Post by L Roebuck on Oct 17, 2005 5:57:34 GMT -5
In search of sinkholes -- Santee State Park’s limestone deposits make for interesting tour
By GAIL GOINS, T&D Santee Correspondent
SANTEE -- Ever hear the phrase: “Who’d a thunk it?” Well, who would think that a walk through the woods to look at limestone sinkholes would be interesting? Certainly not this reporter. But, interesting it was, thanks in part to the information provided by Santee State Park Ranger Seth Caughman.
A one-hour, four-tenths of a mile guided nature walk to Limestone Sinkholes within the park was offered on Oct. 8. Though only a small group attended, the walk was both enjoyable and informative. Let’s start with the basics of what the tour participants learned.
How is limestone formed?
Over millions of years, the earth’s climate fluctuated, changing the shape and position of the continents. The tilting of the continental plates had a dramatic effect on the sea levels. As a result, much of the planet’s water was frozen in the polar ice caps and glaciers during the Ice Age, lowering the ocean levels. In warmer periods, the ice melted, causing the oceans to swell.
These changing conditions determined which plants and sea creatures lived in the oceans. As the animals died, their remains, rich in calcium, settled to the ocean floors, Ranger Caughman said. Over the years, these remains were covered by layers of sediment (dried leaves, grass, plants, trees) and were transformed into limestone, or calcium carbonate, under the influence of pressure and chemical action. This happened fairly quickly.
The rocks at the Santee State Park are known as Santee Limestone, Caughman said. Limestone rock in Santee can be red clay, black or yellow. This formation began 40 to 50 million years ago when a shallow, sub-tropical sea covered the area. This geological formation occurs in an east-west belt across the South Carolina Coastal Plains, Caughman said. The warmer waters were rich in sea animal life and can be seen today in fossilized remains within the rock.
What exactly is a limestone sinkhole?
Sinkholes are natural depressions in the land’s surface that occur where there are underlying deposits of limestone. Most people could walk up on a sinkhole and not know what they were looking at. These geological features are common in Santee State Park, Caughman said, and occur in various stages of development.
On the Oct. 8 walk, the group saw several examples of sinkholes, none of which looked the same. The first appeared to be a large hole in the ground with trees growing out of it. The second, had it not been pointed out, would have gone unnoticed. The third was a beautiful pond untouched by human hands but home to many large alligators and some wood ducks. The fourth looked like another hole, and the fifth sinkhole was a cavern.
A sinkhole usually begins when seeping groundwater or an underground stream dissolves the calcium carbonate of the limestone, creating ducts which eventually expand and form submerged caves, Caughman explained. As years go by, the water levels may drop, either from human consumption (man-made wells, ponds, etc.) or drought, causing the cave to become filled with air. If the expansion is great enough, the roof of the cavern may collapse, thus forming a sinkhole. Sinkholes occur in areas where the overlying soil layer is thin.
Sinkholes monitored for safety
The sinkholes in Santee State Park, Caughman said, serve several purposes. He said the park’s sinkholes have been designated a Heritage Trust site.
“Geological surveys are done here. This is vital for our area and is heavily monitored,” he said, adding that the monitoring, among other things, checks the size and depths of the sinkholes.
Maintaining the safety of the park’s visitors is an ongoing job, Caughman said.
“There is one sinkhole that is deeper than a three-story house, and you could still never see the top of the house. This sinkhole is toward Highway 6 and is a half-mile in the woods,” he said. “Trees are growing in it, and it is starting to fill with debris.”
Limestone was first mined in South Carolina in the 1820s. The rock, which is alkaline based, was crushed and spread in fields to neutralize acidic soil. This process increased crop production. Today, South Carolina’s limestone is used in the production of cement, concrete and in agriculture (to naturalize acid soil for rye grass, cotton, corn), Caughman said. In other regions, limestone is used as dimension stones (for corners of houses or for pillars in homes), poultry grit, railroad ballasts and in sulfur and chemical industries.
Another purpose for limestone sinkholes, the park ranger said, is that they are home to several species of snakes, spiders, frogs and salamanders — all of which play a role in the environment.
The 2,495 acres of Santee State Park are home to several diverse forms of wildlife — whitetail deer, red and gray foxes, raccoons, and colonies of Myotis bats.
For more information about the park, call 803-854-2408.
www.timesanddemocrat.com/articles/2005/10/16/news/doc43532063d13a0259360776.txt
By GAIL GOINS, T&D Santee Correspondent
SANTEE -- Ever hear the phrase: “Who’d a thunk it?” Well, who would think that a walk through the woods to look at limestone sinkholes would be interesting? Certainly not this reporter. But, interesting it was, thanks in part to the information provided by Santee State Park Ranger Seth Caughman.
A one-hour, four-tenths of a mile guided nature walk to Limestone Sinkholes within the park was offered on Oct. 8. Though only a small group attended, the walk was both enjoyable and informative. Let’s start with the basics of what the tour participants learned.
How is limestone formed?
Over millions of years, the earth’s climate fluctuated, changing the shape and position of the continents. The tilting of the continental plates had a dramatic effect on the sea levels. As a result, much of the planet’s water was frozen in the polar ice caps and glaciers during the Ice Age, lowering the ocean levels. In warmer periods, the ice melted, causing the oceans to swell.
These changing conditions determined which plants and sea creatures lived in the oceans. As the animals died, their remains, rich in calcium, settled to the ocean floors, Ranger Caughman said. Over the years, these remains were covered by layers of sediment (dried leaves, grass, plants, trees) and were transformed into limestone, or calcium carbonate, under the influence of pressure and chemical action. This happened fairly quickly.
The rocks at the Santee State Park are known as Santee Limestone, Caughman said. Limestone rock in Santee can be red clay, black or yellow. This formation began 40 to 50 million years ago when a shallow, sub-tropical sea covered the area. This geological formation occurs in an east-west belt across the South Carolina Coastal Plains, Caughman said. The warmer waters were rich in sea animal life and can be seen today in fossilized remains within the rock.
What exactly is a limestone sinkhole?
Sinkholes are natural depressions in the land’s surface that occur where there are underlying deposits of limestone. Most people could walk up on a sinkhole and not know what they were looking at. These geological features are common in Santee State Park, Caughman said, and occur in various stages of development.
On the Oct. 8 walk, the group saw several examples of sinkholes, none of which looked the same. The first appeared to be a large hole in the ground with trees growing out of it. The second, had it not been pointed out, would have gone unnoticed. The third was a beautiful pond untouched by human hands but home to many large alligators and some wood ducks. The fourth looked like another hole, and the fifth sinkhole was a cavern.
A sinkhole usually begins when seeping groundwater or an underground stream dissolves the calcium carbonate of the limestone, creating ducts which eventually expand and form submerged caves, Caughman explained. As years go by, the water levels may drop, either from human consumption (man-made wells, ponds, etc.) or drought, causing the cave to become filled with air. If the expansion is great enough, the roof of the cavern may collapse, thus forming a sinkhole. Sinkholes occur in areas where the overlying soil layer is thin.
Sinkholes monitored for safety
The sinkholes in Santee State Park, Caughman said, serve several purposes. He said the park’s sinkholes have been designated a Heritage Trust site.
“Geological surveys are done here. This is vital for our area and is heavily monitored,” he said, adding that the monitoring, among other things, checks the size and depths of the sinkholes.
Maintaining the safety of the park’s visitors is an ongoing job, Caughman said.
“There is one sinkhole that is deeper than a three-story house, and you could still never see the top of the house. This sinkhole is toward Highway 6 and is a half-mile in the woods,” he said. “Trees are growing in it, and it is starting to fill with debris.”
Limestone was first mined in South Carolina in the 1820s. The rock, which is alkaline based, was crushed and spread in fields to neutralize acidic soil. This process increased crop production. Today, South Carolina’s limestone is used in the production of cement, concrete and in agriculture (to naturalize acid soil for rye grass, cotton, corn), Caughman said. In other regions, limestone is used as dimension stones (for corners of houses or for pillars in homes), poultry grit, railroad ballasts and in sulfur and chemical industries.
Another purpose for limestone sinkholes, the park ranger said, is that they are home to several species of snakes, spiders, frogs and salamanders — all of which play a role in the environment.
The 2,495 acres of Santee State Park are home to several diverse forms of wildlife — whitetail deer, red and gray foxes, raccoons, and colonies of Myotis bats.
For more information about the park, call 803-854-2408.
www.timesanddemocrat.com/articles/2005/10/16/news/doc43532063d13a0259360776.txt