One of the ways a sinkhole can occur is when limestone bedrock dissolves and leaves a large cavity. The ground above then caves in, taking homes, trees and other objects on top with it. This video about sinkholes from the U.S. Geological Survey provides a look into how and where sinkholes can occur.
Nina Sen is a frequent contributor to Live Science’s Life’s Little Mysteries series: an exploration and explanation of our world’s phenomena, both natural and man-made. She also writes astronomy photo stories for Live Science's sister site Space.com.