Learning about sinkholes and what causes them

Learning about sinkholes

Sinkholes mainly occur in what is known as karst terrain, areas of land where soluble bedrock (such as limestone or gypsum) can be dissolved by water. With cover-subsidence sinkholes the bedrock becomes exposed and is gradually worn down over time, with the holes often becoming ponds as the water fills them in.

With a cover-collapse sinkhole this same process occurs out of sight. Naturally occurring cracks and small voids underneath the surface are hollowed out by water erosion, with a cover of soil or sediment remaining over the top. Eventually, as the hole expands this cover can no longer support its own weight and suddenly collapses to reveal the cavern underneath.

What are the warning signs?
In many cases sinkholes don’t form suddenly, they build up slowly over many months or years.

Its the last stage, when the formation of the hole or basin is at the very surface, that’s sudden.

Here are signs that might indicated you have a slow-burning sinkhole on your hands:

Fresh cracks in the foundations of houses and buildings,
Cracks in interior walls,
Cracks in the ground outside,
Depressions in the ground,
Trees or fence posts that tilt or fall,
Doors or windows become difficult to open or close,
Rapid appearance of a hole in the ground,