HOLLY WALKER: You said that brick stamps, you can get lots of information. These coins, what can you actually tell? I mean, some of them still have traces of heads on them. But if they don’t have a face on them, what else can use to date them?
SIMON KEAY: Ah, then you’re in trouble. Well, actually it’s not as– I say that just trying to be funny. But actually it’s not as impossible as that. Because when you– Roman coins are– at any period in time were– the coins that you find were denominations within quite a well-regulated monetary system. And what we know is that they comprise gold coins, silver coins, bronze coins. Now we’re digging in levels of, as you know, about the sixth, fifth, fourth century AD. By that stage, gold coins were very, very rare. They’re very rare to find in archaeological sites. Silver coins are still pretty rare. You can find them– silver siliqua, as they’re called.
But the most frequent coins you find are copper and bronze. And indeed, all the ones we’ve found are copper and bronze. And you can actually tell quite a lot about the chronology of them or the dating of them from those heads and the lettering you see on them.
Because even though there were many, many different varieties, say in the fourth century, many different varieties of coins coming from the mint at Rome or even briefly at Ostia, but mints all over the Mediterranean basin, you can actually look closely and you can actually see enough of the image of the emperor or the reverse of the coin or indeed of the lettering to date that coin probably sometimes within five years or within 10 or 15 years. But remember that the coins are found in– when they’re found in a layer, that gives you a terminus post quem, again, so the layer isn’t dated by the year of the coin or of five years of the coin.
It’s dated to the time after which the coin was issued because it could have circulated for a long time before somebody dropped it. And these ones, you see. You can see quite carefully, if we take one of these out. There are two kinds of coin that we’re finding here. This one, you can see quite a clear head just there. And you can see the writing around the outside. It may look a bit difficult for you to see. But I’m familiar with these enough to know that this is a coin of a fourth century emperor, probably I would say, the Emperor Constantine or one of his family. And that dates it to probably some time in the 320-330’s AD.
So if we found just this in a layer, you could say that that layer dates to some time after the 320-330’s.
In an age without newspapers or radio, Roman coinage also had an important propaganda function. The images and accompanying lettering informed users of the coinage who was Emperor, his Imperial powers and relationship to previous emperors, military victories and other Imperial achievements and relationship to the gods. Occasionally they portrayed Imperial buildings, or even more occasionally an entire harbour, as in the case of the famous Portus issues of Nero and Trajan.
For example, Portus is represented on a coin from the time of Nero (AD 64) where it is described as Portus Ostiensis or Portus Augusti. This coin is a brass sestertius dated to AD 64 that bears the name AUGUSTI S POR OST C which can be expanded to mean, approximately:
“The Ostian Port of the Emperor. By Decree of the Senate and People of Rome”.
Portus is referred to by a variety of Latin names including Portus Ostiensis, Portus Augusti, Portus Urbis Romae, Portus Ostiensis, Portus Ostiae, Portus Traiani, Portus Augusti et Traiani and Portus Traiani Felicis.
You can also see a representation of the Trajanic Basin on a coin from his reign, with the impressive frontage of massive buildings clearly apparent.
There are lots of different ways that coins like the one Simon showed us might have got into the archaeological record. They might simply have been lost – dropped in the course of a normal day working at the port. Or they may have been deliberately hidden, as in the case of a hoard of coins we discovered in the Palazzo Imperiale. Or the coin might even have been thrown away in a ritual way, just like we throw coins in a wishing well or the Trevi Fountain in Rome
It is amazing that coins like the one you saw can be dated sometimes to within a few years, and hence they can help date the context where it is found, via a terminus post quem. As all good archaeologists, you know what that means 🙂
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