PLEASE NOTE:


*

Date sent: Fri, 27 Feb 1998 12:37:10 -0500 (EST)
From: Benny J Peiser B.J.PEISER@livjm.ac.uk
Subject: Re: CC COMMENTS, 27/02/98
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

CAMBRIDGE-CONFERENCE COMMENTS, 27 February 1998
----------------------------------------------

From: Rob McNaught rmn@aaocbn.aao.gov.au

VISUAL FIREBALL SIGHTINGS: A CONSUMER WARNING!

I applaud the comments of David Morrison and Jeremy Tatum. With about
two decades of interest in following up fireball reports and 25 years of
operating all-sky fireball cameras, I have come across this sort of hype
and exaggeration regularly.

The appearance of a story in the media need not have anything to do with
the magnitude of the event. In the USA with such a high population
density, it would be difficult for a fireball to occur away from some
major centre of population. Here in Australia, it is commonplace for a
bright fireball to be photographed over western NSW and have no mention
in the media. Also, an evening fireball is much more likely to be
reported than a morning fireball. When however, a fireball occurs over
a major town and sonic booms are widely heard, the event invariably
makes the national news within hours. Early maps of tornado
distribution in the USA showed a similar bias due to the uneven
population density.

Other news items that compete for space can oust a fireball from being
covered. During the recent huge Pilliga forest fire near here, a bright
fireball was photographed by the one camera station operating that night
(others were affected by smoke). It was weeks before I knew of it when the
film was processed (the long delay caused by the fire).

Once a journalist takes interest in a fireball, it is easy to hunt down
reports of other events. After all, fireballs that light up the ground
occur monthly from any dark location. Thus one fireball suddenly
becomes several with the attendant speculation about increased rates.

It is probably unfair to critise a journalist for having no scientific
training, but it is certainly fair to critise the organisations they work
for, the larger ones at least, if they either do not have scientifically
trained journalists on their staff, or they ask a scientifically illiterate
journalist to cover a fireball report. This results in
misinterpretations and accepting highly questionable statements
from highly questionable sources. As an example of the former, I
was once quoted as saying a fireball had exploded causing
devastation similar to a nuclear explosion and I was seeking help
in finding where it had occurred!!! Well, to be fair, I had said
that, but only when asked about Tunguska. More recently, a
potential meteorite fall near here was widely reported in the
press (at sunset, no cameras operating, over 50 in-situ eyewitness
interviews indicate an end height below 20km and low velocity). A
local newspaper ran a front page story about it, having spoken to
two "experts". One, a local amateur astronomer who operates an
all-sky fireball camera, gave a good factual account of the event,
but his comments were lost in the nonsense and half truths of a
local operator of a public observatory. The story ended up
being about the $ value of the "meteorites". Of course, he may
have been misquoted!

Certainly, scientists do not always agree on the details, or even the
fundamentals, but I am unaware of any serious questions regarding the
physics of small fireballs (centimetre to meter size.
Electrophonic sounds may be one issue). It is thus depressing to
have ill informed comments from people with no background in this
field (planetarium directors, operators of public observatories
and astrophysicists included).

Regarding the perception of a fireball by the human eye/mind, Jeremy is
actually incorrect in saying that there is no information on the actual 3D
motion of the fireball. The human mind has evolved to correctly
interpret changing angular velocity as motion of an object
relative to the observer. Usually this occurs in a rich visual
environment with many other cues to size and distance. In the case
of a fireball, these other cues are lacking (changing size, shape,
intervening haze, obscuration of distant or by near objects etc.),
which certainly results in indeterminacy of the distance, but in
my experience, the observer usually correctly interprets the
general direction of motion of a fireball. The linear deceleration
of the fireball in the atmosphere certainly affects this
judgement, but the changing angular velocity is a strong cue. But
Jeremy is certainly correct in that the projected path across the sky
give the essential data from which the real trajectory is determined.
[A single photograph with timed interruptions CAN result in the
derivation of the radiant (orientation of the real path), by assuming
the early part of the path has near constant linear velocity and
fitting the changing angular velocity to the angular distance covered.
The distance cannot be derived from this technique, but plausible
assumptions can be made.]

Regarding the problem of misperception of the distance of a fireball, this
is where the lack of cues leaves the mind floundering. Almost
certainly, the human mind UNCONSCIOUSLY and directly interprets the
event in terms of more familiar objects with the following result:

it was bright, therefore it is close
it has a high angular velocity, therefore it is close
it is large, therefore it is close

Once it is "seen" to be close, this sets one parameter that many others must
follow. If it appeared to be say, 300 metres away, and was seen at 30
deg altitude, then it will appear to have a height of 150 metres. If
the distant hills are say 500 metres above the observer, this can
result in the PERCEPTION that the fireball was below the height of the
hills, despite being of higher angular altitude. It is unlikely that
this perception once made can be altered, and one has to be very
tactful in explaining this illusion. It can result in resentment at the
arrogance of scientists who ignore what people actually see. [When
sonics are heard some minutes later, the eye-witness is usually aware
of a problem with the perceived distance.] Aurorae "seen" in front of
hills, is presumably caused by the same psychological process. Another
result of this misperceived distance is that the size of the object
becomes fixed. "It was the size of a dinner plate". Asking "The size
of a dinner plate at what distance?" really doesn't help, as the
angular size of the object becomes secondary to the (mis)perceived 3D
size, despite the angular size having primacy as the original sense data.
UFO reports caused by Venus "following" a car is the same overall
psychological process of misperceived distance with all its consequences.
Once the observer becomes fearful of the "UFO", a correct interpretation is
not likely to be possible and again there is resentment if the observed
phenomenon is questioned. The perceptual process most at play here is
called "constancy".

As a final point, I'd like to point out that meteoric fireballs are
probably some 100 times or so more common than satellite re-entry
fireballs. I'm only aware of three satellite re-entries having been
photographed by fireball networks, whereas many hundreds of meteoric
fireballs have been recorded. Re-entries are rarely much brighter than
Venus and typically last for many tens of seconds, going from horizon
to horizon usually with dozens of fragments trailing. Whilst some
meteoric fireballs may be of long duration with numerous fragments
(like Peekskill), they would typically be very much brighter than
Venus. A fireball lasting a few seconds is unlikely to ever be a
satellite re-entry, regardless of the fact that re-entries are much
less common.

Recent events suggest to me that too much importance is being placed on
visual observations of fireballs when there is little or no hard data to back
up the claims. The extent of reporting in the media (including the
internet) may indicate little more than hype or lack of background
knowledge. As Jeremy says, it takes quite a bit of foot slogging (and $
of petrol) to make in situ measurements of visual sightings and usually
for poorly defined results. With the photographed Pribram meteorite
fall, Ceplecha mentions both systematic and large random errors in the
visual observations. In the Eastern Australian Fireball Network, we are
awaiting the next bright fireball, to compare the photographic real
trajectory with that derived solely from visual sightings to assess the
nature of these effects in visual observations. This is necessary in
interpreting eye-witness reports of satellite detected "superbolides".

Without a satellite detection, or good physical data, I fear that most
reported "impacts" will turn out to be hype. If this were to go on for
much longer, there will be widespread cynicism about the phenomenon.

Rob McNaught (rmn@aaocbn.aao.gov.au)

======================

From: Simon Mansfield simon@spacer.com

Benny,

maybe the "increased activity" is mistaken for Iridium satellite
flashes.

Simon



*

Date sent: Fri, 27 Feb 1998 11:24:09 -0500 (EST)
From: Benny J Peiser B.J.PEISER@livjm.ac.uk
Subject: CC DIGEST, 27/02/98
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

CAMBRIDGE-CONFERENCE DIGEST, 27 February 1998
---------------------------------------------

(1) SORRY PEOPLE, BUT I MADE A BIT OF A BOO-BOO
Charles Darwin C.R.Darwin@Westminster.Abbey.uk

(2) A MODEL OF MASS EXTINCTION
M.E.J. Newman, CORNELL UNIVERSITY

(3) EJECTA LAYER AT THE K/T BOUNDARY IN NEW JERSEY
R.K. Olsson et al., RUTGERS STATE UNIVERSITY

(4) ROADBLOCKS ON THE KILL CURVE: TESTING THE RAUP HYPOTHESIS
C.W. Poag, US GEOLOGICAL SURVEY

(5) MASS EXTINCTIONS AND THE SUN'S ENCOUNTERS WITH SPIRAL ARMS
E.M. Leitch and G. Vasisht, CALTECH

(6) LOOKING AT THE K/T BOUNDARY IN THE WESTERN PYRENEES
E. Apellaniz et al., EUSKAL HERRIKO UNIBERTSITATEA

(7) EVALUATING THE FLUCTUATION OF MASS EXTINCTIONS AND RECOVERY
M.L. Droser et al., UNIVERSITY OF CALIFORNIA RIVERSIDE

(8) THE CRETACEOUS-TERTIARY BIOTIC TRANSITION
N. Macleod et al., NATURAL HISTORY MUSEUM

(9) NONLINEAR DYNAMICS AND MASS EXTINCTIONS
R.V. Sole et al., UNIVERSITY POLITECHNIC OF CATALUNYA

=====================================
(1) SORRY PEOPLE, BUT I MADE A BIT OF A BOO-BOO

From: Charles Darwin C.R.Darwin@Westminster.Abbey

Hi folks,

Having followed your research and debates for some while, I think it's
about time to confess that I no longer adhere to the main
conclusions (attached below) of my controversial book published
some 140 years ago. I am sure you will be lenient with me; after
all, I used to be a fellow catastrophist in my early days. I've
come to realise that I got it terribly wrong when I converted to
Lyell's uniformitarian creed. After more than 90 years of sessions
with my psycho-analyst, I now believe that the crisis which
triggered this sudden conversion was not so much due to my
relationship to my mother but rather caused by post-traumatic
stress syndrom from which I suffered under the impact of the
Chilean earthquake. So leave Oedipus out of the deabte.

Cheers, Charly

P.S. I have attached the main paragraph of my flawed theory which
has now become merely of historical interest:

"As all living forms of life are the lineal descendants of
those which lived long before the Silurian epoch, we may feel
certain that the ordinary succession by generation has never
been broken, and that no cataclysm has desolated the whole
world. Hence we may look with some confidence to a secure
future of equally inappreciable length. And as natural
selection works solely by and for the good of each being, all
corporeal and mental environments will tend to progress towards
perfection" (On the Origin of Species by Means of Natural
Selection: or the Preservation of Favoured Races in the
Struggle for Life, 1859)


=====================
(2) A MODEL OF MASS EXTINCTION

M.E.J. Newman: A model of mass extinction. JOURNAL OF THEORETICAL
BIOLOGY, 1997, Vol.189, No.3, pp.235-252

CORNELL UNIVERSITY, CTR THEORY, RHODES HALL, ITHACA, NY, 14853, USA

In the last few years a number of authors have suggested that evolution
may be a so-called self-organized critical phenomenon, and that
critical processes might have a significant effect on the dynamics of
ecosystems. In particular it has been suggested that mass extinction
may arise through a purely biotic mechanism as the result of
'coevolutionary avalanches'. In this paper we first explore the
empirical evidence which has been put forward in favor of this
conclusion. The data center principally around the existence of
power-law functional forms in the distribution of the sizes of
extinction events and other quantities. We then propose a new
mathematical model of mass extinction which does not rely on
coevolutionary effects and in which extinction is caused entirely by
the action of environmental stress on species. In combination with a
simple model of species adaption we show that this process can account
for all the observed data without the need to invoke coevolution and
critical processes. The model also makes some independent predictions,
such as the existence of 'aftershock' extinctions in the aftermath of
large mass extinction events, which should in theory be testable
against the fossil record. (C) 1997 Academic Press Limited.

=========================
(3) EJECTA LAYER AT THE K/T BOUNDARY IN NEW JERSEY

R.K. Olsson*), K.G. Miller, J.V. Browning, D. Habib, P.J. Sugarman:
Ejecta layer at the Cretaceous-Tertiary boundary, Bass River, New
Jersey (Ocean Drilling Program Leg 174AX). GEOLOGY, 1997, Vol.25, No.8,
pp.759-762

*) RUTGERS STATE UNIVERSITY, DEPARTMENT OF GEOLOGICAL SCIENCE,
PISCATAWAY, NJ, 08855

A continuously cored borehole drilled at Bass River, New Jersey,
recovered a Cretaceous-Tertiary (K-T) succession with a dcm-thick
spherule layer immediately above the boundary. Below the spherule
layer, the Cretaceous glauconitic clay is extensively burrowed and
contains the uppermost Maastrichtian Micula prinsii calcareous
nannofossil zone. Spherical impressions of spherules at the top of the
Cretaceous indicate nearly instantaneous deposition of ejecta from the
Chicxulub impact. The thickest ejecta layer shows clearly that a single
impact occurred precisely at K-T boundary time. Above the spherule
layer, the glauconitic clay contains the planktonic foraminiferal PO
and Pa Zones, indicating (1) a complete K-T succession and (2)
continuous deposition interrupted only by fallout of the ejecta layer.
Clay clasts within a 6 cm interval above the spherule layer contain
Cretaceous microfossils and may be rip-up clasts from a tsunami or
possibly a megastorm event. Extinction of the Cretaceous planktonic
foraminifers and burrowing organisms occurs abruptly at the K-T
boundary. Thus, the Bass River K-T succession unequivocally links the
Chicxulub bolide impact to the mass extinctions at the end of the
Mesozoic. Copyright 1998, Institute for Scientific Information Inc.
=============================
(4) ROADBLOCKS ON THE KILL CURVE: TESTING THE RAUP HYPOTHESIS

C.W. Poag: Roadblocks on the kill curve: Testing the Raup hypothesis.
PALAIOS, 1997, Vol.12, No.6, pp.582-590

US GEOLOGICAL SURVEY, 384 WOODS HOLE RD, WOODS HOLE, MA, 02543

The documented presence of two large (similar to 100-km diameter),
possibly coeval impact craters of late Eocene age, requires
modification of the impact-kill curve proposed by David M. Raup. Though
the estimated meteorite size for each crater alone is large enough to
have produced considerable global environmental stress, no horizons of
mass mortality or pulsed extinction are known to be associated with
either crater or their ejecta deposits. Thus, either there is no fixed
relationship between extinction magnitude and crater diameter, or a
meteorite that would produce a crater of > 100-km diameter is required
to raise extinction rates significantly above a similar to 5%
background level. Both impacts took place similar to 1 - 2 m.y. before
the ''Terminal Eocene Event'' (= early Oligocene pulsed extinction).
Their collective long-term environmental effects, however, may have
either delayed that extinction pulse or produced threshold conditions
necessary for it to take place. Copyright 1998, Institute for
Scientific Information Inc.
=====================
(5) MASS EXTINCTIONS AND THE SUN'S ENCOUNTERS WITH SPIRAL ARMS

E.M. Leitch and G. Vasisht: Mass extinctions and the sun's encounters
with spiral arms. NEW ASTRONOMY, 1997, Vol.3, No.1, pp.51-56

CALTECH,PASADENA,CA,91125

The terrestrial fossil record shows that the exponential rise
in biodiversity since the Precambrian period has been punctuated by
large extinctions, at intervals of 40 to 140 Myr. These mass
extinctions represent extremes over a background of smaller events and
the natural process of species extinction. We point out that the
non-terrestrial phenomena proposed to explain these events, such as
boloidal impacts (a candidate for the end-Cretaceous extinction) and
nearby supernovae, are collectively far more effective during the solar
system's traversal of spiral arms. Using the best available data on the
location and kinematics of the Galactic spiral structure (including
distance scale and kinematic uncertainties), we present evidence that
arm crossings provide a viable explanation for the timing of the large
extinctions. (C) 1998 Elsevier Science B.V.

================================
(6) LOOKING AT THE K/T BOUNDARY IN THE WESTERN PYRENEES

E. Apellaniz*), J.I. Baceta, G. Bernaola Bilbao, K. Nunez Betelu,
X. Orue Etxebarria, A. Payros, V. Pujalte, E. Robin, and R. Rocchia:
Analysis of uppermost Cretaceous lowermost Tertiary hemipelagic
successions in the Basque Country (western Pyrenees): evidence for a
sudden extinction of more than half planktic foraminifer species at the
K/T boundary. BULLETIN DE LA SOCIETE GEOLOGIQUE DE FRANCE, 1997,
Vol.168, No.6, pp.783-793

*) EUSKAL HERRIKO UNIBERTSITATEA,ZIENTZI FAK,ESTRATIG & PALEONTOL
SAILA, 644 POSTAKUTXA, BILBAO, BASQUE COUNTRY, SPAIN

This paper summarises our current knowledge about 21 sections across
the K/T boundary from the Basque Country (western Pyrenees), all of
them comprising intermediate-deep basinal facies. This study allowed us
to establish that Sopelana III and Bidart are the best sections for
analysing the extinction of the planktic foraminifers at the K/T
boundary. Detailed analyses of planktic foraminifers from four new
sections allow us to differentiate four biozones, one at the end of the
Cretaceous and three at the beginning of the Tertiary. These analyses
further show that 63 Upper Maastrichtian planktic foraminifers species
reached the boundary where 33 species became extinct. The study also
shows that some species decrease markedly in abundance in the last few
metres of the Cretaceous prior to the extinction event which could be
related to environmental changes at the end of the Maastrichtian. More
than 50 % of the planktic foraminifers, that is 33 species, became
extinct at the end of the Cretaceous. However, most of the extinct
species were rare and only about 20 % of the total Cretaceous
assemblages are involved in the extinction event. The 30 surviving
species, that is less than 50 % of the Cretaceous species, later
disappear through the Pr. longiapertura and P. pseudobulloides biozones
of the beginning of the Tertiary. Above the K/T boundary, samples are
far poorer in planktic foraminifer specimens than those from the
uppermost Maastrichtian and include 16 Tertiary species. Moreover,
together with this extinction event there are impact markers (iridium
and Ni-rich spinels), as well as a high concentration of soot at the
beginning of the Danian at the Sopelana III section. This strengthens
the hypothesis of a causal link between the impact and WT extinctions.
Copyright 1998, Institute for Scientific Information Inc.

========================
(7) EVALUATING THE FLUCTUATION OF MASS EXTINCTIONS AND RECOVERY

M.L. Droser*), D.J. Bottjer, and P.M. Sheehan: Evaluating the
ecological architecture of major events in the Phanerozoic history of
marine invertebrate life. GEOLOGY, 1997, Vol.25, No.2, pp.167-170

*) UNIVERSITY OF CALIFORNIA RIVERSIDE, DEPARTMENT OF EARTH
SCIENCE, RIVERSIDE,CA,92521

Paleoecological changes associated with Phanerozoic mass extinctions
and radiations can be categorized into four nonhierarchical,
nonadditive levels. First-level changes include colonization of a new
ecosystem. Structural changes within an established ecosystem represent
the second level, changes within an already established ecological
structure are the third level, and taxonomic changes within a community
represent the fourth level. Applying these levels to the Ordovician
radiation, end-Ordovician extinction and Silurian recovery, as well as
the end-Permian extinction and Triassic recovery, demonstrate that
paleoecological changes associated with these major events can be
evaluated and compared in a more rigorous manner than previously done.
Results of this analysis demonstrate that use of these levels indicates
that the relative magnitude of an event as measured by taxonomic
criteria may be decoupled from its paleoecological significance.
Copyright 1998, Institute for Scientific Information Inc.

========================
(8) THE CRETACEOUS-TERTIARY BIOTIC TRANSITION

N. Macleod*), P.F. Rawson, P.L. Forey, F.T. Banner, M.K. Boudagher
Fadel, P.R. Brown, J.A. Burnett, P. Chambers, S. Culver, S.E. Evans, C.
Jeffery, M.A. Kaminski, A.R. Lord, A.C. Milner, A.R. Milner, N. Morris,
E. Owen, B.R. Rosen, A.B. Smith, P.D. Taylor, E. Urquhart, J.R. Young:
The Cretaceous-Tertiary biotic transition. JOURNAL OF THE GEOLOGICAL
SOCIETY, 1997, Vol.154, No.Pt2, pp.265-292

*) NATURAL HISTORY MUSEUM, DEPT PALAEONTOLOGY, CROMWELL RD, LONDON SW7
5BD, ENGLAND

Mass extinctions are recognized through the study of fossil groups
across event horizons, and from analyses of long-term trends in
taxonomic richness and diversify. Both approaches have inherent flaws:
and data that once seemed reliable can be readily superseded by the
discovery of new fossils and/or the application of new analytical
techniques. Herein the current state of the Cretaceous-Tertiary (K-T)
biostratigraphical record is reviewed for most major fossil clades,
including: calcareous nannoplankton, dinoflagellates, diatoms,
radiolaria, foraminifera, ostracodes, scleractinian corals, bryozoans,
brachiopods, molluscs, echinoderms, fish, amphibians, reptiles and
terrestrial plants (macrofossils and palynomorphs). These reviews take
account of possible biasing factors in the fossil record in order to
extract the most comprehensive picture of the K-T biotic crisis
available. Results suggest that many faunal and floral groups
(ostracodes, bryozoa, ammonite cephalopods, bivalves, archosaurs) were
in decline throughout the latest Maastrichtian while others (diatoms,
radiolaria, benthic foraminifera, brachiopods, gastropods, fish,
amphibians, lepidosaurs, terrestrial plants) passed through the K-T
event horizon with only minor taxonomic richness and/or diversity
changes. A few microfossil groups (calcareous nannoplankton,
dinoflagellates, planktonic foraminifera) did experience a turnover of
varying magnitudes in the latest Maastrichtian-earliest Danian.
However, many of these turnovers, along with changes in ecological
dominance patterns among benthic foraminifera, began in the latest
Maastrichtian. Improved taxonomic estimates of the overall pattern and
magnitude of the K-T extinction event must await the development of
more reliable systematic and phylogenetic data for all Upper Cretaceous
clades. Copyright 1998, Institute for Scientific Information Inc.

=============================
(9) NONLINEAR DYNAMICS AND MASS EXTINCTIONS

R.V. Sole*), S.C. Manrubia, M. Benton, P. Bak: Self-similarity of
extinction statistics in the fossil record. NATURE, 1997, Vol.388,
No.6644, pp.764-767

*) UNIVERSITY POLITECHNIC OF CATALUNYA, DEPT PHYS FEN, CAMPUS NORD,
MODUL B4,ES-08034 BARCELONA,SPAIN

The dynamical processes underlying evolution over geological timescales
remain unclear. Analyses of time series of the fossil record have
highlighted the possible signature of periodicity in mass extinctions,
perhaps owing to external influences such as meteorite impacts. More
recently the fluctuations in the evolutionary record have been proposed
to result from intrinsic nonlinear dynamics for which self-organized
criticality provides an appropriate theoretical framework. A
consequence of this controversial conjecture is that the fluctuations
should be self-similar, exhibiting scaling behaviour like that seen in
other biological and socioeconomic systems. The self-similar character
is described by a 1/f power spectrum P(f), which measures the
contributions of each frequency f to the overall time series. If
self-similarity is present, then P(f) approximate to f(-beta) with 0 <
beta < 2, This idea has not been sufficiently tested, however, owing to
a lack of adequate data. Here we explore the statistical fluctuation
structure of several time series obtained from available
palaeontological data bases, particularly the new 'Fossil Record 2'. We
find that these data indeed show self-similar fluctuations
characterized by a 1/f spectrum. These findings support the idea that a
nonlinear response of the biosphere to perturbations provides the main
mechanism for the distribution of extinction events. Copyright 1998,
Institute for Scientific Information Inc.

--------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK
--------------------------------
The Cambridge-Conference List is a scholarly electronic network
moderated by Dr Benny J Peiser at Liverpool John Moores University,
United Kingdom. It is the aim of this network to disseminate
information and research findings related to i) geological and
historical neo-catastrophism, ii) NEO research and the hazards to
civilisation due to comets, asteroids and meteor streams, and iii) the
development of a planetary civilisation capable of protecting itself
against cosmic disasters. To subscribe, please contact Benny J Peiser
b.j.peiser@livjm.ac.uk . Information circulated on this network is
for scholarly and educational use only. The attached information may
not be copied or reproduced for any other purposes without prior
permission of the copyright holders.



CCCMENU CCC for 1998

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.