Pt 2: A World Beneath Your Feet; Mystery of Virginia's Karst Formation

Feb 20, 2020

 Along the western spine of Virginia, the Karst formation dominates the underground landscape, storing water in its caves and crevices. It’s part of why this region is responsible for a big percentage of water resources, feeding springs and wells for thousands of miles.  Human activity above ground is taking a toll on the water resources below. 

Karst Protection Specialists,William Orndorff and Katarina Kosič Ficco in an underground stream inside a cave in Montgomery County.
Credit Kurt Holtz

 

In many rural areas of Virginia natural springs supply lucky landowners with drinking water in seemingly endless supply.

But Karst Protection Specialist, Wil Orndorff says it’s not that simple.  “People always have this attitude that springs are this magic, a gift to humankind, that's just an open faucet to an infinite water supply. And that's just not the case.”
 


If climate change brings more frequent storms and hotter summers, as predicted in models for the region, he says, water resources are going to change.  “One of the things we anticipate as a result of climate change is that the aquifer levels will be decreased,” says Orndorff.

Seems counterintuitive that more rain would deplete aquifers, but because warmer temperatures would extend the growing season, plants will need more water.  That means less water reaching the underground Karst.

 “The net effect is going to be less water makes it to the cave, ergo, less water makes it to the aquifer so over time we expect flows in the rivers that are supported by infiltration of water in the Karst are probably going to be decreased as a result of climate change.”

Thanks to the Karst formation, caves are abundant in Virginia. We’re about to enter Tawney’s cave, one of the most visited wild caves in Virginia.

 “So now here we are. We're actually in a bottom of the sinkhole. This particular sinkhole was formed by collapse of a cave and we’re going to go into the cave in a minute.”   Orndorff explains that when you see a sinkhole, you can be pretty sure there’s a cave below. As we head underground, he warns me “Hey, there’s a hole here. Kind of put your butt up there and your feet over there. You don’t want to slip down the hole.”  Definitely not. 

After a lot of crouching and shimmying over gray, green mud with rocks blocking our way, we find ourselves in a large underground space with streams flowing throughout the cave. When you shine a light, you see small pebbles that shimmer in the shallow water like a granite countertop.   

The Karst terrain is fragile and changeable, the limestone and dolomite having been eroded by water since at least the ice age, leaving holes and cut outs in rock.  Orndorff likens the result to swiss cheese.  “So Swiss Cheese isn’t just cheese and it’s not just holes.  It’s the cheese with the holes.  So, that’s what Karst is. It’s a landform type, (like the way) the desert is not a mineral. It’s not a rock. It’s a landform.”

“This room we're in right here, if you look at the wall in front of us and we had a time machine and I was to be able to take you back here 10 years ago, you'd see about 600 little Brown bats all in clusters up on the wall in front of you.“ Millions of bats in this country have died due to white nose syndrome, a disease caused by pathogenic fungus first documented in the US in 2006 in upstate New York and that subsequently spread to bat populations throughout the Eastern and Central United States and Canada. Orndorff says, “The bright spot of all that is that we don't have evidence that any of these bat species have gone extinct yet and here and there we have populations that seem to be stable or increasing.  However, this cave (Tawneys) has had nearly a hundred percent reduction in the number of bats.“

There’s a meter on the cave wall to check for bat activity, required for the mountain valley natural gas pipeline that snakes through this area. Orndorff says the pipeline company has been careful to protect caves like this, avoiding discharge to sinkholes and in one case, changing a proposed route to avoid the Mt. Tabor sinkhole area near Blacksburg. An early route proposed to go directly over Tawneys Cave was also moved once the company was made aware of the cave’s presence.

"They're very cooperative," Orndorff says of the company building the pipeline.  "When there was a hole in the pipeline trench that was losing water into the ground, I didn't find out about that because I went out there. I found out about it because it was reported to me by people working for MVP.”

Orndorff says the current suspension of pipeline construction is not helping water quality in areas where the construction was already in progress, postponing final stabilization and revegetation. Sediment and contaminants potentially carried in runoff from these construction areas can impact everything down stream.  “I mean it gets kind of philosophical, but I think when we interact with the natural landscape, minimal perturbation of the natural landscape should be the goal.”

 If we were to lose our light down here in this cave.  We wouldn’t be able to see our hands in front of our faces. “I have never seen anything so dark.”  But with the help of a seasoned guide who knows what he’s doing, we easily make it back up to find a pristine, winter white landscape as the sun begins to set.