The oil, the coal, the gold, copper, everything-- not only does it leave space, even natural gas opens areas up for water or air invasion- the air breaks the capillary cohesion and ruins wells.
the most recent atrocity is mountain top removal... see http://www.ilovemountains.org to see "the empty spaces"
we/they also leave tons and tons of stuff like space lab out there. John Lydon (Rotten) wrote a song about it back in the early eighties.
the earth is expanding tho, according to the experts, and changing shape, much faster than anyone ever predicted.