Sinkhole Science

A sinkhole is a natural depression in the Earth's surface caused by karst processes, such as the chemical dissolution of carbonate rocks. Sinkholes have no natural external surface drainage, and may be formed gradually by circulating groundwater, or suddenly by a rainstorm.

Sinkhole depressions seem to be a hot topic these days, as they are deteriorating soil across the country, even killing one man, Jeff Bush, last month in Florida. Just a couple of weeks later another man fell victim to what he called, "an unusual depression" on the 14th fairway at Annbriar Golf Club in southern Illinois.

Fortunately, victim Mark Mihal escaped with minor injuries and stated to the Associated Press, "I feel lucky just to come out of it with a shoulder injury, falling that far and not knowing what I was going to hit."

In response to the escalating worry of sinkholes, the United States Geological Survey (USGS) has assured residents that only 20 percent of the United States is susceptible to this kind of disaster, and sinkholes are most likely to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania.

Geologists report sinkholes are common in karst terrain, regions where the soluble rock below the land surface is naturally dissolved by circulating water. Soluble rocks include salt beds and domes, gypsum, limestone, and other carbonate rock.

Cover-subsidence sinkholes are formed over a period of time, resulting in spaces and caverns underground, which are less noticeable and often go undetected.

Although cover-collapse sinkholes are more common, and often occur after heavy rainstorms (sometimes within a few hours), some evidence indicates that drought is responsible as well. In fact, areas where water levels have suddenly been reduced are more prone to collapse formation.

For more information about sinkholes, please visit usgs.gov.

Association news and events are listed at landscapearchitect.com. To view the calendar of upcoming events, visit www.landscapearchitect.com, go to the "Associations/Events" tab and click on "Search for Events."

If your association has news and/or events that you would like featured on landscapearchitect.com, please send your information via email to associations@landscapearchitect.com.