New methods of dating archaeology
This method is useful for archaeologists working in areas where volcanic eruptions have left layers of ash above and below an archaeological deposit.
The volcanic layers can be dated, and the archaeological material will date to the period between those two volcanic eruptions.
Now, UK scientists have found a way to date these artefacts and thus give fresh insight into the history and construction of excavated ruins or items.
Key to the process is the knowledge that there is an ultra-slow recombination of moisture in fired-clay ceramic objects as they chemically combine with moisture from the air, and that this ’rehydroxylation’ process occurs at a predictable rate once an object is fired.
The data can be a little off particularly in younger artifacts, and anything older than about 50,000 years is pretty much too old to be tested because at that point the majority of the C-14 has decayed to practically undetectable levels.
We propose a new method of cross-dating the wood samples based on the classical methods of spectral estimation.
(4/30/01) for instance, earlier, later, more recent, and so forth.
Fortunately, Willard Libby, a scientist who would later win the 1960 Nobel Prize in Chemistry, developed the process known as radiocarbon dating in the late 1940s. In a nutshell, it works like this: After an organism dies, it stops absorbing carbon-14, so the radioactive isotope starts to decay and is not replenished.’Unless the artefact has been left in the Sahara desert, the rate of water absorption will be pretty constant,’ she adds, but notes that this method won’t work for items that have been glazed or painted to seal out moisture.The laboratory procedure is simple: a piece of the ceramic is ’re-fired’ to dry it out and the difference in weight precisely measured.Unless something was obviously attributable to a specific year -- say a dated coin or known piece of artwork -- then whoever discovered it had to do quite a bit of guesstimating to get a proper age for the item.The excavator might employ relative dating, using objects located stratigraphically (read: buried at the same depth) close to each other, or he or she might compare historical styles to see if there were similarities to a previous find.
It is important to remember that this method give the age of the mineral, not the artifact.