Real Science Friday: What Museums Aren't Showing You

[voltaire]

There may also be
mathematical grounds for
thinking so. According to
Mensur Omerbashich
(2006), the procedures
which generate claims that
bedding cycles reflect
multiple kinds of
astronomical cycle are
highly questionable. In the
case he analysed, the
alleged 99% confidence
level was ‘mostly
meaningless in the context
of total-information
quality ’, owing to prior
editing of the data and
failure to distinguish
between signal and noise.
Discrepancies between the
two timescales, some
minor, some major, can be
documented many times
over (e.g. Hilgen &
Langereis 1989, Karner &
Muller 2000, cf Ehrlich
2007). In order to save the
theory, it has even been
suggested that obliquity
can dominate in one locality
and precession, over the
same interval, in another
(Prokoph et al 2001,
Krijgsman et al 2004,
Nederbragt et al 2007).

 

[voltaire]

In
short, like radioisotope
dating, Milankovitch theory
is an example of a scientific
paradigm (Kuhn 1962), an
all-embracing explanation
which provides the
framework within which
‘ normal science’ can operate
but which is not itself
tested or questioned.
Problems are identified and
solved, so far as possible,
within its terms. Anomalies
with the potential to
undermine the paradigm
are ignored, ascribed to
errors in the data, or
accommodated by
modifying the paradigm,
while faith in the paradigm
itself remains strong. Thus,
science can be both critically
questioning in the domain
where normal science takes
place and unquestioning at
the fundamental level
where what is at stake is its
world-view and the sense of
belonging to a brotherhood
of common values and
beliefs.

 

[voltaire]

That said, the phenomenon
of cyclical bedding is real,
and if it does not reflect
Milankovitch cycles, it must
reflect some other rhythm.
To return to the example of
chalk, beds are often very
extensive, and in one case
have have been traced from
outcrop to outcrop over
more than one and half
thousand miles (Gale et al
1999). Climatic
explanations are required
that apply on a global scale.

 

[voltaire]

So what if the warm-cool
cycle of each couplet was of
summer and winter – the
prime astronomical cycle –
rather than precession, so
that we were looking at the
deposit of just one year?
Figure 1 (from Gale et al)
illustrates a series of
couplets from the
Cenomanian part of the
Upper Cretaceous. The grey-
scale fluctuations track the
proportion of clay in the
chalk, from 5-15% in the
light-coloured beds to
10-30% in the darker beds.
The top of each cycle is an
omission surface, where
sedimentation ceased for a
time and animals made
burrows. The marls are
totally bioturbated,
suggesting that they
provided a more
oxygenated or nutrient-rich
environment for deposit-
feeders.

 

[voltaire]

Dense bioturbation does
not take thousands of
years. Experiments have
shown that a small
population of deposit-
feeders, such as the
crustaceans that made the
Thalassinoides-type
burrows (Fig. 1), can churn a
10 cm depth of sediment in
42 days (Gingras et al
2008). Since the chalk and
marl beds are not
homogenised, this is the
kind of timescale that
should be considered when
making interpretations. The
detail of the fabric also
accords with short periods,
as when the walls of later
generations of burrows are
more sharply defined than
earlier ones, indicating an
initially high water content
followed by dewatering and
compaction (Jablonski &
Bottjer 1983).

 

[voltaire]

Another ‘remarkable’
observation – remarkable if
the couplets represent
large, long-term shifts in
climate – is the failure to
show any long-term shifts
in faunal composition
(Lauridsen et al. 2009).
While the fauna in the marl
is more diverse than in the
chalk, their mode of life
remains the same, and no
species are restricted to
just one of the rock types.
They were well adapted to
both environments. The
marked change in water
temperature through the
course of these cycles had
no effect.

 

[voltaire]

Figure 2 shows the δ18O
profile of three chalk-marl
couplets in the ‘white cliffs’
between the English towns
of Dover and Folkestone,
also of Cenomanian age.
The zig-zag pattern follows
that of the greyness scale
(Fig. 1), and since low
oxygen isotope ratios in
sea-floor oozes correlate
with warm sea-surface
temperatures, and vice
versa, explaining this as
the effect of summer and
winter does not seem
unreasonable. The same
pattern may be seen in the
shells of individual
organisms. A study of the
tropical bottom-dwelling
foram Cyclobirculina, for
example, which has a life
span of one year, recorded a
variation in δ18O ratio
from -0.5 in the summer to
+1.5 in the winter (Wefer &
Berger 1980 and Fig. 3).
Growth rate increased with
age, peaking in the spring.
Similar patterns have been
detected in other kinds of
carbonate-secreting
organism, both from the
past (Purton & Brasier,
1999) and from the present
(e.g. Dunbar & Wellington
1981, Hickson et al 1999).

 

[voltaire]

Since coccolithophores are
much smaller than forams
and have a life span of only
days or weeks, the ooze
composed of their remains
would reflect the annual
oscillation collectively, not
individually. They are more
prevalent in the chalk than
the marl and are thought to
represent productivity
blooms (Leary et al 1989).
The chalks are dominated
by microplankton that lived
in the top 100 metres, the
marls by microplankton
that lived in deep water or
on the sea bottom.
Temperatures rose steeply
in the course of marl
deposition, peaked near the
base of the chalk beds, then
fell less steeply (Fig. 2).
Fossil escape burrows have
been reported from some
bases (Leary et al. 1989),
indicating that the rate of
deposition in the lower part
of the chalk beds was
sometimes extremely high.
This would also account for
the relatively sharp
transitions from marl to
chalk. The compositional
difference would be due to
higher rates of planktonic
productivity during the
spring and summer.

 

[voltaire]

In modern settings the rate
of coccolith flux to the
seafloor has also been
observed to vary in annual
oscillations. Around the
Canary Islands
sedimentation peaks in
February/March following
phytoplankton blooms in
the winter (Sprengel et al
2002). In the Arabian Sea
the settling rate peaks in
January and declines to
very low levels in the
months of August to
November (Andruleit et al
2004). Thus the hiatus in
sedimentation at the top of
the chalk beds is directly
comparable to the virtual
cessation of coccolith flux
from late summer to late
autumn in modern seas.
Similar rhythms
characterise the chalks that
formed towards the end of
the Cretaceous, during the
Maastrichtian. As with
outcrops onshore, cores
extracted from the North
Sea show metre-scale
cycles, but here the
alternation is between
compact, intensively
burrowed chalk and porous,
mostly unburrowed chalk
(Scholle et al 1998); in the
lower part of the cycle the
sediment retains its
primary laminated
structure. There is little
bioturbation other than the
vertical escape shafts of
animals momentarily
buried by dumps of
sedimentary snow. Along
with the high porosity this
obviously indicates a rapid
rate of sedimentation.
Further up, the rate slowed,
allowing burrowers to
destroy the laminae. Calcite
cementation began to
harden the seafloor,
enhancing burrow
preservation, but
insufficient time elapsed
prior to the resumption of
heavy sedimentation for
true hardgrounds to form.

 

[voltaire]

In the Central Graben of the
North Sea the chalk cycles
are of non-bioturbated,
mainly laminated beds and
slightly thicker bioturbated
beds (Damholt & Surlyk
2004). The laminated beds
consist of alternating
millimetre-thick, graded,
high-porosity laminae and
non-graded, low-porosity
laminae. The graded layers
are thought to have been
deposited from small-
volume turbidity currents
and suspension clouds, the
non-graded layers from a
rain of pelleted coccoliths
produced directly from the
plankton. In either case,
only the briefest of
timescales is required –
minutes in the case of the
graded laminae, hours in
the case of the ungraded
ones. The bioturbated beds
imply longer timescales,
perhaps a few months,
followed by negligible
sedimentation and then
the commencement of the
next cycle.

 

[voltaire]

According to radioisotope
dating, the Cretaceous
period lasted 80 million
years – a stretch of time
that, accustomed though
we are to such figures, is
unimaginable. Since the
figure is based on data
extraneous to the
properties of the rocks
themselves, those
properties can provide a
test of the timescale, and
as we have seen, in the case
of chalk sequences, they do
not agree with ages of this
magnitude. If we consider
the primary evidence on its
own merits, we have no
grounds for inferring the
miniscule rates of
sedimentation the
radioisotope timescale
imposes.

 

[The Barbarian]

BTW, C-14 in ancient diamonds makes perfect sense, because diamonds normally have a few inclusions with nitrogen in them, and they are found in rock that has several sources of ionizing radiation.

And that's what converts nitrogen to carbon-14.

Just saying...

 

[DavisBJ]

BTW, C-14 in ancient diamonds makes perfect sense, because diamonds normally have a few inclusions with nitrogen in them, and they are found in rock that has several sources of ionizing radiation.

And that's what converts nitrogen to carbon-14.

Baumgardner says he modeled the actual measured radiation in mines to see how much C14 it might create. He says it is way too little to account for the C14 that is seen in diamonds (and coal).

 

[voltaire]

I lost my copy and paste function in midstream. I also got busy, but i want to make a point here. I said the article showed the cretaceous to be 4000 years long. He arrived at this figure by dividing the radiometric age by the length of the precession cycle to get the number of years based on the idea that the precession cycle seen in the sediments was actually equal to one summer winter cycle. If you assume each chalk marl couplet represents a yearly cycle then you actually reach a cretaceous age of 10,000 years by counting the layers.

 

[voltaire]

Here is how you reach 10,000 years of cretaceous age. The white cliffs of dover deposited over a period of 8 million years at the end of the creataceous period. They are 1329 feet in thickness. If you take the average thickness of a chalk marl couplet to be 40 cm, you get 1004 such couplets. That makes 1004 years in duration for the dover chalk if you take each chalk/marl couplet as forming in a summer/ winter cycle. Since the whole radiometric duration for the cretaceous is 80 million years, the real time duration will be ten times that of the dover chalk formation. That gives you a cretaceous age duration of 10,040 years.

 

[The Barbarian]

Baumgardner says he modeled the actual measured radiation in mines to see how much C14 it might create. He says it is way too little to account for the C14 that is seen in diamonds (and coal).

For some reason, I can't find in the literature. Do you have his numbers, or was the margin too small to contain them?

 

[DavisBJ]

For some reason, I can't find in the literature. Do you have his numbers, or was the margin too small to contain them?

I am considering authoring a fairly detailed post addressing the issues of C-14 in diamonds and coal. I will touch on your question there.

 

[DavisBJ]

For some reason, I can't find in the literature. Do you have his numbers, or was the margin too small to contain them?

Here is what I came up with on Baumgardner’s analysis of in-situ production of C-14 in the earth. I have not checked his work. Go to:

http://www.icr.org/i/pdf/technical/...r-a-Recent-Global-Flood-and-a-Young-Earth.pdf

Go to Section 7 starting on Page 28. In summary, he says creation of C-14 in the earth from natural radiation is far too small (by well over a factor of a thousand times) to be meaningful in C-14 dating of coal or diamonds.