DELARANEWS

Craig

Craig Miller, W8CR

The Karst

I first learned about karsts several years ago from a geologist surveying our property prior to building the barn. He was verifying we weren’t going to interfere with the natural flow of ground water (blocking a stream, etc.) being that we live in the watershed of the Scioto River. He was admiring the exposed rock wall in the ravine behind us as well as the collection of large boulders scatter about dropped off many years ago from those pesky glaciers. He commented that this area is a hotspot for karsts. “What’s a karst?”, I asked, “How do you spell it? I’ve never heard of such a thing.” He said they are basically sinkholes of various sizes and shapes, all indicating a void, or cavern, below the surface. Many karsts drain deep into the ground eventually reaching the aquafer. Some can be very dangerous. He described witnessing a whirlpool of water flowing into the earth after a heavy rain, animals and people can easily be sucked in, only to disappear forever. A likely cause of unexplained disappearances of hunters and hikers over the decades. Each one is different, some are just indents in the surrounding topology others are clearly visible holes in the ground, leading down to nothingness. (Images courtesy of Ohio Department of Natural Resources) Ohio Department of Natural Resources did a thorough survey of karsts all over the state compiling a sophisticated map allowing you to drill down on every known sinkhole. Each is given an identification number along with photos taken during field visits. https://gis.ohiodnr.gov/website/dgs/karst_interactivemap/ According to the interactive map, many karsts are located along the Scioto River valley that runs through this part of Delaware County. Red dots indicate confirmed karst locations. I noticed a karst is even documented on our neighbor’s property about a hundred or so yards away. * * * There is a grove of black walnut trees just beyond the pond on our property, it’s rather peaceful there as long as you don’t roll your ankle or get beaned by a falling walnut. There are about 20 trees clustered around a depression in the soil. Over the years I simply assumed it was a hole dug out in need of dirt to fill in someplace else on the land. There are rather mature black walnuts growing around the depression, nothing inside it though, so it must have been there for quite a long time. After seeing the ODNR karst map I was amazed how many sink holes are in the immediate vicinity, I began to wonder if we may have such a geological wonder in our midst. Just the other day, I decided to research further before contacting ODNR to see if they were interested in taking a look. I figured, if this is a naturally forming depression, the layers of soil should match the surrounding layers, if not, it may very well be a man-made artifact. Using a posthole digger, I punched through the sod around the depression, on average there was 3 to 4 inches of topsoil before reaching clay. Inside the depression, I got mixed results, some areas had rich loam before reaching clay, other areas looked like it was disturbed, not firm layered soil. Plus, I was hitting something solid which may be rocks or tree roots. Using a spade, I decided to just go for it and dig in to see what was below. I kept hitting more and more obstruction. What is down there? (Next page)
DELARANews

Craig

Craig Miller, W8CR

The Karst

I first learned about karsts several years ago from a geologist surveying our property prior to building the barn. He was verifying we weren’t going to interfere with the natural flow of ground water (blocking a stream, etc.) being that we live in the watershed of the Scioto River. He was admiring the exposed rock wall in the ravine behind us as well as the collection of large boulders scatter about dropped off many years ago from those pesky glaciers. He commented that this area is a hotspot for karsts. “What’s a karst?”, I asked, “How do you spell it? I’ve never heard of such a thing.” He said they are basically sinkholes of various sizes and shapes, all indicating a void, or cavern, below the surface. Many karsts drain deep into the ground eventually reaching the aquafer. Some can be very dangerous. He described witnessing a whirlpool of water flowing into the earth after a heavy rain, animals and people can easily be sucked in, only to disappear forever. A likely cause of unexplained disappearances of hunters and hikers over the decades. Each one is different, some are just indents in the surrounding topology others are clearly visible holes in the ground, leading down to nothingness. (Images courtesy of Ohio Department of Natural Resources) Ohio Department of Natural Resources did a thorough survey of karsts all over the state compiling a sophisticated map allowing you to drill down on every known sinkhole. Each is given an identification number along with photos taken during field visits. https://gis.ohiodnr.gov/website/dgs/karst_interactiv emap/ According to the interactive map, many karsts are located along the Scioto River valley that runs through this part of Delaware County. Red dots indicate confirmed karst locations. I noticed a karst is even documented on our neighbor’s property about a hundred or so yards away. * * * There is a grove of black walnut trees just beyond the pond on our property, it’s rather peaceful there as long as you don’t roll your ankle or get beaned by a falling walnut. There are about 20 trees clustered around a depression in the soil. Over the years I simply assumed it was a hole dug out in need of dirt to fill in someplace else on the land. There are rather mature black walnuts growing around the depression, nothing inside it though, so it must have been there for quite a long time. After seeing the ODNR karst map I was amazed how many sink holes are in the immediate vicinity, I began to wonder if we may have such a geological wonder in our midst. Just the other day, I decided to research further before contacting ODNR to see if they were interested in taking a look. I figured, if this is a naturally forming depression, the layers of soil should match the surrounding layers, if not, it may very well be a man-made artifact. Using a posthole digger, I punched through the sod around the depression, on average there was 3 to 4 inches of topsoil before reaching clay. Inside the depression, I got mixed results, some areas had rich loam before reaching clay, other areas looked like it was disturbed, not firm layered soil. Plus, I was hitting something solid which may be rocks or tree roots. Using a spade, I decided to just go for it and dig in to see what was below. I kept hitting more and more obstruction. What is down there? (Next page)