as well as the
excursion itself depends on a number of participants (and it's a
hard
work to prepare it)! Of course, this your info will be just
preliminary, and later you can abandon your participation in the
conference and/or the excursion, if your plans change in the
future.
I already have several responses from people who want to take
part in
the conference and in the excursion (from USA, Germany, and
Sweden),
and put them on the list.
More info is to be posted soon.
============
(6) ASTEROID 2000 QW7
From Jonathan Shanklin <jdsh@bas.ac.uk>
Dear Benny,
As Kelly says the interest was mostly for amateurs who could see
the
asteroid in relatively small aperture telescopes. I observed it a
couple of times with the Northumberland refractor at Cambridge,
estimating it at 13th magnitude. It was fascinating to watch the
object
as the motion was obvious within a minute. This was
particularly clear
when it passed close to a star as you could watch the position
angle
changing rapidly.
Regards,
Jonathan Shanklin
j.shanklin@bas.ac.uk
British Antarctic Survey, Cambridge, England
http://www.nerc-bas.ac.uk/public/icd/jds
British Astronomical Association, Comet Section
http://www.ast.cam.ac.uk/~jds
=============
(7) NEW EVIDENCE FOR ABRUPT GLOBAL COOLING EVENT
From Harvey Leifert <HLeifert@agu.org>
Swedish tree rings find a 17th century BC cold event
By wiggle-matching carbon-14 determinations against the
radiocarbon
calibration curve, Grudd et al. ["Swedish tree rings provide
new
evidence in support of a major, widespread environmental
disruption in
1628 BC"] present a new and continuous 200-year tree-ring
chronology
for the period 1695-1496 BC. The chronology was obtained from a
peat
bog in south-central Sweden that preserved a dead forest.
Extremely
narrow tree-rings indicate that a severe cooling occurred in 1637
BC.
While this climatic event may have been regional, the frost event
that
affected this Swedish forest has also left its signature in
California,
central Europe and the British Isles, suggesting a climate change
of
perhaps hemispheric extent.
Authors: Hakan Grudd, Climate Impacts Res. Ctr., Sweden; Keith R.
Briffa, Climatic Res. Unit, U. East Anglia, Norwich, United
Kingdom;
Bjorn E. Gunnarson, Hans W. Linderholm, dept. of Physical
Geography,
Stockholm U., Stockholm, Sweden.
=============
(8) GLOBAL WARMING TREND GOES BACK AT LEAST 150 YEARS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
University Communications
University of Wisconsin-Madison
09/07/00
150-year global ice record reveals major warming trend
By Brian Mattmiller, bsmattmi@facstaff.wisc.edu
From sources as diverse as newspaper archives, transportation
ledgers
and religious observances, scientists have amassed lake and river
ice
records spanning the Northern Hemisphere that show a steady
150-year
warming trend.
The study, which includes 39 records of either freeze dates or
breakup
dates from 1846 to 1995, represents one of the largest and
longest
records of observable climate data ever assembled. University
limnologist John Magnuson led a team of 13 co-authors who
contributed
to the report, to be published in the Sept. 8 issue of the
journal
Science.
Sites ranges from Canada, Europe, Russia and Japan. Of those, 38
indicate a consistent warming pattern. The average rate of change
over
the 150-year period was 8.7 days later for freeze dates; and 9.8
days
earlier for breakup dates. A smaller collection of records going
well
past 150 years also show a warming trend, at a slower rate.
"We think this is a very robust observation: It is clearly
getting
warmer in the Northern Hemisphere," says Magnuson. "The
importance of
these records is that they come from very simple, direct human
observations, making them very difficult to refute in any general
way."
Magnuson says the observational nature of the study is "both
its
strength and its weakness," and the results do not offer
specific proof
that greenhouse gases are driving the warming trend. However, the
findings are consistent with computer-generated models that have
been
developed to estimate climate change from greenhouse gases over a
125-year time period, he says.
The findings also correspond to an air temperature increase of
1.8
degrees Celsius over the past 150 years. A temperature change of
0.2
degrees Celsius typically translates to a one-day change in
ice-on and
ice-off dates.
Freeze dates were defined in the study as the observed period the
lake
or river was completely ice-covered; the breakup date was defined
as
the last ice breakup observed before the summer open-water phase.
Ice records have valuable attributes for climate researchers,
Magnuson
says. They can be gathered across a wide range of the globe, and
in
areas traditionally without weather stations. Their primary
weakness is
that early observers did not document the methods used.
"Of course, 10,000 years ago the Midwest was covered by ice,
so we know
it's getting warmer," he says. "What's troubling and
scary to people is
that these rates in recent decades are so much faster."
Climate models have predicted a doubling of total greenhouse
gases in
the next 30 years or so, a change that could potentially move the
climate boundaries for fish and other organisms northward by
about 300
miles, approximately the length of the state of Wisconsin,
Magnuson
says.
The records in this study are part of a decade-long project led
by
Magnuson and the UW-Madison Center for Limnology to build a
database of
lake and river ice records from around the world. The project was
supported by the National Science Foundation's Long-Term
Ecological
Research program, which emphasizes tracking and understanding
global
changes.
"It's kind of a new science, you might call it network
science,"
Magnuson says. "We reached out to colleagues around the
world and asked
for these records. It turned out some people had very rich stores
of
data."
The records in this study represent the longest and most intact
of 746
records collected through the project. Some individual records
are of
astonishing lengths, with one dating back to the 9th century,
another
to the 15th century and two more to the early 1700s.
For example, Lake Suwa in Japan has a record dating back to 1443
that
was kept by holy people of the Shinto religion. The religion had
shrines on either side of the lake. Ice cover was recorded
because of
the belief that ice allowed deities on either side of the lake --
one
male, one female -- to get together.
Lake Constance, a large lake on the border of Germany and
Switzerland,
has a peculiar record dating back to the 9th century. Two
churches, one
in either country, had a tradition of carrying a Madonna figure
across
the lake to the alternate church each year it froze.
Two other long records come from Canada's Red and McKenzie
rivers,
which date back to the early 1700s and were kept because ice
cover and
open water were critical to the fur trade. Records from Grand
Traverse
Bay and Toronto Harbor, both on the shores of the Great Lakes,
reflect
their prominence as shipping ports.
Other records included in the study are from lakes Mendota,
Monona and
Geneva from Wisconsin; lakes Detroit and Minnetonka from
Minnesota;
lakes Oneida from New York and Moosehead from Maine; Lake
Kallavesi
from Finland; and the Angara River and Lake Baikal from eastern
Russia.
Another finding in the study, based on the 184 ice records from
1950 to
1995, showed the variability in freeze and breakup dates
increased in
the last three decades. Magnuson says it might be related to
intensification of global climate drivers such as the El Nino /La
Nina
effects in the Pacific Ocean.
Magnuson says the ecological effects of global warming are only
beginning to be studied. But studies already exist that have
shown the
northern ranges of some butterflies and birds have been extending
northward.
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