The Science of Sustainability

A New Radiocarbon Yardstick from Japan

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Pristine leaf fossils from Lake Suigetsu allowed radiocarbon dates to be calibrated against absolute dates from annual sediment layers. Photo courtesy Richard Staff

Every historian knows about the Rosetta Stone, which had an ancient Egyptian text carved on it in three different scripts, two of which had long resisted translation. The ability to cross-correlate the scripts—to calibrate their alphabets—opened up a huge body of knowledge to scholars. Climate researchers, as well as archaeologists and geologists, look for similar natural records that allow us to calibrate different yardsticks of time. A paper published today in the journal Science unveils a superb "document" of conditions during the last 53,000 years in a single place: Japan's remarkable Lake Suigetsu.

In 2006, researchers drilled into the mud at the center of Lake Suigetsu and carefully extracted four long cores of sediment. They found that the top part of this sedimentary record consisted of thin annual layers—varves—representing about 60,000 years of time. Varves are close to the ideal time record, but the conditions that favor them are rare. And this record also contained abundant plant remains, allowing three different timekeeping "scripts" to be calibrated against each other: varves, tree rings, and radiocarbon. The first two are considered the most nearly perfect measure of absolute time, but radiocarbon is a much more important yardstick, although the stick is not quite straight.

Radiocarbon, or carbon-14, is a wonderful tool for determining the age of recent organic remains—"recent" to a geologist, that is, meaning the last few tens of thousands of years. Radiocarbon is an unstable isotope of carbon that is formed by cosmic radiation at the edge of space and rains down upon us constantly, becoming incorporated in every living thing. The minute a living thing dies, it stops replenishing its radiocarbon and the radiocarbon slowly fades away with a half-life of 5730 years. Radiocarbon dating, then, is simple in principle: you sort out the carbon atoms and see how many carbon-14 atoms there are among the common carbon-12 atoms. The carbon in living matter contains about one part per trillion carbon-14, and after eight ten half-lives there would be 1/1024th of it left, or one part in a quadrillion. With the errors and uncertainties of measurements at this level, one or two more half-lives is as far as physics can take us.

Radiocarbon is complicated by factors on Earth and in heaven. Its formation in the upper atmosphere changes with the balance in cosmic radiation from the sun and from the galaxy at large. Also, global warming and cooling puts different amounts of air at the altitude where radiocarbon is made. So radiocarbon production is not constant. And on Earth, radiocarbon circulates differently in the air, on land and in the ocean.

The record in Lake Suigetsu is so promising because of the varves and the perfectly preserved fossil leaves. The varves march nicely right through the whole time span of radiocarbon, and the fossils can then give us a really accurate description of the bends and warps in the radiocarbon yardstick.

The researchers used tree rings as the gold standard; their record here extends back to about 12,000 years ago. Tree rings were carefully matched against the varves, enabling the count to continue further into the Pleistocene based on varves alone. But Lake Suigetsu was not perfectly still all that time. The record of varves was interrupted by landslides from shore (perhaps caused by earthquakes), volcanic ash beds, and occasional fadeouts where no layers were visible. As a result even the varve record was about 6 percent uncertain by 40,000 years ago.

At this point the researchers brought in a more accurate yardstick: cavestone formations from China and the Bahamas, which were securely dated by both the radiocarbon and the uranium-thorium methods. This step pinned the Lake Suigetsu record to the very long uranium record, in principle knitting the varve record into the entire tapestry of geochronology.

The value of the oldest part of the Lake Suigetsu record is in establishing a radiocarbon yardstick for the continents during this time. Until now, most radiocarbon dates of that vintage have been from deep-sea organisms. So for ice age climate researchers, Suigetsu is their newest Rosetta stone.

California's Clear Lake is also a very old lake, and this year researchers took new sediment cores there. Today's Science paper will surely give them clearer sight into Clear Lake's deep past.

Additional Info:

Suigetsu Varves 2006
Radiocarbon Web-Info

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Category: Blog, Geology

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Andrew Alden

About the Author ()

Andrew Alden earned his geology degree at the University of New Hampshire and moved back to the Bay Area to work at the U.S. Geological Survey for six years. He has written on geology for About.com since its founding in 1997. In 2007, he started the Oakland Geology blog, which won recognition as "Best of the East Bay" from the East Bay Express in 2010. In writing about geology in the Bay Area and surroundings, he hopes to share some of the useful and pleasurable insights that geologists give us—not just facts about the deep past, but an attitude that might be called the deep present. Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.
  • highlander1715

    I think I will forward this article to Congressman Paul Broun (R-Ga.) because he thinks,
    "You see, there are a lot of scientific data that I've found out as a scientist that actually show that this is really a young Earth. I don't believe that the earth's but about 9,000 years old. I believe it was created in six days as we know them. That's what the Bible says."

    • http://www.facebook.com/elp.tique Elp Tique

      Interestingly, that is not what the Bible says… that is what Congressman Broun says. Same exact scenario that took place with Galileo. The Church said the universe was earth centric while Galileo proved them wrong. However, the Church's belief was not Biblical at all (no mention in the Bible about centricity of anything), rather it was Aristotelian.

      • Mauricio Chiessi

        Accuracy is needed here. It was the Catholic Church that said the earth-solar system was earth centric and not the church. And the church is not the Catholic Church. Secondly, the Bible does agree with Galileo because it strongly says that Christ is the center of the universe and is likened to the sun in many verses. Also the natural man is earthly. And we revolve around Christ! Not Christ around us.

        • Dizchord

          You are all idiots. It was Copernicus who first posed the idea of Heliocentrism, Galileo simply supported his ideas.

        • Stretcher Bearer

          "The Church" was Indeed what we call the Catholic Church, catholic by definition is "universal' a More accurate statement would be the Holy Roman Church. And No there was no Competing "western" Churches at this time excepting maybe Zoroastrian, Coptic Christianity, And The Semi-western Byzantine Church.. And This was Platonic Theory…
          The Concept of an Infinite, Old Earth and universe does not conflict in anyway with Christian Doctrine, in my opinion. I've always believed that evolution works under the "Creation Theory" If we look at the symbolic and archetypal aspects of Adam and eve, think of it as when man's Mind finally evolved and awoke to something other than a base instinctual survival mode and there i think you find that history begins. And in effect saying that the earth is only 900 years old, is slightly dismissive of the fact that a complex civilization had been in place and built pyramids before the Egyptians, Namely The Nubians at about 15,000-to 10,000 B.C…..We always want to forget about the fact that Egypt Jacked some of it's beliefs and Pyramid building from the already established Nubians, and this is only Occidental history…

    • http://squeakysoapbox.com/ Rich Wilson

      More alarming is when people like Sen. James Inhofe says we don't need to worry about climate change because God promised us he's never flood the planet again. And rainbows, so, everything's ok. We can keep burning oil and coal as much as we want.

    • Prestorjohn

      Even a primitive hunter gatherer reading the first chapter of Genesis would be able to conclude that the days mentioned therein are not our 24 hour days. The first day was for creating light, but the sun, moon and stars are not created until the fourth day. The 24 hour day that we and the most primitive man knew is based on the time distance from sunrise to sunrise or noon to noon, sunset to sunset, etc. take your pick, "Day" does not have meaning as a unit of time without the sun. So stop with this nonsense adding something into the Bible that it clearly is not saying. The sun was not created till the fourth day.
      More people read their own issues into the Bible than just reading it for what is actually saying.

      • Unsooper

        A couple of things: George Lemaitre was a Belgian priest and physicist who is credited by many with originating the Big Bang theory. You might reconsider knee jerk dismissal of religion and the Christian church–it is as human as you are. Also there is a lot of evidence that a few billion years ago the Earth day was anywhere from 2.5 to 5 hours long. Things change. Try to remember that as you do.

      • throughthedust

        I agree that the creation day does not have to be literal.
        The fact is that the, ( Scriptures, in stating, “In the beginning God created the heavens and the earth” (Ge 1:1), leave matters indefinite as to time. This use of the term “beginning” is therefore unassailable, regardless of the age scientists may seek to attach to the earthly globe and to the various planets and other heavenly bodies. The actual time of creation of the material heavens and earth may have been billions of years ago.) (not mine)
        Psalm 90:4 KJVFor a thousand years in thy sight are but as yesterday when it is past , and as a watch in the night.

      • Jason

        You are correct in the fact that the sun, moon, & stars were created on the fourth day. However, a "day" is not always associated with the sun, moon, or stars. It is the time it takes the earth to rotate on its axis. The sun, moon, and stars were to mark signs and seasons and days and years..To try to "read into" the meaning more than a literal day is out of context. The same word "day" is used for the fifth and sixth day after the fourth. Why should it be any different? ….To allow for geologic ages of millions of years or some life before the creation of Adam? That would not follow sound doctrine because there was NO death before the fall of Adam.

  • http://twitter.com/mself2 Matthew Self

    "after eight half-lives there would be 1/1024th of it left". Shouldn't that be 1/256th left?

  • Greg

    "The carbon in living matter contains about one part per trillion carbon-14, and after eight half-lives there would be 1/1024th of it left, or one part in a quadrillion."

    I believe it would take ten half lives before there was 1/1024th of it left.

    • Andrew Alden

      Thanks! I must have missed a finger while I was counting half-lives!

  • REMAN

    Amazing and wonderful that science continues to prove itself worthy and makes Congressman Paul Broun (R-Ga.) and all the other baaa sheep look stupid. Hey Paul, maybe you should give up TV, cell phones, cars, planes, Doctors, etc because they were not part of the "bible" and let your "faith" save you from life. Get a life sheep! America is GREAT because of science and not its fake / pretense of religion.

    • tompsul

      Whew. Thanks, I would hate to give up my dentures.

  • muzzle flash

    radiocarbon dating makes the assumtion that the source of the energy that causes the formation of the carbon 14 isotope has always been constant for tens of thousands of years.
    Where is the data that indicated this is in fact true? Fluctuations in the source energy over centuries needs to be accounted for otherwise the calculations would indicate time variations that do not exist.

    • Jim

      How stupid of the scientists not to think about that! Especially when Bible says:

      And lo! I shall play with the cosmic ray flux of the earth's atmosphere to deceive the stupid scientists!
      Psalm 97:62

      (Really, "Muzzle flash"? Why perpetuate the fundamentalist redneck stereotype?)

    • number9

      Did you actually read the article?
      "The varves march nicely right through the whole time span of radiocarbon, and the fossils can then give us a really accurate description of the bends and warps in the radiocarbon yardstick."

    • pinutos

      muzzle flash, are you sure you read the same article that I did? Since the entire thing was about how they can use the info from the lake to determine the fluctuation in carbon-14 production?

      • muzzle flash

        This article and many others go to great length to explain the dispersion of carbon 14 and the linear degredation of the trace element in the once living samples. This is useful to arrange some samples in chronological order with regard to when they may have been alive. My statement addresses only the huge leap of faith required to state with certainty that the source energy has been level for eons. Without this information you are making precision calculations begining with radom data

        • pinuto

          yet, by correlating firm chronology (the layers in the lake) to carbon-14 content in the leaves at each layer they're accounting for the effect of all energy sources that affect carbon-14 creation. No leap of faith at all – pure measurement. Counting.

          • muzzle flash

            We only have the energy reading for the present. What does the graph of one data point look like?

          • tompsul

            muzzle flash, if you keep second-guessing these erudite scientists, I'm gonna slide back into Bible reading and thumpin. Wait. I was never there. Never mind.

          • pinutos

            @9435d380a14e281cf209de797115d0f8:disqus we already have the energy levels in the past as measured by the changing ratios of carbon-12 and carbon-14 in the material in the lake. We have the material with those varying ratios embedded in layers laid down on the lake bed, year by year, which allows us to determine, year by year, the energy levels.

          • pinutos

            @9435d380a14e281cf209de797115d0f8:disqus we already have the energy levels in the past as measured by the changing ratios of carbon-12 and carbon-14 in the material in the lake. We have the material with those varying ratios embedded in layers laid down on the lake bed, year by year, which allows us to determine, year by year, the energy levels.

    • brown noser

      That is what this article is about. A way to calibrate those types of variances.

      • muzzle flash

        "Radiocarbon is an unstable isotope of carbon that is formed by cosmic radiation at the edge of space and rains down upon us constantly" quote from the article.
        Just saying How do we know this is true? If you accept this assumption it all fits together. Why am I assumed to be a wing nut for asking how do we know this ?

        • Andrew Alden

          Put it this way, if you prefer: the universe, in particular the part about carbon-14 generation, acts precisely as if it were true.

  • highlander1715

    I printed out the article and faxed it to Congressman Broun's Washington office at 202-226-0776 with the suggestion that he resign from the Sub-Committee on Investigations and Oversight of the Committee on Science, Space and Technology on which he serves.
    How can he serve on any committee with the word Investigation in the title if his mind is so absolutely closed to most modern scientific thinking. He is an embarrassment to his State, Party and Country.

  • Rational Thought

    Well in my "day", people used to think before they spoke. Oh wait ….which "day" was that? That one 24 hour period 50 years ago? A day does not have to mean 24 hours. It can mean a period of time.

  • http://www.facebook.com/jswhitford John S. Whitford

    "Radiocarbon is complicated by factors on Earth and in heaven." What role does this imaginary 'heaven' play?

    • keithdsny

      Heaven, or heavens, is from what I can tell, referring to anything extra-terrestrial or extra-atmospheric. In plane English, space, sun(solar flares and CME's), asteroids, or the thousands of tons of space dust that enter our atmosphere and land on the ground/sea every year.

  • veritasspiritus

    These R pols know better but it pays the bills to keep "ministering" to their base, ignorant white southerners. I was 36 years old when I met a person who did not believe in evolution. It was quite a moment for me. This intellectually impoverished well meaning wretch actually professed to believe God had "aged" fossils to fool the unfaithful! Now when you have that depth of intransigence, reason has no place at the table.

    FYI

  • anderson

    I read the comment section hoping to find some meaningful discussion.. and all I read was semi rants by egocentric atheist/christians/politicos and worse… this is science, it is not the goal of science to prove disprove religiouse or antireligous beliefs… the goal of science is to find the most accurate explanation, measurement, equation, available with the information that is known…and it should not apologize for any collateral damage done to someones personal belief system….

  • ratpuke

    the bible was written by men drunk on wine and high on mushrooms so take it from threre

    • tompsul

      Wine and mushrooms? Keep going, but leave out the Bible.

  • AlwaysRight

    The bible (and other texts) is not real you knuckleheads. In 200 years the people of the earth are going to LAUGH at how stupid you people are. Just like we laugh at natives who use to worship trees. You will be a sad joke in the pages of history since you WASTED your life worshiping something that is fake.

    • tompsul

      Perhaps if we still worshiped trees, the Environment would be pristine? – lol