scientists disagreed, arguing that the top of the core was
20 That would imply that the upper section of
the E49-19 core was potentially datable by the radiocarbon
method (even within a uniformitarian framework), which
would mean that the uppermost E49-18 data were indeed
usable for their analysis.
Third, before performing their analyses, the Pacemaker
authors had to assign tentative timescales to the two cores.
Critical to these timescales, especially for the longer E49-
18 core, was an assumed age of 700 ka for the most recent
magnetic reversal boundary, the Brunhes–Matuyama (B–M)
magnetic reversal boundary. This age was based on K-Ar
dating of volcanic rocks which recorded this reversal.
However, uniformitarian scientists have since revised the
age of the B–M reversal boundary upward to 780 ka.
Incredibly, it seems that uniformitarian scientists never
bothered to see what effect this age revision would have on
the original Pacemaker results!
I have recently reperformed the Pacemaker frequency
domain calculations, using the same method as the paper’s
authors, but taking into account this revision to the age
of the B–M reversal boundary, as well as the inclusion of
the previously excluded data from the second core. These
changes dramatically weaken, if not completely invalidate,
the original argument for Milankovitch climate forcing
presented in that paper.
In order to understand the original and new Pacemaker
results, it is necessary to consider some background material.
Foraminifera, oxygen isotope ratios,
and marine isotope stages
Microscopic marine organisms called foraminifera
construct shells composed of calcium carbonate, CaCO3.
When these organisms die, their remains become part of the
debris accumulating on the seafloor. Scientists often measure
the amount of 18O in a foraminiferal shell compared to the
amount of 16O and calculate a quantity called the oxygen
isotope ratio, denoted by the symbol δ18O.
If one plots δ18O values from a sediment core as a function
of depth, many ‘wiggles’ are readily apparent (figures 2
and 3). These oxygen isotope values are thought to be global
climate indicators: maximum values of δ18O within seafloor
sediments are thought to indicate times at which global ice
volumes were largest, and minimum δ18O values are thought
to indicate times when global ice volumes were smallest.
Because uniformitarian paleoclimatologists think that the
δ18O signal is a global climate indicator, they believe that
the same basic pattern of δ18O wiggles present in one core
should be present in other cores. Of course, they recognize
that changes in sedimentation rate, local weather effects,
etc., can alter or distort this signal. Nevertheless, they believe
that it is possible to ‘match’ δ18O features within one core to
corresponding δ18O features in another core, even if the two
cores are separated by great distances. Hence, they believe
it is possible to transfer ages assigned to prominent δ18O
features within one core to (presumed) corresponding δ18O
features in another core.
To facilitate this wiggle-matching process, uniformitarian
scientists have invented a numbering system involving
marine isotope stages (MIS). Our present-day climate
is part of MIS 1, which includes the so-called Holocene
epoch. The most recent ice age corresponds to MIS 2-4,
and most of MIS 5. MIS 5 was originally classified entirely
as an interglacial, but secular paleoclimateologists now
restrict the interglacial classification to the earliest δ18O
‘trough’ within MIS 5, substage MIS 5e.
26 Likewise, MIS
6 corresponds to the penultimate (second-to-last) ice age.
Generally, the boundaries between marine isotope stages
occur at the depths at which the δ18O values have transitioned
halfway from a very low to a very high δ18O, or vice versa.
The oxygen isotope values from the RC11-120 and E49-18
sediment cores are shown in figures 2 and 3, along with the
approximate MIS boundary locations.
Age assignments for marine
isotope stage boundaries
Before the Pacemaker authors could analyze the
RC11-120 and E49-18 data, they had to assign timescales
to these two cores. Radioisotope dating methods cannot
generally be used to date the deeper sediments (although
protactinium-thorium dating is theoretically capable of
dating sediments thought to be less than 175,000 ka old27),
and uniformitarian scientists believe that radiocarbon dating
methods can only be used on the uppermost sediments.
Hence, uniformitarian scientists used the long western
Pacific V28-238 core to indirectly assign ages to the
sediments. They chose this particular core because it was
believed to have the most nearly constant sedimentation
rate of all the cores that had been examined.
minerals within the sediments showed a reversal of the
earth’s magnetic field at a depth of 1200 cm within the V28-
238 core. Uniformitarian scientists had already used K-Ar
dating to assign an age of 700 ka to volcanic rocks showing
this same reversal. Hence, they concluded that the sediments
at a depth of 1200 cm within the V28-238 core were 700 ka
old. By assuming that the top of the V28-238 core had an
age of 0 ka and that the seafloor sediments at that location
had accumulated at a nearly constant rate, they were able to
assign tentative ages to the first 21 MIS boundaries within
the core (figure 4).
29 The results of these calculations are
shown in table 1 (third column from left), as are the results