PLEASE NOTE:


*

CCNet 33/2001, 1 March 2001
---------------------------


"Future historians looking back at the search for Earth-threatening
asteroids will find a footnote for events that unfolded last week. [...]
What emerged from the data was a tiny object moving in what appeared to be
a strikingly Earthlike orbit around the Sun. Calculations suggested that
it had passed very near the Moon last August and would come within
360,000 miles (580,000 kilometers) of Earth on February 23rd. The Minor
Planet Center (MPC) in Cambridge, Massachusetts, assigned it the
preliminary asteroid designation 2001 DO47. [...] from the outset
there were suspicions by the MPC staff that 2001 DO47 might be artificial
and thus more reflective than a typical asteroid making it smaller yet.
[...] By February 25th they heard from McDowell, who identified the
mystery spacecraft as Wind, a NASA probe, and confirmed that an engine
burn had indeed been scheduled for February 23rd."
--Dennis di Cicco, Sky & Telescope, 28 February 2001


"My idea could solve the missing smaller craters, the sunken areas
and the angular rocks that may have been eroded out of the astroid's
surface. Moderate to large impacts could cause an asteroid to vibrate
like a tuning fork, the loose surface dust would ride along the surface
seeking low spots in the weak gravity like a fluid bed. Smaller impact
craters would be filled in while larger craters, or newer smaller
craters, may leave a sunken like look. Rocks could travel along the
surface a short distance (didn't I read once that a rock left a short
trail?) loosening more dust for the next impact exposing angular rock that
may be former impactors or hard accetions within the asteroid."
--Dave English, 28 February 2001



(1) BIG EARTHQUAKE JOLTS NORTHWEST: DEMAGE ESTIMATED IN BILLIONS
    The New York Times, 1 March 2001

(2) ANOTHER "ASTEROID" IDENTIFIED AS SPACECRAFT: LESSONS LEARNED FROM THE
SG344 DEBACLE
    Larry Klaes <lklaes@bbn.com>

(3) NEAR SHOEMAKER PHONES HOME FOR THE LAST TIME
    Ron Baalke <baalke@jpl.nasa.gov>

(4) LOUIS FRANK CLAIMS TO HAVE FOUND NEW EVIDENCE FOR SMALL COMET THEORY
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(5) RARE METEORITES REKINDLE CONTROVERSY OVER BIRTH OF THE SOLAR SYSTEM
    Stanford News Service <stanford.report@forsythe.stanford.edu>

(6) NEAR: AWAKENED FROM THE DEAD?
    Space.com, 28 February 2001

(7) EROS POINTS WAY TO PHOBOS AND DEIMOS
    S. Fred Singer <singer@sepp.org>

(8) DUST MIGRATION ON SMALL BODIES
    Dave English <prospector@sd.znet.com>

(9) THE "CHRISTMAS" COMET
    Mark Kidger <mrk@ll.iac.es>

(10) IMPACT VOLCANISM CLARIFICATION
     Mark Boslough <mbboslo@sandia.gov>

(11) IR, PLUMES & SCIENTIFIC AMERICAN
     Hermann Burchard <burchar@mail.math.okstate.edu>

(12) CO2 AS A DINO-KILLER AMPLIFIER?
     Jon Richfield <richfield@telkomsa.net>

(13) ABSTRACTS FROM GEOLOGICAL SOCIETY OF AMERICA 2000
     Michael Paine <mpaine@tpgi.com.au>

=============
(1) BIG EARTHQUAKE JOLTS NORTHWEST: DEMAGE ESTIMATED IN BILLIONS

From The New York Times, 1 March 2001
http://www.nytimes.com/2001/03/01/national/01QUAK.html

SEATTLE, Feb. 28 - The Pacific Northwest was rocked today by the most
powerful earthquake to hit the area in 52 years, a 40-second tremor that
shattered windows, crumbled bricks and buckled pavement across Seattle and
cracked the Capitol dome in Olympia, Wash., a dozen miles from the quake's
epicenter.

At least 215 people were injured, at least 8 seriously, and officials said
property damage would easily run into the billions of dollars......

http://www.nytimes.com/2001/03/01/national/01QUAK.html

===============
(2) ANOTHER "ASTEROID" IDENTIFIED AS SPACECRAFT: LESSONS LEARNED FROM THE
SG344 DEBACLE

From Larry Klaes <lklaes@bbn.com>

WAIT, IT'S ONE OF OURS

From Sky & Telescope, 28 February 2001
http://www.skypub.com/news/news.shtml#wind

A puzzling "asteroid" designated 2001 DO47 turned out to be of terrestrial
origin. The Wind spacecraft was launched in 1994 to study the interaction
between the solar wind and Earth
magnetosphere. This plot shows the probe's looping trajectory from May 1999
to April 2000. Courtesy International Solar-Terrestrial Physics program,
NASA/Goddard Space Flight Center.
http://www.skypub.com/news/images2001/010228news02.gif

Future historians looking back at the search for Earth-threatening asteroids
will find a footnote for events that unfolded last week.

It began on the evening of February 18th when a fast-moving object was
spotted in western Cancer by the Arizona-based Spacewatch team - the
patriarch of contemporary searches, which has been looking for near-Earth
objects (NEOs) with a 36-inch telescope since the 1980s.

During the next two days amateur and professional observers at more than a
dozen locations around the world tracked thetracked the 16th-magnitude
object as it raced eastward crossing a Moon's diameter of sky every 90
minutes.

What emerged from the data was a tiny object moving in what appeared to be a
strikingly Earthlike orbit around the Sun. Calculations suggested that it
had passed very near the Moon last August and would come within 360,000
miles (580,000 kilometers) of Earth on February 23rd. The Minor Planet
Center (MPC) in Cambridge, Massachusetts, assigned it the preliminary
asteroid designation 2001 DO47.

While certainly an interesting object, 2001 DO47 posed no threat. Even if it
were headed toward Earth, its estimated diameter of only 10 meters would
have made it too small to survive a passage through our atmosphere.
Furthermore, from the outset there were suspicions by the MPC staff that
2001 DO47 might be artificial and thus more reflective than a typical
asteroid making it smaller yet.

"We would have liked to check out the artificial possibility before
announcing the object," notes MPC associate director, Gareth Williams, "but
our resident expert, [Sky & Telescope contributing editor] Jonathan
McDowell, was observing in Arizona and initially out of reach."

The story took another twist when observations of the object made on
February 23rd by John Rogers in California and the undersigned in
Massachusetts - both members of the worldwide network of amateurs who
measure positions of asteroids and comets - were internally consistent but
significantly out of step with the earlier sightings.

"2001 DO47 has switched on its engine," is how Williams described the
situation to MPC director Brian Marsden, who concurred with Williams that
the object must be artificial.

By February 25th they heard from McDowell, who identified the mystery
spacecraft as Wind, a NASA probe, and confirmed that an engine burn had
indeed been scheduled for February 23rd.

Launched on a mission to study the solar wind and Earth's outer
magnetosphere in late 1994, Wind spends most of its time far from Earth, but
it also makes occasional swings by the Earth and the Moon during orbital
maneuvers. The spacecraft is 2.4 meters (7.9 feet) in diameter and 1.8
meters (5.9 feet) high.

Marsden told Sky & Telescope that, inspired by the 2001 DO47 incident, the
MPC has now added the orbital information of about a dozen spacecraft to its
computers, which should help identify these objects when they turn up in the
data from NEO surveys.

- Dennis di Cicco

Copyright 2001, Sky & Telescope
=============
(3) NEAR SHOEMAKER PHONES HOME FOR THE LAST TIME

From Ron Baalke <baalke@jpl.nasa.gov>

For Immediate Release
February 28, 2001

Media Contacts:
Helen Worth
(240) 228-5113
helen.worth@jhuapl.edu

Mike Buckley
(240) 228-7534
michael.buckley@jhuapl.edu


The End of an Asteroidal Adventure
NEAR Shoemaker Phones Home for the Last Time

Tonight at 7 p.m. (EST) NASA's Deep Space Network antennas will pull down
their last Near Earth Asteroid Rendezvous (NEAR) mission data, bringing to a
close the first mission to extensively study an asteroid. NEAR, which was
the first mission in NASA's Discovery Program of low-cost, scientifically
focused space missions, and the first to land on an asteroid, has delighted
astronomy neophytes and scientists alike.

"NEAR has raised the bar," says Dr. Stamatios Krimigis, Space Department
head at The Johns Hopkins University Applied Physics Laboratory in Laurel,
Md., which built the spacecraft and managed the NEAR mission. "The
Laboratory is very proud to have managed such a successful mission and
worked with such a strong team of partners from industry, government and
other universities. The team had no weak links and the result was an
historic mission that surpassed everyone's expectations."

"This mission has been successful far beyond what was in the original
mission plan," says NEAR Mission Director Dr. Robert Farquhar of APL. "We
got the first images of a C-class asteroid when we added a flyby of asteroid
Mathilde in 1997; we added two low altitude series of passes over the ends
of Eros this past October and January that gave us spectacular images from
2.7 kilometers above the surface; and we achieved the first landing of a
spacecraft on an asteroid on Feb. 12. All this at no extra cost. When you
talk about ' faster, cheaper, better,' this is what 'better' means."

On Feb. 12 at 3:01:52 p.m. (EST), NEAR Shoemaker made a gentle,
picture-perfect 3-point landing on the tips of two solar panels and the
bottom edge of the spacecraft body. But the mission wasn't finished yet.
Much to the amazement of the mission team and millions of observers around
the world who were following the descent, the touchdown was so elegant that
the craft was still operating and sending a signal back to Earth even after
landing.

Jumping at the chance to get "bonus science" from the spacecraft, which had
already collected 10 times more data than originally planned, the mission
team asked for and got a 10-day extension and then four more days of DSN
antenna time, enabling NEAR Shoemaker to send back data through Feb. 28. The
extension was granted to allow the gamma-ray spectrometer to collect data
from an ideal vantage point about four inches from the surface. The
spectrometer team quickly redesigned software and uploaded it to the
spacecraft so they could begin collecting elemental composition readings.

The results were spectacular.  "This is the first gamma-ray experiment that
has ever been done on the surface of a body other than Earth," says Dr.
Jacob Trombka, of NASA's Goddard Space Flight Center, in Greenbelt, Md., who
heads the gamma-ray spectrometer team. "In fact, we can say it's the first
feasibility study of how to design an instrument to be used on a rover that
could select samples from the surface, look for the presence of water, or
map the surface for the purpose of future mining."

The gamma-ray spectrometer team was able to retrieve data for a period of
seven days after the spacecraft landed. "Right now we know we have good data
with strong signatures," Trombka says. "But it will take months to
scrutinize what we've collected. What we're looking for is information that
will help us more precisely classify Eros and determine the relationship
between the asteroid and meteorites that have fallen to Earth."

NEAR Shoemaker now rests silently just to the south of the saddle-shaped
feature Himeros as the asteroid twists more and more away from the sun with
each rotation, moving the southern hemisphere into its winter season and
temperatures as low as minus 238 degrees Fahrenheit (minus 150 centigrade).

Project Scientist Dr. Andrew Cheng of APL, says the glamorous part of the
mission is over but now scientists can get down to studying the data,
including the more than 160,000 detailed images taken by the spacecraft. "We
solved mysteries, we unveiled more mysteries. Now we're sharing the amazing
amount of data that we collected with scientists all over the world, to sort
through and debate and hopefully to help us discover facts about Eros and
our solar system that no one knows today."

For more information on the NEAR mission, including a gallery of images,
visit Web site: http://near.jhuapl.edu.

============
(4) LOUIS FRANK CLAIMS TO HAVE FOUND NEW EVIDENCE FOR SMALL COMET THEORY

From Andrew Yee <ayee@nova.astro.utoronto.ca>

University Relations
University News Services
University of Iowa

CONTACT:
GARY GALLUZZO
(319) 384-0009; fax (319) 384-0024
e-mail: gary-galluzzo@uiowa.edu

Release: Embargoed 1 a.m. EST, March 1, 2001

UI researcher finds new evidence for small comet theory

IOWA CITY, Iowa -- In a paper published in the March 1, 2001 issue of the
American Geophysical Union's Journal of Geophysical Research, University of
Iowa physics professor Louis A. Frank says that he has found new evidence to
support his theory that the water in Earth's oceans arrived by way of small
snow comets.

Frank reports that he obtained pictures of nine small comets among 1,500
images made between October 1998 and May 1999 using the Iowa Robotic
Observatory (IRO) located near Sonoita, Ariz. In addition, he says that the
possibility of the images being due to "noise," or electronic interference,
on the telescope's video screens was eliminated by operating the telescope
in such a manner as to ensure that real objects were recorded in the images.
This operation of the telescope utilized two simple exposure modes for the
acquisition of the images. One scheme used the telescope's shutter to
provide two trails of the same small comet in a single image, and the second
scheme used the same shutter to yield three trails in an image.

"In the two-trail mode for the telescope's camera, no events were seen with
three trails, and for the three-trail mode, no events were seen with two
trails," he says. "This simple shutter operation for the telescope's camera
provides full assurance that real extraterrestrial objects are being
detected." Frank notes these images with the IRO confirm earlier reports of
small comet detection using the ground-based Spacewatch Telescope during
November 1987, January 1988 and April 1988.

The small comet theory, developed in 1986 with UI research scientist John
Sigwarth from data gathered using the Dynamics Explorer 1 satellite, holds
that about 20 snow comets weighing 20 to 40 tons each disintegrate in the
Earth's atmosphere every minute. Over the lifetime of our planet, the comets
would have accounted for virtually all of the Earth's water. The small comet
theory has been controversial almost from the beginning, with some
scientists suggesting that images identified as small snow comets actually
result from electronic noise on satellite sensors and other researchers
asserting that the images represent a real phenomenon. In 1997, Frank
revealed a series of photographs taken by Visible Imaging System (VIS)
cameras designed by Frank and Sigwarth and carried aboard NASA's Polar
spacecraft as further proof of the existence of the small snow comets.

Robert A. Hoffman, senior scientist at NASA's Goddard Space Flight Center,
Greenbelt, Md. and project scientist for both the Dynamics Explorer 1 and
the Polar spacecraft missions, says that because satellite-based imagery
related to the small comet theory has been interpreted in different ways,
ground-based imagery is a good alternative.

"Due to the controversy surrounding the interpretation of the images from
space-borne detectors taken primarily in ultraviolet wavelengths,
ground-based visible observations with sufficient signal-to-noise appear to
be the most practical approach to obtaining clear evidence regarding the
existence of these objects. I hope more such studies will be performed,"
Hoffman says.

Frank, a UI faculty member since 1964, has been an experimenter,
co-investigator, or principal investigator for instruments on 42 spacecraft.
His instruments include those used to observe the Earth's auroras, as well
as those used to measure energetic charged particles and thin, electrically
charged gases called plasmas. He is a Fellow of the American Geophysical
Union and the American Physical Society, a member of the American
Astronomical Society, American Association for the Advancement of Science
and the International Academy of Astronautics, and a recipient of the
National Space Act Award.

Further information, including images of two small comet trails, can be
found at the following web site:
     http://smallcomets.physics.uiowa.edu/iro/

(Note to editors and reporters: Frank will be traveling out of the country
from Feb. 26 through March 3 and will be unavailable for interviews during
that time.)

==========
(5) RARE METEORITES REKINDLE CONTROVERSY OVER BIRTH OF THE SOLAR SYSTEM

From Stanford News Service <stanford.report@forsythe.stanford.edu>

2/28/01

CONTACT: Mark Shwartz, News Service (650) 723-9296;
         mshwartz@stanford.edu

COMMENT: Anders Meibom, Department of Geological and
         Environmental Sciences (650) 725-6536 or
         (650) 736-0752; meibom@pangea.stanford.edu

EDITORS: Anders Meibom`s study, ``A new astrophysical setting for
         chondrule formation,`` appears in the March 2 issue of Science
         magazine.

EMBARGOED until Thursday, March 1, at 2 p.m. U.S. Eastern Time

Relevant Web URLs:
http://www.psrd.hawaii.edu/Sept00/primitiveFeNi.html
http://www.cwru.edu/affil/ansmet/
http://hubble.esa.int

Rare meteorites rekindle controversy over birth of the solar system

A new meteorite study is rekindling a scientific debate over the creation of
our solar system.

The study, published in the March 2 issue of the journal Science, is based
on the microscopic analysis of two rare meteorites recently discovered in
Antarctica and Africa.

Most meteorites found on Earth are believed to be fragments of asteroids -
ancient rocks and that formed during the creation of the solar system about
4.56 billion years ago. Thousands of asteroids still orbit the Sun in the
asteroid belt between Mars and Jupiter, about 140 million miles from Earth.

"Asteroids and meteorites are solids that never got incorporated into the
planets. These objects have survived, unchanged, for 4.56 billion years,"
says physicist Anders Meibom, a postdoctoral fellow in the Stanford
Department of Geological and Environmental Sciences who co-authored the
Science study.

Chondrites and chondrules

Using electron microscopy and other laboratory techniques, Meibom and his
colleagues conducted a detailed chemical analysis of two chondrites -
primitive meteorites made up of thousands of tiny round particles called
chondrules.

 ``Chondrules are among the oldest objects in the solar system, dating back
to the birth of the Sun,`` says Meibom, ``so when we look at chondrules,
we`re actually looking at the very first steps towards the creation of our
solar system.``

Meibom points out that most chondrules are made of silicates and metals that
can only be produced at very high temperatures. Exactly how chondrules
formed in the early solar system is a hotly debated topic among scientists.

``The conventional view,`` notes Meibom, ``is that chondrules started out as
dust balls in the asteroid belt region some 4.56 billion years ago.  Today,
the asteroid belt is ultra-cold, but at that time, the temperature was just
below 700 degrees Fahrenheit.  The dust balls melted after they were zapped
by quick bursts of lightning or shock waves, which briefly raised
temperatures to about 3000 degrees F.``

According to this theory, as the melted particles cooled, they turned into
millimeter-size chondrules, which eventually clumped together to form larger
chondrites.

New theory

But in 1996, astronomer Frank Shu of the University of California proposed a
different theory based in part on dramatic images from the Hubble Space
Telescope, which - for the first time - allowed astronomers to witness the
actual birth of new stars elsewhere in the Milky Way.

The Hubble revealed that most young stars are created from enormous disks of
whirling gas and dust.

As the disk contracts, it rotates faster and faster, funneling tons of
interstellar dust toward the center, where temperatures reach 3000 degrees F
or more - hot enough to melt metal and vaporize most solids.

The rotating disk also produces enormous jets of gas capable of launching
debris far into space at speeds of hundreds of miles per second.

Using the Hubble images as a guide, Shu proposed that chondrules in our
solar system were created near the hot central disk of the newly emerging
Sun - not in the relatively cool asteroid belt hundreds of millions of miles
away.

According to Shu, dust particles were melted by the Sun, then launched into
space by powerful jets of gas and solar wind. While in flight, the molten
particles solidified into spherical chondrules, some of which landed in the
asteroid belt a few days later. Others ended up as the raw materials that
formed the Earth, Mars and the rest of the planets in our solar system.

According to Meibom, the March 2 chondrite study in Science magazine gives
Shu`s version of chondrule creation a tremendous boost.

 ``Our findings demonstrate that Frank Shu`s ideas are not just some
fantasy,`` he notes. ``We now have actual rocks that provide hard numbers,
which fit very nicely into the general framework of Shu`s theory.``

Rare meteorites

Meibom and his colleagues based their study on two rare meteorite specimens
- HH 237, a grapefruit-size chondrite recovered from the Hammadah al Hamra
region of north Africa; and QUE 94411, a walnut-size sample collected from
the Queen Alexander mountain range in Antarctica.

``Most chondrites are only seven to ten percent metal by volume, but these
two specimens are about 70 percent iron and nickel,`` says Meibom.

Microscopic analysis revealed that these iron-nickel compounds formed by
condensation from hot gas when the temperature was around 2500 degrees F.

 ``Because HH 237 and QUE 94411 contain pristine samples of condensed iron
and nickel, we were able to determine that these metal grains formed on a
time scale of a few days. Furthermore, the newly created metal grains must
have been transported out of their hot formation region very quickly.

``Shu`s model provides those kind of temperatures and time scales, and the
jets certainly provide a way to kick the grains out to much colder regions
of the solar nebula,`` adds Meibom.

 ``The scenario we are suggesting is that of a big blobs of hot gas rising
up through the disk - almost like bubbles in boiling spaghetti sauce. As the
gas bubbles rose and cooled, silicate and metal grains began to condense out
of the gas. When these grains got close enough to the surface of the disk,
they became trapped in the powerful jet streams. Days later, the particles
arrived in the asteroid belt, where the relatively cold temperatures
preserved them from destruction.``

These chondrites allow us to look at the very frontier of the solar system,
concludes Meibom.

``For the first time, we`re really building a bridge between what we observe
in the meteorites and what astrophysicists like Shu are telling us.``

Frank Shu agrees.

``In these two very special meteorites we finally have direct evidence that
certain portions of rock had to move from some place very hot to some place
very cold in a very short period of time,`` comments Shu. ``This is a very
important study.``

Meibom`s other collaborators in the Science study are Alexander N. Krot and
Klaus Keil of the University of Hawaii; Sara S. Russsell and Timothy E.
Jeffries of the Natural History Museum in London; and Conel M. O`D.
Alexander of the Carnegie Institution of Washington`s Department of
Terrestrial Magnetism.

-30-

By Mark Shwartz

-------------------------------------------------------

News Service website:
http://www.stanford.edu/news/

Stanford Report (university newspaper):
http://www.stanford.edu/news/report/

Most recent news releases from Stanford:
http://www-leland.stanford.edu/dept/news/release/curindex.html

To change contact information for these news releases:
email: stanford.report@forsythe.stanford.edu
Phone: (650) 723-2558

=========
(6) NEAR: AWAKENED FROM THE DEAD?

From Space.com, 28 February 2001
http://www.space.com/missionlaunches/missions/near_awakening_010228.html

Is it possible that NEAR Shoemaker could survive its long, deep sleep? There
is some speculation at APL that awakening the probe after its long
hibernation might be feasible.

Given full sunlight will fall upon the spacecraft once again in August 2002,
reactivating solar-powered NEAR Shoemaker might be worth thinking about,
said Helen Worth, APL spokeswoman.

"As we've learned with NEAR Shoemaker, the impossible always seems to become
possible. There are no plans at this time to do such a thing. But it
wouldn't be unreasonable to look into the idea," Worth told SPACE.com.

"It would give us another opportunity to learn more about what happens to a
spacecraft. If we can't contact it later, if we tried to, we would learn
something from that too. Whether they're going to even attempt that...it
hasn't been decided at this point," Worth said.

In 2002, Eros is much closer to Earth. Reestablishing a radio link with the
asteroid-sitting spacecraft might be reasonable and feasible.

"This idea has not been thoroughly examined. It's something that needs to be
looked at to determine if it's even possible. We're not there yet. I'm sure
there are people who are thinking about it already, but it hasn't been
pursued at this point, or seriously proposed," Worth said.

Copyright 2001, Space.com
 
============================
* LETTERS TO THE MODERATOR *
============================

(7) EROS POINTS WAY TO PHOBOS AND DEIMOS

From S. Fred Singer <singer@sepp.org>

Dear Benny

Eros resembles in size and shape (and to some extent in appearance) the
Martian moons Phobos and Deimos. But are they related? Do they have similar
bulk density, structure and composition?

Some years ago, I believe in 1968, in the Geophys J of the Royal
Astronomical Society,  I wrote a paper testing the hypothesis that Phobos
and Deimos are captured asteroids. If one calculates their present
near-circular orbits backward in time, using tidal perturbations, one finds
similar (initial) parabolic orbits.  This is a surprising result; nothing
else supports capture.  One can deal easily with the time-scale problem by
assuming stronger (than today) tidal dissipation in Mars, perhaps by
primeval oceans. But how to account for the near-zero inclinations of the
moons? And small bodies are extremely difficult to capture (certainly by
tidal dissipation).

There are alternatives: The moons could be the remnants of a much larger
body (from which they were separated) that has now disappeared by
spiralling into Mars because of tidal perturbations.  [See the "push-pull"
tidal mechanism in my 1968 paper.]

Another possibility: Phobos and Deimos are planetesimals and remnants of the
formation of Mars.

So---one of the encouraging things about NEAR is the successful landing on
the surface. For the Martian moons, this is a much easier problem since they
are locked in rotation facing Mars. Now the Eros gamma-ray experiment
becomes very important; it needs to be duplicated for Phobos and Deimos. We
don't even know if the moons have similar compositions! But how exciting if
we can establish identical compositions for all three bodies.

Another comparative study would involve the migration of dust on the
surfaces.  Perhaps that could account for differences in appearance. [In the
case of Phobos, the gravity field of Mars may play an important role.]

ON TO MARS!

Fred

S. Fred Singer, President
Science & Environmental Policy Project
http://www.sepp.org

==========
(8) DUST MIGRATION ON SMALL BODIES

From Dave English <prospector@sd.znet.com>

Dear Benny:

I read with interest the report by Jeffery Bell about the lack of small
impact craters on Eros, the apparent erosion of angular rocks to its surface
and J. Fred Singer's well founded idea of electrostatic dust transport, but
it may be much simpler than that.

My idea could solve the missing smaller craters, the sunken areas and the
angular rocks that may have been eroded out of the astroid's surface.

Moderate to large impacts could cause an asteroid to vibrate like a tuning
fork, the loose surface dust would ride along the surface seeking low spots
in the weak gravity like a fluid bed. Smaller impact craters would be filled
in while larger craters, or newer smaller craters, may leave a sunken like
look. Rocks could travel along the surface a short distance (didn't I read
once that a rock left a short trail?) loosening more dust for the next
impact exposing angular rock that may be former impactors or hard accetions
within the asteroid.

If this idea has merit then the size of the last impactor should be able to
be calculated by the appearance of the sunken areas which will reflect the
type of motion and so the energy generated by the impact. I know that in
panning gold many different motions and taps can cause very different
results in the gold pan. I'm not a scientist, just an idea person with
practical knowledge about virbration and fluid bed type motions, which the
dust in the weak gravity should mimic after larger impacts that would
vibrate the asteroid like a tunning fork causing the dust to seek low spots,
exposing new angular rock, and causing further surface erosion by scraping
and pounding by loose rock.

                                                           Dave English
                                                           Oceanside,
California
 
prospector@sd.znet.com

============
(9) THE "CHRISTMAS" COMET

From Mark Kidger <mrk@ll.iac.es>

Benny:

I would strongly recommend that Jonathon Shanklin checks the source
reference about the propects of Comet C/2000 WM1 (LINEAR) at:
http://www.meteors.com/cometlinear/comet_linear_is.html

as I have already made several of these points and show the whole range of
*possible* light curves of which a magnitude 2 object is the best case
headline event. All the projections show that the brightest magnitude will
be reached around closest approach to the Earth around late November and not
at perihelion when the comet will be significantly fainter. At this time it
will still be a northeern hemisphere, evening object although after closest
approach it will go rapidly south.

Comet Kohoutek is possibly a bad example as it did briefly reach negative
magnitude in late December 1973 according to groundbased observers (and
rather brighter for the Skylab astronauts). There is no possibility at all
that Comet LINEAR will get that bright.

I hope that this clears things up.

Mark

============
(10) IMPACT VOLCANISM CLARIFICATION

From Mark Boslough <mbboslo@sandia.gov>

A few inaccuracies crept into the March Scientific American article.

1) Our seismic focusing calculations showed that the peak in seismic energy
dissipation is in the asthenosphere both antipodal and directly beneath the
point of impact. We suggested that for a sufficiently large impact the
increased melting in the asthenosphere would be a significant contributor to
any impact-induced volcanism, but we did not speculate about effects on
pre-existing plumes or extinctions (although these ideas are worth
considering). Our idea was that a narrow column of hotter mantle could
create an instability that *looks* like a plume (as opposed to a classic
fluid plume that pushes its way up from the CM boundary).

2) I'm not sure where the "may not have been antipodal" phrase came from.
The impact antipode was clearly something like 30 degrees from the Deccan
Traps at the time of the K/T boundary.  If the Deccan Traps are
impact-induced it was not the Chicxulub impact (which came too late and in
the wrong place!) but an earlier impact either into the east Pacific or into
India.

3) We suggested that an impact might generate the same surface
manifestations normally associated with mantle plumes (i.e. flood basalts
and long-lived hotspots). We did not connect them to superplumes which is
what Dallas Abbott proposed. It was Jon Hagstrum of the USGS who suggested
the connection to sea level, weathering, ocean chemistry, sediments, etc.
The ideas of Abbott and Hagstrum are also interesting worth considering--but
they're not mine as the article implies.

Mark Boslough
Sandia National Laboratories

-----------------------

Scientific American, March 2001
http://www.sciam.com/2001/0301issue/0301scicit3.html

...One of those events is Chicxulub--and its relation to the Deccan Traps.
Mark Boslough of Sandia National Laboratories modeled the so-called seismic
focusing that would occur from an impact event on the earth's innards.

A large energy release on one side of the earth would set off seismic waves,
which would travel through the mantle and converge at the opposite side, or
antipode, creating another energy peak. That energy would be converted to
heat, raising temperatures in the mantle and increasing melting of the rocky
material--thereby heightening the effects of any plume already there and
further contributing to conditions that lead to extinctions.

Abbott is unsure of the exact mechanisms that would strengthen an existing
plume, but one possibility is that increasing temperature differentials
between the core and the mantle would cause fingerlings of hot core rock to
enter the earth's crust. The subsequent increase in volcanism and release of
climate-affecting gases would be more than expected for a superplume or
impact event alone.

Thanks to plate tectonics, however, the Deccan Traps may not have been
antipodal at the time of the Chicxulub impact. If they weren't, Boslough
says, "you would have to propose a second impact," directly opposite the
Traps, "in the eastern Pacific, on seafloor that's been subducted." Any
geological evidence would be gone.

"You have to figure out what is in the geological record" to draw any firm
conclusions, Boslough says. From his models, an impact might produce the
same kinds of surface manifestations attributed to superplumes: flood
basalts, large changes in sea level, radically increased mechanical erosion
that alters ocean water chemistry, and sediment deposits that indicate a
global change has occurred.

But Abbott and Isley think there is hard evidence for impact-enhanced
superplumes: certain types of rocks associated only with superplumes, say,
or some kind of universal, physical characteristic in the earth consistent
only with major plume events. For now, though, not enough evidence exists to
indict superplumes as an extinction accomplice....

===========
(11) IR, PLUMES & SCIENTIFIC AMERICAN

From Hermann Burchard <burchar@mail.math.okstate.edu>

Dear Benny,

In his note posted on CCNet Feb 23, Andrew Glikson certainly shot down my
guesswork concerning abundance of Ir in Hawaii, Sibiria, and the P/Tr
boundary.  Scientific facts are really great, thanks, Andrew! It's an honor
of sorts to come into the crosshairs of an expert geochemist like
yourself.

Another matter are these globs of rising fluid in the mantle, referred to in
the Scientific American quote supplied by Michael Paine. This is based on
the idea of mantle circulation, and has never seemed plausible to me in the
form in which it has often been stated (I hope to read a few of the original
articles soon, now that I have references, thanks in part to some of Andrew
Glikson's papers).  Although certain steady state boundary conditions can
lead to transient plumes this doesn't seem to fit the long-lived mantle
plumes which we observe.

There are two kinds of locations where mantle melts and rises, (1) spreading
zones or rifts and (2) plumes or hotspots. The basic mechanism is the same
in both cases. See my CCNet-notes, Feb 15 and 19, where I tried to suggest
an alternate, simpler genetic theory of origin:  The pressure is lowered due
to reduced overburden of crustal rocks. Lower pressure forces a phase
transition leading to equilibrium at a lower Gibbs energy (melting).  The
melting is adiabatic, no extra heat is supplied.

For a plume the inititial event is excavation of crustal rocks in the impact
explosion. Melting is the next step with mantle upwelling. Formation of a
long-lived plume is on its way, without any voodoo cooperation of impact and
with no "accomplice" plume. Why look for "fingerlings" in an evenly heated
mantle with a simple phase transition theory being available?  There is no
need to have the plume hotter than surrounding mantle. The original event
left a pore, thus retaining a lower pressure than the surrounding mantle
rocks, which is surprisingly rigid.

In the other case, of a spreading ridge, once it is started -- e.g., by
erosive removal of overburden -- the familiar pattern evolves where a kind
of circulation occurs at sinking geosynclines which often run parallel to
spreading zones. To me, this seems to be due entirely to surficial isostasy
coupled with phase transition melting at spreading rifts, which supplies the
driving force.  There is no sign that internal instabilities lead to deep
mantle circulation.  Radioactive processes heat the mantle evenly, I am
guessing, being the ultimate source of energy which needs to be dissipated.
The mantle is not being heated from below although heat flux is outward
everywhere.

Naturally, if one accepts causal links between flood basalts and transient
mantle plumes, then one may be more inclined to reject the suggestion made
by Robert Dietz to the effect that Norilsk is an impact site like Sudbury.
This is why I emphasized facts known about the Idaho flood basalts and the
Yellowstone hotspot as a long-lived "walking plume", moving about 600 km in
15 Ma from its origin in far Eastern Oregon or Western Idaho according to
the USGS, or 40 mm/a (the Columbia river plateau further West appears to
have a separate origin if I read the USGS correctly).

In rejecting the short-lived plume theory of basalt eruptions, I look for
signs of a traveling plume related to known flood basalts, such as the
Sibirian traps. Chances are good, I believe, that the latter chain of
mountain ranges will be found to have progressively younger ages as one
moves East from Norilsk to the Pacific coastline.  Ages for seamounts, such
as 65 Ma for the western-most mount in the Emperor chain are doubtful,
reportedly being difficult to establish.  I get an average rate of 40 mm/a
upon taking the kinks out of the Norilsk-Hawaii path. By dead
reckoning, the bend west of Midway Island comes to about 65 Ma, perhaps
related to the K/T impact(s).

One point to add:  The basement rocks under the Northern Yucatan just might
turn out to be a pluton datable to 65 Ma extruded from a mantle plume caused
by (as opposed to: co-operating with) the Chicxulub impact, as predicted by
my model. The plume failed to break through to the surface, but mantle rock
rose in a plutonic intrusion. Conditions were not favorable for basalt to be
brought to eruption by an impact plume, as at other places:

 (1) Sudbury,
 (2) in Western Idaho, where the Yellowstone hotspot started according to
USGS,
 (3) at the Shiva crater giving rise to the plume which caused the Deccan
flood basalts,
 (4) at Norilsk (apparently still controversial despite Robert Dietz).

The Yucatan plume then migrated East at 40 mm/a (same rate a for the Norilsk
and Yellowstone plumes), creating the Greater Antilles until dying out or
merging with the West-Atlantic geosyncline.  Here, too, I predict the island
mountain chain as it tapers to the East will turn out to have progressively
younger plutonic basements.

Although undoubtedly real, antipodal effects need not be considered any
longer for the Deccan if my plume formation theory (is this not really an
ancient theory?) should find acceptance. The Norilsk-Falklands antipodal
effect could still be true, and I believe it is, except the impact was in
Sibiria.

Regards,

Hermann G.W. Burchard
        
=============
(12) CO2 AS A DINO-KILLER AMPLIFIER?

From Jon Richfield <richfield@telkomsa.net>

I have often wondered about the KT extinction event (who hasn't?). I suspect
that such a global disaster must have been more complex than many of us tend
to assume when we contemplate hypotheses like asteroidal disasters or
volcanism. Apart from the whole thing having been a far
longer process than people tend to think of when we speak of an "event",
large events tend to entail other large events and the larger the systems
are, the likelier it is that there will be emergent effects.

Also, we are sitting on a time bomb far more alarming to me than say, global
warming, though the two are not independent. The event at Lake Nyos has
shown that it is not a purely academic speculation either. In our deep sea
we have quantities of dissolved free CO2 that boggle the
mind.  Let a small seashell sink in the deeps, say a Foraminiferan, and it
is likely to dissolve in the carbonic acid before it hits the sea floor. Set
even a large fraction of it free and our atmosphere would become
unbreathable. This would relegate the greenhouse effect to the status of a
minor detail. 

What keeps the stuff down for the moment is the density gradient, as
stabilised by temperature and solutes, but the situation is at best
metastable. Once set up a convection current going, and the evolving gas
could amplify it disastrously, gassing us all to death with a giant soda
siphon. 

Now, suppose a dino killer were to hit a large body of deep sea containing
about as much CO2 as there is gas in the atmosphere in total. (This is very
little actually. Remember, condensed to water density,  our atmosphere would
only be some ten metres deep. You could lose it in the ocean!)  Now, apart
from all the putative effects of a large impact, the tidal waves, fires,
global winter and so on, we could have a soda fountain lasting maybe days or
weeks, till that body of sea water has too little CO2 left to drive the
flow.  It might gas only say, half the planet; and perhaps not very well at
that, but why do I get the feeling that giant animals might suffer worse
than tiny ones? 

There is every reason to believe that things were not much different in the
sea towards the end of the Cretaceous. 

I have seen speculations that a rock hitting huge carbonate deposits might
release huge volumes of CO2 and I accept this, but I think that the soda
siphon mechanism would more plausibly release really huge volumes over a
longer period and potentially from a smaller impact.

Also, for all we know, dinosaurs and other large fauna of the day may have
had a physiology more sensitive to CO2 than their contemporary mammals did.

And what such a mechanism might have meant to the ecology, I blanch to
think. It might not have killed all the big beasts, but it might have killed
a lot of asteroid survivors over tens of millions of square kilometres, that
otherwise could have re-established the status quo ante impact. 

Just wondering.  Any ideas on this?  

Cheers,

Jon

=============
* ABSTRACTS *
==============

(13) ABSTRACTS FROM GEOLOGICAL SOCIETY OF AMERICA 2000

From Michael Paine <mpaine@tpgi.com.au>

Dear Benny,

Franco Pirajno (Geological Survey of Western Australa) suggested I take a
look at the abstracts of the Annual Meeting of the Geological Society of
America on the subject of impacts and volcanic eruptions. He was spot on! I
have quickly selected some that cover topics raised on CCnet. You
may wish to post the following as an "essay" since it is rather large.

regards
Michael Paine

2000 GSA Annual Meeting -- Reno, Nevada

http://www.geosociety.org/cgi-bin/annual-meeting-abstracts-query.pl

Abstract 50935

HYDROCODE SIMULATIONS OF CHICXULUB CRATER COLLAPSE

Presented by Collins, Gareth S.
Authors:
      Melosh, H. J.,
      Morgan, J. V.,
      Warner, M. R..

Key words: Chicxulub, complex, crater, collapse, hydrocode

In Session 73 T6. Impact Crater Excavation, Modification, and Ejecta
Distribution Mechanisms (GSA Planetary Geology Division) Tuesday, November
14, 2000 AM in Room: Ballroom D at 09:30 AM for 15 min.

Abstract: The lack of a definitive model for complex crater collapse has
been due in no small part to the absence of large impact craters on the
Earth, and to the near impossibility of probing the subsurface on other
planets. This situation changed following the discovery of the buried
Chicxulub impact structure in Yucatan, Mexico. The Chicxulub Seismic
Experiment obtained data that clearly illustrate the third dimension of a
complex crater and provide new insight into the kinematics of complex crater
collapse. It is with this motivation that we have embarked upon an
integrated multi-disciplinary study, coupling numerical hydrocode modelling
with interpretation of the seismic data. Here we present results from
simulations of the collapse of a Chicxulub scale impact crater using the
SALE hydrocode. In simulating the Chicxulub impact event numerically our
approach has been to model only the collapse stage of the cratering process.
The collapse begins at approximately the moment of maximum penetration, when
the transient cavity is assumed to be parabolic in cross section. The early
stages of the impact event are approximated by the Z-model of excavation.
The transient over-pressure due to the impact generated shock wave is
assumed to be entirely dissipated and the target material stationary.
Consequently, the simulation considers the competition between the gravity
driven collapse of the unstable cavity and the inherent material strength
properties of the post-shock target. In order to allow the relatively low
driving forces associated with the excavated cavity to modify the transient
craters form, a temporary material weakening mechanism is employed: Acoustic
fluidization.
Our simulations show that, for appropriate impact parameters, temporary
fluidization of the target allows the formation of internal peak and ring
structures analogous to those observed in terrestrial and extra-terrestrial
craters. Analysis of the dynamic evolution of the crater during the
simulation suggests a model for the generation of the peak-ring at
Chicxulub. Observations from the seismic data support this model in addition
to other aspects of the final simulated crater structure.

Abstract 51639

IMPACT MELT EJECTA SOURCES: COMPARISONS BETWEEN SEVERAL IMPACT STRUCTURES
AND THEIR EJECTA

Presented by Whitehead, James
Authors:
      Spray, John G.,
      Grieve, Richard A.F..

Key words: impact, ejecta, tektite, Popigai, provenance

In Session 73  T6. Impact Crater Excavation, Modification, and Ejecta
Distribution Mechanisms (GSA Planetary Geology Division) Tuesday, November
14, 2000 AM in Room: Ballroom D at 11:00 AM for 15 min .

Abstract: Ejected, impact-generated glasses have been identified in several
regions. These include the: 1)North American tektites of the eastern
seaboard of the U.S.A., the Caribbean Sea and the Atlantic Ocean; 2) Haitian
tektites; 3) moldavites of the Czech Republic; 4) irghizites of Kazakhstan;
5) Ivory Coast tektites off west Africa, and; 6) the Australasian tektites
of southeastern Asia and Australia. Although a source impact structure has not
been identified for the 0.8Ma Australasian tektites, the other impact ejecta
have been geochemically correlated with their sources. These impact
structures are, respectively: 1) Chesapeake Bay, Virginia (35.5 Ma); 2)
Chicxulub, Mexico (65 Ma); 3) Ries, Germany (15 Ma); 4) Zhamanshin,
Khazakhstan (0.9 Ma), and; 5) Bosumtwi, Ghana (1 Ma). In situ melt rocks in
impact structures commonly have compositions distinct from those of the
ejected melts, complicating the correlation between melt ejecta and their
source crater. Compositional analyses of melt ejecta from impacts into
heterogeneous targets have suggested that only near-surface rocks are
represented in the ejecta, whereas in situ melts may be derived from deeper
in the target. However, new isotopic data for some impact ejecta melts
derived from the 100 km diameter Popigai impact structure, Siberia are
similar to those of in situ Popigai melt rocks (tagamites). The ejecta melts
appear to have an Archaean basement source similar to that of the tagamites,
despite this source having been buried by up to 1 km of sedimentary and
volcanic rocks. Isotopic variation of other Popigai ejecta may result from
the melting and ejection of isotopically heterogeneous target gneisses
and/or the mixing of basement-derived melts with various amounts of the
fused cover sequence. We review the processes responsible for target rock
fusion, ejection and final distribution. Taking into consideration crater
scaling, we also discuss whether ejecta possessing a basement signature from
Popigai are unusual when compared with ejecta from other impact structures
which possess an exclusively surficial source.


Abstract 50470

GIANT IMPACT CRATERS LEAD TO FLOOD BASALTS: A VIABLE MODEL

Presented by Elkins Tanton, Linda T.
Authors:  Hager, Bradford H.

Key words: crater, flood basalt, mantle convection

In Session 202   Planetary Geology: Impacts, Io, Asteroids and Ishtar
(Venus) (Posters) Thursday, November 16, 2000 AM in Room: Hall C at 08:00 AM
for .

Abstract: Previous researchers have suggested that giant impacts might
trigger flood basalts, but no plausible mechanisms have been presented.
Impactors striking the Earth at cosmic speeds carry
enough energy to vaporize both themselves and up to 100 times their mass of
country rock. Though even this cannot provide enough energy to directly
create a flood basalt province, it does significantly thin the lithosphere
through vaporization and excavation. The crust under a large crater will
subsequently rise through isostatic rebound, creating in about ten thousand
years a dome-shaped elevation of the bottom of the lithosphere. The lateral
temperature gradient resulting from this lithospheric dome could trigger
vigorous upper-mantle convection. Mantle material in the upward flow would
melt adiabatically in sufficient volume to produce a flood basalt province.
Numerical experiments support this conceptual model for formation of flood
basalts from giant impact craters. As the lithosphere at the crater site
cools and returns to a flat thermal gradient, convective flow would slow and
eruption cease. Any thermal perturbation would be long erased by 65 Ma, as
it has been under Chicxulub. The Deccan and Siberian flood basalts are both
located on crust of appropriate thickness, and have brief episodic eruptions
like that produced by our models. A possible impact site for the Deccan has
been suggested.

Abstract 50288

LARGE OCEANIC IMPACTS AS THE CAUSE OF ANTIPODAL HOTSPOTS AND GLOBAL MASS
EXTINCTIONS

Presented by Hagstrum, Jonathan T.

Key words: hotspots, flood basalts, impacts, extinctions

In Session 202     Planetary Geology: Impacts, Io, Asteroids and Ishtar
(Venus) (Posters) Thursday, November 16, 2000 AM in Room: Hall C at 08:00 AM
for .

Abstract: Hotspots occur as sites of intraplate volcanism or as sites of
locally intense activity on mid-ocean ridges. It is widely accepted that
hotspots result from narrow upwellings in the mantle called 'plumes', but
there are major drawbacks with this model. Oddly, hotspots tend to occur in
near-antipodal pairs. In addition, all sites antipodal to continental, and
likely oceanic, flood basalts for the last 250 m.y. were in the deep ocean.
Large deep-ocean impacts differ from continental ones in several major ways:
they generate mega-tsunamis with >=1 km run-up heights on a hemispheric
scale, they launch immense quantities of water high into the atmosphere, and
they likely generate much greater amounts of seismic energy due to the
'mudcapping' effect of the deep ocean. The impact's seismic energy is
focused by Earth in the antipodal asthenosphere, and the resultant heating
and melting, and fracturing of the overlying lithosphere, could lead to
flood-basalt eruptions, rifting, and hotspot volcanism. Such bipolar crises
perhaps best explain the regression-transgression (r-t) pulses, ocean
isotopic anomalies, and flood-basalt volcanism that are associated with the
major Phanerozic extinctions. The great end-Cretaceous extinction might have
been initiated by the oceanic 'Socorro' impact at 67-68 Ma, and the on-land
Chixulub impact at 65 Ma was its coup de grāce. The greatest end-Permian
extinction was also possibly a double impact event, with r-t pulses, flood
basalts, and mass extinctions occurring at both the end-Guadalupian and
end-Tatarian Stages.

Abstract 50659

DO LARGE IMPACTS STRENGTHEN MANTLE PLUMES AND PRODUCE KOMATIITES?

Presented by Abbott, Dallas H.

Key words: komatiite, impact, mantle plume, periodicity

In Session 140 T12. Superplume Events in Earth History: Causes and Effects I
(GSA International Division) Wednesday, November 15, 2000 AM in Room:
Ballroom B at 09:15 AM for 15 min.

Abstract: A connection between large impacts and mantle plumes is suggested
by a spectral analysis of time series of mantle plume rocks and impacts over
the last 256 Ma. Contrary to previous assertions, the dominant period
derived from spectral analysis of the impact time series is not 30+/-3 Ma.
The largest spectral peak in the impact spectrum is at 64+/-10Ma, with
a secondary peak at 30+/-3 Ma. This spectral pattern is replicated in
spectral analyses of time series of all mantle plume rocks, and flood
basalts+dikes+layered intrusions. The only spectrum with its highest peak at
30+/-3Ma is the spectrum for high Mg rocks. The high Mg rocks include
komatiites, picrites and other extrusives with maximum MgO contents above
10%. We speculate that the similarity in the dominant spectral peaks derived
from the impact and plume time series is due to strengthening of existing
plumes by the seismic energy released during impacts. The exact mechanism of
plume strengthening is not known. Perhaps the resulting seismic waves help
to coalesce melt pockets. If impacts do strengthen existing mantle plumes,
it could explain why komatiites are not always plume tails. It could also
help to explain why komatiites were more abundant during the Archean, when
impacts were larger and more frequent.

Abstract 50882

LATE HOLOCENE CLIMATE CHANGE AND ANTHROPOGENIC ENVIRONMENTAL DESTRUCTION IN
A TROPICAL SETTING: EVIDENCE FROM CAVE CALCITES, ISLA DE MONA, PUERTO RICO.

Presented by Lundberg, Joyce
Authors:
      Brown, M.,
      Ford, D. C.,
      Troester, J. W..

Key words: Paleoclimate, Speleothem, Isotopes, Holocene, Tropical

In Session 100 Paleoceanography and Paleoclimatology II: Quaternary Tuesday,
November 14, 2000 PM in Room: B5 at 03:30 PM for 15 min .

Abstract: For tropical regions high resolution paleoenvironmental records
are rare. Speleothem often contain such information but few tropical sites
have been studied. We investigated stable
isotopes and petrography of unaltered tropical speleothem from Isla de Mona,
Puerto Rico. This island has largely been uninhabited, but was extensively
mined for guano from 1880 to 1927.
A 22 cm long stalagmite was dated by C-14, studied petrographically, and
sampled every mm for oxygen and carbon isotopes. The record extends from AD
750 to present, a linear growth rate of 0.18 mm/year. Ice core records from
Quelccaya Peru give tropical Late Holocene temperature and precipitation
changes. Oygen isotopes from Mona cave calcites show cyclical variations
that correlate with temperature, a negative relationship suggesting that
cave temperature control is dominant. Carbon isotopes also show cyclical
changes that anti-correlate with temperature, interpreted as an increase in
biological activity with temperature. Petrographic changes are not cyclical,
but show a correlation of elongate crystals with warm, wet periods and short
crystal with drier periods. The most significant climatic change was the
Little Ice Age, from ~1520 to 1880, marked by a dramatic shift in ice core
temperature records, and calcite oxygen and carbon isotopes. The severe
drought of ~1750-1820 shown in the ice core precipitation records correlates
with a shift in the carbon isotopic values that is consistent with a shift
to C4 vegetation. This time period is also marked by a band of very short,
round crystals. The impact of guano mining is marked in all three calcite
indices. The shift of oxygen and carbon isotopes in response to higher
temperatures at the end of the Little Ice Age is abruptly interrupted for
the period of mining. Crystal form also shows an unexpected shortening at
this time of increasing precipitation and temperature.

Abstract 51002

EVIDENCE FOR A CRETACEOUS-TERTIARY BOUNDARY SLUMP-GENERATED TSUNAMI ON THE
NEW JERSEY MARGIN.

Presented by Browning, James V.
Authors:
      Olsson, Richard K.,
      Miller, Kenneth G..

Key words: K/T, boundary, tsumani, Chicxulub

In Session 41     Paleoclimatology and Paleoceanography (Posters) Monday,
November 13, 2000 PM in Room: Hall C at 01:30 PM for .

Abstract: A Cretaceous-Tertiary boundary (K/T) section with a 6-cm-thick
spherule layer with shocked minerals and elevated iridium values was
recovered in November 1996 in the Bass River Borehole (New Jersey Coastal
Plain Drilling Project, ODP Leg 174AX). Above the spherule layer small clay
clasts, containing calcite-replaced tectites and Cretaceous foraminifera and
dinoflagellates, occur in the lower 10 cm of the Danian. This interval of
clay clasts is a marker for the K/T in outcrops and other boreholes where a
spherule layer is absent. The clasts are interpreted as ripups that were
transported by tsunami activity shoreward from a deeper part of the
Maastrichtian sea floor. Evidence from the New Jersey shelf is consistent
with a major tsunami ath the K/T boundary. Olsson and Wise (1987) showed
that a long hiatus with missing Maastrichtian and upper Campanian strata was
encountered in exploration and stratigraphic test wells in the Baltimore
Canyon Trough beneath the New Jersey continental margin. DSDP Site 605
located east of the Baltimore Canyon Trough at the foot of the New Jersey
continental slope terminated in the upper Maastrichtian (Abathomphalus
mayaroensis Zone) indicating that the hiatus is confined to the outer
continental shelf and upper slope. The area of the hiatus encompasses at
least 30,000 square kilometers of the Maastrichtian outer continental shelf
and upper slope and may represent a giant slump scar. A tsunami triggered by
seismic shaking from the Chicxulub impact at this area would have reached
the New Jersey Coastal Plain in less than ½ hour. Surface seismic waves
generated from the K/T impact at Chicxulub, Yucatan would have arrived in a
little less than 10 minutes, about the time of the arrival of the
ejecta-vapor cloud. The fact that the Bass River clay clasts contain
replaced tectites indicates that the tsunami took place after deposition of
the tectites and that the two events closely followed one another.


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*

METEOR(ITE) CRASHES INTO YORKSHIRE FIELD

From Ananova, 1 March 2001
http://www.ananova.co.uk/news/story/sm_224291.html

Police have cordoned off a field after a meteor crashed into the ground in
North Yorkshire.

A woman walking her dog heard an explosion followed by a rush of air as she
walked near a field at Hopgrove, near York. She saw a smoking crater in the
ground, said a North Yorkshire Police spokeswoman.

"A curator has been down from the Yorkshire Museum and has identified that
we do have a meteor and a suitable crater for it to sit in."

The area was cordoned off by police following the incident.

---------
DOG WALKER TELLS OF 'METEORITE' SHOCK

From Ananova, 1 March 2001
http://www.ananova.co.uk/news/story/sm_224486.html?menu=

A woman who saw what is thought to be a meteorite crashing to earth has
spoken of her shock.

Silvia Mercer says the rock crashed into the ground near York just yards
from where she was walking. Mrs Mercer was with dogs when the crater
appeared on the edge of a field close to her home in Hopgrove.

"It was very frightening. It was a bit of a shock," said Mrs Mercer. "I
thought my last moments had come. I was very shaken. It could have hit me.

"I heard this terrific bang and then a smaller bang and when I looked around
there was a big cloud of smoke.

"There was a hole in the ground with smoke bellowing out of it. I had no
idea what it was."
[a photo of the small impact crater has been provided by the Press
Association at http://www.ananova.co.uk/news/story/sm_224486.html?menu=]

Army bomb disposal experts from Catterick are at the scene.

Police cordoned off the area and stopped traffic from entering Hopgrove Lane
South, where the crater appeared.

PC Peter McCreedy said the hole was 10 inches in diameter and at least a
metre deep.

He said it started making popping and cracking noises, believed to be caused
by background radiation.

Copyright 2001, Press Association

---------
SPACE ROCK FALLS ON YORK

From BBC, 1 March 2001 (16.00 GMT)
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1196000/1196688.stm
 
A meteoroid has landed in a field in York, UK, narrowly missing a woman
walking her two dogs.

North Yorkshire police were called to the Hopgrove area of the city
after Silvia Mercer heard a rush of air and a loud explosion at 0800GMT.

They found a smoking crater, about 15 centimetres (six inches) wide and
just under a metre (three feet) deep, in a nearby field.

Officials from the Yorkshire Museum have confirmed it was made by a rock
falling from space. It is almost 10 years since any such similar event
has been recorded on the UK mainland.

'Last moments'

Mrs Mercer said she was frightened as the rock crashed to the ground
just metres away from where she was walking. "It was a bit of a shock,"
she said.

Police set up a cordon while the meteorite was investigated
 
"I thought my last moments had come. I was very shaken. It could have
hit me.

"I had no idea what it was. I went to have a look but could not see to
the bottom of the hole. It was quite deep.

"I don't know anything about meteorites but after this I will be quite
interested to know what happens to it."

'Popping and crackling'

The area was cordoned off by police after the meteorite - the name given
to the lump of material that survives the impact - started making
"weird" noises.

Pc Peter McCreedy said: "It started making popping and cracking noises,
which are not usual.

"Experts from York University have been here with radioactive detection
equipment. The noises are believed to be caused by background
radiation."

Army bomb disposal experts from Catterick were called to the scene and
gave the all-clear for the rock to be taken away and examined by
experts.

Some doubt

The last meteorite to be picked up off the ground on the UK mainland was
found by retired civil servant Arthur Pettifor. A 767-g (27 oz)
meteorite hit a hedge in his garden in Glatton, near Peterborough, in
the May of 1991.

Golf-ball sized fragments of space rock were recovered after a fall on
County Carlow in the Republic of Ireland in the November of 1999.

Meteoriticist at the Natural History Museum in London, Dr Matthew Genge,
said he would like more information before he could be certain the
Yorkshire rock was a meteorite.

"There are certain factors that identify a meteorite and from what I've
heard, some things today just aren't consistent with that," he said.

"For example, they don't smoke when they hit the ground, but then they
do make a noise because, as they are travelling faster than the speed of
sound, they are often accompanied by a sonic boom."

Copyright 2001, BBC

------------
NO OBJECT FOUND ACCORDING TO MUSEUM OFFICIAL

From Kelly Beatty <kbeatty@skypub.com>

Benny...

false alarm. according to Niel (sp?) Sterio, press officer for the York
Museum, there is no object, meteorite or otherwise. the electrical cable
that the falling object supposedly struck on impact in fact itself
exploded, blowing a hole in the ground from below. everyone was
apparently misled by the witness's insistence that something had whizzed
past her though the air prior to the explosion.

Kelly



CCCMENU CCC for 2000

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