...ever looked for signs? "Life After People" has got me thinking : If their were a civilization here before humans, in "deep time", would we even know what to look for, and would their be anything at all?
We would probably recognise them by the charecteristic sign of all human cultures - their rubbish. Materials like gold, glass and ceramics would last pretty much forever in sedimentary rocks as long as they are not subducted into a plate boundary or melted by volcanic activity.
There ought to be evidence of mining - quarries, tunnels and spoil heaps preserved in the geological record. The pollution created by an industrial society would be preserved as layers of sedimentary rock containing high levels of pollutants like lead.
I like Douglas Adam's idea that the end of an industrial society would be marked by a layer composed entirely of shoes - the "shoe horizon". The idea being that when things get really bad people buy a new pair of shoes to cheer themselves up.
Oh and - based on our own history - there would be a very rapid and global mass extinction of species with no obvious geological cause.
