As part of Prep III’s Geography, we have been studying the structure of the Earth. Under our feet is a thin crust lie layers of molten rock which swirl around an iron core. We have made maps that show the edges of great chunks of rocky crust which float on this sea of magma, like pieces of a gigantic jigsaw puzzle, and discovered that these tectonic zones are the scenes of seismic upheavals – earthquakes, tsunamis and volcanoes!
So we had to have a go at making our own, didn’t we?
Science, History and Geography collided like three great tectonic plates in the classroom: we have studied Geology, the Roman Empire and volcanoes…and it all came together in one word – Pompeii.
Having located famous volcanoes, one of which was Vesuvius, an active mount which stands to the North of Pompeii near the Bay of Naples, we read about the eruption of AD79 which buried the city and its inhabitants under thirty feet of ash.
Our next question was, “Could we re-create the disaster on a smaller and less destructive scale in the classroom?”
Answer: Yes.
Having borrowed a large sand tray from Prep II, we used a bag and a half of builders’ sand which was a bit on the dry side. Somebody said they had once helped their dad to mix cement, so we followed their advice and made a “well” in the centre of the sand pile, poured in water and found that “many hands make light work”, and sand that would stick together.
Half the class decided to work on the Vesuvius mound while the others used lolly sticks to carve roads and buildings into a flat sand plaque, recreating Pompeii from a CGI aerial reconstruction of the city. The final product looked quite convincing, if not entirely historically accurate, and small paint pot was pushed into the crater of Vesuvius to make a main vent.
To create the eruption, we set up a chemical reaction between ethanoic acid and sodium hydrogen carbonate (or vinegar and baking powder if you prefer), mixed with a little orange paint for effect. This was tested and results were disappointing….until we decided to use A LOT of both reagents.
With bated breath the ingredients were mixed….and a huge plume of orangey froth poured out of the crater, down the slope of the mountain and spread around the city wall of the doomed Pompeii! Most gratifying. We realized that Pompeii itself was not destroyed by lava, but buried under a cloud of tons of hot ash and poisonous gases (pyroclastic flow) however, a little artistic license was allowed. Well done Prep III – we love it when a plan comes together!
