Archaeologists like disasters, at least when they’re not personally involved with them. Not because they’re particularly psychopathic, but because of the ‘Pompeii premise‘. Archaeologists excavate ruins, and these are abandoned sites. However, abandonment is a process, it takes time. So what you see when you dig a site isn’t a site as it was, but what remains of a site after it’s abandoned. People take useful things away with them, so the distribution of artefacts isn’t going to the same as it was when the site was actually in use.

At least, that’s usually how the ruins are formed. Sometimes though fate takes a hand.

The best-known example is Pompeii, where the city wasn’t evacuated before Vesuvius started raining ash on it. It means that what archaeologists found in Pompeii was a lot closer to a site put on pause, and preserved, instead of one that was robbed and decayed. The ‘Pompeii premise’ is that what you see is a snapshot of the site in use. There are other sites around the world where the Pompeii premise might apply. For example, there’s a buried village in New Zealand and in El Salvador there’s Joya de Cerén.

Joya de Cerén was a Mayan village. Farahani et al. have been investigating this site and they say that around AD 660 Loma Caldera erupted causing ash to fall on the village. Happily, they report the place was evacuated but they also note something else. There was quite a rush to abandon the site, so a lot of material was left behind. In particular, there was no time to gather food. What was left were the foodstuffs in the houses and also the crops in the gardens and fields around the houses. If you could identify the plant remains in the house, you could see what was used on-site and how it was stored.

You can just start digging and look for carbonised remains of plants. However seeds are small and easily missed, so what the team used was a common technique in archaeology – flotation. What you do is get dry soil, put in a tank and add water from below. The idea is that as the water rises it lifts the remains you’re looking for. There’s an example from another archaeological site in the video below.