People always seem to be digging up stuff from below the ground - artifacts, buildings and entire cities. Often they are below a current city.
My question is - where do the layers covering the stuff keep coming from? Once upon a time the city was at the ground level and people were walling the streets, and now it is buried underground. Did the ground sink slowly? How did the old stuff get covered by new stuff? Where did the new stuff come from, considering it would take a lot of material to cover an entire city!
How come these ruins are never seem to be at the top? Has anyone done a study of this?