The hole pictures brings back bad memories.  Out in the desert here around San Diego are lots of abondonded mine shafts.  About 20 years ago on a Boy Scout campout, my son came across one and was peaking over the edge.  Of course he fell in.  Lucky he landed about 20 feet down onto a platform - or else it would have been about a 100 foot fall.  Took us hours to get him out because the sides of the shaft kept collapsing on him...  He ended up with bumps, bruises, and scrapes, but no broken bones.  

LVS - Where Learning is Fun!  
http://www.lvsonline.com/index.html