PLEASE NOTE:
*
Subject: Comments by Paul Heinrich on Barbiero's pole shift
paper
To: cambridge-conference@livjm.ac.uk
Date sent: Mon, 14 Apr 1997 01:00:45 -0500 (CDT)
From: pib@nwu.edu
Geologist Paul V. Heinrich offered the following comments about
Flavio Barbiero's paper on pole shifts being caused by relatively
small impacts.
-- Phil "Pib" Burns
Northwestern University, Evanston, IL. USA
pib@nwu.edu
http://pibweb.it.nwu.edu/~pib/
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D
=46rom heinrich@intersurf.com Sun Apr 13 06:39:30 CDT 1997
In article <334e46ec.1797805@news.easynet.co.uk>, =
Ian Tresman (ian@knowledge.co.uk) posted the below URL posted =
as one of three articles that supposedly support catastrophism
and =
rapid pole shifts.
"On The Possibility Of Very Rapid Shifts Of The Poles, by F.
Barbiero"
http://www.unibg.it/dmsia/dynamics/poles.html
At that web page, I found an explanation of a model proposed by
Dr. Barbiero. On that web page, he wrote:
>ON THE POSSIBILITY OF VERY RAPID SHIFTS OF =
>THE POLES
>
> Flavio Barbiero
>
>Summary : - Evidence exists that the poles have changed =
>position during the past ages. =
Problem 1, no such evidence exists. This I have discussed =
concerning claims about Earth crustal shifts by Mr. Graham
Hancock in his book the "Fingerprints of the Gods"
(FOG) =
the evidence that he rehashes from "The Path of the
Pole" by
Dr. Hapgood. There is a lack of any evidence that that the
Earth's crust has shifted as and when Dr. Barbiero claims it
shifted. in contrast, there is overwhelming evidence that
such pole shifts have not taken place. I discussed a lot of
these problems and contrary evidence which Dr. Barbiero
ignores in respect to FOG at:
http://www.intersurf.com/~heinrich/wildside.html
>This possibility, however, so far has been disregarded on =
>the basis that such a phenomenon is thought to be physically
=
>impossible. =
Problem 2, The structure of the crust and mantle, which Dr. =
Barbiero blithely ignores, precludes the shifting of the crust =
as a single piece. No matter how hard a meteorite impacts
the surface of the Earth, all that such impact can do is blow
a large hole in it. If large enough, e.g. Mars-size, the object
could blow a chunk of the crust and part of the impactor into
orbit to form another Moon, e.g. Melosh (1994, p. 224-225).
>The following article shows the possibility of very rapid
shifts =
>of the poles due to the impact of astronomical objects as
small =
>as a half-kilometer diameter asteroid.
An interesting aspect of his arguments is the derivation of the
size of asteroid needed to cause a polar shift. The way in =
which Dr. Barbiero determines the size of the impactor needed =
to cause pole shifting is not only incorrect, but it
completely ignores the physical processes by which cratering =
occurs. It fails to provide any justification for the =
minimum size of the meteorite needed create the torque =
which he claims is needed for pole shifting.
>......material deleted...........
>Calculation of the size an asteroid should have to cause the
=
>shifting of the poles
>
>According to equation 4) to displace the axis of rotation of
for =
>instance 20 degrees, an asteroid hitting the Earth must
develop =
>an impulsive torque of the following value:
>
>C20=B0 =3D 8,87 . 10 25 Kgmt.
>
>It is therefore easy to calculate the size and speed that =
>such an asteroid must have.
That assumes a person knows what they are doing. :-) :-)
>The impulsive force Fi developed on impact with Earth by the
=
>asteroid is given by:
This statement, as explained below is completely wrong as
anybody who has taken the time to study cratering processes
should know. =
>Fi=3DMa . a
Here, Dr. Barbiero falls victim to the common misconception =
concerning meteorite and asteroid impacts. Here, he apparently
presumes that an impactor, whether it be a meteorite or asteroid,
penetrates the ground, it stopped like a bullet shot into a block
of wood. In this type of model, the kinetic energy of the bullet
is transferred directly to the block of wood as a force that can
=
create a torque. Unfortunately, this only happens in the case =
of very small meteorites (Melosh 1994). =
In simple terms, a meteorite or asteroid moving at hypervelocity
penetrates the earth until it is halted by resistance. At this =
point, the energy generated during deceleration is absorbed by
the =
intense compression of the impactor, either a meteorite or an =
asteroid, and the strata in front of it. Given the hypervelocity
of =
the impactor, it is physically impossible for the energy of
impact
to be transmitted as Fi for any distance before both impactor and
=
adjacent strata decompress. Almost immediately, rapid =
decompression, which is essentially an explosion of the =
compressed material, occurs. This explosion produces a nearly =
circular crater (Melosh 1994). The result of all of this is that
energy generated by the impact is directed into a massive
explosion
rather then transmitted into the Earth as Fi. Thus, the equation
" Fi=3DMa . a" is totally useless as a means of
calculating Fi
because, only a very small percentage of the momentum of the =
impactor is transmitted into the Earth as any sort of directed =
force that can cause torque.
The energy released by such an impact is related to mass (Ma) =
times the velocity (v) squared of the meteorite, asteroid, or
comet. =
This energy is released by a massive explosion that transforms
impact energy into crater excavation, vaporization of the
asteroid, =
vaporization of impacted deposits, melting of impacted deposits,
=
fragmentation and deformation of impacted surface, lateral
jetting =
of ejecta, and generation of seismic waves. The seismic and =
other shock waves are dissipated spherically. Thus, very little,
=
if any, will go into the formation of torque, Fi, as the kinetic
=
energy is transformed into a vast explosion (Melosh 1994).
>where =
>
>a =3Ddv/dt is the acceleration the asteroid undergoes on
impact.
Parameter "a", acceleration is simply irrelevant to the
calculation
of Fi. The energy generated by the deceleration of an impactor
goes into compressing the meteorite or asteroid and strata in
front of it until they explosively decompress. Little if any of
this energy goes into Fi because the explosion of the impactor
occurs before rocks can transmit this force by deformation.
>Ma is the mass of the asteroid
Mass is an important aspect of the energy of impact. Dr. =
Barbiero, if nothing else, has this right. :-) :-)
>To calculate the acceleration, a, we can assume the asteroid
=
>has, on impact, a speed:
>
>v =3D 5 . 10 4 mt/sec.
It is "m/sec," not "mt/sec" as there is no
torque involved
in the initial impact. Furthermore, as noted above, not all,
if any at all, of the energy of the impact goes into a torque.
Thus, to talk about "mt/sec" is grossly incorrect.
Regardless, Dr. Barbiero fails to provide any justification for
assuming that the velocity of the impactor is 5 km/sec. The =
average inter-solar velocities for meteorites and asteroids is =
about 20 km/sec. Thus, this is the value typically used in =
calculating the energy released by impacts, e.g. Schmidt and =
Housen (1987) and Melosh (1994, Figure 7.3). The lowest
reasonable value for this is 10 km/sec. In the case of comets, =
their incoming speeds can be higher. Depending on whether =
the comet comes from within or out of the solar system, their =
velocities may range up to 72 km/sec (Neathery et al. 1997, =
Rahe et al. 1994).
>To calculate dt we have to rely on an estimate. In a very =
>conservative way, considering the depth of known craters, =
>we can presume that the depth of the crater caused by that =
>impact to be 500 m, which means that the speed of the
The rational for the 500 m depth given above is hopelessly
vague. So few craters have been fully defined by drilling =
or have been eroded as to make data concerning crater depth
extremely unreliable at present. Because craters can range =
in depth from a kilometer or so to less than a couple hundred
meters and current lack of quality data, there exists no basis =
for presuming or calculating that a crater will be of any
specific =
depth. Furthermore, the depth of crater is dependent on =
many factors, including the density of the impactor relative =
to the impacted material, size of impactor, speed of impactor, =
angle of impact, and other factors.
Typically, craters are described and ranked according to
diameter. This is a parameter that is more readily and =
consistently measured or, at least estimated, for an impact
structure. Often, the depth of such structures are estimated, =
not measured, using an empirical relationship given by =
Grieve and Pesonen (1992, p. 6) between the apparent depth =
(Dd) of an impact crater and its diameter (D). For crater depth =
of 500 m, 0.5 km, that Dr. Barbiero presumes above, the =
diameter of his hypothetical crater would be about 1.55 km =
according to equations developed by Grieve et al. (1989).
As far as impact craters go, this is awfully small.
>asteroid decreases from 5.104 to 0 mt/sec, in a space of =
>500 meters. The time in which this happens is approximately =
>one hundredth of a second, that is:
Again, the deceleration of an impactor has little if anything
to do directly with the torque, Fi, generated by a meteorite
or asteroid impact. The energy produced by the impact does =
not go into torque, but rather into the explosive excavation =
of the crater, which causes the melting and vaporization of the =
impactor and impacted strata, fragmentation and deformation =
of strata in which the crater is created, and seismic energy. =
Very little, if any, of the energy of the impact will go into =
any sort of torque, Fi, as defined by Dr. Barbiero. =
The seismic energy will radiate spherically from the impact =
site and be dissipated as they wave expands away from =
the impact site. In some places, the refraction and reflection =
of seismic energy will cause the seismic waves to be in =
phase in some places and out of phase in others. Thus, =
strength of the seismic energy will be highly variable away =
>from the impact depending on the specific location of a
place. =
Compression and compaction of sedimentary strata =
will quickly absorb pressure waves (Melosh 1994). Thus, =
the energy from a major impact will not be completely =
distributed as a torque as Dr. Barbiero incorrectly assumes.
>dt =3D 0.01 sec.
Furthermore, "dt" as calculated above by Dr. Barbiero
is even =
more meaningless. The depth of the crater fails to represent the
=
depth of penetration of the impactor as he assumes in the above =
calculations. The initial transient crater is formed, not by the
meteorite itself, but by cratering processes which creates a hole
much deeper than the impactor, e.g. meteorite, asteroid, or =
comet, that has impacted. Almost immediately, the sides of the
transient crater collapse and to varying degree isostatically =
rebound forming a much shallower crater whose depth fails =
to be directly related to the diameter as Dr. Barbiero claims =
(Melosh 1994). Thus, the depth of a crater further fails as =
an indicator of the distance that an impactor decelerated as his
=
calculations incorrectly assume.
>The average acceleration of the asteroid will therefore be:
>
>am =3D dv/dt =3D 5.104 / 0,01 =3D 5. 106 m/sec2
>
>The acceleration peak is certainly much higher. In a =
>conservative calculation we can assume it to be double =
>the average value. We will have then:
>
>a =3D 5.10 4 / 0.005 =3D 10 7 mt/sec2
>
>And therefore:
>
>Fi =3D Ma . 10 7 kg
This result is fictional as he incorrectly assumes that all of
the
energy produced by the impact goes into torque, Fi, which
is clearly incorrect. Also, the equation used is inappropriate =
and unusable for calculating the Fi produced by an impact.
Finally, the numbers are based upon a crater depth of 500 m
fails to represent any representative impact and the true
distance
of deceleration. Thus, because the above calculations based =
on flawed equations, unsupported values, and incorrect =
interpretations of impact processes, the value of Fi=3DMa.10.7 =
kg lacks any basis in fact.
>The torque developed by this force will obviously be:
>
>Ci =3D Fi . Ri
>
>where
>
>Ri is the arm of the torque.
>
>The value of Ri can be between 0 and Ro *approximates* =
>6,4 106 mt, that is the
>
>radius of the Earth. For statistical reasons we can put:
>
>Ri =3D * Ro =3D 3,2 106 mt
The problem here is that the value he uses for Fi lack any
basis in reality.
>The mass of the asteroid will therefore be:
>
>[Image] =3D 2,77 1012 kg
>If the density of the asteroid is of 3 Kg/dm3, we will have =
>a volume of:
>
>Va =3D 0,92 km3
>
>that is then a lithic asteroid of approximately a 1000 metres
=
>diameter. This calculation is very conservative. We can =
>realistically suppose that an object of half that size is
enough =
>to develop a torque of sufficient value for a huge =
>shift of the poles.
The calculated value for this impactor is grossly incorrect =
because of the problems discussed above with Dr. Barbiero =
incorrect assumptions concerning cratering and impact =
processes. Thus, he lacks any factual basis for determining =
the size of the meteorite or asteroid as claimed above.
The flawed nature of his calculations is clearly demonstrated
by the work of Grieve et al. (1989) which indicates a crater
with a true depth of 0.5 km would have an expected diameter =
of 1.55 km. Yet. the calculations of Dr. Barbiero reconstruct
an impactor with a diameter of 1.0 km which he halves to only
0.5 km. If rocky or iron impactors of only 0.35 km diameter
can produce craters of about 6 km (Neatherly et al. 1977),
then it is highly unlikely that an impactor of either 0.5 km or
1.0 km would have produced a crater of just 1.55 km in =
diameter regardless of the impact conditions.
>Probability of a shifting of the Poles due to an asteroid
impact
>
>Following are the essential conditions necessary to cause =
>a shift of the poles by an asteroid falling on Earth:
Unfortunately, this discussion is premature as he has failed =
to establish the size of the impactor needed to create the Fi =
that he claims to cause crustal shifting. Because of =
numerous errors and misconceptions about cratering =
processes involved in the above calculations, I find the =
resulting conclusions to be totally lacking any validity.
Editorial Comment
It is strange that the catastrophists who are most fond of =
using impacts to explain everything from glacial tills and =
climate change to Carolina Bays are the people who seem =
to be least knowledgeable about the processes of impact
cratering. A basic requirement, in my opinion, for anyone =
interested in meteorite and asteroids impacts is to have at =
least read and somewhat understood the material presented by
Melosh (1994). Although the book has been available since
its first edition in 1989, many catastrophists seem adverse =
to even reading it. Although in the above discussion, I =
have simplified, for discussion sake, and might have
misread some concepts from Melosh (1994), at least, I =
have made this effort which very few catastrophist seem =
have done.
>.....material deleted.........
References Cited
Grieve, R. A. F., and Pesonen, L. J., 1992, The terrestrial =
impact cratering record. Tectonophysics. vol. 216, pp. 1-30.
Grieve, R. A. F., 1989, Garvin, J. B., Coderre, J. M., and
Rupert, J., 1989, Test of a geometric model for the =
modification stage of a simple impact crater development.
Meteoritics. vol. 24, pp. 83-88.
Neatherly, T. L., King, D. T., Jr., and Wolf, L. W., 1997,
The Wetumpka Impact Structure and Related Features. =
Guidebook for the Annual Meeting of the South Eastern
Section, Geological Society of America, Auburn, Alabama,
March 26, 1997, Department of Geology, Auburn =
University, Auburn, Alabama.
Melosh, H. J., 1994, Impact Cratering: A Geologic Process.
Oxford Monographs on Geology and Geophysics no. 11,
Oxford University Press, New York.
Rahe, J., Vanysek, V., and Weisman, P. r., 1994, Properties of
cometary nuclei. In T. Geheris (ed.), pp. 597-634, Hazards due to
Comets and Asteroids. Tucson, University of Arizona Press.
Schmidt, R. M., and Housen, K. R., 1987, Some recent advances
in the scaling of impact and explosion cratering. International
Journal of Impact Engineering. vol. 5, pp. 543-560.
Below are other suggested reading from IMPACT CRATERING ON =
EARTH Canadian Geological Survey at:
http://gdcinfo.agg.emr.ca/crater/paper/cratering_e.html
Chapman, C. R., and Morrison, D., 1989, Cosmic Catastrophes, =
Plenum Press, New York, 302 p.
Gehrels, T. (ed.), 1994, Hazards due to Comets and Asteroids. =
Univ. Arizon Press, Tucson, 1300 p.
Grieve, R. A. F., 1990, Impact cratering on the Earth, Scientific
=
American, vol. 262, pp. 66-73.
A.R. Hildebrand, A. R., 1993, The Cretaceous/Tertiary =
boundary impact (or the dinosaurs didn't have a chance). =
Journal of the Royal Astronomical Society of Canada, vol. 87, =
pp. 77-118.
Sincerely,
Paul V. Heinrich All comments are the
heinrich@intersurf.com personal opinion of the writer and
Baton Rouge, LA do not constitute policy and/or
opinion of government or corporate
entities. This includes my employer.
"Afterall, if the present is *not* the key to =
the past, it is at least *a* key to the past."
-Flessa (1993) in Taphonomic Approaches to
Time Resolution in Fossil Assemblages (The
Paleontological Society)