One May evening in 1981, a resident of Winter Park, Florida (USA) noticed a nearby
sycamore tree suddenly disappear from sight. The tree had fallen into a newly created
hole that rapidly expanded until, within the day, it had swalled homes, shops,
automobiles, a pool, and a grove of trees. The final hole was 350 feet wide, 125 feet
deep, and it had consumed 160,000 cubic yards of ground.
The Winter Park sinkhole was a large example of a sinkhole, a collapse of earth that
occurs in places where groundwater has dissolved limestone bedrock and filled it with
cavities into which the soil falls.
Sinkholes generally occur during dry periods, when the natural water levels in the
limestone bedrock lower. The water moves downward into the cavities, carrying along the
layers of clay and sand that support topsoil, which then collapses.
Sinkholes are often found in Florida, Alabama, Pennsylvania, and others. In Kentucky,
they have created a large area of rolling terrain. In New Mexico, numerous sinkholes are
connected by natural trenches, forming a line that stretches across the plains. In China,
South Africa, and the Caribbean islands, millions of sinkholes have created basins and
pits more than 1,000 feet deep.
Geologists can easily identify areas in danger of sinkhole collapses, and they estimate
that 15 percent of the earth’s surface rests on such territory. Researchers are still
working on how to prevent such an event.