With the Wild Things: Sinkholes

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|a With the Wild Things: Sinkholes |h [electronic resource].

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|a Ft. Myers, Florida : |b Whitaker Center in the College of Arts and Sciences, Florida Gulf Coast University.

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|a 5 podcasts, approximately 1 minute each in length

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|a Please contact the owning institution for licensing and permissions. It is the users responsibility to ensure use does not violate any third party rights.

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|a Source: Sinkholes 1 Length of Segment: 00:01:11 Hi, I'm Dr. Jerry Jackson, out with the wild things. Sinks, or sinkholes, are holes on the Earth's surface where underlying rock has collapsed. Water collects in sinkholes and seeps back into the underground aquifer that provides much of our drinking water and the source of water for Florida springs. In an otherwise relatively flat state, sinks provide dimples on the surface and windows to the world below. Some of Florida's most unique habitats are associated with sinks and several sinks have been protected as state or private parks or recreational areas. Sinks form in two ways. Sometimes currents of water flowing through the limestone foundation of Florida hollow out a passageway to the point that the roof is eroded away and caves in. Such sinks often leave sides showing the limestone architecture and geological history of our state, often revealing the entrances of caves. In other cases, surface water erodes and dissolves limestone near the surface, and the surface simply settles in, leaving an increasing depression in the earth. Such subsidence can continue to occur for millennia, growing in extent as well as in depth over time.

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|a Source: Sinkholes 2 Length of Segment: 00:01:14 Hi, I'm Dr. Jerry Jackson, out with the wild things. As Florida's human population grows, the incidence of sinks occurring in populated areas has grown. Sometimes, this has been with disastrous results. In 1981, a Winter Park home, six vehicles, and parts of two streets dropped into a 300 foot wide, 100 foot deep sinkhole. Geologists and engineers learned from such events, but prediction of sinkhole formation remains largely a guessing game. Sinkholes are a part of life in North and Central Florida, but rare in South Florida. Sinkholes are formed as water erodes and weakens the underground architecture of Florida's backbone, but human actions can play a role in sink formation. Water not only erodes limestone to create tunnels and caverns beneath Florida, but it provides some support. During times of drought and over-use of water resources, the level of ground water goes down, removing support and weakening the roofs of underground caverns and tunnels. Sinks sometimes fill with water to become a lake; wildlife quickly moves in, some of it helped by the conditions favoring sink formation by way of water-filled tunnels through the limestone.

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|a Source: Sinkholes 3 Length of Segment: 00:01:15 Hi, I'm Dr. Jerry Jackson, out with the wild things. One of Florida's largest sinkholes, and the only officially designated state geological site, is Devil’s Millhopper State Geological Site a few miles northwest of Gainesville. Some estimates place its origin at more than 20,000 years ago. Fossils at the bottom attest to its prehistoric origin and use by early Native Americans. Only 500 feet across, Devil's Millhopper is steep-sided and 120 feet-deep; 232 wooden steps take visitors to the bottom, allowing a cross-section view of Florida's geological history and unique habitats created by the sink. Steep sides result in shading. Small springs create waterfalls that contribute to the beauty and coolness of the sinkhole, buffering it from the changed world above. Streams return water to the underground system. Devil's Millhopper provides habitat for the rare red-legged purse web spider and habitats for ferns, violets, jack-in-the-pulpit, and other plants characteristic of more northern hardwood forests. Many of these creatures are relics, left behind as the cooler climate of the Ice Ages warmed, and our current flora and fauna developed.

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|a Source: Sinkholes 4 Length of Segment: 00:01:15 Hi, I'm Dr. Jerry Jackson, out with the wild things. Sinks result from collapse of limestone rock that was eroded away by water. We sometimes find chains of sinks, one depression or sink hole after another following the course of an underground stream channeled through the rock. Leon Sinks on the Apalachicola National Forest in Leon County includes a chain of many linked sinks, gateways to the hidden world below. The trail to the sinkholes leads past several depressions, sink holes in the making, where the limestone is being dissolved by water seeping down from the surface. Rain is naturally slightly acidic and acidity of the water is increased by decay of pine needles and other ground litter. This acid water reacts with the limestone, hastening creation of the sink. In 1999, cave divers set a record by traveling more than 14,000 feet through submerged limestone caves from the Big Dismal Sink in Leon County to Cheryl Sink in Wakulla County. They thus demonstrated how unique cave crayfish and other creatures can become dispersed through a wide area, and how pollutants at one site might have an impact on distant cave communities.

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|a Source: Sinkholes 5 Length of Segment: 00:01:12 Hi, I'm Dr. Jerry Jackson, out with the wild things. Divers in Florida sinkholes have made astonishing discoveries of evidence of prehistoric life. Bones of mastodons, camels, giant ground sloths, saber tooth tigers, and other creatures of the Ice Age litter the bottom of North Florida sinks. Some older sink holes that have been filled in are discovered during construction activities and yield important fossils. The most famous such site in Florida is the eighteen million year old Thomas Farm Bone Bed in Gilchrist County. Fossils attest to the ancient age of the sinks and wildlife that roamed prehistoric Florida, but new bones are still being added as new sinkholes appear. A sinkhole can form abruptly when the roof of an underground cavern collapses. Any animal on the surface at the time may find itself trapped in a 100 foot-deep steep-sided hole from which escape is impossible. The bones of victims are often preserved from normal decay by the high mineral content of the water at the bottom. Sink holes remain as natural pitfall traps, capturing the unwary and preserving a continuing record of life in the region.

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|a Sinkholes.

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|a Dr. Jerry Jackson.

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|t Sinkholes 1

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|t Sinkholes 2

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|a dpSobek.

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|a Everglades Digital Library: Reclaiming the Everglades.

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|a With the Wild Things.

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|a dpSobek |c Everglades Digital Library: Reclaiming the Everglades

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|a Everglades Digital Library: Reclaiming the Everglades