In karst lands, what goes down comes up

To anyone with an interest in the geology of the Helderberg Plateau, one of the pleasures of late March and early April is to take a drive around its back roads to see what the waters of the spring melt-off are doing.

When the snowpack of the plateau is subjected to the first temperatures in the 40s and 50s — especially when combined with a soaking spring rain — the cliffs and valleys gush with waters; their musical sounds signal that, though temperatures may yet perversely drop to unseasonably cold levels, the arrival of spring is irreversible.

And especially in regions with karst topography — where limestone bedrock has dissolved away to produce sinkholes and caves and springs — gullies that are normally dry may be flowing with temporary streams that vanish suddenly into gaping sinkholes, or spring unexpectedly from the ground, producing gurgling freshets that will be dry by early summer.

One chilly day about two weeks back, when the ground still had large patches of crusty snow and temperatures hovered near freezing, I took a drive along a gravel road not far from the hamlet of Knox to a monster sinkhole that lies much less than a stone’s throw from that road.  It is large enough to show on topographic maps, and a geologic map of the rock layers (“stratigraphy”) of the area shows that, in its steep-walled, 50-foot depth, it punches through the surface Becraft limestone bedrock into the underlying New Scotland limestone.

Its picturesque rocky walls often drip with runoff and in warm months are green with mosses and ferns and wildflowers.   At any time of year, it may take a stream and the waters have been dye-traced to a spring well over a mile away, indicating that somewhere beneath its muddy, rubble-strewn bottom there is a cave of considerable size.

Since I was a college student, I have been watching this sink, hoping that some fine day, following the spring floods, enough of the debris will have been washed through to admit explorers to the cave’s uncharted reaches: every cave explorer’s dream!

What I saw through the driver’s window even before I got out of my car unnerved me:  I could see a couple of discarded tires littering one wall of the sink and, when I stepped out and could see the bottom, I spied several more.

But then I saw something far worse.

Directly in front of me, less than 20 feet down into the sink, were a number of rotted deer carcasses, perhaps half a dozen in all.  The lowest ones were nothing but skeletons but those closest to the road still had hide.

Fifty feet or so to the right was another, and there appeared to be two more farther around below the rim of the sink, all of them perched on its steep walls, meaning that, when rain fell, it would pass through the carcasses and sink through the debris at the bottom, eventually finding its way to the cave system’s resurgence point.

I could just imagine what kind of crud and disease the carcasses might carry and all of it would be in the waters flowing from the unsuspecting owner’s spring.

The alluring sinkhole had become a dumping ground.

A week later, I returned with a camera and a friend, long-time caver Thom Engel, a retired Department of Environmental Conservation employee.   This day was substantially warmer than the week before — now temperatures were in the low 60s, meaning that anything that had been frozen on my previous visit was likely to have thawed.

And no sooner had we stepped out of the car when we were hit with a slow breeze that carried the pungent, frightening stink of carrion.  Besides the decayed corpses of the several deer and the rejected tires, there was other less-identifiable trash visible in the bottom of the sinkhole.

I quickly shot a couple of pictures and then we got back into the car and sped away from the vile-smelling vapors carried on the breeze.  So much for the poet’s “gentle springtime zephyrs.”

It has long been illegal to dump waste into surface streams; what landowners today would pour used oil or dump the carcasses of dead domestic animals into a stream passing through their property? And, in any case, their downstream neighbors would be quick to see where their stream is picking up its filth.

Yet generations of people living on karst topography have seen sinkholes as tempting places in which to dispose of waste.  A sinkhole, after all, may be very deep: a fire in the chicken coop kills a hundred hens, the work horse or ox goes to its reward, the much-worked-on pickup truck finally rolls over and dies — and the dead creatures or vehicles are dumped into a handy sinkhole, covered with a couple of tons of “clean fill” — and voila!  The dead stuff is gone forever.

Not!

Sinkholes are not the “black holes” of modern astronomy and science-fiction, and a trip into them is not one-way. Soil — especially when it lies thickly over bedrock — can be a natural filter, and small amounts of pollutants can be trapped in subsoil as water infiltrates down to the water table.

But in landscapes with limestone bedrock exposed, surface streams frequently flow into sinkholes and then directly into karst aquifers — or “underground streams” to put it simply — and contaminants can enter the water table in a matter of moments.

There is no filtration of pollutants and extensive cave systems can carry them for miles, even under hills and ridges.  Pity the landowner who discovers that the formerly pristine water source that springs from a mossy fracture in a cliff is suddenly redolent with the odor of anti-freeze or the stink of animal carcasses; and try to understand the bewilderment of a farmer perhaps miles away who cannot understand how the burned-out washing machine and the corpse of the cow that were buried in the convenient sinkhole that lies in a hedge row on his farm is polluting a spring that might be in the next township.  After all — his ancestors have done that for generations, as other trash-laden sinkholes on the property bear witness.

But to understand is not to excuse.

I have deliberately been vague as to the whereabouts of the sinkhole that is the subject of this article and that has become a vile dumping ground.  But what is going on there is illegal, and the New York State Department of Environmental Conservation has been informed of its exact location.

I am hopeful that those responsible for this disgusting flouting of the pollution laws — even if they are not apprehended — will at least read this, know that their crime is now public knowledge — and cease and desist.

Editor’s note: Bob Loden owns the land on Middle Road in the town Wright with this sinkhole and says it has been in the family since 1918. He is 65 now and, for as long as he can remember, people have dumped in the sinkhole.

He is well aware of the cave beneath it — as a young man, he explored Skull Cave, also on Middle Road — and says that, when a dye test was run on the Loden sinkhole, the dyed water flowed out of Bogardus Spring, near Route 433, which is “a couple of miles away as the crow flies.”

Loden went on, “Unfortunately, shall we call them local residents, feel that it’s a place they can throw all sorts of things...We have to get in there and clean all the crap out.” In the past, when the Lodens have found out who threw items in the sinkhole, they have had them clean it up.

“There are some people we feel are repeats and we’d love to catch them,” he said.

Loden said that there are quite a few sinkholes in the area — some larger than the one featured in the column — but its proximity to the road is what draws the waste.

On Wednesday, Loden said, the sinkhole was filled nearly to the brim with water. “A lot of times, things that float wash out,” he said.

— Melissa Hale-Spencer