How did ancient cities become underground?

Answer 1

Well Corbin,

it is not just "ancient" cities but even parts of cities from as late as the 1920's and such.

Urban sprawl and expansion creates waste, as in landfill and all the debris from a building being torn down as to place up a new one. Guess what the contractors, being to lazy to haul out the bricks, stone, and such just level it and build on top.

Flooding as in urban settings is a major factor. It is amazing how many places have seem major floods in the last century, mostly in the USA and also the UK I have many examples.

Even in the mid 20th century most "rebuilt" over the new soils
deposited. Again to expensive to haul away after a fire, flood, earthquake, well tamp it down and rebuilt.

Amateur archaeologists and such as bottle hunters or those folks with metal detectors know where to look: I live in a city that suffered a major flood about a hundred years ago: it changed the map.

I read that london is always finding stuff under the sites of new construction from Roman graves to well WWII german bombs.

People lived and built near rivers, streams, often in flood plains. So one does not need a volcano to cover a city; the cities own garbage will suffice!

Answer 2

All answers here are correct, and the last two are excellent. I'd only add that the effect of garbage - mostly organic waste, accumumulating around and in towns shouldn't be underestimated. You also need to take into account that the degree of 'submersion' is not constant, nor indeed always catastrophic (as in the case of a flood or earthquake), but sometimes episodic, following the 'rise and fall' of the civilization.

While societies in 'full flower' might have efficient garbage removal systems, a socienty 'in decay' generally does not, and in such circumstances animals are often brought into the city, and gardens and public places converted into cropping and grazing areas. If the decay of the society is accompanied by depopulation (war and disease) then the houses and buildings in many areas become vacant, and the stonework/brickwork is often taken away (to be used elsewhere) leaving just the foundations. The grazing animals, and the grass then easily cover the foundation with manure and new growth. Because the animals are concentrated in the former city (close to the remaining inhabitants) the rate of deposit of manure etc is much higher than you'd see in open countryside.

A city might go through many cycles of decay and prosperity, and the periods of decay can last for many years. Our impression that ancient cities were 'continually' and fully occupied until the moment that they were abandoned doesn't fit with the historical record. You only have to look at an old industrial area in a modern city to get the point.

As prosperity returns and the population grows again, the grazing areas are 'smoothed' flat (the point being made by the earlier contributors) and new building set up on top of the old, sometimes re-using the old foundations, but often not, as they had been buried and 'lost' to sight.

Answer 3

Most ancient cities did not begin underground, they began at ground level and gradually the city was built on top of them. Good examples of this include Sacramento, California, which has so many floods in the 1800s that they raised the level of the streets to the bottom floor of buildings, making two story buildings only one story, and three story buildings two. They are still there today. Edinburgh Scotland had streets that were so infested with plagues that they closed them up, sealed them off, and then built right on top of them. Ancient cities in Greece, the Middle East, etc. were built on top of the rubble of the previous cities. Cities would be damaged by fire or attack or war or disease or earthquake and the people would just build on top of what was left after the disaster. Gradually it build up higher and higher. That is why archaeologists sometimes have to dig down through many feet and layers to get to where they want to be, but they are digging through history as they go.

Answer 4

Destruction by wars, earthquakes and other natural disasters; the passage of time covering the remains with sand, dirt, debris, later to be uncovered by archeologists.