PLEASE NOTE:


*

CCNet 129/2001 - 4 December 2001
================================


"The only thing necessary for evil to prevail is for good men to do
nothing."
--Edmund Burke

 
"Shoemaker was right - again. More than 20 years ago, the late
planetary geologist Eugene Shoemaker concluded from his analysis of
moon craters that some 2,000 asteroids more than a kilometre wide have
some chance of hitting the Earth and causing serious damage to life on this
planet. Now we have the first results from three years of observation with
the world's most powerful asteroid-search telescope, which suggests that
there are around 1,250 one- kilometre or larger asteroids in
"near-Earth" orbits. This is statistically in good agreement with
Shoemaker's original estimate."
--Terence Dickinson, The Toronto Star, 2 December 2001


(1) DEEP IMPACT AND THE MASS EXTINCTION OF SPECIES 65 MIO YEARS AGO
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(2) ABOUT 1,250 BIG ASTEROIDS IN NEAR-EARTH ORBIT
    The Toronto Star, 2 December 2001

(3) WEEKEND FIREBALLS
    NASA Science News for December 3, 2001

(4) JAPANESE SATELLITE DROPS TO EARTH
    Space.com, 3 December 2001

(5) DOUBTS ABOUT ALH84001: THE JSC MARS METEORITE TEAM RESPONDS
    Michael Paine <mpaine@tpgi.com.au>

(6) GENESIS SPACECRAFT BEGINS MISSION TO COLLECT SAMPLES OF THE SUN
    NASANews@hq.nasa.gov

(7) A CURVE BALL INTO THE SNOWBALL EARTH HYPOTHESIS
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(8) CHRONOLOGY OF THE BC/AD SYSTEM
    Duncan Steel <D.I.Steel@salford.ac.uk>

(9) PSALM 18
    Göran Johansson <goran.johansson@certec.lth.se>

(10) STICK TO SCIENCE
     R.C.L.Wilson@open.ac.uk <R.C.L.Wilson@open.ac.uk>

================
(1) DEEP IMPACT AND THE MASS EXTINCTION OF SPECIES 65 MIO YEARS AGO

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

Public Relations
GeoForschungsZentrum Potsdam (GFZ)
Telegrafenberg
D-14473 Potsdam, Germany

Contact:
Franz J. Ossing, ossing@gfz-potsdam.de, ++49 (0)-288-1040

PRESS-INFORMATION: 03.12.2001

Deep Impact and the Mass Extinction of Species 65 Mio. Years Ago

Start of the Chicxulub Drilling Project in Yucatan, Mexico

On December 3, a scientific deep drilling projects starts on the Yucatan
Peninsula, Mexico into the Chicxulub crater that was formed some 65 million
years ago by the impact of an asteroid, which is believed to have caused the
extinction of the dinosaurs and other species. In the opening ceremony the
governor of the province of Yucatan, Patricio P. Laviada and the President
of the Autonomous University of Mexico, Juan R. de la Fuente will
participate as well as numerous scientists, engineers, and regional
politicians. The German delegation consists of
the German ambassador to Mexico, Dr. Wolf-Ruthart Born and Prof. Rolf
Emmermann, chair of the executive board of the GFZ Potsdam. Prof. Emmermann
is also the chairman of the International Continental Scientific Drilling
Program (ICDP) which sets up the organizational framework of the Chicxulub
Project.

This drill site named Yaxcopoil-1 (YAX-1) is situated 40 kilometers
southwest of the province's capital Merida. It is intended to give insight
on the one hand into the size and material properties of the projectile, the
amount of released impact energy, the structure of the crater and the
physico-chemical processes related to the impact. On the other hand, the
research aims at the effects of this catastrophic event on environment and
life on Earth.

Chicxulub and the Cretaceous-Tertiary Boundary

About 65 million years ago at the boundary between the Cretaceous (the last
geological period of the Mesozoic) and the Tertiary eras, a large asteroid
came rushing out of space at a velocity of more than 25 km per second and
impacted the Earth at the tip of the Yucatan platform. The enormous amount
of energy generated by this impact, equivalent to 10 thousand times the
world's nuclear arsenal, ejected into the atmosphere huge quantities of dust
particles and gases. The asteroid with a diameter of more than 10 km
impacted into a shallow ocean and penetrated the Earth's crust down to a
depth of several kilometers. It vaporized, melted and shattered ocean water
and the Yucatan target rocks composed of carbonate and sulphate. As a
result, a crater some
200 km in diameter formed. Over a short period of time (a few minutes)
several hundred billion tons of CO2, SO2 and water vapor released by the
vaporized target rock were injected into the Earth atmosphere. An abrupt and
global perturbation of the Earth System followed: the climate became
unstable, the fine dust suspended in the atmosphere blocked sunlight,
decreasing or even stopping photosynthesis. This ecological catastrophe is
believed to have caused the famous Cretaceous-Tertiary (KT) boundary mass
extinction which saw the demise of the dinosaurs and more than 50% of the
Earth fauna and flora on land and in the oceans.

The hypothesis that an asteroid or comet impact induced the mass extinction
at the KT boundary was first proposed in 1980 by a team from the University
of California at Berkeley led by Nobel price laureate physicist Luis Alvarez
and his geologist son Walter. Very controversial at first because of its
catastrophic aspect, this hypothesis was confirmed in the early 1990's when
scientists realized that the impact structure which lay buried under
approximately 1 km
of Yucatan platform sediments was in fact the long-sought KT boundary crater
predicted by the Alvarez hypothesis. This huge bowl-shaped structure,
centred at Puerto Chicxulub near Merida is clearly outlined by gravity and
magnetic geophysical anomalies. It had first been identified as a potential
impact crater by geophysicists Antonio Camargo-Zanoguera and Glen Penfield
while exploring the potential oil reserves of Yucatan for Pemex. The
structure had been drilled, although unsuccessfully for oil. In the early
nineties, studies of the recovered core samples confirmed that the Chicxulub
structure was indeed a huge impact crater.

Dating of the impacted lithologies indicated that it was precisely of KT
boundary age, coeval with the mass extinction. Exactly how the Chicxulub
impact induced the perturbation of the Earth System and the mass extinction
of organisms is not yet fully understood. The study of the crater and its
internal lithology in the framework of the ICDP scientific deep drilling
project will provide answers to this fundamental question.

Cratering: an important process in the formation of planets

The ICDP deep drilling project in the Chicxulub crater will also help Earth
scientists to understand better the mechanisms of crater formation.
Cratering is a key process in formation and evolution of the rocky planets.
With a diameter of approximately 200 km Chicxulub is one of the largest and
best preserved craters on Earth. Chicxulub can thus serve as a proto-typical
and accessible large planetary impact structure providing key information as
to the formation and early evolution of Earth and both dry (Moon, Mercury)
and volatile-rich planets (e.g. Venus).
- End of message -

A high resolution picture of the structure of the magnetic field of the
Chicxulub crater can be found at:
     http://www.gfz-potsdam.de/news/foto/chicxulub/

More information is available on the internet at:
     http://icdp.gfz-potsdam.de

IMAGE CAPTION:
1D- and 3D-images of the magnetic anomalies of the inner Chicxulub crater
ring compiled from aeromagnetometry measurements of the GFZ aero-campaign
"MEXAGE" (Mexico Aerogeophysical Experiment).

The anomalies are sharply bounded within the inner crater. Long-wavelength
anomalies are generated by larger melt bodies deeply buried in the crater,
short-wavelength anomalies are caused by overlaying breccia. (Graphics: U.
Meyer, GFZ Potsdam)

================
(2) ABOUT 1,250 BIG ASTEROIDS IN NEAR-EARTH ORBIT

>From The Toronto Star, 2 December 2001
http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1007247680830&call_page=TS_News&call_pageid=968332188
492&call_pagepath=News/News


Terence Dickinson
THE UNIVERSE
 
Shoemaker was right - again. More than 20 years ago, the late planetary
geologist Eugene Shoemaker concluded from his analysis of moon craters that
some 2,000 asteroids more than a kilometre wide have some chance of hitting
the Earth and causing serious damage to life on this planet. Now we have the
first results from three years of observation with the world's most powerful
asteroid-search telescope, which suggests that there are around 1,250
one-kilometre or larger asteroids in "near-Earth" orbits. This is
statistically in good agreement with Shoemaker's original estimate. In the
1950s, Shoemaker was the first to prove that craters on Earth are the result
of asteroid impacts. During his life (which tragically ended four years ago
in a traffic accident), Shoemaker was the guru of asteroid-impact research,
racking up an impressive record of correct predictions.

.....

Copyright 2001, Toronto Star 

================
(3) WEEKEND FIREBALLS

>From NASA Science News for December 3, 2001
http://science.nasa.gov/headlines/y2001/ast03dec_1.htm?list20392

Pieces of a Proton rocket disintegrated in Earth's atmosphere this weekend,
startling sky watchers in western Europe and at least seven US states.
 
Dec. 3, 2001: After the recent Leonid meteor storm sky watchers have been
hungry for more shooting stars. This weekend they got one.

On Saturday night, Dec. 1st, around 10:15 p.m. CST, a sensational fireball
glided over the US Midwest. Automobile traffic stopped. Airline pilots
peered in amazement through cockpit windows. And emergency phone lines were
jammed.

"It was breathtaking!" said Greg Bakker of Hull, Iowa. "My wife and I were
driving home around 10:30 CST when I saw the lights. I pulled the vehicle to
the side of the road and we sat there awestruck. There were about 8 objects
-- fiery yellow in color and slow-moving, much slower than any of the Leonid
meteors I saw last month."

Indeed, what Bakker saw was no meteor. It was the remains of a Russian
Proton rocket that had left Earth only 10 hours earlier carrying three
navigation satellites to orbit. The satellites were deployed successfully,
but pieces of the rocket fell back to Earth and disintegrated.

Rick Bordignon was in a commercial airliner bound for Las Vegas when he saw
them. "I was looking out the left window into the starry night when I
noticed an approaching light," he recalled. "I was thinking... Hmmmmm, looks
like a missile. But rather than raise a general sense of panic by yelling
'Incoming!,' I did the next best thing and got out my camera.

"I snapped one picture (above), but my camera is poor in low light. So I
stopped to adjust the settings. When I looked out again I was amazed by what
I saw: hundreds of objects with colorful glowing tails! So I snapped another
one (inset) but it only picked up the brightest fragments -- and it was
shaky, too.

"The light plume [seemed to] go up and over our plane. After it was gone I
looked around to judge the reactions of the other passengers -- and I swear
everyone was sleeping!

"When I got off the plane, I tracked down the pilot. He said every pilot in
the Midwest saw it and it was the 'buzz of the frequencies.' They had never
witnessed anything like it before."

The eye-catching display had actually begun hours earlier. Alan Pickup, a
satellite decay expert who works at the United Kingdom's Astronomy
Technology Centre at the Royal Observatory in Edinburgh, explains:

"The rocket, a Proton or 'SL-12', was launched from the Baikonur Cosmodrome
in Kazakstan at 18:04 UT on Dec. 1st. An 800 kg metal casing from the fourth
stage of the rocket was on its third orbit around Earth when it burned up in
the atmosphere over southern England and France at about 22:35 UT."

Welshman Chris Evans was just stepping out of a restaurant in the French
countryside when the casing soared overhead. "At first it was a single large
fireball," says Evans, "but then it broke into about 30 or 40 smaller ones,
like a giant fireworks display. It was absolutely magnificent." Other
observers in the region noted a lingering trail and a "smoky halo" around
the Full Moon.

Meanwhile, another even bigger piece of the rocket -- its 4,200-kg third
stage -- was decaying. The third stage hadn't dropped as fast as the casing
had done. But finally, about six hours later, it too began to glow.

Shannon Rudine at the University of Texas McDonald Observatory spotted the
rocket at 10:18 p.m. CST on Dec. 1st (0418 UT on Dec. 2nd). "When I first
noticed it, it had already broken into dozens of slow-moving incandescent
fragments. Several were brilliant white, each nearly as bright as the planet
Jupiter," he recalled

The flaming debris continued from there northeast over Oklahoma, Kansas,
Nebraska, Missouri, Iowa and South Dakota -- dazzling thousands of onlookers
along its path.

Many witnesses saw the fireball because it moved in such a leisurely way
across the sky. There was plenty of time to pull over and step out of the
car, or call a friend to the window. What a change of pace from the Leonids!
Genuine meteors zip across the sky in a few seconds or less. The difference
is mainly speed: Manmade space debris returns to Earth traveling 7 or 8
km/s, while Leonid meteoroids strike the atmosphere at 72 km/s -- ten times
faster.

Furthermore, meteoroids, which are fluffy bits of comet dust, are mostly
smaller than grains of sand and less massive than a gram. They disintegrate
quickly. A Proton rocket, on the other hand, weighs thousands of kg. Such a
massive object can burn and glow for a long time, especially when it skims
almost horizontally through the atmosphere as this one did.

Even so, some sky watchers missed the spectacle.

"I was sitting in my living room on Saturday night when I heard a thunderous
boom," says Matt Hilger of David City, Nebraska. "It was loud, but not quite
loud enough to pull me away from Sports Center on TV. Moments later, a
friend phoned to tell me about the event, but," he lamented, "it was too
late...."

"Next time I hear a sonic boom late at night," he says, "I'll definitely
look out the window."

Editor's note: After this story was published we received reports that sky
watchers in New Mexico also saw the fireballs, adding to the list of US
states already mentioned above.

============
(4) JAPANESE SATELLITE DROPS TO EARTH

>From Space.com, 3 December 2001
http://www.space.com/news/satellite_reenter_011203.html

By Leonard David
Senior Space Writer

WASHINGTON -- Weighing in at over a ton, the Japanese Earth Resource
Satellite-1 (JERS-1) plunged from orbit and reentered the Earth's atmosphere
today. Pieces of the defunct spacecraft likely survived the fiery fall and
hit Earth.

The estimated reentry time -- predicted by U.S. and European Space Agency
(ESA) tracking officials -- is thought to have been approximately 8:40 a.m.
EST, with the craft diving deep into a remote region of the southern
hemisphere. A final assessment of the exact time and reentry spot is
expected within a few more hours.

The JERS-1 had been circling Earth since February 1992, rocketed into orbit
by the National Space Development Agency of Japan (NASDA) courtesy of an H-1
Launch Vehicle from Tanegashima Space Center.

The satellite was replete with a large solar panel and radar antenna. At the
time of launch, it tipped the scales at about 1.4 tons ( 2,800 kilograms).

Studies performed by NASDA reentry experts showed that much of box-shaped
JERS-1 structure would disintegrate completely as it took a tumble toward
Earth. Frictional heat as satellite hardware streaks through dense layers of
atmosphere should have destroyed the parts completely.

However, some titanium materials used in the craft's propellant tanks were
thought likely to beat the heat as they streak through the atmosphere, then
smack into the ground or ocean. NASDA re-entry analysts say that a modest 15
pounds (7 kilograms) of titanium might survive to the ground, at a maximum.

Difficult to predict when and where

It is difficult to predict the exact time of reentry and where satellite
fragments may fall. Odds were good, however -- given that most of Earth is
water-covered -- that the remains of JERS-1 would safely flutter into
seawaters.

Solar activities make it difficult to predict the exact timing of satellite
burn-ups. For this reason, there is a plus or minus 5-hour error window up
to a day prior to the satellite's re-entry.

NASDA was networked with NASA, as well as Japan's Bisei Spaceguard
Association in Okayama Prefecture, Japan, in a cooperative effort to help
predict the satellite's atmospheric re-entry.

JERS-1 operated far longer than its initial two-year design life.

The spacecraft gathered data on global landmasses, while making more
pinpoint land survey observations. It was extensively utilized for
agricultural, forestry, and fishing purposes, environmental protection,
disaster prevention and coastal surveillance, with emphasis on locating
natural resources.

Use of the remote sensing craft ended in October 1998.

Another day, another fall

It seems that another fall of space junk caught the attention of skywatchers
on December 1. A large display of falling objects blazed through clear skies
over Texas, Oklahoma, Kansas, and Nebraska.

According to Nicholas Johnson, head of the space debris office at the NASA
Johnson Space Center in Houston, Texas, Saturday's fall of space flotsam has
been identified. It was an upper stage of the Russian Proton launch vehicle
that inserted three GLONASS (navigation) satellites into orbit on December
1, he told SPACE.com.

Copyright 2001, Space.com

===============
(5) DOUBTS ABOUT ALH84001: THE JSC MARS METEORITE TEAM RESPONDS

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

Dear Benny

The NASA Astrobiology Institute has just posted the following.

regards
Michael Paine

Doubts About ALH84001: The JSC Mars Meteorite Team Responds.
http://web99.arc.nasa.gov/NAIRedesign/stories/doubts.cfm

Based on a SpaceRef.com release
 
Buseck et al. have "rediscovered" an anaytical method developed in 1947 by
Dennis Gabor for defining the morphology of crystals using electron
microscopy. Unfortunately, the Buseck et al. paper adds nothing to further
the understanding of the issue of life on Mars. It demonstrates that these
authors fail to understand the work of Thomas-Keprta et al, 2001 who used a
transmission electron microscope to image individual microscopic particles
at multiple angles and orientations. From this, the 3-D morphology of the
particles could be reconstructed. The technique used by Buseck et al. also
uses a transmission electron microscope to image microscopic particles at
many different angles in order to reconstruct a 3-D image. These two
techniques, for this particular application, are essentially identical.

The Buseck et al. PNAS paper is interesting in that they do not examine
ALH84001's population of likely biogenically produced magnetite crystals or
the reference MV-1 magnetite crystals; these magnetite populations are the
central issues in the debate and without studying either population, at
best, their conclusions are irrelevant to the question of life on Mars.
Buseck et al. describes the 3-D geometry of a magnetite crystal from "an
undescribed, uncultured magnetotactic coccus collected from Sweet Springs
Natural Reserve, Morro Bay, CA." It is unclear why they would describe just
any magnetite from a previously undescribed strain and compare the geometry
of one crystal with one of the best described terrestrial magnetite
populations, that of strain MV-1. Buseck et al. are trying to compare a
quick study of "oranges (i.e., his undescribed magnetites) with a
well-defined study of "apples" (magnetites from ALH84001 and MV-1).

Buseck et al. are trying to lay claim to discovering an analytical method of
defining morphology of nanocrystals. Such work has been done for decades
using conventional TEM techniques. We see no scientific basis for the Buseck
et al. comments "we argue that the existing crystallographic and
morphological evidence is inadequate to support the inference of former life
on Mars" when he has not examined the magnetites in ALH84001 or MV-1.

The statement at the conclusion of the Buseck et al. PNAS contribution is
another example of researchers trying to use data to refute a scientific
hypothesis when the data does not apply to the arguments. One must consider
all the lines of evidence used to reach the conclusions. Furthermore, Buseck
et al. state that three of the four lines of evidence proposed by McKay et
al. 1996 have been refuted; that is incorrect. Gibson et al. 2001 (in
Precambrian Research) show additional evidence to support all the original
lines of evidence of possible biogenic activity within ALH84001 and its
carbonate globules are valid. Additional evidence for possible biogenic
activity was also described for two younger Martian meteorites-Nakhla (1.3
billion years old) and Shergotty (165 million years old) in that same report
(Gibson et al. 2001).

The Buseck et al. paper appears to be little more than a poorly disguised
advertisement for the technique of electron tomography, an attempt to
capitalize on the intense debate surrounding the issue of life on Mars to
gain publicity. We have been looking forward to the scientific results from
Buseck et al. and were very disappointed.

==============
(6) GENESIS SPACECRAFT BEGINS MISSION TO COLLECT SAMPLES OF THE SUN

>From NASANews@hq.nasa.gov

Donald Savage
Headquarters, Washington              Dec. 3, 2001
(Phone: 202/358-1547)

Martha J. Heil
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0850)

RELEASE: 01-238

GENESIS SPACECRAFT BEGINS MISSION TO COLLECT SAMPLES OF THE
SUN

NASA's Genesis mission is officially open for business today, as it extends
its special collector arrays to catch atoms from the solar wind. The atoms
it collects, believed to have been part of the solar nebula "cloud" from
which our solar system developed, will help scientists gain a better
understanding of the conditions in the distant past before the Earth and
other planets formed.

Genesis, managed by NASA's Jet Propulsion Laboratory (JPL), Pasadena,
Calif., is the agency's first sample return mission since the last Apollo
mission in 1972, and the first ever to return material collected beyond the
Moon.

Genesis orbits a point in space, about 1 million miles from Earth in the
direction of the Sun, where the gravities of Earth and the Sun balance. The
spacecraft first opened its outer shell, then last Friday opened its inner
science canister to reveal collector arrays. Today, these arrays fanned out
like petals to catch heavier atoms of the solar wind.

"We expect to start getting particle hits right away," said Dr. Donald
Burnett, Genesis principal investigator, of the California Institute of
Technology (Caltech), Pasadena. "Now we've gotten to the real focus of the
mission: the start of science, leading to the return in 2004 and the
analysis phase of the mission."

This treasured smidgen of the Sun will be preserved in a special laboratory
at NASA's Johnson Space Center, Houston, for study by scientists over the
next century. It will help them answer fundamental questions about the exact
composition of our star and the birth of our solar system.

Sample collection will conclude in April 2004, when the spacecraft begins
its return to Earth. In September of that year, the samples will arrive on
Earth in a dramatic helicopter capture. As the sample-return capsule
parachutes toward the ground at the Utah Testing and Training Range of
the U.S. Air Force, specially trained helicopter pilots will catch the
capsule in mid-air to prevent the delicate samples from being disturbed by
the impact of a landing.

Scientists say that the surface of the Sun, from which the solar wind
originates, has preserved the composition of the era when the solar system
formed. Study of Genesis' samples will yield the average composition of the
solar system to greater accuracy. It will also give clues about the process
that led to the incredible diversity of environments in today's solar
system.

Genesis carries four instruments: bicycle-tire-sized solar-wind collector
arrays, made of materials such as diamond, gold, silicon and sapphire
designed to entrap solar wind particles; an ion monitor, to record the
speed, density, temperature and approximate composition of the solar wind
ions; an electron monitor, to make similar measurements of electrons in the
solar wind; and an ion concentrator, to separate and focus elements like
oxygen and nitrogen in the solar wind into a special collector tile.

The ion and electron monitors were turned on several months ago in
preparation for their role during solar wind collection. The monitors
communicate with Earth frequently and will give a periodic solar-wind
weather report. "It has been exciting watching the space weather so far,"
said Dr. Roger Wiens of Los Alamos National Laboratory, N.M., head of the
team that operates the instruments. "We've had a rather stormy autumn in
space, which has been great for checking out
our instruments."

JPL, a division of Caltech, manages the mission for NASA's Office of Space
Science, Washington. Lockheed Martin Astronautics, Denver, designed and
built the spacecraft and will operate it jointly with JPL. Major portions of
the payload design and fabrication were carried out at the Los Alamos
National Laboratory and at Johnson Space Center.

Additional information is available on the Internet at:
          http://genesismission.jpl.nasa.gov

==============
(7) A CURVE BALL INTO THE SNOWBALL EARTH HYPOTHESIS

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

Geological Society of America
Boulder, Colorado

Contact:
Martin J. Kennedy
Department of Earth Science
University of California, Riverside
Riverside, CA 92521-0423
E-mail: martink@mail.ucr.edu
Phone: 909-787-2025

Ann Cairns
Director - Communications and Marketing
acairns@geosociety.org, 303-357-1056

FOR IMMEDIATE RELEASE: December 3, 2001

GSA Release No. 01-63

A Curve Ball into the Snowball Earth Hypothesis?
By Kara LeBeau, GSA Staff Writer

The idea that the Earth was encased in ice some 650 million years ago has
sparked much scientific debate in recent years. In the ongoing Snowball
Earth "fight," scientists continually uncover and report new evidence that
supports their respective views. Martin Kennedy, from the University of
California, Riverside, has just tossed a curveball into the Snowball Earth
theory with new data he reports in the December issue of GEOLOGY.

The Snowball Earth hypothesis proposes that during several profoundly cold
periods of Earth's history that occurred from 750 to 600 million years ago,
the ocean was covered by a thick sheet of ice. This would have had a huge
impact on early life on Earth, and would have just about wiped it out
entirely. Scientists generally agree that ice sheets reached low latitudes
on the planet during severe glaciation, but the idea of a completely
ice-covered ocean is what's being disputed.

Kennedy and his colleagues' most recent research reveals that life in the
oceans during the "snowball" event basically went on as usual. This new data
is difficult to reconcile with the effects on life an entirely ice-covered
ocean would have imposed, and this fundamentally challenges the Snowball
hypothesis.

This new evidence also supports alternative models, such as Kennedy's
post-glacial release of methane from massive Clathrate destabilization that
he proposed in last May's issue of GEOLOGY.

For the last six years, Kennedy has collected limestone and dolomite rocks
from Precambrian glacial deposits to establish a record of carbon isotopic
variation through the glacial interval. These data indicate consistent
positive isotopic values from glacial rocks in northern Namibia, central
Australia, and the North American Cordillera.

"The criteria was that they had to occur in a marine succession and they
should not be detrital but precipitated in situ," Kennedy said. "I also
wanted to have as many examples as possible to establish a global record and
discount local effects or misinterpretation from a single locality. While
one interval might be lacustrine, it is unlikely that all are, and since
they all show roughly the same positive values then it is more likely to be
a meaningful result."

His evidence shows that the carbon isotope 13C to 12C ratio was actually
higher during the glaciation indicating the presence of a healthy and
productive marine ecosystem. This ratio dropped only after the ice had
melted and this suggests that other influences other than those proposed in
the Snowball hypothesis must have been active.

"If there was no photosynthesis or life in the ocean, the carbon isotope
values would be the same as the mantle," Kennedy said. "Only the presence of
life causes a difference in those values. We did not find isotopic evidence
that a global ice sheet impacted overall marine productivity. We would think
that if an ice sheet covered the oceans, it would have had an impact on
marine production or photosynthesis and we find no carbon isotopic evidence
for this. The oceans just look normal."

To read the abstract of this article, go to: www.gsajournals.org. To obtain
a complimentary copy of this or any other GEOLOGY article, contact Ann
Cairns, Geological Society of America.
 
============================
* LETTERS TO THE MODERATOR *
============================

(8) CHRONOLOGY OF THE BC/AD SYSTEM

>From Duncan Steel <D.I.Steel@salford.ac.uk>

Dear Benny,

Scott Raeburn (CCNet 3 Dec) discusses the chronology of the BC/AD system
with reference to the traditional (as opposed to actual) birthdate of Jesus
Christ. Scott closes by saying/asking:

>Dionysius Exiguus may not have known zero, but I think he certainly
knew what he was doing.
>Can anybody with better access to sources confirm or refute this
analysis?

Unfortunately the analysis Scott gives is flawed in several respects, and
the question of "whether Dionysius Exiguus may not have known zero" is
irrelevant. This is all a matter I have discussed in considerable detail in
my book 'Marking Time' (Wiley, New York, 2000). Various discussions have
also appeared in the journal 'Astronomy & Geophysics' in the past
couple of years, from the pen of George Wilkins in particular. As did Scott,
I write from a humanist/atheist standpoint.

Dionysius Exiguus did not consider the *birthdate* of Jesus, as such. He was
charged with producing a tabulation of Easter from AD 532 onwards, a matter
he began to consider in AD 525 after papal instruction. Dionysius, however,
also back-calculated Easter dates, even to before the Crucifixion (which is
a peculiarity in itself). It happens that 532 is the Victorian cycle (named
for Victorius of Aquitane): seven days in a week times four years in a
quadrennial leap-year cycle (i.e. Julian calendar) times 19 years in a
Metonic cycle (19 solar years is very close to 235 synodic months). That
drove Dionysius back to the year we call 1 BC (and the 'BC' terminology came
very late: 17th century, due to Petavius, I believe).

Now to events within 1 BC. Easter, the subject of Dionysius's interest,
hinges on the spring/vernal equinox. That equinox is *traditionally* on
March 25 (repeat, the twenty-fifth: New Year in Britain until 1752, and
still the origin of the income tax year here starting with April 6). March
25 is variously known as Lady Day/the Feast of the Annunciation/the Feast of
the Incarnation. This is when the Archangel Gabriel appeared and told Mary
that she would bear the Son of God. Thus it may be thought of as being the
time of *conception*.

Counting forwards a nine month gestation period from March 25 (traditional
equinox) one comes to December 25 (traditional winter solstice) and thus
Christmas. Jesus (traditionally!) was born that day, but he was Jewish, and
(traditionally, again) Jewish boys do not start life until their
circumcision and naming ceremony on the eighth day post partum, hence
January 1st (the Feast of the Circumcision), as Scott states. That makes AD
1 January 1st the start of the era.

Dionysius, however, did not use an AD/BC framework. As I noted, he was
concerned only with Easter dates. His year numbering used the term *anno ab
Incarnatione* (year from the Incarnation), and thus he counted only forwards
from the date we would call 25 March of 1 BC. Problems of "not knowing about
zero" or "years before Christ" simply do not arise. Neither does the paradox
of Jesus being "born in the year we call 1 BC", so long as one comprehends
the meaning of "the start of life" for a Jewish baby.

The adoption of the chronological framework invented by Dionysius was
facilitated by the work of the Venerable Bede about two centuries later (end
of the 7th century/start of the 8th), and hence the eventual introduction of
the Anno Domini scheme, counting from the traditional date of the
circumcision of Jesus on AD 1 January 1st.

It is interesting to note that in many countries, and Britain in particular,
the dating scheme used when March 25 was New Year counted *from the wrong
year*. That is, the year numbering counted from March 25 of AD 1, rather
than Dionysius's March 25 of 1 BC. (That is called the Florentine style as
opposed to the Pisan style, which is correct; that is, it follows
Dionysius.) People get worried about eleven days being "lost" from 1752 in
Britain (leaving it with 355: that year was leap), but the really short year
was 1751, lasting from March 25 until December 31, only 282 days. On the
other hand, if Britain had been using the 'correct' Pisan style then the
problem would have been worse (the 282 dates would have needed to have been
counted all over again in order to synchronise with the calendar in use on
the Continent).

That's enough!  As I wrote, I go into more detail in 'Marking Time.'

Kind regards,

Duncan Steel

=============
(9) PSALM 18

>From Göran Johansson <goran.johansson@certec.lth.se>

About your latest message I would like to point out that the date for psalm
18 is uncertain. I spent 20 minutes at the university library yesterday
evening. It appears that the uncertainty interval is circa 1000-500 BCE. So
which impact is it related to? I have a few from this period, and without
better data, it is hard to find out if it is related to one of those I know
about, or if it is some other impact.

Yours sincerely
Göran Johansso
University of Lund, Sweden

MODERATOR'S NOTE: Duncan Lunan's suggestion about Psalm 18 relates to folk
memory, i.e. oral tradition that is impossible to date. It is not even
certain whether the fiery imagery of Psalm 18 refers to a historical/local
impact event (for an alternative, i.e. volcanic interpretation see CCNet, 3
Dec).

===========
(10) STICK TO SCIENCE

>From R.C.L.Wilson@open.ac.uk <R.C.L.Wilson@open.ac.uk>

Benny,

As a fairly frequent visitor to the Middle East, I am very concerned about
events in Israel and elsewhere, but would prefer that CCNet sticks to
science.

Chris Wilson

MODERATOR'S NOTE: Chris, In view of the terrorist mass murders in recent
months, I have been trying to stick to the scientific attempts to explain
the historical backgound to these events. Apocalyptic mass murder is not
just a current threat, but a historical phenomena. Its roots go back many
centuries and are strongly associated with apocalyptic movements and real or
imagined natural catastrophes. It is also a cultural phenomena in need of
scientific analysis and elucidation (see also The Big Bang and the Big Bomb:
Examining the Role of Science and Technology in apocalyptic Belief Systems
http://www.mille.org/publications/winter2000/helland.PDF). Humanistic
scientists have a duty not only to dicipher and understand this menace. We
ignore apocalyptic terror and mass murder at our peril. As a scholarly
network that deals with catastrophic events and celestial hazards almost on
a daily basis, it is essential to understand the apocalyptic mind set
(present in extremists of various totalitarian sects and religions) that is
threatening the openess and humanistic tradition of many societies. Let us
not forget Edmund Burke timeless warning: "The only thing necessary for evil
to prevail is for good men to do nothing". BJP


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