They'd have to take recycling to a whole new level, to place the different metals separate geological seams, however. If the human race were wiped out this aft

They'd have to take recycling to a whole new level, to place the different metals separate geological seams, however. If the human race were wiped out this afternoon, and you came back in 100 million years, you'd still be able to tell the difference between a mineral seam and a landfill or scrap metal merchant.