Detectorists find set of Roman coins, scientists identify sacrificial offerings

Experts at Leiden University have found evidence that a set of Roman coins found near the River Aa in the DutchBrabant was not "just ordinary" treasure, but the long-stored offerings of travellers seeking a safe ford across the river. The assemblage was discovered by brothers Wim and Nico Schaijk using metal detectors in a field near the village of Berlicum in November 2017; a newly published study takes their find to the next level.
The brothers found a total of 103 bronze sesterces and four silver denarii in a freshly ploughed field by the banks of the River Aa. Most of the coins date from the 1st and 2nd centuries. After the announcement by Portable Antiquities of the Netherlands, the site was investigated by archaeologists in 2018. A test probe revealed that the coins came from a layer of soil with a thick natural iron concretion that matched the iron crust of the coins. The excavation also revealed two other Roman coins, a hairpin and a fragment of a probable ring from a horse harness.

The oldest identifiable coin is a silver denarius from the Roman Republic struck by Calpurnius in 90 BC. The other three denarii are coins of Vespasian and Trajan. A significant number of the coins are unidentifiable because most of the 105 copper sesterces are extremely corroded. The last datable coin is a coinage of Marcus Aurelius (161-180 AD). It may not be the youngest in the assemblage, however, as 2nd century Roman copper coins were in circulation in North Brabant until the 3rd century.
The considerable range of ages of the coins and their location suggest that they were deposited on the site for a smallsmall portions and regularly over more than a century, suggesting accumulation rather than deposition of the hoard in a single event. The coins and jewellery lay on the banks of the river in an area that was regularly flooded by water and permanently waterlogged. Votive offerings were often left around or in bodies of water because rivers, lakes, waterfalls, and wetlands had considerable ritual significance.

According to the authors of the report, it is likely that a crossing (ford) existed at the Aa River in Roman times two thousand years ago. Many coins depict military and religious symbols. There was probably a deliberate choice of particular coins, and it is likely that travellers used these coins to ask the gods for help in crossing the river. The vast majority of people at the time could not swim, so any such "help" was very welcome. Of course, no help is free...

Chemical analysis found that a crust of iron hydroxide began to form on the coins very soon after they were deposited. There is no evidence of erosion or washout because the coins were found on a marshy bank and if they had been exposed to erosion or washout, they would certainly have moved in the opposite direction - i.e. from the bank to the river bottom. Any scouring had only a minimal impact on the location of the coins, which were found in a narrowed and shallow part of the river. No remains of a bridge or other structure were found; it was probably a natural ford. Archaeologists assume that the coins were thrown into the water on the bank to provide safe passage for people about to cross the river.
The coins are proof that Roman activity in what is now the Netherlands was not just focused on fortifications around the Rhine and Waal rivers: "In a land registry entry from 1832, one of the earliest detailed maps of the Netherlands, my colleagues noticed that there was a path across the river at that time," said Leiden University researcher Liesbeth Claes. She added: "There was obviously a ford at this point where people could cross the river more easily. Later, the ford fell into disuse. This information, together with the discovery of coins, convinced us that travellers in Roman times used the ford as a safe crossing point. It may not have been a particularly fast-flowing river, but it was especially important for traders to transport their goods safely to the other side. And there's also the fact that in ancient times rivers always had a sacred meaning."

Coins with military themes seemed to be more than popular in the set, "At first I thought it was strange, because what does a military theme have to do with safe passage? But then I realised that something similar was quite common in pre-Roman times: we regularly find gifts of axes, swords and helmets in various rivers and wetlands. It could have been a custom that continued in Roman times, but in a slightly different way - using coins with these symbols. That realisation was an important turning point in my academic career," Liesbetch Claes concluded.

The authors of the study highlight the benefits of professionals working with amateurs: "The enormous added value of this research is the close collaboration between archaeologists from the Rijksdienst, the Water Board, Portable Antiquities of the Netherlands (PAN), Heemkundekring De Plaets and the detectorists. The latter in particular are becoming more important every year in scientific archaeological research in the Netherlands. Increasingly, professional archaeologists are assisted in the discovery of important sites by colleagues who go out into the field with metal detectors in their spare time."

Roman Němec

One of the Schaijk brothers' coins

Brothers on the search

Sources: cultureelerfgoed.nl, universiteitleiden.nl