In 79AD, Vesuvius erupted, destroying the cities of Herculaneum and Pompeii. In Herculaneum, a single pyroclastic surge incinerated the inhabitants. But in Pompeii, the eruption preserved as well as killed. So, when archaeologists rediscovered the city in the eighteenth century, the human remains in Pompeii reappeared: in buildings, on roadsides and all within the layers of hardened ash and tufa rained down on the doomed town by Vesuvius. To date, archaeologists have rediscovered around 1150 of these unfortunate victims of nature. About 100 have been studied and displayed, their bones encased in a cast made by pouring plaster into the hollow shape created by their bodies in the tufa.

Exactly how did this unique form of preservation arise? And how does it help inform our understanding of the past?

Vesuvius: Destroyer and Preserver

The eruption of Vesuvius began at around lunchtime, arguably on the 24th August 79AD. In the early hours of the following morning, the eruption reached it’s fatal, concluding stages. Three pyroclastic surges- a mix of hot gases and ashes from the collapsing eruption column- travelling at 100kph finally reached Pompeii. The first surge just skimmed the city walls, but the final one overwhelmed the whole city, killing anyone still alive. However, these fatal surges also preserved. For its rain of fine ash fell over Pompeii, covering the city until only the remains of its tallest buildings were visible above the debris.

Buried within the ash fall were the inhabitants of Pompeii. In the bottommost layers are the earliest victims of the eruption. These bodies decayed in the usual way, leaving just skeletal remains behind.   However, the bodies of victims of the pyroclastic surges had a different fate. For the fine ash fall encased their remains, hardening to form a porous shell. As the soft tissues of the bodies decayed, they leached away through this later. But by then, the hardened ash had captured and preserved their final postures at the moment of death.

Waking the Dead

In 1777, excavators found the remains of a young woman at the Villa Diomede. As well as her skeleton, the outline of her breasts and body shape was apparent in the material packed beneath her.

The excavators discovered other examples as exploration continued. But the excavators had no way of preserving them. But in 1864 Giuseppe Fiorelli, the director of the excavations, found a way of maintaining the shapes of the bodies.

Fiorelli’s excavators discovered empty pockets in the ash in a lane named the Alley of the Skeletons. Inside, it was possible to make out human bones. But instead of digging through the ash to remove them, Fiorelli instructed the diggers to pour plaster into the hollow.

They left the plaster to harden for a few days, then chipped off the outer layers of hardened ash. What was revealed was a full and detailed plaster cast of the body of a citizen of Pompeii at the moment of death.

Modern Developments in Casting

Archaeologists have looked at other ways of recreating the appearance of Pompeii’s dead. In 1984 at Oplontis, a skeleton was cast using resin rather than plaster. Wax was injected into the void around the victim’s bones, left to harden, and then coated in plaster. Once the ‘plaster cast’ had set, the wax was melted out and replaced with liquid epoxy resin- to produce a durable, transparent cast, which allowed the victim’s jewellery and hairpin to be viewed in situ on the body.

But this cast remains unique – for despite its many advantages, resin casting is tricky and expensive. For now, plaster casting continues where appropriate.

“The technique remains the best to obtain perfect replicas of the victim’s bodies.” explained anthropologist Pier Paolo Petrone in an interview with the author.

In a 2010 interview with the BBC, Stefania Giudice, a conservator from Naples national archaeological Museum described how modern preservers cast new finds. The process is by no means simple. Plaster has to be mixed to an exact consistency; thick enough to support the skeletal frame but not so thick it obliterates the fine details of the cast. It then needs to be carefully poured.

‘The bones are very brittle,’ explained Giudice, ‘so when we pour in the plaster we have to be very careful; otherwise we might damage the remains, and they would be lost to us forever.’

As a bonus, the visual information from the external features of the casts can now be supplemented by other means. “nowadays we can better adopt X-ray techniques like 3D-CT scan to investigate the human content of plaster casts.” said Pier Paolo Petrone.

Human Archaeology

Out of the 1150 bodies recovered from Pompeii, in all only 100 have been preserved in cast form. Archaeologists have successfully cast not only humans but also pigs, and a dog complete with teeth and collar.

For the experts involved in the study of these remains, there is no doubt that they are dealing with the remains of real people-even if much of what remains of their humanity is in plaster form.

Looking closely at the details of many of the casts it is not hard to see why.  Details of hairstyles, clothing-even facial features are preserved. One of the most affecting is that of a four-year-old boy found at the House of the Golden Bracelet. Part of what is presumed to be a family group, he was discovered alongside an adult male and female -with a younger child still on her lap. The little boy’s clothing is visible as are his peaceful facial features.

“It can be very moving handling these remains when we apply the plaster,” said Stefania Giudice, “Even though it happened 2,000 years ago, it could be a boy, a mother or a family. It’s human archaeology, not just archaeology.”

Learn more about the eruption of 79 AD, how it affected Pompeii —  and how the archaeology of the site illustrates the tragic, final chapter of the city’s story in Discovering Pompeii