Subsidence Sinkholes
The formation of a subsidence sinkhole is illustrated below. Note that the geologic conditions include soluble bedrock (such as limestone) covered by relatively thin deposits of sediments. This type of sinkhole tends to form naturally and is not greatly affected by human activities.
(1) Initially the bedrock contains fractures and small cavities that have formed by dissolution, but no land subsidence has occurred.
(2) Small cavities and cracks grow larger through
time, and sediments from above are slowly carried down
by infiltrating rainwater to fill the voids forming in the bedrock.
(3) Sediments from the upper layers continue to fill in the openings in the bedrock, gradually causing a depression to form at the land surface. If water collects in the
depression, a new lake also forms.
source: Hydrology of Central Florida Lakes--A Primer.