are known in Florida for swallowing up houses
and highways. Florida
is made up of sand and limestone, and in times
of rain huge caverns form in the limestone
to fill with excess water. Then, when there
is a drought, all that underground water flows
away leaving the cavern empty and unsupported.
The roof of the cavern collapses, and the size
of the empty cavern determines how many houses
the marsh water will rapidly fill in any new depression,
but every now and then you can see a small sinkhole
like this one in a dry area
this is in a secluded spot there is no danger of
anyone walking into it - or of it swallowing a house.
The dirt and vegetation will soon fill in the hole,
and there will be no sign it was ever there ...unless
a tree falls over to mark the spot!