Sinkholes are caused by underground erosion. They happen in areas where the ground is primarily made of limestone. When water rushes through the limestone during a downpour or flood, the water wears away holes that are much like caves. As more and more limestone gets worn away, the weaker the walls of the hole become until the roof caves in, creating a sinkhole. Since sinkholes can grow up to 60 feet in just a few hours, it is important to know if your property is susceptible. Here are some things to look for in your yard. If you have some of these symptoms, you may be in a sinkhole zone.
Look for round patches of dead grass or plants in your yard.
Check for cracks in your pool, foundation, sidewalks and patios, windows or doors that won't close anymore and for leaning trees or fence posts.
Look for pools of water in your yard that are usually not there after a rain.
Pour a glass of water from your tap and look in it for sediment.
Check for dents or holes in your yard.