Eli5; Archeology/Geology – as you go down you can “see into the “past”…


I’ve seen this for years and always wondered. When they(geologist/ archeologist) dig down to “discover” things- why is it buried? Where does that dirt come from? Stupidly I would think the earth was getting “bigger” or maybe only some places get buried with age and others loose dirt. What is the process for things thousands of years old getting covered in layers of dirt? How can we tell the age by the “depth”?

In: 2

There are many reasons so it could be one or a combination of factors. The first thing to understand is “survivorship bias”.

Things that didn’t get buried or lost, would likely be taken apart or destroyed. So most of the things that survived thousands of years would be lost or buried to preserve them. So when things are dug out of the ground, it is BECAUSE they’re buried that they survived. The rest didn’t.

For human built things like cities etc, it isn’t until recently that we have big machines to excavate and move large amounts of material quickly. In the past, the quickest way to build on the same location was to bury the stuff and build on top of it. For example, if a village or settlement is in a good location by a river etc and people wanted to live there, they’d tear down the old stuff that they wanted, bury the remaining and build over things that were previously there. This was practically the only thing they could do.

In areas where plant growth etc are in abundance, things will naturally get buried over time. Leaves fall on things, then get broken down into soil. Then more things grow on that soil and deposit more leaves, branches and roots, that turn into soil. Then more things grow on that soil etc. Given enough time soil will cover stuff.

Things like wind deposited sand, volcanos, mud slides, etc only tend to bury stuff as well.

Remember at the end, the stuff that didn’t get buried probably got destroyed either by weather, erosion etc or by humans and animals.

Erosion or volcanoes, combined with silt from rivers and decaying plant material build up over centuries to bury cities and monuments in a thick layer of soil. is deposited on the site over time which buries sites. https://youtu.be/EofirRBIh28