Bodies left cavities in ash that Romans filled with plaster. CT scanning of these casts revealed last meals, diseases, and even a pregnant woman frozen in time.
The Chemistry of Catastrophe
The eruption of Mount Vesuvius in 79 AD was a chemical and geological one. It began with a column of superheated tephra and gases shooting up to 33 kilometers into the sky. For the city of Pompeii, this meant a rain of lightweight pumice and ash for hours. The destructive force came from pyroclastic surges—fast-moving clouds of hot gas and volcanic matter.
These surges were devastatingly hot. The first surge to hit Pompeii had a temperature between 180–220°C, with later surges reaching 220–260°C. Closer to the volcano, in Herculaneum, temperatures soared to 500°C. This extreme heat was the first step in the preservation process. It instantly vaporized soft tissues and bodily fluids, killing the inhabitants in fractions of a second. The fine volcanic ash then enveloped the bodies. Mixed with rain, the ash formed a cement-like layer that hardened around the deceased, recording their final posture in detail. This created an anaerobic (oxygen-free) environment, halting the normal process of decay and leaving a hollow cavity as the soft tissues eventually decomposed.
Science of the Plaster Casts
For nearly 1,800 years, these cavities lay hidden within the hardened volcanic debris. In the 1860s, archaeologist Giuseppe Fiorelli devised a technique to reveal the forms within. When his excavators discovered a void, they would carefully pour liquid plaster of Paris into it. The plaster (calcium sulfate hemihydrate) would fill the space left by the body and harden into a durable cast, creating a detailed statue of the person at their moment of death.
Today, these casts are subjects of scientific study. Non-invasive technologies like CT scans and portable X-ray fluorescence (pXRF) allow scientists to peer inside without damaging them. These scans reveal the skeletal remains held within the plaster. Analysis of the bones provides information about the victims' age, sex, and health. Studies have revealed evidence of conditions like tooth decay and gum disease. The chemical composition of the bones can be analyzed to understand diet and potential geographical origins. This modern chemical analysis connects researchers to the people of the ancient Roman world, though researchers must carefully account for potential contamination from the plaster itself.
💡Fun Facts
The eruption of Vesuvius released 100,000 times the thermal energy of the atomic bomb dropped on Hiroshima.
In nearby Herculaneum, the intense heat was so extreme it turned one victim's brain material into glass through a process called vitrification.
The famous "Pompeian Red" wall color is often actually yellow ochre pigment that was chemically altered by the heat and gases of the eruption.
Archaeologists have found perfectly preserved carbonized loaves of bread in ovens, some still showing the baker's stamp.
Generally 9:00 AM to 7:00 PM during high season (April-October) and until 5:00 PM in the low season (November-March). Last admission is 90 minutes before closing. Always check the official website for current times.
Admission
Tickets cost around €22. Visitors with disabilities and one companion receive free admission.
Accessibility
The site has an accessible route called "Pompeii for All," which covers over 3 km of the park. However, many areas have uneven, ancient paving. Wheelchairs can be requested at the Piazza Anfiteatro entrance.