Morgan Meis in The Smart Set:
Sometime during the late summer, or perhaps the early fall, of the year 79 C.E., Mount Vesuvius erupted near Naples. The result was instant death for the people, plants, and animals in the Roman town of Pompeii, which is about five miles from Mount Vesuvius. A Volcanologist named Giuseppe Mastrolorenzo recently (2010) published a definitive study of death in Pompeii. The living things, he concluded, died from the intense heat of the volcanic blast. Basically, they were flash fried. In one of the multiple pyroclastic surges produced by the eruption, “temperatures outdoors — and indoors,” wrote Mastrolorenza, “rose up to 570°F and more, enough to kill hundreds of people in a fraction of a second.”
The ash and the volcanic mud came a little later. Pompeii was buried under this ash and volcanic matter, preserving the town in the instant in which it had been flash fried. The world then gradually forgot about Pompeii. It had been wiped from the face of the earth. Then, at the end of the 16th century, Pompeii began to resurface. The accidents of weather, of rain and flood and earthquake and further volcanic eruptions brought bits of the city back into the light of day. It took many years for people to realize that what was down there was Pompeii. It wasn’t until the mid-18th century that excavation of the city was begun in earnest. The excavation has been going on ever since. There are still objects and structures being discovered.
In the 1860s, something else incredible happened at Pompeii. A man named Giuseppe Fiorelli was named director of excavations at the site. Ingrid D. Rowland writes about Fiorelli in her new book, From Pompeii: The Afterlife of a Roman Town (Harvard University Press, 2014). Fiorelli, Rowland writes, “was one of the first archeologists to excavate stratigraphically, that is, by removing layers of earth from the top down.” With this method of archeology, Fiorelli and his team began to notice “oddly shaped bubbles” in the layers of ash. Fiorelli came up with an ingenious idea. He shot liquid plaster down into those bubbles. When the plaster hardened, the shapes could be dug out from the earth and ash. The bubbles, it turned out, were the molds created in the ash from the objects and physical bodies (people, animals) that had been covered in the ash after the eruption, and which had then decomposed. The bubbles didn’t collapse, since the ash had hardened over the centuries. As Rowland puts it, “the organic remains of the town survived as hollow voids within the pumice.”