A variety of methods are used to date an ice core. The most direct method is to count annual layers in much the same way that tree-rings can be counted to determine the age of the tree. However, the layers in ice cores are not generally visible in the ice. They only become apparent when the core is analysed for a chemical signal that varies with the seasons, which most signals do, to some extent. In fact the clearest dating is obtained when several seasonal signals are examined and compared. Many cores however come from regions where the yearly snowfall accumulation is too small for the annual layers to be distinguished, and other methods of dating must be used.
Also, how much does it cost to date the core? How are samples acquired without destroying the ice? I imagine keeping the ice intact as much as possible would be extremely valuable.
Some of the answers to these questions are available on the Ice Core Basics page. Ice cores can be dated using counting of annual layers in their uppermost layers.
Dating the ice becomes harder with depth. Usually multiple methods are used to improve accuracy. Common global stratigraphic markers are palaeo-events that occur worldwide synchronously, and can allow wiggle-matching between ice cores and other palaeo archives e. For the ice matrix, these global stratigraphic markers can include spikes in volcanic ash each volcanic eruption has a unique chemical signatureor volcanic sulfate spikes. For the gas phase, methane, and oxygen isotopic ratio of O 2 have been used Lemieux-Dudon et al.
Uranium has been used to date the Dome C ice core from Antarctica. Dust is present in ice cores, and it contains Uranium. At lower temperatures, the difference is more pronounced. If the site has experienced significant melting in the past, the borehole will no longer preserve an accurate temperature record. Hydrogen ratios can also be used to calculate a temperature history. Deuterium 2 Hor D is heavier than hydrogen 1 H and makes water more likely to condense and less likely to evaporate.
It was once thought that this meant it was unnecessary to measure both ratios in a given core, but in Merlivat and Jouzel showed that the deuterium excess reflects the temperature, relative humidity, and wind speed of the ocean where the moisture originated. Since then it has been customary to measure both.
Water isotope records, analyzed in cores from Camp Century and Dye 3 in Greenland, were instrumental in the discovery of Dansgaard-Oeschger events -rapid warming at the onset of an interglacialfollowed by slower cooling. Combining this information with records of carbon dioxide levels, also obtained from ice cores, provides information about the mechanisms behind changes in CO 2 over time.
It was understood in the s that analyzing the air trapped in ice cores would provide useful information on the paleoatmospherebut it was not until the late s that a reliable extraction method was developed. Further research has demonstrated a reliable correlation between CO 2 levels and the temperature calculated from ice isotope data. Because CH 4 methane is produced in lakes and wetlandsthe amount in the atmosphere is correlated with the strength of monsoonswhich are in turn correlated with the strength of low-latitude summer insolation.
Since insolation depends on orbital cyclesfor which a timescale is available from other sources, CH 4 can be used to determine the relationship between core depth and age.
This means that the trapped air retains, in the ratio of O 2 to N 2a record of the summer insolation, and hence combining this data with orbital cycle data establishes an ice core dating scheme. Diffusion within the firn layer causes other changes that can be measured. Gravity causes heavier molecules to be enriched at the bottom of a gas column, with the amount of enrichment depending on the difference in mass between the molecules.
Colder temperatures cause heavier molecules to be more enriched at the bottom of a column.
Dating ice core methods
Greenland cores, during times of climatic transition, may show excess CO2 in air bubbles when analysed, due to CO2 production by acidic and alkaline impurities . Summer snow in Greenland contains some sea salt, blown from the surrounding waters; there is less of it in winter, when much of the sea surface is covered by pack ice. Similarly, hydrogen peroxide appears only in summer snow because its production in the atmosphere requires sunlight.
These seasonal changes can be detected because they lead to changes in the electrical conductivity of the ice.
Biblical Dating #4 Ice Core Dating
Placing two electrodes with a high voltage between them on the surface of the ice core gives a measurement of the conductivity at that point. Dragging them down the length of the core, and recording the conductivity at each point, gives a graph that shows an annual periodicity. Such graphs also identify chemical changes caused by non-seasonal events such as forest fires and major volcanic eruptions. When a known volcanic event, such as the eruption of Laki in Iceland incan be identified in the ice core record, it provides a cross-check on the age determined by layer counting.
If the date of the eruption is not known, but it can be identified in multiple cores, then dating the ice can in turn give a date for the eruption, which can then be used as a reference layer. Many other elements and molecules have been detected in ice cores.
Both hydrogen peroxide H 2 O 2 and formaldehyde HCHO have been studied, along with organic molecules such as carbon black that are linked to vegetation emissions and forest fires. Some of the deposited chemical species may interact with the ice, so what is detected in an ice core is not necessarily what was originally deposited. Another complication is that in areas with low accumulation rates, deposition from fog can increase the concentration in the snow, sometimes to the point where the atmospheric concentration could be overestimated by a factor of two.
Galactic cosmic rays produce 10 Be in the atmosphere at a rate that depends on the solar magnetic field. The strength of the field is related to the intensity of solar radiationso the level of 10 Be in the atmosphere is a proxy for climate. Accelerator mass spectrometry can detect the low levels of 10 Be in ice cores, about 10, atoms in a gram of ice, and these can be used to provide long-term records of solar activity.
Meteorites and micrometeorites that land on polar ice are sometimes concentrated by local environmental processes. For example, there are places in Antarctica where winds evaporate surface ice, concentrating the solids that are left behind, including meteorites.
Meltwater ponds can also contain meteorites. At the South Pole Stationice in a well is melted to provide a water supply, leaving micrometeorites behind.
These have been collected by a robotic "vacuum cleaner" and examined, leading to improved estimates of their flux and mass distribution. The well becomes about 10 m deeper each year, so micrometeorites collected in a given year are about years older than those from the previous year.
It provides information on changes in vegetation. In addition to the impurities in a core and the isotopic composition of the water, the physical properties of the ice are examined. Features such as crystal size and axis orientation can reveal the history of ice flow patterns in the ice sheet. The crystal size can also be used to determine dates, though only in shallow cores.
In an Louis Agassiz drilled holes in the Unteraargletscher in the Alps ; these were drilled with iron rods and did not produce cores. The first scientist to create a snow sampling tool was James E. Churchdescribed by Pavel Talalay as "the father of modern snow surveying". They are simply pushed into the snow and rotated by hand.
Ice Core Drilling Projects
The first systematic study of snow and firn layers was by Ernst Sorge, who was part of the Alfred Wegener Expedition to central Greenland in - Core quality was poor, but some scientific work was done on the retrieved ice. The International Geophysical Year - saw increased glaciology research around the world, with one of the high priority research targets being deep cores in polar regions. SIPRE conducted pilot drilling trials in to m and to m at Site 2 in Greenland; the second core, with the benefit of the previous year's drilling experience, was retrieved in much better condition, with fewer gaps.
Soviet ice drilling projects began in the s, in Franz Josef Lan the UralsNovaya Zemlyaand at Mirny and Vostok in the Antarctic; not all these early holes retrieved cores. The Dome C core had very low accumulation rates, which mean that the climate record extended a long way; by the end of the project the usable data extended toyears ago.
Incores were retrieved from the Allan Hills in Antarctica in an area where old ice lay near the surface.
The cores were dated by potassium-argon dating; traditional ice core dating is not possible as not all layers were present.
The oldest core was found to include ice from 2. Inscientific discussions began which resulted in the Greenland Ice Sheet Project GISPa multinational investigation into the Greenland ice sheet that lasted until A location in north-central Greenland was selected as ideal, but financial constraints forced the group to drill at Dye 3 instead, beginning in The hole did not reach bedrock, but terminated at a subglacial river.
The core provided climatic data back toyears ago, which covered part of the last interglacial period. Ice cores have been drilled at locations away from the poles, notably in the Himalayas and the Andes.
IPICS International Partnerships in Ice Core Sciences has produced a series of white papers outlining future challenges and scientific goals for the ice core science community. These include plans to:.
From Wikipedia, the free encyclopedia. Cylindrical sample drilled from an ice sheet. See also: Ice-sheet dynamics. See also: Ice drilling. Sliver of Antarctic ice showing trapped bubbles.
See also: History of scientific ice drilling. Paleoclimatology: Reconstructing Climates of the Quaternary. Amsterdam: Academic Press. Cheltenham, UK: Stanley Thornes. In Blais, Jules M.
Dordrecht, Netherlands: Springer. Retrieved 3 June Annals of Glaciology. East Greenland Ice Core Project.
Retrieved 17 June Archived from the original on 28 June The New Yorker. National Ice Core Laboratory. Archived from the original on 4 May Retrieved 21 May Eos Trans AGU. Memoirs of National Institute of Polar Research 49 : Archived from the original on 14 July Climate of the Past.
The Cryosphere. ScienceX network. Retrieved 29 May Encyclopedia of Quaternary Science.
Aug 01, Show that ice core dating methods are not independent and open to significant reinterpretation. The root of the problem is the uncritical acceptance of the uniformitarian paradigm. Paul H. Seely has written a rebuttal to creationist's ice sheet and ice core interpretations in the December Perspectives on Science and Christian Faith, a Author: Michael J. Oard. To demonstrate the methods used in dating ice-cores I will use the Vostok ice-core as an example because I found plenty of literature on it and because it is an Antarctic ice-core which was what the original post was about. How It Was Collected The Vostok Ice-Core was collected in East Antarctica by the Russian Antarctic expedition. These all have independent methods of dating, and so the timing of a major climate shift or volcanic eruption can be used to synchronise the age scales. Most Australian ice core research has been conducted at Law Dome, a small icecap some km in diameter on .
Amsterdam: Elsevier. EGU General Assembly Vienna, Austria. Retrieved 5 September Journal of Quaternary Science. Archived from the original on 13 February Quaternary Science Reviews. Global and Planetary Climate Change. It seems to me that this would produce the same things we see in the ice cores that are now attributed to a long series of unchanging seasons.
Now, guys, I have spent a lot of time working on posts discussing evolutionism seriously in the past, especially in regards to mutations, etc. Agree or disagree, you have to admit the time on my part! So I am asking for time now from you. Not mocking, not throwing stuff up in the air and laughing about it - but the time to think some of this through. Yes, I will try to find out more as we go and different things are brought up, if they are, but for now, at first, why wouldn't this be an acceptable model to work with theoretically?
I have reproduced the article here so that I can respond to it in context. First of all, thank you for the link to it. Before I begin, I want to mention that the dating and the article are done with the presupposition of both long ages and not only uniformitarianism but gradualism. Understanding that I do not accept these presuppositions and will be looking at the evidence presented from the standpoint of recent creation and catastrophic interruptions in history, I will approach the article from a "devil's advocate" point of view as far as evolutionists are concerned.
The quoted article is in italics. Antarctica is the coldest, windiest, highest and driest continent on Earth. That's right - the driest! Antarctica is a desert. The annual precipitation of snow, averaged across the continent, is about 30 centimetres, which is equivalent to about 10 centimetres of water.
Ice Core Dating
In some locations as little as 2 centimetres water equivalent is recorded. For those confused by metrics, 10cm is a little less than 4 inches. Because of the low temperatures, however, there is little or no melt.
Thus the snow has accumulated year after year for thousands of years and, with time, is compressed to ice to form the Antarctic ice sheet. Approximately 98 per cent of the Antarctic continent is covered by the ice sheet which is on average about 2, metres thick and, at it's deepest location, 4, metres thick. It is due to this thick ice mass that Antarctica is, on average, the highest continent. Since the ice sheet is formed by the accumulation of snow year after year, by drilling from the surface down through the ice sheet, we drill our way back in time.
Ice drills are designed to collect a core as they cut through the ice, so samples are collected that are made up of ice deposited in the form of snow many thousands of years ago. As the snow is deposited on top of the ice sheet each year, it traps different chemicals and impurities which are dissolved in the ice.
The ice and impurities hold information about the Earth's environment and climate at the time of deposition. A variety of different analyses techniques are used to extract that information.
One measurement, the oxygen isotope ratio or delta value, measured using a mass spectrometer on melted samples of the ice, gives us an indication of the temperature at the time the ice was deposited as snow. Measuring the delta value at many depths through the ice core is equivalent to measuring the air temperature at many times in the past. Thus, a climatic history is developed. Climatic temperature against time from delta measurements taken on the ice core drilled at the Russian station, Vostok, in central Antarctica Figure 2.
Available data from this ice core so far extends back aboutyears. However, drilling of the core still continues, and it is expected that, when drilling is completed in a few years time, an age ofyears will have been reached. This was an ice age period. These short warmer periods are called inter-glacials. We are in an inter-glacial now. Fromto about 20, years ago, there was a long period of cooling temperatures, but with some ups and downs of a degree or two.
From about 18, or 19, years ago to about 15, years ago, the climate went through another warming period to the next inter-glacial, - the one we are now in.
Ice core dating using stable isotope data 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. saporiviafrancigena.com is a platform for academics to share research papers.
What is being seen here is two possible ice ages, the first one being somewhat less and perhaps shorter than the second. Removing the time element, which is gradualistic and uniformitarian, what might just as easily be seen is the ice age that is postulated as arising out of the Flood catastrophe, with a warmer period for several hundred years, and then the massive volcanic activity thought to be present at the time of Peleg, which would have resulted in a much more severe ice age.
During the formation of both ice ages, the storms would have had to be constant, one on top of another with very little time in between, and very fierce. This would also account for what is seen in the ice cores. Figure 2 also includes a graph of the concentration of dust in the ice core. High concentrations of dust occur at the same times as the colder periods shown on the temperature graph. There are several possible reasons for this: the air is drier during colder periods, thus, there may have been more deserts; the ice sheets were more extensive and sea levels lower, thus there would have been more exposed, dry land; there may also have been more storms, or at least more violent storms.
All of these factors would increase the amount of dust lifted into the atmosphere to then be blown over Antarctica and deposited with the snow on the surface of the ice sheet. Colder periods are normally times of less precipitation, as cold air is dry. The writer here is postulating more deserts by presuming a worldwide cold and dry climate. I think he may be presuming too much. A warmer world in the tropic and temperate zones, particularly where the oceans are concerned a few degrees warmer temperature in the oceans would vastly increase the rate of evaporationwould provide the precipitation for the massive snowfalls required for the laying down of not only the polar caps but for the advent of the ice age s as well.
One thing I noticed here is that the author also mentions more land being exposed during the ice age sand when I mentioned that, I was ridiculed on this forum. One thing that is not mentioned in this article is the composition of the dust. Does it show high or low amounts of volcanic material? And at which levels? I would be curious to know this.
Figure 2. Dust concentration, climatic air temperature as inferred from del measurementsand concentration of carbon dioxide and methane from measurements of trapped air are plotted against time before present. After Lorius et al. The snow near the surface of the ice sheet is like a sponge with channels of air between the snow grains.
As more and more snow is accumulated on top, the underlying snow is compressed into ice and the air forms bubbles in the ice. Ice cores therefore can be analysed not just for the chemical and physical properties of the ice, but also for the properties of the air trapped in the ice. These bubbles are actual samples of the atmosphere up to thousands of years ago. So, analysis of them can tell us much about the atmosphere in the past.
Concentrations of carbon dioxide and methane measured in the air bubbles trapped in the ice are shown in Figure 2 along with temperature and dust graphs. Carbon dioxide and methane are greenhouse gases and the similarity between the graphs for their concentrations and the temperature change graph indicates that the greenhouse effect is real and that it has been around for many thousands of years.
That is only if you are presuming many thousands of years. I studied that chart for some time. What I saw corresponds to the idea that a post flood ice age would have less dust due to winds because everything was wet. But then you have that period in between ice ages where you see a rise in carbon dioxide as the plant life on earth was re-established and thrived.
This corresponds with the rapid rise in temperature which melted the ice. Now, keep in mind that we are ONLY talking about the one pole here - the south one. These measurements do NOT tell us what the rest of the world was like at the time. As we move to the left in graph two, or toward the present, there is a sudden rise in the dust factor.
This would easily result from volcanism and the changes in relative air temperatures, and even changes in relative areas of sea temperatures, around the world.
The would cause the massive winds that seek to equalize the temperatures. More dust at a time of increasing cold and the rapid onset of a much worse ice age. Then, to the far left of the graph, a rapid rise in temperature again as the dust settles down and the temperatures and thus the pressures have also settled.
The earth warms again and the ices melt, leaving what is left on the poles. You see, if one does not presume long ages, many rapid storms in a time of fluctuating temperatures and world upheaval can account for what we see in that graph.
Aug 27, More discussion of this age model for the Chatham Rise core follows. Dating of Ice Cores. Despite the apparent circular reasoning in these dating methods, one might object that timescales for the Greenland and Antarctic deep ice cores agree with expectations of the astronomical theory, thus validating these old-earth saporiviafrancigena.com: Dr. Jake Hebert. Ice Core Dating. By sampling at very fine intervals down the ice core, and provided that each annual layer of snow is thick enough, several samples from each year may be measured for the different chemical properties. It has already been seen that the delta value is related to . Other ways of dating ice cores include geochemisty, wiggle matching of ice core records to insolation time series (Lemieux-Dudon et al. ), layers of volcanic ash (tephra) (Vinther et al., ), electrical conductivity, and using numerical flow models to understand age-depth relationships (Mulvaney et al., ), combined with firn.
Has there been a significant increase in the atmospheric concentration of greenhouse gases since the industrial revolution?
The answer is yes, as can be seen from Figure 3 which shows the concentrations of carbon dioxide in the atmosphere, measured in the bubbles from an Antarctic ice core from Law Dome near Australia's Casey Station. The concentration of carbon dioxide has increased from about parts per million to parts per million, which is a rise of 25 per cent since the middle of last century.
Nitrous oxide and other greenhouse gases also show similar trends from analysis of the ice-core bubbles.