Originally Posted by Jodie
If stone was not used for buildings then I would think very little would be left to excavate unless it was something suddenly cataclysmic,
You would be wrong. Take a modern skyscraper: it has all sorts of glass, metal, and other bits that would clearly indicate that something is going on. And if nothing else there's this great bloody hole in the ground where the foundation used to be, arranged in a manner that simply doesn't exist outside of human involvement. We've found all sorts of ancient buildings from that sort of evidence. Then there are the ancillary facilities--the farms, the mines, the factories/processing stations, etc. Even stone-aged peoples left processing stations (debatoge, limestone pit ovens, things like that); a city would require immensely greater numbers of all of that, which would make it far easier to detect.
To get rid of a city you have to scour the area down to at least the maximum depth of the deepest foundation. And there's really very little that can do that.
As far as sea level rising, submurged artifacts may in fact be better preserved than their terrestrial counter-parts. Water doesn't make iron rust--repeatedly dipping iron into water and exposing it to air makes it rust. Just putting it in water would do remarkably little. The issue would be more that the wildlife would cover the artifacts, making them a tad difficult to detect (but certainly not impossible; we do this all the time).