SINKHOLES By Jewel Miller WHAT ARE SINKHOLES v

SINKHOLES By: Jewel Miller

WHAT ARE SINKHOLES? v Sinkholes are depressions or holes in the land surface that occur throughout west-central Florida. They can be shallow or deep, small or large, but all are a result of the dissolving of the underlying limestone.

HOW MANY SINKHOLES ARE THERE? v “There are two basic kinds. One is called a cover-subsidence sinkhole. You find these in places like the Shenandoah Valley, or in sandier soils where you've got a void underground. As the soil above transports itself into that cave in the rock, the ground slowly subsides. So it's not catastrophic. It subsides over time. It could be over years; it could be over hundreds of thousands of years. ” v “The other kind is what we call a cover-collapse sinkhole. This is the one that makes the news. It tends to occur in clay, because clay holds soil together like glue. As with cover subsidence, soil is leaching into a cave below, but it creates a void in the soil that moves upward. You can't see it on the surface. Then, all of a sudden, the bridge over top of that void can't hold anymore and it collapses—just like we saw in Florida last week. ”

WHAT ABOUT SINKHOLES AROUND THE WORLD? Great Blue Hole, Belize – The first sinkhole in the list, and by far the most amazing is the Great Blue Hole. It is a large submarine sinkhole off the coast of Belize. ” The hole is circular in shape, over 300 m (984 ft) across and 124 m (407 ft) deep. It was formed during several episodes of quaternary glaciation starting over than 150, 000 years ago. ”

SINKHOLE OCCURS AT FLORIDA RESORT v http: //www. cnn. com/2013/08/12/us/florida-resort-sinkhole/

DO ANY HUMAN ACTIVITIES CAUSE SINKHOLES? v We also cause sinkholes when we start putting up parking lots and buildings and changing what we call the hydrologic regime. Instead of the water naturally soaking into the ground, it's now running off and being concentrated—being put into the ground at one point.

IS THE FREQUENCY OF SINKHOLES INCREASING? v The answer is we don't know, because we just don't have enough data. Sinkholes aren't widespread events like hurricanes or earthquakes. They're very localized. A lot of karst areas are agricultural, because they tend to have very good farming soil. And sinkholes happen all the time in farmers' fields.

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