MINNEAPOLIS - Sinkholes can swallow up earth in an instant and cause damage or even worse. A sinkhole in Floridaclaimed the life of a 36-year-old manon Thursday.

"They can be unpredictable," said Greg Brick, author of the book "Subterranean Twin Cities." "It's why we have an entire profession, geotechnical engineering."

Sinkholes happen in Minnesota, too. Some occur naturally like the massive indention in the Longfellow neighborhood of Minneapolis; a sinkhole 30 feet deep which occurred 3,000 years ago. Others can be caused by broken water mains. But most in Minnesota are found in the southeast corner where there have been hundreds.

"They tend to be found in what are known as karst areas where you have the limestone bedrock that can be easily dissolved by water," says Brick.

In the Twin Cities, you have what geologists call the "classic layer cake" of limestone then St. Peter sandstone.

To learn more about the bedrock in Minnesota, visit

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