Monday 4 March 2013

The archaeology of tea and cake


Today’s blog is somewhat whimsical, but definitely still informative about important matters of archaeology. It’s also an excuse to make cake.

In archaeology, whenever we dig into the ground we are looking for artefacts from the past. However, we also want to know when these artefacts date to, and how different artefacts relate to each other throughout time. One of the ways that archaeologists do this is through soil.

This is known as stratigraphy, which is a term from geology. The underlying principle is that in one generation to the next, soil gets treated in different ways (e.g. an era of heavy rain will leave different soil to a dry era), and so time creates layers in the soil - different colours and consistencies. Archaeologists use these changes in the soil to delineate time periods.

When digging a site, archaeologists take great care to faithfully depict the layers of stratigraphy in order to correctly sequence the site, and any artefacts found. This sequence is mapped out in a Harris Matrix, which shows how the soils relate to each other, like a soil timeline.[1]

So, I’ve made a cake that has these layers, although sadly there are no artefacts buried inside (but there are smarties).



That’s five layers of “soil” (three sponge, two buttercream), and grass (with worms) on top.

The idea of the stratigraphy cake is not new, and many people have already done it much better than I have here (a quick internet search will show you several mouth-watering examples). However, it was definitely a cake-day here in Cambridge, and it tastes great.

But wait! I hear you cry. Surely you can’t have cake without a nice cup of tea? And anyway, it’s in the title for this week’s post. You’d be correct, of course. Any good archaeologist loves a good cup of tea, and it’s really the only way to start the day, especially when you’re out on dig and have possibly just woken up in a tent.

Another tool that archaeologists use in relation to soil is the Munsell colour system, which classifies colours in terms of hue, value, and chroma. It allows archaeologists to offer a consistent and quantifiable definition for each colour, meaning that someone else can understand what context they are talking about, without any confusion about colour perception.


Another beautiful thing about the colour chart is that the colours of soils correspond with the colours of tea. So if you like milky tea, you can specify an exact colour higher up on the scale when instructing someone how to make your tea. The lower colours may perhaps correspond to a mug of rich, dark cocoa.

In other words, all archaeology, and soil, is basically just tea and cake (and maybe coffee, or cocoa). Now you can teach your friends/spouse/children/minions to create your perfect cup of tea by pinning up a Munsell colour chart in your kitchen. Easy.




[1] A lot more complicated that my brief description makes it sound, for more see here.
[2] Image from http://nesoil.com/images/munsell.jpg

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