Relative dating ice cores
How far into the past can ice-core records go? Scientists have now identified regions in Antarctica they say could store information about Earth's climate and greenhouse gases extending as far back as 1. By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future. Now, an international team of scientists wants to know what happened before that. At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1.
Oldest ice core: Finding a 1.5 million-year record of Earth's climate
It is not uncommon to read that ice cores from the polar regions contain records of climatic change from the distant past. Research teams from the United States, the Soviet Union, Denmark, and France have bored holes over a mile deep into the ice near the poles and removed samples for analysis in their laboratories. Based on flow models, the variation of oxygen isotopes, the concentration of carbon dioxide in trapped air bubbles, the presence of oxygen isotopes, acid concentrations, and particulates, they believe the lowest layers of the ice sheets were laid down over , years ago.
Annual oscillations of such quantities are often evident in the record. Are these records in the ice legitimate? Do they cause a problem for the recent-creation model of earth history? What are we to make of these data? This article will show that the great ages reported for the bottom layers of ice sheets depend on assumed models of past climate and are not the result of direct counting of layers.
An alternative model of recent glacier formation following the Flood described in Genesis will be suggested. The Greenland Society of Atlanta has recently attempted to excavate a foot diameter shaft in the Greenland ice pack to remove two B Flying Fortresses and six P Lightning fighters trapped under an estimated feet of ice for almost 50 years Bloomberg, Aside from the fascination with salvaging several vintage aircraft for parts and movie rights, the fact that these aircraft were buried so deeply in such a short time focuses attention on the time scales used to estimate the chronologies of ice.
If the aircraft were buried under about feet of ice and snow in about 50 years, this means the ice sheet has been accumulating at an average rate of five feet per year. The Greenland ice sheet averages almost feet thick. If we were to assume the ice sheet has been accumulating at this rate since its beginning, it would take less than years for it to form and the recent-creation model might seem to be vindicated.
However, life is never as simple as implied above. In making our calculations, we did not take into account the compaction of the snow into ice as it is weighted down by the snow above. Neither did we consider the thinning of ice layers as the tremendous weight above forces the ice at lower levels to squeeze out horizontally. More importantly, we did not consider the average precipitation rate and actual depths of ice for different locations on the Greenland ice sheet.
When these factors are taken into account, the average annual thickness of ice at Camp Century located near the northern tip of Greenland is believed to vary from about fourteen inches near the surface to less than two inches near the bottom Hammer, et al. If, for simplicity, we assume the average annual thickness to be the mean between the annual thickness at the top and at the bottom about eight inches , this still gives an age of less than years for the foot-thick ice sheet to form under uniformitarian conditions.
Although occasional ambiguities occur, it is relatively easy to count annual layers downward from the surface through considerable depths in the Greenland ice sheet. This is possible because of the large precipitation rates in Greenland and the preservation of the annual effects. It is also possible with a high degree of accuracy to cross check the counting of annual layers with occasional peaks in acidity and particulates from the fallout of historic volcanic events.
Hammer, et al. About a dozen historical volcanic eruptions are evident in the ice core from Crete in central Greenland. Several unknown eruptions are also documented in the ice core record. The confidence in the chronology becomes less the lower in the ice sheet one goes, however. The amplitude of the annual oscillations slowly decreases relative to other factors, and historic markers are fewer and farther apart.
Glaciologists estimate that uncertainties in identification of layers will probably limit the number of countable layers to less than about 8, Hammer, et al. The claims that layers of ice were formed , years ago or more come primarily from interpretation of ice cores in Antarctica Jouzel, et al. The Soviet Antarctic Expeditions at Vostok in East Antarctica recovered an ice core which was almost 7, feet long in a region where the total ice thickness is about 12, feet Lorius, et al.
Since the current precipitation rate is so much less than Greenland on the order of one inch per year the crude calculation of age, without corrections for compression and horizontal motion for the lowest layers is more than , years. However, such estimates are critically based on the assumption that the accumulation rate has not varied greatly over the past. In Greenland, the high precipitation rates not only provide relatively thick annual layers for analysis, but the accumulating snow quickly seals off the ice beneath and protects the record from metamorphosis by pressure and temperature changes in the atmosphere.
In Antarctica, by the time the ice has been buried deeply enough to no longer be influenced by the atmosphere, annual variations have been greatly dampened by diffusion Epstein, et al. Through a second-known relation between temperature and precipitation rate, again observed in today's atmosphere, the accumulation rate for a given layer is calculated Lorius, et al. Once the accumulation rate is calculated for each layer, the depth and age for each layer in the ice is calculated by integrating the annual accumulation downward from the surface.
There are several historical markers in Antarctica which can be used to cross check these calculations for the past few thousand years. But historical volcanic events are not known beyond a few thousand years in the past which provide any certainty to the calculation of age. This method would be reasonably reliable if precipitation rates had been similar in the past.
However, some creationist models predict significant quantities of snow immediately after the Flood Oard, From a creationist perspective, it would be extremely valuable to thoroughly explore these ice-core data. We would not assume that the precipitation rate has always been similar to that of today. We would expect considerably higher precipitation rates immediately following the Flood.
The "annual" layers deep in the Greenland ice sheet may be related to individual storms rather than seasonal accumulations. If these evidences are found, direct information on conditions following the Flood would be available to us. Nothing in the ice-core data from either Greenland or Antarctica requires the earth to be of great age. In fact, there are good reasons to believe that the ice cores are revealing important information about conditions following the Flood of Genesis and the recent formation of thick ice sheets.
Reports of ice-core data containing records of climatic changes as far back as , years in the past are dependent upon interpretations of these data which could be seriously wrong, if the Genesis Flood occurred as described in the Bible. Further research on ice-core data should be a high priority for creationist researchers. Barnola, J. Raynaud, Y. Korotkevich, and C.
Lorius, Bloomberg, R. Epstein, S. Sharp, and A. Gow, Hammer, C. Clausen, W. Dansgaard, N. Gundestrup, S. Johnsen, and N. Reeh, Clausen, and W. Dansgaard, Johnsen, S. Dansgeard, and H. Clausen, Jouzel, J. Merlivat, Jonzel, J. Lorius, J. Petit, C. Genthon, N. Barkov, M. Kotlyakov, and M. Petrov, Lorius, C. Merlivat, J. Jonzel, and M. Pourchet, Jouzel, C. Ritz, L. Merlivat, N.
Barkov, Y. Korotkevich, and V. Kotlyakov, Oard, M. Cite this article: Larry Vardiman, Ph. Ice Cores and the Age of the Earth. Skip to main content. More Ice Age. The Mystery of Wooly Mammoths. Millions of wooly mammoths once lived around the world, particularly in extremely cold places. These elephantine creatures present a major mystery Celebrating a Broken Climate "Pacemaker".
There is strong geological evidence for one ice age.
Although radiometric dating of ice cores has been difficult, Uranium has been used to date the Dome C ice core from Antarctica. Dust is present. Methods for Dating Ice Cores By: Melanie Goral, vacuumfurnacedesign.com Basic Outline • Ice Cores rich ƍ18O and becomes ƍ18O poor – Can compare relative temperatures with.
It is not uncommon to read that ice cores from the polar regions contain records of climatic change from the distant past. Research teams from the United States, the Soviet Union, Denmark, and France have bored holes over a mile deep into the ice near the poles and removed samples for analysis in their laboratories. Based on flow models, the variation of oxygen isotopes, the concentration of carbon dioxide in trapped air bubbles, the presence of oxygen isotopes, acid concentrations, and particulates, they believe the lowest layers of the ice sheets were laid down over , years ago. Annual oscillations of such quantities are often evident in the record.
What is relative dating?
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years.
Australian Antarctic Division: Leading Australia’s Antarctic Program
Why use ice cores? How do ice cores work? Layers in the ice Information from ice cores Further reading References Comments. Current period is at right. From bottom to top: Milankovitch cycles connected to 18O.
Ice consists of water molecules made of atoms that come in versions with slightly different mass, so-called isotopes. Variations in the abundance of the heavy isotopes relative to the most common isotopes can be measured and are found to reflect the temperature variations through the year. The graph below shows how the isotopes correlate with the local temperature over a few years in the early s at the GRIP drill site:. The dashed lines indicate the winter layers and define the annual layers. How far back in time the annual layers can be identified depends on the thickness of the layers, which again depends on the amount of annual snowfall, the accumulation, and how deep the layers have moved into the ice sheet. As the ice layers get older, the isotopes slowly move around and gradually weaken the annual signal. Read more about - diffusion of stable isotopes - how the DYE-3 ice core has been dated using stable isotope data - how stable isotope measurements are performed - stable isotopes as indicators of past temperatures - how annual layers are identified using impurity data. Move the mouse over individual words to see a short explanation of the word or click on the word to go to the relevant page.
A variety of methods are used to date an ice core.
I was wondering how ice cores are dated accurately. I know Carbon 14 is one method, but some ice cores go back hundreds of thousands of years. Would other isotopes with longer half-lives be more accurate?
Ice Cores and the Age of the Earth
Ice core basics
.Studying ice cores in Antarctica - Natural History Museum