What is C-14 dating and how is it data?

No, Carbon-14 dating is not another way to meet your true love, unless you are looking to date a fossil. I have dated some fossils in my life, but that story is for a different blog.  Seriously, C-14 dating is a technique used to determine the age of an artifact, which could be a pot sherd, a bone, wood, cloth and even plants.  It is used a lot in archaeological and anthropological research and as such C-14 measurements can be recorded and kept as data.

 Ok, what is C-14?

What happens is very interesting.  See: http://science.howstuffworks.com/environmental/earth/geology/carbon-141.htm Actually, it sounds like it is more of a demolition derby to me.  First, the sun sends out cosmic rays which sounds very science fiction to me, but it happens all the time; in fact I read that every person gets hit by about half a million cosmic rays every hour. No wonder I feel beat all the time!  These cosmic rays not only hit people, they hit atoms which creates new cosmic rays called atomic neutrons. These atomic neutrons also begin bombarding everything in their way including banging into nitrogen atoms. This creates carbon-14 and carbon-12 atoms.  Personally, I think the cosmic rays, neutrons and atoms need a time out for all this colliding and hitting.

Anyway, the key thing is that all this anti-social behavior results in the C-14 atoms being radioactive, and as well all know, there is a half-life to anything radioactive.  In this case, it turns out that C-14 has a half-life of 5700 years.  But we are not finished yet.  When carbon-14 interacts with oxygen on planet earth, it turns into carbon dioxide, which the plants soak up and then we humans and our animal friends eat.  Yes, even if you are a vegetarian you are getting carbon dioxide! And you are getting a certain amount of radioactive C-14 and some C-12, and apparently the amount we have in our system is pretty much constant. Until we die.

Once we die the amount of C-14 in our bodies starts to lessen, but the C-12 amount stays the same. Scientists have been measuring the carbon in plants, animals and organic things so they know about how much is present in for example, a living tree.  And using some fancy equations which I will not go into here, it is possible to measure how much C-14 is left in a biological or geological artifact as compared to how much C-12 is present.  Scientists can do this for things that are up to 60,000 years old.  Isn't that cool! This technique was discovered by a guy named Willard Libby in 1949.

OK, so how does this turn into a data file?

So, the data that is gathered in C-14 dating is the number of years or age of an artifact.  It can be recorded as something like 10,000 years, 36,000 years, 700 years, and so on.  And this is good, but most researchers also record other details like where the artifact came from, a description of the artifact, and who gathered the artifact and with what instruments.  This could include the date the artifact was found; geographic details such as latitude and longitude, depth, what was found next to or around the artifact; or the name of the researcher or project; equipment used; and maybe even a text description or abstract. All of these items can be recorded as fields in a spreadsheet. I am still researching this but it seems that the kind and amount of metadata recorded varies depending on what is being dated.

At tDAR a search reveals some datasets based on C-14 dating.  Within tDAR the metadata is extensive and includes ways to identify and describe each column. There are details on the data type (text, numeric, etc.), the type of value, the category the measurement would be identified by, and if created, the ontology used by the investigator to organize the details. Depositors also record items such as site name, type of site, the anthropological or archeological culture (i.e., late archaic), the material being measured (i.e., fauna), the method of collection or investigation type (i.e., excavation). And there are some generic items such as a record number, a DOI and resource language.

So, what does this mean for long term data management?

Although there is a lot of effort required for finding artifacts and dating them, the results can be organized into a spreadsheet and described in such a way that others can use and re-use the material.  tDAR has a useful metadata structure, but one could also use other XML-based metadata schemas.  I am not sure if these data files will be around for the next 60,000 years, but with proper management they could be around for some time to come.