From: alanf@tekig6.PEN.TEK.COM (Alan M Feuerbacher)
Newsgroups: talk.origins
Subject: Re: Back to "Bales Scales"
Date: 26 Sep 92 00:33:14 GMT
Organization: Tektronix, Inc., Beaverton,  OR.

In article <7081@tekig7.PEN.TEK.COM> bobb@tekig1.PEN.TEK.COM (Robert W Bales) writes:
> [....]
>a. I don't know the cause of varves and ice cores which appear to give an age
>   of > 50,000 years for the earth.
>
>b. These dating techniques rely on counting layers.  If a layer is produced in
>   a period of other than a year, the count of layers will not give the age in
>   years.
>
>c. Ice cores and varves, even if accurate, only go back a tiny fraction of the
>   accepted age of the earth. (200,000+ years if I remember right.) They do
>   not establish the earth is 4.5 bllion years old.
>
>d. All the evidence must be considered.  While the simplest explanation for
>   varves is that the earth is 200,000 years old, there is other evidence (as
>   I have pointed out before) for which the simplest explanation is that the
>   earth is < 50,000 years old.  Obviously, one of the "simplest explanations"
>   must be false.  It is not correct, logically or scientifically, to chose to
>   believe some evidence and ingore other evidence.  Both possibilities
>   should  be considered.
>-----------

I've found a great deal of information showing that ice cores, ocean
bottom sediment cores, and varves must have taken long ages to form.
The most important point, however, is that these independent geological
phenomena correlate well with one another and with radiometric dating.  
The following article brings up a few points of interest.


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   Young-earth creationists believe that the earth is less
than a few hundred thousand years old.  The following infor-
mation about ancient varves gives strong evidence that the
earth is _at least_ hundreds of millions of years old.

   _Ice Ages: Solving the Mystery_  [1] describes the fasci-
nating discovery in the 1970s of the correlation between ice
age climate cycles and variations in the earth's orbit.  In
the first half of the 20th century Milutin Milankovitch
worked out an astronomical theory of how the orbital cycles
affected climate.  Later, others expanded on his work and
correlated climate related data found in ocean bottom sedi-
ment cores with the astronomical cycles.  The cycles pre-
dicted by Milankovitch's theory and discovered in the ocean
sediments turned out to have the longest variation at
100,000 years, with shorter variations superimposed at about
41,000, 23,000 and 19,000 years.  The book described the
confirmation of the correlation:

   .... According to the expanded version of the astro-
   nomical theory developed by Mesolella and Kukla, cli-
   matic oscillations should occur as four distinct
   cycles: a 100,000-year cycle corresponding to varia-
   tions in eccentricity; a 41,000-year cycle correspond-
   ing to variations in axial tilt; and 23,000- and
   19,000-year cycles corresponding to variations in pre-
   cession.  In the summer of 1974, Imbrie performed the
   long-awaited test.  Spectral analysis indicated that,
   as expected, the dominant climatic pulse was a
   100,000-year cycle, which appeared on both the iso-
   topic and the radiolarian spectra as a large peak.
   But three other peaks--smaller but nevertheless dis-
   tinct--also appeared on the spectra (Figure 42).  On
   the isotopic spectrum these cycles were 43,000 years,
   24,000 years, and 19,000 years long.  On the tempera-
   ture-radiolarian spectrum, they were 42,000 years,
   23,000 years, and 20,000 years long.

   These results were everything for which Imbrie and his
   colleagues had hoped.  Each of the cycles found in the
   Indian Ocean cores matched the predicted cycles within
   five percent.  That such a coincidence might occur by
   chance alone seemed highly unlikely.  Before long,
   Nicklas G. Pisias provided additional evidence in sup-
   port of the astronomical theory.  Using a more power-
   ful spectral method, he found a statistically signifi-
   cant 23,000-year cycle in core V28-238.  CLIMAP inves-
   tigators--realizing that their isotope records from
   the Pacific and Indian oceans matched the correspond-
   ing parts of isotope records already known from other
__________________________
  1 John Imbrie and Katherine Palmer Imbrie,  _Ice  Ages:
    Solving the Mystery_, pp. 167-173, Enslow Publishers,
    Short Hills, New Jersey, 1979.








                            - 2 -



   oceans--felt justified in concluding that the succes-
   sion of late Pleistocene ice ages had indeed been
   triggered by changes in the earth's eccentricity, pre-
   cession, and tilt....

   Convinced now that major climatic changes were caused
   by astronomical variations, and that the 41,000-year
   and 23,000-year climatic cycles followed systemati-
   cally behind variations in tilt and precession, Hays,
   Imbrie, and Shackleton announced their findings in an
   article in _Science,_ which appeared on December 10,
   1976: "Variations in the Earth's Orbit: Pacemaker of
   the Ice Ages."

   A century after Croll published his theory and 50
   years after Milankovitch mailed his radiation curves
   to Koppen and Wegener, two cores from the Indian Ocean
   confirmed the astronomical theory of the ice ages.  At
   last, geologists had clear evidence that the motions
   of the earth in its orbit around the sun triggered the
   succession of late Pleistocene ice ages.  Exactly how
   this triggering mechanism operated, and why the
   100,000-year cycle of orbital eccentricity appeared to
   be so strongly impressed on the climatic record of the
   last half-million years were still unknown.  But, for
   the moment, it was enough to know that Milutin
   Milankovitch, traveler through distant worlds and
   times, had led the way to solving a major part of the
   ice-age mystery....

   It is amazing that Milankovitch's mathematical theory,
first published about 1920, could be so accurately confirmed
50 years later by two independent geological phenomena.
This theory was further confirmed in a most unusual way.
_The Innocent Assassins_ describes how lake varves of two
types form today, and then describes what was found in simi-
lar ancient lakes: [2]

   During the Eocene epoch, a lake basin formed in North
   America, covering large parts of what are now the
   states of Colorado, Wyoming, and Utah.  The area had
   previously been traversed by rivers flowing east, but
   in connection with the rise of the Rocky Mountains a
   barrier was formed to the east.  Thus arose Fossil
   Lake, and waxed greater and greater, finally to cover
   an area of about 13,000 square kilometers, with a
   depth of up to 100 meters.  It was thus about half the
   size of Lake Erie, and twice that of Great Salt Lake.

   Judging from the sediments that lie beneath and above
   those of Fossil lake, it existed for about one-third
__________________________
  2 Bjorn  Kurten,  _The  Innocent Assassins_, pp. 88-94,
    Columbia University Press, New York, 1991.








                            - 3 -



   of the Eocene epoch.  The lake-bottom sediments show a
   fine lamination with alternating light, lime-rich
   bands and dark ones containing a great deal of organic
   matter.  There is also rich fossil flora and fauna
   (especially fish and insects).  The flora indicate a
   climate of a subtropical type with two annual rainy
   seasons, and if the varves are interpreted on that
   basis (two dark bands to a year), it can be seen that
   the entire pile of sediments was formed during a time
   period of 6.5 million years.

   According to radiometric dating, the Eocene epoch
   started about 55 million years ago, and ended about 35
   million years ago.  Its total duration would then be
   about 20 million years.  One-third of that is 6.7 mil-
   lion years, or very close to the number of years that
   can be counted in the lake-bottom silts of Fossil
   Lake.  The agreement is almost too good to be true,
   but there you are.  Radiometric dating is supported by
   the chronology based on annual varves.

   The longest consecutive sequence of annual varves that
   I have happened upon, in a far from systematic search,
   comes from eastern North America and constitutes about
   40 million years.  It dates from the later part of the
   Triassic period and the early part of the Jurassic
   period, and so has an age of about 220-180 million
   years before the present.  My authority is Paul E.
   Olsen.

   The geography of the earth at the beginning of the
   Triassic period was very unlike that of the present
   day.  All continents were then collected into a single
   supercontinent, called Pangaea ("all land").  Then
   began the birth of the Atlantic:  a great rift valley
   running in a northeast-southwest direction started to
   form.  It has its counterpart in the present-day Rift
   Valley of East Africa, which also marks the place of a
   future ocean.  The Triassic valley, a string of at
   least thirteen elongated basins, extended from Nova
   Scotia to North Carolina.  In the basins, very fine-
   grained lake sediments were deposited (forming the so-
   called Newark Supergroup) with annual laminae, total-
   ing some 40 million.  Parts of the rift valley are now
   covered by the sea, but the southern part is dry, as
   are patches further north.

   The sediments preserve a record of climatic changes,
   especially an alternation between dry periods, when
   the water was low, and times of high precipitation and
   high waterlines.  During the former, annual varves
   tend to be very thin, drying cracks are formed, and
   there are numerous footprints of reptiles, in some
   cases so perfectly preserved that you can count the








                            - 4 -



   scales on the soles.  At high water, the drying cracks
   are absent, and the sediments contain a great amount
   of organic matter, especially fish remains.

   As it happens now, these climatic changes are cycli-
   cal:  they tend to return at regular intervals.  Their
   periodicity is complicated, however, because it is a
   combination of several cycles differing in length.
   (Each cycle represents a sequence from low through
   high to low water.)  The most important periods are
   about 25,000, 44,000, 100,000, and 400,000 years in
   length, respectively.  These are figures that cause
   the geochronologist to smile in recognition.  They
   have to do with changes in the rotation of the earth
   around the sun,

(Note how closely the numbers match those of the Milankovitch
cycles previously found for the recent Ice Ages)

   known from astronomical calculations, and have turned
   out to drive the climatic changes during the Ice Age
   as well--that is, during the last two million years or
   so of earth history.  Now the analysis of the Newark
   Supergroup sediments proves that the same factors
   affected climates as long as 200 million years ago.

   And so the geological time scale, originally dated by
   radiometry, is corroborated by two additional and com-
   pletely independent methods of study:  from analysis
   of annual varves, and from astronomical observations.

   The preceding descriptions of the confirmation of the
Milankovitch theory and its correlation to ancient lake sed-
iment layers is unequivocal evidence that the ice ages
really occurred, and that the earth has existed for many
hundreds of millions of years.  It provides a striking con-
firmation of the validity of radiometric dating techniques.

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Alan Feuerbacher
alanf@atlas.pen.tek.com
Newsgroups: talk.origins