General Question

El_Cadejo's avatar

How do ancient cities get buried?

Asked by El_Cadejo (34387 points ) October 16th, 2008

I mean everyone has read about archaeological digs and how they discover these ancient cities buried by the sands of time.But where does all the dust/sand/dirt come from? Im sure some of this comes from mountains erroding, but it still seems to me like it would take a huge mountain to erode to cover a whole city.

PS im not talking about cities like Pompeii that were located next to a volcano.

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22 Answers

robmandu's avatar

Sometimes, a newer city is simply built on top of the old one.

Magnus's avatar

By bastards with shovels.

Spargett's avatar

Fires tend to be a big culprit of this.

Harp's avatar

There’s a good explanation here.

jvgr's avatar

In adding to robmandu’s note, Jerusalem (inside the walls) was a very hilly city. Every successive conqueror, razed buildings and pushed the rubble into the valleys and started to build their own buildings.

El_Cadejo's avatar

@Harp ahhhh thank you for that link, just what i was looking for.

loser's avatar

I always thought they were just shy.

laureth's avatar

Dirt and dust blow around. There are whole dunes that move around with the wind, slowly but surely. In the 1930s, so much soil blew away from the American heartland that it became known as the “dustbowl.” These are just the big dramatic things we can see, but even over the thousands of years it takes to bury these cities, the little bit of dirt blowing around that we don’t even consciously see can bury it just fine.

A farmer with some marginal land can plant grass, and as his cattle eat the grass, the buildup of humus (good fertile soil) from the dieback of the grass can improve the land enough to make it a good farm in less than a generation. I’m not surprised that some archaeological sites from 30K BCE are found under 9 feet of soil. The steppes are nothing but a dirtbuilding machine!

Next time some fall leaves blow into a corner near your house, check out how they decompose and add just a little to the dirt. If you can imagine a jungle dropping all its leaves every year on a site, you’ll see why they get buried so easily.

AlfredaPrufrock's avatar

This is a really great question! I can see volcanoes erupting, tidal waves, earthquakes, etc. but like why is there a whole city under London, Paris, and New York? I know leaves decompose and create dirt that builds up but you would think that people would notice a foot of dirt outside their door…

That’s a great site, Harp!

El_Cadejo's avatar

@laureth yea i considered the dust and dirt being blown around, but then while some cities were being covered others would have to be uncovered. Another question to consider is if there is decomposing leaves and all building up dirt, is the earth larger than it was before?

harps link pretty much answered this question, just some things i thought about prior to posting the Q

AlfredaPrufrock's avatar

I think it gets redistributed. Matter is neither created nor destroyed.

El_Cadejo's avatar

@alfredaprufrock yes but the earth does accumulate ~10,000 tons of meteor dust a year

elchoopanebre's avatar

Great question, uberbatman. I’ve been wondering this myself.

laureth's avatar

I don’t think people would notice a foot of dirt outside the door when the city has been abandoned for a thousand years.

fireside's avatar

lol, you mean they didn’t leave behind someone to keep the place clean?
not very green of them to just use the land and then take off while there’s space dust accumulating.

El_Cadejo's avatar

Sub question. Why do these cities get abandoned long enough for them to be completely covered in dirt/sand?

obviously this question excludes cities that were built over

laureth's avatar

Very often, back in the day, they’d run out of resources – one of the reasons that one Native American civilization (I can’t remember the name of it, sorry) collapsed and abandoned its city was that they’d used up all the firewood within a few days walk.

Sometimes war can cause a place to be abandoned, because there aren’t any survivors to carry on. This is what’s already happening in places like Darfur, as homes and cities revert back to nature.
http://www.scidev.net/en/news/satellite-images-put-all-eyes-on-darfur.html

Sometimes the environment changes and makes a place inhospitable, like here: http://www.msnbc.msn.com/id/26405051/wid/18298287/

It’s amazing how fast nature can take over a place where people haven’t lived for even a few years. If you’re interested in the subject, I recommend a book: “The Earth Without Us” by Alan Weisman.
http://www.worldwithoutus.com/did_you_know.html

El_Cadejo's avatar

awesome answer laureth thanks

ROBROY01's avatar

You know, out of all of the possible explanations I have seen for this on the web (and they are ALL plausible and well thought out), I have not seen a single mention of Noah’s Flood leaving behind sediment from the world-wide flood, burying much of the civilizations of the ancient world. Let us not forget there are world-wide flood myths in nearly every culture of the ancient world too. After all, Archaeology does an excellent job of proving the Bible, so why not a world-wide flood event too? The Bible notwithstanding, there is still plenty of archaeological evidence to support a world-wide flood event anyway.

Ancient buildings built on bedrock, out in the middle of nowhere, with very little water, STILL gets buried and I cannot believe that simple atmospheric dust (also known as aeolian dust) or even wind-born dust can completely bury these giant stone buildings (not made of mud bricks). That kind of dust is loose anyway, which would still blow around and be pretty hard to stick to any one place enough to be combined with water (and it would need a LOT of water) over the centuries to make it pack solid enough to require a shovel to unbury it.

Just food for thought… :)

Response moderated
SavoirFaire's avatar

@ROBROY01 “I have not seen a single mention of Noah’s Flood”

Yeah, we don’t go in for mythology much around here. And that’s what the global flood “theory” is—a myth.

“Let us not forget there are world-wide flood myths in nearly every culture of the ancient world too.”

Actually, this is false. Global flood myths were very common in ancient cultures that were located near a body of water that flooded regularly. But they are not at all common in ancient societies that were located near stable bodies of water or that relied on rainfall, reservoirs, and/or aqueducts for their water supply.

“Archaeology does an excellent job of proving the Bible”

Not really. Archaeology tells us that a few of the historical people, places, and events mentioned in the Bible were real. But it does not verify the majority of the Biblical narrative. In fact, it raises quite a few questions about stories found in the Bible. Sometimes these questions are just a matter of scale (i.e., the Bible seems to depict things in ways more grandiose than the physical record suggests). Other times, there are questions about the very reality of elements described in the Bible.

Ultimately, however, discovering that the Bible kept an accurate record of the size and placement of cities, the lineage of their rulers, or the wars in which they engaged wouldn’t really do anything to validate the theology found alongside it. After all, I could take a collection of the most accurate history books ever written, duplicate and combine their contents, and then sprinkle completely made up passages of religious propaganda all throughout the book; but the reliability of the historical passages wouldn’t do anything to support the religious passages. That’s just not how evidence works.

“The Bible notwithstanding, there is still plenty of archaeological evidence to support a world-wide flood event anyway.”

No, there is not. What there is evidence for is that much of the world has, at various times in (relatively) recent history, been subjected to flooding events. What there is not evidence for is that these flooding events were actually a single flooding event that occurred everywhere in the world at the same time. In fact, the pattern of geologic evidence suggests a protracted series of separate flooding events. Given that the planet started retreating from an ice age about 12,000 years ago, this is not even remotely surprising.

“Ancient buildings built on bedrock, out in the middle of nowhere, with very little water, STILL gets buried”

As has been more than adequately covered by previous answers, flooding isn’t the only way to bury a city. In the case of a stone city, which seems to be your main concern, the most likely scenario is that it was abandoned, went through a period of decay, and then was built over by new settlers.

But even if flooding were the only way to bury a city, that still wouldn’t require a global flood. Many rivers flood every year. Plenty of places get occasional flooding just from rainfall. Abandoned aqueducts will eventually collapse and cause water damage to a crumbling city. And there are non-global weather events that still have a massive impact. The 2004 tsunami, for instance, hit coastal villages in eleven different countries.

Furthermore, just because a place is in a desert in the middle of nowhere today doesn’t mean it was always that way. Weather patterns change. Rivers get diverted. The Sahara desert used to be wet, lush, and fertile. Now it’s not. The world is not static.

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