I have a question that’s been bugging my wife for a while and I can’t offer a succinct explanation.
When watching history programmes we often see the remains/foundations of old houses and roads – dating to the Roman times and even older. Most recently was a Roman building in the basement room of an 20th century office block in central London.
Her question is how it is possible that houses and roads are built on top of older versions. Is it subsidence caused by weather or tectonic plates or is it the more simple notion that they are literally built on top of the former dwellings? (I doubt the latter as they wouldn’t be so preserved if this was the case?).
Anyway, if anyone can put her mind at rest I’d be a happy husband; a google search didn’t throw up anything relevant.
People were lazy, had limited resources and messy.
The old building was either deliberately or accidentally destroyed (fire, war, whatever). Some of the easier to remove pieces would be cleared away, but most wouldn’t be. So you just keep building up.
Note that garbage would be thrown all over the place, especially in the streets but also on top of ruins, increasing the local height. It is usually a good idea to start a new building at the new higher elevation rather than digging down to the old foundation.
In the Middle East, you get tells that grow to incredible sizes. They usually built on crumbly old mud bricks rather than clear them out. Removing stone pieces would be even harder work.
Plants play a big role in burying old buildings. If you look at something that’s been abandoned for a few years, you can see weeds growing in certain places. And little trees too. As time goes by, these either grow or die, and eventually you have soil, which is an invitation for additional plant growth. Imagine this happening over centuries and millenia.
We also continue to do this. We construct landfills, and when they are full, seal them carefully, put soil over them, and build parks. Here are 10 of those: Garbage to Green: 10 Landfills Turned into Nature Preserves - WebEcoist At some point, the land will be redeveloped, and an office building or apartment complex will be constructed. Then that construction will be razed and wham, instant archeological site.
See, you probably don’t think landfills are interesting historically. But that is just our flavor of irreverence. Early Christians probably didn’t care at all about the pagan Roman constructions crumbling all around them, they just piled dirt upon them to build a house, or abbey. Only later do people start to care.
Today, when we demolish a building, we have heavy diesel or steam powered equipment to remove every last trace of it.
Prior to this heavy equipment, foundation stones would have to be removed by hand, beast, or by winches powered by either. This would be grueling work. Instead, they would simply reuse as much of the original foundations when possible, or bury the the foundations and build on top. Since the foundations were of stone, they would basically last forever.
As an example, there is a thousand year old reservoir under Constantinople. Digging up old foundations might undermine the roof of the chamber, so new buildings simple went up over the footprints of older buildings. Modern construction over the chamber uses the same techniques!