A New Radiocarbon Yardstick from Japan |
[Via KQED QUEST ]
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.
A yearly layer of sediments that go back over 40,000 years, calibrated by radiocarbon dating and tree rings at the recent end, and by uranium-thorium measurements in caves at the older end.
From the paper’s conclusions:
Together, these [the radiocarbon determinations ] give us a single, quasi-continuous record of purely atmospheric 14C° covering the full range of the radiocarbon technique. This will greatly benefit calibration of terrestrial radiocarbon samples in the period 12.5 to 52.8 kyr B.P. and will enable direct correlation between other key climate records and the Lake Suigetsu record itself, without any assumptions of climatic synchrony. An atmospheric record of 14C° over this whole time scale also facilitates a more comprehensive understanding of the long marine records in their oceanic context, rather than simply assuming that they represent atmospheric 14C°.
One of the errors from radiocarbon dating is that the input values of 14C – the radioactive isotope of carbon that only gets incorporated into living tissue – can vary somewhat by environmental factors, such as volcanic activity. By doing radiocarbon dating organic matter from yearly varves in the lake, they can get exact 14C/12C ratios by year, calibrating values with a precision unheard of until now.
Here is what the varves look like.
So now, this one record is tied at both ends into well defined geological systems allowing us to use not only radioactive dating approaches but also ones based on more ecological systems – tree rings, lake sediment and cavestone formations. All three are also based on information from continental sources not from the ocean, which can have very different conditions.
By now having a calibration tool for all these, we can much more easily tie specific recent geological event, ecosystems and animals to a specific time, using non-radioactive approaches. Records from otehr lakes can be much more easily placed on this timeline, not only enhancing it but also providing insight into local conditions. Comparisons with ice cores from Greenland or Antarctica will also be important.
So, now that we have a pretty much yearly record of geological events back more than 60,000 years, calibrated to multiple independent timelines. How will Young Earth creationists continue to make their inane arguments?
I figure they will just ignore the data. That is the main technique they use. That way they do not have to deal with the fact that these data are either true or their version of God is a liar who purposely planted this data simply to fool us.