How the Roman Empire can be linked to geochemistry

Aug 15, 2017 No Comments by 602 views

Throughout our geological education, we are taught to think in terms of deep time. To forget about weeks and months and focus on the millions and billions. However, when the time span of human history is taken into consideration, the geological time scale never seems to fit, discounting the Anthropocene of course. As a result, I have never thought that investigating the geochemical composition of a rock or mineral could give any insight into the history of man. Until now.

Attending the evening talks in the “Geochemistry for the Understanding of Cultural Heritage” session, two talks grabbed my attention. To start with, the keynote talk by Francis Albarede was full of information on how geochemical insights can help tell the story of man. However, one piece of evidence regarding the piping structure in Naples following the Vesuvian eruption in 79 AD, really caught my eye. As was the case in most Roman cities at the time, the pipes transporting the water around the ancient city of Naples were made of lead. Using Pb dating techniques, Albarede was able to deduce that the lead in the pipes prior to the eruption of Vesuvius was Hercynian in age and, most likely, had to be imported to Naples. In contrast, the analysis of the lead pipes laid down after the eruption proved to be much different in age and composition. But, what does this information tell us? The contrasting composition and ages of the lead pipes indicate that the ancient city of Naples went through a rebuilding process following the Vesuvian eruption. This may seem obvious that a city would repair itself after a natural disaster, but, I never thought geochemistry would be the discipline to reveal it.

 

Artists impression of eruption of Mt Vesuvius 79AD

 

The second talk was by K.J. Westner and was entitled “Rome’s rise to power as deduced by analysis of silver coinage”. In this talk, Westner highlighted the how the Ag composition of the coins used by the people of the Roman empire was an indication the expansion of the empire itself. This work was fascinating in its simplicity. It was clearly shown that through the analysis of major elements the weight per cent of Ag within the coins increased through time, emphasising the Roman expansion into new territories which contained significant amounts of mineable silver, such as the Iberian peninsula. These advances allowed the Romans to create a purer form of currency, a bonus for society at the time as it eventually leads to the removal of taxation.

An assortment of silver coins used as currency by the Roman Empire.

Although I could not mention all of the content, both of these talks were excellent in highlighting the use of geochemistry in an area of research I did not think it could be used

General, Goldschmidt 2017, On the Rocks

About the author

Tadhg Dornan is a PhD researcher in the iCRAG raw material research spoke. Tadhg graduated from Trinity College Dublin with an honours degree in Geology in 2016 and soon after started a PhD under the Supervision of Dr. Robbie Goodhue. His research mainly focuses on pyrite, a commonly occurring iron sulphide mineral, and its role in the deterioration of concrete when oxidised. As part of his research, Tadhg will attempt to elementally analyse the grains pyrite found in the concrete of damaged properties and try and fingerprint a quarry source for the material.
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