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It is the Greenland Ice Sheet that exhibits annual cycles of one or more of the variables down an ice core.
Ice cores have been drilled deep into both the Antarctica and Greenland ice sheets. These cores represent snowfall that has turned to ice. During snowfall on top of the ice sheets, dust, air, acids, etc. are added and eventually incorporated into the ice. Some of these parameters oscillate during the seasons and can be a signature for an annual layer of snowfall. The annual snowfall over Antarctica is normally too small to resolve annual layers down an ice core. It is the Greenland Ice Sheet that exhibits annual cycles of one or more of the variables down an ice core.
One of the most used annual variables in Greenland ice cores is the oxygen isotope ratio in the ice. Oxygen comes in three isotopes, depending on the number of neutrons in the nucleus of the atom. For practical purposes, the ratio between oxygen-18 and oxygen-16 is the variable used, oxygen-17 being too small to be useful. Oxygen-18 has two more neutrons than oxygen-16 and has a higher mass. Because of the different mass, the ratio of these isotopes will vary during evaporation and condensation cycles, which are correlated with temperature. So during summer, warmer temperatures result in a higher oxygen-18/oxygen-16 ratio of the snowfall, while in winter the ratio is lower. This seasonal oscillation can be measured down Greenland ice cores. Furthermore the oxygen isotope ratio can provide a general location in the core for the ice formed during the Ice Age and the ice that fell afterwards.
Glaciologists claim that they can count 110,000 annual layers downward from the top to near the bottom of the Greenland ice sheet (Meese et al., 1997). This analysis was performed on the American GISP2 core drilled between 1989 to 1993 from the top of the ice in central Greenland to bedrock at about 10,000 feet deep (Oard, 1995). The GRIP core was drilled nearby at the same time by a European team. It is further claimed that the very basal ice is 250,000 years old (Dansgaard et al., 1993), or possibly 2.4 million years, back to the time of the original buildup of the ice sheet (Souchez, 1997). This is obviously much too old for the short Biblical time scale. Is their claim of so many annual layers justified?
I will show that the interpretation of annual layers is good near the top of the ice cores, but becomes increasingly in error the lower down the core. The reason for this is because uniformitarian scientists view the ice sheet as maintaining equilibrium, about the same height and shape, for a few million years. Thus they view each annual layer as becoming greatly compressed the deeper in the ice sheet. The number of annual layers is simply an outgrowth of their extended time scale.
On the other hand, creationists view both the Greenland and Antarctica Ice Sheets as products of a post-Flood rapid Ice Age, plus additional ice added after the Ice Age (Oard, 1990). In this model, annual layers would be very thick in the lower portion of the Greenland Ice Sheet (the Ice Age portion determined by the oxygen isotope ratio) with decreasing annual layer thickness higher up in the ice sheet. Since the Ice Age ended about 4000 years ago, the compression of the ice sheet has been much less than uniformitarian scientists believe, but still substantial (Vardiman, 1993). So, one annual layer deep in the ice sheet may represent 100 or even 1000 uniformitarian ‘annual cycles.’ In this case, the claimed uniformitarian annual cycles represent oscillations that are much less than annual.
Uniformitarian scientists believe the earth is billions of years old. As a result, they believe that many ice ages repeated over the last 2 to 3 million years. Thus, they assume that the Greenland and Antarctica Ice Sheets have existed for many millions of years. Furthermore, they believe these ice sheets have more or less maintained their present height in a state of equilibrium during all this time. They think the amount of snow and ice added each year has been approximately balanced by the ice that is lost by melting and calving of icebergs into the ocean. The weight of the ice causes vertical compression and horizontal flow, since ice is like a plastic (Figure 1). From these assumptions, they have developed flow models of the ice sheets with the annual layers thinning to paper-thin near the bottom (Figure 2).
These assumptions and interpretations result in a vastly different history of the ice sheet than that of a post-Flood rapid ice age model (Oard, 1990). Because of the flow model over millions of years, they have deduced that the bottom of the ice sheet is around 250,000 years or older. Even older ice may exist, they believe, but is presumed to be too small to resolve as the annual layers are paper-thin, and this ice would presumably have mixed with ice of other ‘ages.’
In the creationist model the ice over Greenland and Antarctica builds rapidly for about 500 years during a rapid ice age (Oard, 1990). Then the amount of snowfall tapers off during the next 200 years of deglaciation. The amount of snowfall should generally be proportional to the temperature of the North Atlantic Ocean, the height of the building ice sheet, and the distance from a main storm track. During a 700-year post-Flood Ice Age, the oceans would have gradually cooled and the ice sheet thickened with time. Since the Ice Age ended about 4000 years ago, precipitation from the present climate would continue to build up the ice sheet. This precipitation would be greater immediately after the Ice Age because the ice sheet would have been thinner. During all the time since the Flood, the ice sheet would be compressing vertically and stretching horizontally (Figure 1), but this would be much less than in the uniformitarian model. Annual layers would be quite thick in the Ice Age portion of the Greenland ice cores (approximately the lower half of the 10,000 foot thick GRIP and GISP2 cores), and would decrease in thickness in the upper portion of the ice sheet. The annual layer before compression probably would average around 20 feet of water equivalent per year at this location in Greenland. (Other areas of Greenland would have had a lower accumulation rate based on the Ice Age portion of other Greenland ice cores.) The difference between the annual layer thickness down the GRIP ice core of central Greenland between the uniformitarian model (De Angelis et al., 1997, p. 26,683) and a creationist estimate is given in Figure 3. The creationist estimate of currently preserved annual layers is based on 1) high Ice Age accumulation, 2) a decreasing accumulation after the Ice Age as the ice sheet continued to thicken, and 3) compression caused by the weight of the ice above. Larry Vardiman (1993) has worked out these variables for the Camp Century ice core in northwest Greenland.
From these flow models, uniformitarian scientists estimate the approximate thickness of each annual layer from the top of the ice to near the bottom. At the top, the annual layers start at about 30 inches of compacted snow. This snow will compress to 9.5 inches of ice or .25 metres per year (Meese et al., 1997, p. 26,411). The annual layers show up quite well near the top of the ice core. Uniformitarians and creationists agree that these measurements are annual layers. However, the annual layer thickness after compression in each model, represented in Figure 3, soon diverges significantly, and the agreement soon ends. For example, 2000 meters or 6500 feet down the GISP2 Greenland ice core, the assumed annual layer thickness is about 2 centimeters or one inch in the uniformitarian model (De Angelis et al., 1997, p. 26,683). From Figure 3, the creationist estimate would be around 200 centimeters or 6.5 feet, 100 times the uniformitarian estimate.
The assumed thickness of the annual layers is important because it determines the number of measurements of the variables one makes going down the core sample. Based on the expected annual thickness, uniformitarian scientists take enough measurements to resolve what they believe is each annual cycle. For oxygen isotope oscillations, they normally need eight measurements per annual cycle to pick up the ‘annual’ signature. However, oxygen isotope measurements that were the basis of the annual layers in other Greenland cores were only resolved down to about 300 meters or 1000 feet in the GISP2 core (Meese et al., 1997, p. 26,412). So they have relied on other variables, such as cloudy bands, electrical conductivity, laser-light scattered from dust, major ion chemistry, and volcanic ash bands (Alley et al., 1997; Meese et al., 1997). The expected annual layer down the core also determines what they conclude with these other variables.
This being the case, then how do creationists explain the many more claimed annual oscillations in the particular variables in the uniformitarian model? As each annual layer becomes more compressed, molecular diffusion has the habit of smoothing out the amplitude of the annual layers with depth in the uniformitarian model. Within the creationist model, there has not been time for much diffusion. However, the climate during the Ice Age would have had warmer winters and cooler summers, which would lessen the amplitude of the annual oscillation. So, I would expect lower amplitude annual oscillations in ice core variables during the Ice Age, especially with the oxygen isotope ratio.
Furthermore, the ice sheet during the Ice Age would have been lower and warmer at the time the snow was building. This would have resulted in more melt or hoar frost layers (cloudy bands), which is one of the variables used for annual layer determinations. Therefore the uniformitarian scientists are claiming as annual variations oscillations that occur within the year.
The variables used to determine annual layers can be produced many times during a year in the creationist model. Very short term oscillations representing as little as a day or two show up in the variables (Grootes and Stuiver, 1997). A storm has a warm and cold sector with different measurements of the variables. These storm oscillations may be on the order of several days. These storms can produce problems in annual counting, even in the uniformitarian paradigm, as Alley et al. (1997, p. 26,378) state:
“Fundamentally, in counting any annual marker, we must ask whether it is absolutely unequivocal, or whether nonannual events could mimic or obscure a year. For the visible strata (and, we believe, for any other annual indicator at accumulation rates representative of central Greenland), it is almost certain that variability exists at the subseasonal or storm level, at the annual level, and for various longer periodicities (2-year, sunspot, etc.). We certainly must entertain the possibility of misidentifying the deposit of a large storm or a snow dune as an entire year or missing a weak indication of a summer and thus picking a 2-year interval as 1 year.”
Besides subannual oscillation, other non-precipitation variables such as snow dunes, can add subannual layers.
Adding to the problems of making accurate measurements is the fact that cold or warm weather patterns can run in cycles, anywhere from a week to even a season. These cold or warm spells are typical today at any one place in the mid and high latitudes. These spells would also cause oscillations over periods of a month or longer (Shuman et al., 1995). So, there are any number of possible explanations for oscillations in the variables at smaller scales than the annual cycle. These are what the uniformitarian scientists are measuring as supposed annual cycles the deeper they go in the ice core.
The uniformitarian scientists do not believe these subannual cycles exist because of their assumed great compression of the ice sheet based on their old-Earth time scale. This is how they manage to ‘squeak out’ 110,000 years.
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