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Why does Florida have so many sinkholes? Welcome to the layer cake

Parts of Florida sit on brittle layers that can collapse. News 6’s chief meteorologist explains

ORLANDO, Fla. – In Central Florida, we’re notorious for a lot, but one thing that scares every homeowner? Sinkholes.

So why are they so common, especially here in Central Florida?

We bring in a layered cake.

devil's food cake on a white background (bonchan)

Well, not a literal cake.

Now the base of this cake is limestone, made up of small, broken-up shells from millions of years ago. The problem with limestone is that it’s very soft and very porous, so as rainwater and groundwater run through it, it slowly wears it away, creating bigger tunnels, creating bigger issues.

A graphic showing a cross-section of Florida's geology around the Floridan Aquifer, including the layers of limestone, clay and sand that makes up the peninsula. (Manatee County Water Atlas)

Now that wouldn’t be a huge deal, but the problem is that right on top of that limestone is a layer of sand, not the sturdiest.

Now, since sand doesn’t hold up very well on its own, the moment that limestone gets a hole big enough, the sand eventually collapses. And that is where we have problems.

Devil's Den in Williston, Florida. (Christopher Raines)

This is especially true for much of western Central Florida. Pasco, Hillsborough, and Hernando counties even make up an area known as “Sinkhole Alley.”

While most sinkholes tend to be small, like around roadways, we still have some bigger, notorious sinkholes that can eat up cars and homes. Did you know our most notorious sinkhole? Lake Eola, in the City Beautiful.

Lake Eola in Orlando, circa 1908. (State Archives of Florida)

The sinkhole began forming in 1873, filling with groundwater from the aquifer, 200 feet below the surface, to form a lake. The owner of the property, Jacob Summerlin, the “Cattle King of Florida,” donated the land around the lake to the city in 1883.

More recently, in 1981, “Lake Rose” formed in Winter Park. The sinkhole swallowed the home of Mae Rose Owens, part of a Porsche dealership, parts of several businesses, and a community swimming pool.

[WATCH: Flashback: 1981 Winter Park sinkhole]

Because sinkholes can form anywhere in Florida, not just in “Sinkhole Alley,” it’s important to know your risk and to know what’s covered in the event your home is damaged. Not all insurance policies cover damages to your home due to a sinkhole, but Florida Law does require insurance companies to cover “catastrophic ground cover collapse.”