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To not understand this about archeology

(26 Posts)
CloneMeNow Tue 17-May-16 12:37:10

How come it's underground?

I mean, how is the surface of the earth rising so much that stuff is buried down underneath? Why are Roman or prehistoric ruins several metres underground? What happened to bury them? How exactly does this happen.

Maybe I'm missing something really basic, but i don't get it? What is making the surface of the earth constantly get higher?

Whowouldfardelsbear Tue 17-May-16 12:40:56

Isn't it the foundations of the buildings they find? That'd be why they're underground. (I know nothing about archaeology do may be another explanation!).

Whowouldfardelsbear Tue 17-May-16 12:41:27

So (not do)

HumphreyCobblers Tue 17-May-16 12:47:14

I have sometimes wondered about this. But then I live on a farm, and it is amazing how quickly stuff disappears when just left. We had a load of old chicken houses in the orchard and most of the iron wheels have gone under ground now, grass grows over them and the soil level seems to increase with the years.

500internalerror Tue 17-May-16 12:49:07

Partly because only foundations are left - the rest gets reused/knocked down/stolen etc.

Partly because land does shift & change over long periods of time. And many archaeological sites are under ancient rubbish tips!

Partly because we do have ancient preservation above ground but you don't think of it archaeology , it's 'old buildings' !

BestZebbie Tue 17-May-16 12:49:51

In cities it is because people tend to just build directly on top of what was already there - usually the rubbish of decades of previous habitation, and the detritus of the buildings that were there before.

In the countryside you get topsoil deposited by years and years of plants growing and dying, and matter getting blown in by the wind - often rural remains aren't that deep, and that is why they get easily damaged by ploughing.

Two other points:
1) You are usually looking at things that were buried even when they were in use - post holes, rubbish pits, graves - which gives them a head-start.

2) Just as many (actually, probably a whole lot more) sites are getting lost to erosion - but we don't get to see those as they are destroyed. You only get to dig up things that have managed to stay preserved for all the time until now, which is why there are a disproportionate amount of some times of remains in certain types of environment but most stuff gets lost. The study of how this works (usually wrt fossils) is called taphonomy.

TheNoodlesIncident Tue 17-May-16 12:51:28

When plants die they decay and by the action of worms, beetles etc, are pulled back into the soil. Soil is basically composed of bits of rock/sand, clay and decomposed matter, such as plants (stems, roots, leaves), animal remains and sundry bits and bobs. So over thousands of years the soil level rises.

Remains of of Roman or prehistoric buildings tend to be the foundations, floors, etc, so would have been very low to the ground in the first place.

If human beings disappeared off the planet, in as little as a hundred years' time, roads and motorways would be covered with a layer of grass and the world would be nicer

WhatchaMaCalllit Tue 17-May-16 12:53:49

That's not a bad question so I've googled "Why is archaeology always buried?" and here are some responses:

ask.metafilter.com/237694/How-do-things-get-buried-in-dirt-over-thousands-of-years

www.straightdope.com/columns/read/813/how-come-archaeological-ruins-are-always-underground

girlywhirly Tue 17-May-16 13:32:26

Try to think of the surface of the earth as something that is constantly changing, rather than just a surface. Animals, humans, natural things like volcanic eruptions, tsunami's, earthquakes, flooding, drought, erosion all contribute to this. Remember that it isn't always noticeable, it can happen quite slowly. Rivers change their courses, coastlines can be eroded in places, built up in others, and that's without human input.

ConferencePear Tue 17-May-16 13:37:53

I don't think anyone has mentioned flooding. Sites near to rivers can be inundated and silt , or even stone once the water recedes. Over a long period things disappear.

liquidrevolution Tue 17-May-16 13:38:33

And just to confuse things you sometimes have archaeology which has been purposely buried beneath soil. Its badly worded but think of church graveyards where the ground level of the graveyard is higher than the street outside. Soil was added to increase the amount of burials resulting in the higher ground level.

Also you need to consider how much easier it is to cover something over and build on top, rather than remove it.

liquidrevolution Tue 17-May-16 13:39:24

This is the only thing I can find on google to demonstrate layers...

BrandNewAndImproved Tue 17-May-16 13:43:45

I've always wondered this as well.

CloneMeNow Tue 17-May-16 14:16:47

Great replies, thank you!

So, with the constant production of topsoil by worms, then Planet Earth is slowly expanding? (As the topsoil gets higher)? Or does erosion (topsoil being blown away) counteract this?

Perhaps I should have studied more geology. Unfortunately all we seemed to cover at school was oxbow lakes.

Palehorse Tue 17-May-16 14:39:47

It's called Site Formation, and it can vary depending on the location of the remains (urban, rural?), weather/ground conditions, the nature of the archaeological deposits (wood, stone, burnt, organic etc.) and many other factors.

For example, a wooden (say Iron Age) house built at the base of a hill slope in a non-waterlogged area will leave little trace once the wood has rotted other than foundations (shallow ditches, post-holes, maybe a hearth) and could be covered by metres of colluvium (soil washed down the slope) after a couple of thousand years.

It's easy to see formation processes at work: have a look at a derelict building next time you pass. You'll see leaves, weeds and detritus building up around the edges of buildings, maybe beginning to partially cover carparks or open areas. You'll see weeds and plants sprouting from walls and guttering. Eventually the roof will cave in, maybe it'll be set fire to (as abandoned structures often are!), maybe useful bits (internal cabling/metals, stone/bricks) will be taken off to use elsewhere. Now times that by several hundred years and it's easy to see how what remains ends up underground.

Seryph Tue 17-May-16 14:42:05

Well it is also really variable. For example in some places the archaeology is much closer to the surface, like in Cyprus where you can pick up 5000 year old pottery from the ground as you walk about, and in other's it is much deeper (the Roman pavement under St. Bride's church in London which is a good twelve feet below modern street level).
Human's tend to settle in a place they really like and then use it for a very long time. We just keep rebuilding on top of what went before. Some archaeological sites really have created huge changes to the landscape, like Çatalhöyük in Turkey, which when it was last occupied would have been 20m above the plain it sits on. It's made up of, I believe at last count, 18 layers of building that have slowly built the whole settlement up from the ground!

booklooker Tue 17-May-16 16:38:31

I spend a fair bit of time in wonderful York, I am always taken aback by how far below street level the Merchant Adveturers Hall is.

I find it so hard to imagine that was street level a few hundred years ago.

LittleMissBossyBoots Tue 17-May-16 16:42:30

It's accumulation of dust. I'm doing my bit for future generations. It won't be long before they'll need to dig to get through to the stuff on my windowsill.

sonlypuppyfat Tue 17-May-16 16:42:31

Brilliant question I've always wondered this

Katkincake Tue 17-May-16 16:49:30

I was just at that spot last thurs for our honeymoon, if only if we'd peered through the clear screens that let you look at the construction site instead of dodging people selling selfie sticks!

Basically it's built on top of at a time when it wasn't seen as historic and / or of significance like it is now, i.e. used as foundation to other more important things needed at the time like the road that runs past there or other buildings. There's amazing things under a lot of uk buildings, like an ancient wine cellar for Henry 8th under the mod building on Whitehall.

LurkingHusband Tue 17-May-16 16:49:39

There was a fascinating program a few years ago about archaeology from space - this American archaeologist had used satellite imagery to scour Egypt for evidence of previous civilisations.

It was amazing how much the Nile has moved in a few thousand years. The ruins of some ports were hundreds of miles inland.

Plus they found a legendary city which had been moved - stone by stone - across the desert.

Sadly it's all being destroyed as I type. **ing "treasure hunters" sad.

Furiosa Tue 17-May-16 16:58:39

CloneMeNow Not a dumb question at all!

This was basically the first essay I had to write for my Archaeology degree grin

I'm having flashbacks!

RhodaBull Tue 17-May-16 17:02:13

I'm so pleased someone started a thread on this - I've always wondered. grin at Oxbow lakes. The only thing I've remember from O Level Geography!

Things move - eg The Strand (clue in the name) actually abutted the Thames at one time and now it's some distance away.

What I wonder is why Cavemen? Where are these caves? None round here. Why were there caves in cavemen times and where did they all disappear to?

JinRamen Tue 17-May-16 17:07:29

I don't think the earth would get bigger, as it is all recycled and there is only a finite amount of matter?

Furiosa Tue 17-May-16 17:15:30

No the earth isn't expanding with more soil. And not all sites are buried.

A better question would be "why do some archaeological sites remain visible in the landscape while others do not?"

I'm sure you could come up with a couple of hundred reasons yourself just thinking about that!

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