There is an intersting correlation between the first and last occurrences of
various planktonic species and the oxygen isotope record. Water is made up
of two forms of water, normal water in which the oxygen in the water
molecule is of the isotope with molecular weight 16, and the second, much
rarer form of water, heavy water, in which the oxygen in the molecule has a
molecular weight of 18. The heavy water is harder to evaporate from the
ocean surface since it requires more energy and thus is preferentially left
behind in the evaporative process. The sediments at the bottom of the oceans
have been studied for the ratio of oxygen 16/oxygen 18. It has been found
that the ratio of O16/O18 varies in the sediments in a relatively cyclic
pattern every 41,000 years which matches the variation in the earth's
obliquity. [Obliquity is the tilt of the earth] (Raymo et al, 1989. This
variation is interpreted as being due to the entrapment of ice in glacial
age icecaps. The theory being that since O16 is more easily removed from
the oceans, glacial ice should be isotopically light leaving behind an
isotopically heavy ocean. Then the sediments of the ocean would have more
O18 during glacial periods and less during interglacials.
Now, the altering of the isotopic ratio of the entire ocean is something
that cannot occur instantaneously. The ocean waters circulate for thousands
of years before sufficient mixing can occur to increase the isotopic weight
of the entire ocean.
The reason I bring this up is that researchers have numbered the excursions
of the O16/018 curves starting at 1 going back to more than 120 in the
Pliocene.Now these excursions of the O16/O18 curves occur throughout the
ocean and the first appearances (FAD) and the last appearances (LAD) of
various planktonic forms of life coincide with the changes in O16/O18.
"The foraminiferal and nannofossil datums listed in Tables 4
and 5 are plotted in Figure 10. The first abundant appearance of
sinistrally oiled Neogloboquadrina pachyderma occurs at all three
sites (607, 609 and 552A) within stage 64. This datum thus
appears synchronous from 42o to 56oN latitude and dates at 1.66
Ma, within the age range proposed by Weaver and Clement. The
first appearance datum (FAD) of Globorotalia inflata (d'Orbigny)
is found within stage 78 at sites 607 and 609 but may fall
slightly earlier at 552A. This event is dated at 1.96 Ma, ~100
kyr younger than the age proposed by Weaver and clement.
"The last appearance datum (LAD) of Neogloboquadrina
atlantica falls on the transition between stages 95 and 96 at
site 607, on the stage 94-95 transition at site 609, and within
stage 95 at site 552A. Our estimated age of 2.28-2.31 Ma is in
agreement with that proposed by Weaver and Clement. The LAD of
Globorotalia puncticulata, not dated by Weaver and Clement, falls
within stage 96 at 607, on the 96/97 boundary at site 609, and
within stage 97 at site 552A. This datum appears to be time
transgressive disappearing first at the more northern sites, and
dates from 2.31 to 2.35 Ma. Unlike G. puncticulata, which has a
subtropical/transitional affinity, N. atlantica, a polar/subpolar
species disappears earliest at the most southern site."
"Of the nannofossil datums, Discoaster brouweri (LAD) falls
within stage 72 at all three sites, and Discoaster triradiatus
acme (FAD) falls within stage 82 at sites 607 and 609 (this datum
was not identified at site 552). These events are dated at 1.83
Ma and 2.03 Ma, respectively, ~50 kyr younger than published
estimates. At sites 607 and 552, the last appearance of
Discoaster pentaradiatus is associated with the first large
glacial event (stage 100), although it may occur slightly later
at site 607. At site 609, the midpoint of this datum is located
within stage 101. Our age estimate of 2.37-2.44 Ma is not
significantly different from the age range proposed by Backman
and Pestiaux.
"The LAD of Discoaster surculus is poorly constrained at
sites 607 and 552 and appears to be time transgressive,
disappearing earlier at the northern sites. Ages for this datum
range from 2.34 to 2.5 Ma. The LAD of Discoaster tamalis also
appears to be transgressive, again occurring earlier at the
northern sites. Ages for this datum range from 2.62 to 2.72 Ma.
"Within this limited data set, it appears that all of the
FADs, and most of the LADs, occur during glaciations, perhaps
indicating that faunal compositions are most likely to
evolve/overturn during periods of enhanced environmental stress.
In addition, FADs appear to be more synchronous than LADs, the
opposite of the suggestion of Dowsett. The continued correlation
of biostratigraphic and magnetic datums to high resolution
[del]18O records should allow us to evaluate globally, the
synchrony of datums to better than 10 kyr."~M. E. Raymo et al,
"Late Pliocene Variation in Northern Hemisphere Ice Sheets and
North Atlantic Deep water Circulation," Paleoceanography
4(1989):4:413-446, 427-428
There is no way to explain this within the framework of a global flood that
I am aware of. It takes time to change the isotopic content of the ocean
and why the first and last appearances of organisms would be fairly well
correlated with isotopic excursions in a flood is beyond me.
Now the other issue which comes up here is whence came the new species? Did
God create the new species at each FAD? And considering that there are
forms which are only found in the Recent (<10000 years), is God still
creating these forms from time to time and how do we recognize when he creates?
If one holds that these microscopic forms are due to evolution one has a
much simpler time.
glenn
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
and
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm