Sinkholes

Sinkholes may open slowly over several years or collapse catastrophically. Take a look at some of the sinkholes on this page. Some are brand new. All of them are enlarging constantly. Sinkholes are produced by three processes going on simultaneously:

1. limestone rocks dissolve, and
2. collapse into the created voids, where
3. flowing water transports soil and rock fragments away, down into caves below.

Sinkholes cannot be plugged inexpensively by dumping in rocks. This is because sinkholes have multiple drains downward and sideways. Generally all the buried rock around a sinkhole is weak and weathered. In karst, contractors sometimes test the site by drilling down to "auger refusal", meaning when the auger hits a rock. Buried rocks in karst may be free floating boulders, loose limestone, or thin cave roof beds.

(October 2006) Sinkhole on Sharp Farm near proposed site. The opening is about 3 feet wide, but its depression area measures 30 feet across. Note the grass beaten down by drainage.

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