What Is A Sinkhole?
It's a long way down, hope you have insurance
This is photo-shopped, but you never know what lurks down there....
Pretty....but not the mountain view most people would expect
Bedrock Common with Sinkholes
Natural/Human Sinkhole Causes
Natural Causes: Erosion, cave collapses
Human Causes: Abandoned mine collapses, water main breaks, sewer collapses, overpumping, weight of new material, etc