Pompeii

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay

Probable pre-eruption appearance of Vesuvius. Naples is off the left side of the picture. Note that Pompeii is on the coast, even though it is not now.

A day or so into the eruption, gas pressure in the magma chamber falters and the eruption cloud begins to collapse. Pyroclastic flows rush down the flanks of Vesuvius. Herculaneum, being closer, is hit first.

Eventually Pompeii is hit, but by this time most survivors have fled. How many were overtaken in flight, we don't know. The summit collapses into the magma chamber. Nobody ever sees this event directly because of pyroclastic flows.

Post eruption, Vesuvius has collapsed to form a caldera, the outer rim of which is Monte Somma. The scene is colored like the pre-eruption scene, but in reality, everything is covered thickly with gray ash and pyroclastic flows. Probably the deposits extend the beach outward from the site of Pompeii.

Later eruptions build the present summit of Vesuvius, while sedimentation builds the shore outward, leaving Pompeii landlocked.

Satellite view of Vesuvius.

Pompeii

	In the archaeological museum in Naples is a painting of Vesuvius (center) as a single tall cone with no suggestion of Monte Somma. Discoveries in the 1980's of pyroclastic flow deposits from the 79 AD eruption led to a reassessment of the eruption as a caldera collapse event.
	Summit of Vesuvius with Monte Somma to the left.
	Vesuvius from the east, with part of Monte Somma on the right.
	Vesuvius from the east, with part of Monte Somma on the right.

The Fallen

Judging from its size, Pompeii had about 20,000 residents. The unlucky ones died in the eruption and were buried by ash, which hardened around them. The bodies decayed away, except for the bones. The casts were filled with plaster to recreate the forms of the victims.

Only about 10% of the population was entombed, creating the impression that the eruption began mildly enough and that only stragglers, maybe looters, were caught. That all changed in the 1980's when excavations at Herculaneum showed clear evidence of pyroclastic flows and mass violent death.

The pyroclastic flows hit Pompeii half a day later than Herculaneum, so more people escaped. Still, it's possible that a lot of people were caught in flight and entombed beyond the city limits.


	Left and below: a person who died trying to shelter his or her face, and a dog. I feel sorrier for the dog. Not that I don't feel sorry for the human, but the dog probably died wondering why his master didn't come to save him.

Street Scenes

	Roman chariot wheels had a uniform width, which was incorporated into road design and eventually railroads. Not! A thoroughly debunked urban legend. Stepping stones in Pompeii were uniform to allow traffic to pass, but nobody traveled far by land with water transport so easy in the Mediterranean, and spacings in one town had nothing to do with any other town. And there have been dozens of different railway gauges in use around the world.
	The ruts in the paving stones probably began along seams between stones, where wheels beveled off the edges. Once a rut became established, all succeeding traffic followed it, deepening it.
	Frankly, Pompeii has been over-excavated. Without adequate funds to protect it, the ruins are subject to the ravages of weather. It would be better to decide upon key areas to keep open and backfill the rest.

Everyday Life in Roman Times

Cave canem: Beware of the dog. A pupular entryway design in Roman homes.
	Left an oven. Below: Roman fast food. Served hot, no questions asked. "How long has that been sitting there?" was one of the questions they didn't ask. The jugs were filled with hot water, kept hot by fires under the counter. Pots of food were immersed into the jugs.


Above: Lead pipes. The one on the left is attached with a clamp identical to one you could buy in any hardware store.	Below: If you were rich you had pipes. Regular folks had to make do with public fountains.

	An ancient Roman muffler? More likely a pressure chamber to smooth out pressure surges in the water mains, or possibly a sediment trap.

Above: a grist mill	Below: Amphorae. The points at the bottom facilitated pouring but presented a problem with standing them up.

They May Not Know Art, But They Know What They Like

	Yes, this is just what it looks like. So are the pictures below. And if you want this hidden, "for the children," trust me; your kids know where to find stuff much more explicit than this.

Artifacts From Pompeii

	Most of these objects are in the Archaeological Museum in Naples. By the First Century, reasonably clear glass was commonplace.

	Spoons. There's pretty much only one way to pick up soup. Forks, on the other hand, wouldn't come along for 1500 years. People picked things up with their knives or fingers.
	Ornaments of rock crystal. The interesting item here is the faceted stone second from far right. It's not a natural crystal shape but an ideal mathematical shape called an icosahedron. Someone visualized this shape and carved it from a piece of hard quartz.
	And the really fascinating thing is it has an identical twin in the Archaeological Museum in Istanbul.

	Is this the "clothing optional" section?
	Lifelike sea life painting.
	A famous and widely reproduced painting of a young patrician couple.
	A famous, charming, downright cute painting of a young woman trying to figure out what to write next.
	A wooden chest
	A helmet from the gladiatorial school. Hollywood does an atrocious job with history, but we actually know what people wore in ancient times.
	Those horns you see in gladiator films actually existed.

An Artistic Riddle

	A bit of a mystery. If I didn't know where this was from, I'd say the color scheme, trees and building style looked Chinese. Once is a riddle, but when you see several examples, as well as numerous rooms painted red, black, and dark green, it certainly begins to look like someone in Pompeii knew Chinese style.

The Palaestra

The Amphitheater

	Painting of the amphitheater
	And the real thing

Modern Pompeii

The Pyroclastic Deposits

	At left: the sequence of deposits. The lower section is small lapilli a centimeter or so in diameter. The first phase of the eruption dropped lapilli, not dangerous in itself, except when it got too deep to walk through and heavy enough to collapse roofs. Above that is finer ash flow material. The uppermost dark layer may be mudflow. At right, below: cross-bedded ash, suggesting currents powerful enough to erode the deposits, and rapidly changing, probably turbulent, flow directions.

	Pointing to a brick in the ash flow. The flow was powerful enough to fling bricks.