Radiocarbon dating, right? How does that work, and how can we ensure its accuracy?
In: Planetary Science
Archeology is about human history not the world in general so we so we can use multiple methods that relate to human behaviors. First and the oldest is to look for inscriptions and texts get a dates off those, build a time time line off them all and then start looking for dateable events to tie those to our calendar system. Famous documents like the [Abydos list of pharoahs](https://en.wikipedia.org/wiki/Abydos_King_List) the [Turin king list](https://en.wikipedia.org/wiki/Turin_King_List) as well as others can provide dates across hundreds and thousands of years for at least a rulers reign. So we know that if we find an inscription dated to the reign of Rameses II is comes before X pharaoh and after Y pharaoh. Then we just need a length of reign for each and an entire chronology can be built. Even without dates we have some information. We know no ruler is legitimately going to live more than 100 years, and more likely only going to reign for 20-30.
Next we take events like solar eclipses, the appearance of comets, known battles or rulers and chronologies of other civilizations and compare them to what we generated. If two civilizations saw the same supernova we can accurately tie the reign of a king in civilization A to the same time as that of another king in civilization B. Once we can build a timeline for one civilization we can often tie it to anther through things like diplomatic correspondence, or trade in certain goods such as pottery.
Once we have a rough chronology we can start to look at art and architecture. Styles change over time and humans produce [a tremendous volume of pottery](https://en.wikipedia.org/wiki/Monte_Testaccio). Shards from that pottery last a long time. If we can date one shard of one style to reign X then everything in the same style will be roughly the same time period. So we someone goes out and digs up a new site and finds pottery from that style they know the site is from that period. This use of pottery goes back before we have written documentation. We can look at a pot shard from ancient Crete and say it from the Black cord period (made up I’m not familiar with Cretan pottery) but we know the black cord period came before the black sphere period and after the solid black period giving us at least an order for items found around the shards. Over the past several hundred years we have built up tremendous databases of pottery styles. Now we just need other evidence to apply dates, that evidence can be the written record or more scientific tools.
Yes in recent times we can use radiocarbon dating. We can also us dendrochronology. We have built extensive databases of the war/cold periods going back thousands of years in some locations and can look at the tree ring patterns of wooden objects to see where the match giving us a year.
All these things go hand in hand and refer back to each other and need to match. A radiocarbon date of 4000 B.C., a dendro date of 3900 B.C., a pottery date of 3950B.C. and an inscription we calculate to 2800B.C. tells us something is wrong somewhere, likely with the inscription evidence since its the one that is the outlier. This is were the accuracy comes in. All of the methods have a margin of error but if all the dates fall in the same range we can say with confidence that its an accurate date.
But once we have good records in multiple areas we can with confidence find a single piece of evidence, say a pot shard and date a site to a specific time even if we dont find other evidence a the site because we have tied that style at other sites to other evidence.
EDIT: oh and we can do the same with some geology. Certain fossils and shells are only found in rocks of certain time periods so finding the same shell somewhere else tells us that rock is from the same time (geologically) as the first. Then tie in other isotope dating, erosion and weathering dating, deposition times to create new rock etc and a timeline can be built on the order of billions of years.
Latest Answers