MINNEAPOLIS - Sinkholes can swallow up earth in an instant and
cause damage or even worse. A sinkhole in Florida claimed the
life of a 36-year-old man on 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 mngs.umn.edu.
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