What Really Happened at Pompeii on 24th August AD79?
What Really Happened at Pompeii on 24th August AD79?
Introduction
On 24th August AD79, Mount Vesuvius, a large volcano overlooking the Bay of Naples, erupted. It is famous for the way that it destroyed the Roman town of Pompeii, and in doing so, preserved the agony of Pompeii's unfortunate inhabitants. This is shown above in this 17th century sketch showing the Vesuvius erupting. The fact that this sketch was drawn almost 2000 years after the eruption is typical of pictures and accounts of the eruption, as there is only one surviving first-hand account of the eruption, coming from Pliny the Younger, who was living with his uncle, Pliny the Elder, who was the admiral of the Roman Fleet at Misenum, a town at the North side of the Bay of Naples, the other side to Pompeii which was further south. Despite Pliny the Younger's first hand account of the eruption, there are many different theories as to what killed the people of Pompeii. Using various different sources, in this essay I aim to investigate what really destroyed Pompeii and killed the people of the town.
Monte Somma Mount Vesuvius
This picture shows the view of Mount Vesuvius from Naples. This is roughly the view that Pliny the Younger would have got when viewing the Vesuvius erupting. From the view in the picture above, Pompeii would be on the other side of the mountain. Monte Somma is the remnant of the Vesuvius before the eruption of the Vesuvius in AD79 and indicates that in AD79 most of the cone of the Vesuvius was blown away by the eruption. The Mount Vesuvius in the photograph is the new cone that has grown up over the years since AD79.
Main Essay
Until recently, scientists often ignored the evidence that was presented before them. The mystery of what happened to the people of Pompeii was often put down to the victims being trapped and killed by lava flow. However, this theory has now been disproved, after the 1944 eruption of the Vesuvius. This occurred during the Second World War, when the Vesuvius erupted, spewing out lava in the direction of the city of San Sebastiano. When it first spew from the mouth of a volcano lava, actual molten rock, is seeringly hot and very fluid, but by the time it has flowed down the mountain for a few miles it is cooler, more solid and moves at a snail's pace. It poses little real risk to life and death. In San Sebastiano people survived because although they couldn't halt the lava's progress, they could see it coming and get out of the way. Pompeii is 9 miles from the Vesuvius and lava from the volcano would probably have taken 6 days to get there. In fact, no lava has ever been found in the debris that covered that covered these people, a fact that many early scientists ignored. Also, I know that the people of Pompeii were not killed by slow moving lava, because of what was said in a paper published online by the National Archaeological Institute of America, which said that,
'At Herculaneum, which suffered in much the same way as Pompeii' by the volcano. By studying the bone fragments and the positions of the remains of 48 victims from the beach site, the anthropologists argue that they have established "beyond a doubt" that they died in a fraction of a second after being exposed to blast of 750-degree Fahrenheit heat.'
If the people of Pompeii were not killed by a lava flow, then what did kill them? Could they have been buried or killed by the 'hail of pumice,' described by Pliny the Younger. This seems unlikely, as although Pumice stones can hurt they are light and porous. They could cause those who were unable to walk, being either too ill or old, to be buried, but could not be the cause of death for the vast majority of the people of Pompeii. Also, the Pompeii bodies were found on top of the 6ft of pumice rock and ...
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If the people of Pompeii were not killed by a lava flow, then what did kill them? Could they have been buried or killed by the 'hail of pumice,' described by Pliny the Younger. This seems unlikely, as although Pumice stones can hurt they are light and porous. They could cause those who were unable to walk, being either too ill or old, to be buried, but could not be the cause of death for the vast majority of the people of Pompeii. Also, the Pompeii bodies were found on top of the 6ft of pumice rock and ash that blanketed the streets. If the heavy rock showers had killed them they should have been buried underneath it. Something over than showers of rock had killed the people of Pompeii.
Until recently, the only other explanation given for the deaths of the Pompeiians was that Pompeii had been buried by a very rapid ash fallout. Yet there are a number of reasons why the people of Pompeii could not have been choked and buried by a rapid ash fall. For a start, a lot of the bodies discovered at Pompeii had been hit by a terrible force, as described by the Italian Archaeologist, Antonio Varone,
'The Woman's skull was sliced in half. Wooden beams were violently smashed into her body as she lay on her side. The force must have been incredible. Not only was half her skull missing, but her left leg was missing as well.'
To find out what really did destroy Pompeii on 24th August AD79, it is necessary to look at Pliny the Younger's account of the eruption. Pliny described a very strange phenomenon in his account. Writing to his friend Tacitus, he wrote, 'A cloud was rising up; in form it most resembled a pine-tree. It rose vertically, in fact, like a very tall trunk and then spread out as if in branches. This was probably due to it being pushed by a rising current and then, on this ceasing or being overcome by the weight, spreading itself out. In some parts it was white and in others black and dirty because of the earth and ash it contained.'
The picture below shows a colour drawing of the eruption as described by Pliny the Younger. Despite being around 1pm in the afternoon, the picture shows total darkness. This was caused by the huge ash clouds blocking out the light.
Until recently to many vulcanologists this would have seemed impossible. However, modern vulcanologists witnessed an extraordinary event, which changed everything. When Mount Saint Helens in America erupted in 1980 it was a revelation and it happened under the gaze of modern science. The side of the mountain exploded and became a blistering wave of rock and ash that scorched and smashed everything in its path. It combed through vast forests of fully-grown fir trees and knocked them flat, moving at a speed of more than 100 miles an hour.
This is called a pyroclastic flow and is described below.
'Within a few hours of a lateral blast, hot mixtures of volcanic gas, pumice, and ash sweep down the flank of the volcano at speeds up to and over 100 miles an hour. These mixtures of gas, pumice and ash are called pyroclastic flows. The temperature of these pyroclastic flows are extremely hot - more than 1200 degrees Fahrenheit. The huge ash plume rising from the volcano often hides the pyroclastic flows that occur beneath them. These flows deposit pumice and ash in layers as thick as 60 feet. Pyroclastic flow deposits are easily eroded by wind and water because they are made of loose ash and pumice. Fan-shaped deposits known as the Pumice Plain form. It is called the Pumice Plain because it is covered with pyroclastic flow deposits.'
To vulcanologists, it seemed that 2000 years ago Pliny had got it right when he described the eruption. Two years later El Chichon in Mexico went off in another large explosive eruption, even more like Pliny had described. Molten material shot 20 miles high to form a towering mushroom cloud. Later, when the energy of the blast was no longer strong enough to keep the dense column aloft, it collapsed and cascaded down the mountain in convulsive waves. Super-heated ash churned around ground-hugging rock and gas in a racing, burning avalanche. It was another pyroclastic flow. A pyroclastic flow is worlds away from a slow, predictable lava flow that early scientists thought has destroyed Pompeii. After these two eruptions, a new science in the understanding of pyroclastic flow developed.
This picture above actually shows a pyroclastic flow occurring at Mount Saint Helens. The pyroclastic flow is seen in the area shown by the arrow. It is seen hugging the side of the mountain while the ash clouds rise above the pyroclastic flow. What amazed scientists who studied the eruptions at Mount Saint Helens and El Chichon was that burning rocks and ash could flow so fast and so powerfully, moving as if they were liquid. The flow is fluidised because it contains water and gas from the eruption, water vapour from melted snow and ice from the top of the volcano, and air from the flow overriding air as it moves down slope.
There is more evidence that it was a pyroclastic flow that hit Pompeii, other than those discussed above. The case for the destruction of Pompeii by pyroclastic flow gained further credibility after the discovery of an ancient chamber near the AD79 sea front at Herculaneum. At Herculaneum, the deposits from the volcano caused the sea to retreat from the town, meaning that seaside villas in AD79 are now more than 100 feet from the sea. Archaeologists found hundreds of skeletons, most of the population of Herculaneum, hiding in the chamber. What was most shocking was the terrible burns that they had suffered from. The people of Herculaneum had the time to hide, but what had killed had been violent had incredibly hot, so hot that the people had been burned down to their bones, which were black. The only type of eruption that could have cause this type of burn is a pyroclastic flow, due to the extreme heat. Also, plugs of ash were found in the nostrils of the people killed at Herculaneum, which would have caused the people of Herculaneum to struggle with their breathing.
Another piece of evidence that supports the theory of a pyroclastic flow at Pompeii is a recent investigation by the geologist, Haraldur Sigurdsson. He was attracted to Pompeii by the writings of Pliny. When he first arrived in Pompeii he was appalled by the standard of the excavations, and the assumptions made by scientists as to what really happened at Pompeii. What appalled Sigurdsson was the fact that, although archaeologists had excavated with care and thoroughness bodies, cultural remains and pottery, they had unfailingly ignored the rocks and soil that lay all around them, covering the town. Sigurdsson became convinced that the rocks gave major clues as to what went on in AD79 and that this had been neglected before he arrived in Italy. Sigurdsson said that,
'I was struck by the fact that the interpretations that had been put forward about the eruptions were clearly wrong. The conventional wisdom was that Pompeii had been buried by very rapid ash fallout. There'd been just a enormous snowstorm except of pumice and ash and that the people and the city had been buried in just a few hours by this fallout, so those were the views that had been presented up till the 1980's. This was just assumed. Yet the Pompeii bodies were all found on top of the 6ft of pumice rock and ash that blanketed the streets.
Rather than making any assumptions, Sigurdsson travelled to a quarry a few miles away from Pompeii. The layers of volcanic material laid down by the Vesuvius over the years can been seen in the rocks here, and in a narrow band of rock can been seen the chronology of the terrible 18 hours described by Pliny.
Sigurdsson described the rock layers of AD79 in the following way,
'We start at the base with the Roman soil, beautifully rich soil, and that is overlaid by this 2 centimetre layer which is the first explosion, probably the night before the main eruption. Towards, the upper part of this layer we see that the pumice is getting darker and it's starting to begin to form the grey pumice and then that is overlain by a surge, this dark grey layer that doesn't look very conspicuous is actually the most deadly part of the eruption. That represents the rock that invaded and overwhelmed Pompeii and that led to the death of the citizens in Pompeii that were working on top of the grey pumice fall.'
Sigurdsson realised that it was the narrow dark layer was what had killed the citizens of Pompeii. He discovered evidence of a violent flow, so he knew that it could not have simply fallen from the sky like a shower. Also, Sigurdsson knew that the layer was not made up of ash or mud, but consisted of a rock called tephrite, charcoal and various other miscellaneous materials. Sigurdsson knew that charcoal and tephrite only form at exceptionally high temperatures, and would have formed part of a pyroclastic flow.
The rock above is tephrite found at Pompeii. It is known to be formed at high temperatures as it is made up of large crystals. Large crystals form when the rock takes a long time to cool, and for the rock to take a long time to cool, it would have to have been formed at a high temperature.
Now I have established beyond any reasonable doubt that it was a pyroclastic flow that destroyed the town of Pompeii. To establish the when each of the stages of the pyroclastic flow occurred it is necessary to study the writings of Pliny.
Misenum Herculaneum Pompeii
pm - Pliny wrote that he saw, 'A cloud was rising up; in form it most resembled a pine-tree. It rose vertically, in fact, like a very tall trunk and then spread out as if in branches. This was probably due to it being pushed by a rising current and then, on this ceasing or being overcome by the weight, spreading itself out. In some parts it was white and in others black and dirty because of the earth and ash it contained.'
This was caused by a build up of gases cracking the Vesuvius' core. Molten rock shoots high into the air, fragmenting and cooling, forming a cloud of dust and pumice that blew south-east over Pompeii and blocking out the light.
2pm-12am - Pliny wrote that in Stabiae, 'The houses now tottered under repeated and violent concussions [caused by the falling pumice stones], and seemed to rock to and fro as if torn from their foundations.'
He also wrote that, ' It was now day everywhere else, but there a deeper darkness prevailed than in the most obscure night.'
A blanket of pumice stones 1 metre deep was smothering Pompeii. The roofs of buildings were beginning to collapse under the strain, although few died at this stage. Many people began to flee the city.
am - 8.30am 25th August - Pliny wrote that, 'That night the earthquakes became so violent that the earthquakes became so violent that one might have thought that the world was not being merely shaken but turned topsy-turvy.'
This was the first pyroclastic surge cloud. The cloud column collapsed and hot gas, rock and dust swept down the flank of the Vesuvius at over 100km an hour, pulverising Herculaneum and killing those sheltering in the seaside chamber that was discovered in 1982.
Four more surge clouds followed this, the last occurring at 8.30am. The 2nd hit Herculaneum and the 3rd ran out of energy just before hitting Pompeii. However, it made breathing in the city difficult.
The fourth surge cloud killed the remaining people left alive in Pompeii. The boiling hot ash filled wind that hit the city at 300 km an hour killed them almost instantaneously.
The final surge cloud swept the countryside around Pompeii and Herculaneum, killing many of those who had fled Herculaneum and Pompeii. Around 10,000 of Pompeii's residents are killed.
pm Pliny wrote that, 'At last this dreadful darkness was attenuated by degrees to a kind of cloud or smoke, and passed away; presently the real day returned, and even the sun appeared, though lurid as when an eclipse is in progress. Every object that presented itself to our yet affrighted gaze was changed, covered over with a drift of ash, as with snow.'
Heavy rain three days later caused the mudslide that buried Herculaneum.
Pompeii remained buried and forgotten for about 1,670 years until 1592, although the plateau where it had once stood was always known as 'Civita', or the city. Finally, in 1748, Don Rocco de Alcubierre, a Spanish Engineer, heard rumours that workers had found the ruins of houses. He believed they might belong to the city buried in the eruption of AD79. In April of that year, Alcubierre started digging in the street that is now as Via della Fortuna. Over 250 years later, 4/5 of Pompeii has been excavated, and the excavations continue. Only just, over 2000 years, we are beginning to realise what really happened to the people of Pompeii on 24th August, AD79.
A Mosaic found at Pompeii
The peristyle from the House of the Faun
Bibliography
. Pompeii by Peter Connolly
2. The Buried Cities of Pompeii and Herculaneum by Alfonso de Franciscis
3. Pompeii Archaeological Guide by Baldassare Conticello
4. In Search of Pompeii by Giovanni Caselli
5. BBC Horizon: The Curse of Vesuvius, narrated by Haydn Gwynne
6. Pictures of History by John Hauser
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