Caves are mysterious places even for those of us who have spent decades in exploring and trying to understand the agents of nature that formed them, and it should be noted that for a large percentage of the world’s population, caves are “terra incognita.” Someone once called the subterranean world “The Eighth Continent,” and it is probably far less familiar to most people than anything they might have learned about Antarctica.
Think of the number of stories, novels, films, and TV shows that are set wholly or partially in caves, often wildly — even hilariously — inaccurately portrayed to those who are knowledgeable about them, but undoubtedly appealing to some aspect of the human subconscious that has a fear of dark, unknown chambers that exist in what is melodramatically — but not inaccurately — described as the “bowels of the earth.”
It is therefore not surprising that visitors to caves often ask questions that, due to the questioners’ innocence, might seem pretty silly to those among us whose avocation — and sometimes vocation — involves the sport and science of caving.
When I first started teaching a high school earth science course to freshmen and a geology and astronomy survey course for seniors, I still harbored a remnant of a notion instilled in me in one of those education courses required of aspiring secondary-school teachers, sometimes taught by a professor who seemingly has never been within a mile of a classroom filled with adolescents (said Mike cynically): that notion being that the only dumb question is the one that is not asked.
But that got kicked out of me after a couple of years when I was finishing up a two-week unit on stars and stellar evolution with my seniors.
We had talked about the birth of the universe — old beyond imagining — and we had analyzed the Hertzsprung-Russell diagram; we had compared the sun with red dwarf stars and massive blue giants, discussed the formation of red giants, neutron stars, and black holes; and we had looked at dozens of slides of open clusters of blazing stars arrayed about a nucleus like swarming bees; spectacular nebulae spangled with gases and dust of every color of the spectrum; spiral galaxies, barred spirals, elliptical galaxies, irregular galaxies, all of them fantastically huge and beautiful beyond belief — and all of them sufficient to make one wonder in the silence of one’s bed at night if those folks who believe in intelligent design might just be on to something.
I was wrapping up our discussion in preparation for a test on the unit the next day when I remarked that, in spite of all the discoveries made by wondrous instruments such as the Hubble Telescope, there were still many things that we do not know about stars.
At that moment, a rather sleepy-looking student who shall remain nameless and who — as I recall — had not shown much more than tentative signs of life during his weeks in my classroom, raised his hand. When I called on him, he asked, “When the astronauts go up in the space shuttle, can they go outside?”
Confused by the seeming irrelevance of the question I replied, “Yes, of course. But what does that have to do with the test tomorrow?”
The look on his face suggested he had hit on something that had evaded all those amateur astronomers like Steven Hawking and Neil DeGrasse Tyson and he said smugly, “Well, next time they go up there, why don’t they just go outside and get a couple of stars, and bring them back down to Earth?”
Needless to say, the reaction of some of the more knowledgeable students in the class was — shall we say — less than charitable toward the student’s question and they showed it, while I tried not to crack a smile at this young man’s total cluelessness and gently explained what he should have known weeks before: Stars are a bit too large and hot to fit into the cargo bay of a space shuttle.
How much of a cave is underground?
Anyone who has ever guided a group of tourists through a commercial cave or taken a group of wet-behind-the-ears novices on their first “wild” cave trip has, of course, heard many, many preposterous inquiries — and it requires the patience of Job not to roll the eyes, sigh like a spouting whale, and say, “That is a seriously silly question.”
Years ago, when I had taken another group of students on a week-long trip to Mammoth Cave, we were on what was called the Historic Tour, and our guide — all decked out in his Park Service uniform and Smokey-the-Bear hat — told the crowd of about a hundred that the only dumb question was the one they didn’t ask.
After a couple of fairly intelligent questions that had to do, as I recall, with the age of the cave and the great size of the passageways, the ranger pointed to an anonymous hand waving above the crowd and said, “Sir?” At which point came the question, “Is all of this cave underground?”
I have made it a point whenever I am taking a tour through a commercial cave to ask the guide — when I can catch him or her out of earshot of the rest of the tourists — what is the silliest question they have ever been asked. As it happens, that question about whether all of the cave is underground is a fairly common one.
If the guide can resist the temptation for sarcasm, he or she might say simply, “All that we know of it is.” A guide once told me he had replied, “All of it except for the gift shop and cafeteria” — and drew not a smile from the questioner who seemed to accept those areas as, indeed, being parts of the cave.
Compendium of questions
And, so what follows is a compendium of questions that either I have been asked or questions I have acquired from commercial cave guides.
— 1. How long did it take the Indians to carve this cave out?
This is also a surprisingly common question asked of cave guides. People who have no understanding of erosion and chemical weathering are bound to be mystified and awed by the great size of some cave passages — Mammoth Cave’s Main Passage has room for a modern jetliner to fly through it.
But caves form because surface water has picked up carbon dioxide from the atmosphere or from decaying plants and becomes mild carbonic acid. When this acid comes in contact with calcium carbonate — the main constituent of limestone and marble — it dissolves it to a solution of calcium bicarbonate, which then washes away.
Given the right conditions and enough time, the process can form out huge cave passages. And as for that silly question: If Native American Indians had carved the cave — what on Earth did they do with all that rock they hauled out?
— 2. How thick are the walls of the cave?
The sedimentary rock from which most caves are dissolved forms in layers, which often cover thousands of square miles. In the Helderberg area, most of our large caves (including commercialized Howe Caverns and Secret Caverns) have formed in one of three types of limestone: the Manlius, the Coeymans, or the Onondaga.
The Manlius limestone is found as far west as Syracuse and as far south as Port Jervis; the Coeymans stretches from New York to Virginia; and the Onondaga stretches as far west as Detroit. Each of these areas consists of thousands of square miles, so trying to figure how thick the walls are would be a monumental task, but a good answer would be, “Really, really thick
— 3. How much of the cave hasn’t been discovered yet?
One would think that the response to this question would be something flippant, such as, “We won’t know until we discover it.” But, in fact, it is sometimes possible to come up with an intelligent answer.
If the known passages in a cave have formed in a geographic region throughout which the same geologic conditions exist, there is a good possibility that many more passages have formed under sections that have not been surveyed. By measuring the length of passages in a set area, one might by inference conclude that a lot more of the cave has not yet been discovered and perhaps even extrapolate a rough estimate of how much.
At Mammoth Cave in Kentucky, for example, the same geologic conditions exist for hundreds of square miles, beneath some of which are over 400 miles of explored cave. But, by extrapolation, geologists have concluded that there could be in excess of one thousand miles of the cave when — or if — Mammoth is ever fully explored.
— 4. Is any of the light down here natural?
Since caves are roofed by solid rock that can be many hundreds of feet thick, with rock walls that can be hundreds of miles thick, and with bedrock floors that may literally stretch to the Mantle of the Earth, it is highly unlikely that any natural light could enter beyond what cavers romantically but accurately call the “Twilight Zone.”
This is the region near a natural entrance to a cave into which dim sunlight may reach, and that may have unusual ecologies, featuring both plants and animals that exist in a world of feeble light and perhaps wildly changing seasonal temperatures.
Sport cavers carry their own lights (a minimum of three is the requirement) and commercial caves have complex and often expensive electrical systems for lighting.
— 5. How many undiscovered entrances to the cave haven’t been found yet?
When asked such a question, cave guides must be tempted to say, “We’ll know when they have been discovered.”
But again, what seems to be a no-brainer actually can have a rational, scientifically based answer. Caves form in regions of limestone or marble bedrock known as “karst.” Karst areas usually are characterized by mainly subterranean drainage of runoff into extensive cave passages, numerous springs, streams that tend to go underground shortly after they get started, and a surface pock-marked with the depressions known as “sinkholes,” which permit surface waters and sometimes human explorers to enter the caves below them.
But sinkholes can become occluded: wholly or partially blocked up by sediments and other natural debris that may effectively cut off everything but water from entering the cave systems.
Scientists known as hydrogeologists who study the effect of local geological conditions on water flow — above as well as below ground — have developed a technique known as “dye tracing” to permit following the flow of water to places humans cannot go. This process involves placing harmless dyes in water that is sinking into the ground and then watching the suspected resurgence points to see if the dye-laced waters emerge, indicating there has been a connection.
My young research assistant Devin Delevan is pictured standing at the brink of a vertical sinkhole near the village of Clarksville, an area known to have extensive cave systems. Though in the photograph the sinkhole is dry, in times of heavy precipitation dye could be added to water, pouring into it and a connection might be determined.
Karst areas often have hundreds of such sinkholes, many of which could be hooked into a cave system through this method, even if a human could not physically enter the cave. Numerous previously “unknown” entrances could thus be identified.
— 6. What happens if there is a fire while we are in there?
This question was actually asked of me some years ago when I was guiding a group of students from a downstate New York college through Clarksville Cave.
One young man took a look at the cave’s tight, intimidating entrance and a vision must have passed through his head of a dozen students madly fleeing from flames and battling each other to get out of the cave. His question elicited a burst of laughter from several of his fellow students who were clearly aware that there was nothing within the cave that would be capable of a conflagration.
I assured him of that fact and his face turned red and I expect his question went the rounds through the dorm that night, much to his embarrassment.
— 7. How much does it cost to air-condition (or heat) this cave?
Since limestone and marble and other kinds of dense rock are good insulators, beyond its Twilight Zone a cave will remain pretty much the same temperature all the year around. Caves generally will assume the average ambient temperature of the area in which it is located, making caves seem cool in summertime and warm in winter — everything being relative to temperatures outside the cave at a given time.
In the Helderberg/Schoharie area, yearly average temperatures are about 50 to 52 degrees Fahrenheit, and that tends to be the temperature of our caves. No artificial cooling or heating is required.
Two truly preposterous queries
There are undoubtedly many more Seriously Silly questions that cave scientists and guides have to deal with, but then there are the ones that are truly preposterous or totally incoherent, and I will end with two of these.
Not long ago, I was touring a commercial cave with a group of students and popped my question to the guide, a young woman college student. She did not hesitate for even a moment. Last year, she told me, she and several other guides had been asked a question that was the talk of their crew for several weeks: People on tours were asking, in all seriousness, “Is this the cave that was moved from New Jersey?”
Understand: The visitors’ portion of this cave is over half a mile in length and in places 60-feet high. How and from where the idea had circulated that it had been moved from another state no one seemed to know, but, not wanting to risk losing her job over a condescending reply, the guide had answered simply, “No, it’s been right here in Schoharie for thousands of years.” The guide reported that no one in her group had even cracked a smile.
At the same cave the year before, I had posed my question to a young man who was majoring in geology at a local college. He told me that some weeks before, while his group was standing on the banks of the cave’s gurgling underground stream, a visitor had asked “Is the water in this stream real? Or is it natural?”
Aware that the man’s question was absolutely serious — but unable to decipher its meaning and unwilling to prolong the issue by asking the man to explain what he meant — the guide replied, “Actually, we have both in the cave.”
The man nodded and seemed satisfied.
And that stunner and the one my student asked me about packing up stars in the space shuttle and bringing them back to Earth have permanently put an end in my mind to the notion that the only dumb question is the one you don’t ask. Professors of education, take note.
By Mike Nardacci
The term “geopoetry” seems to have been coined by Scottish poet Kenneth White to describe geologic writing that shows “the relationship of the Earth and the opening of a world.” The idea is that the few known facts of a situation are combined with intelligent speculation to evoke its mystery and wonder — but not necessarily to provide definitive answers.
I have always believed that anyone who aspires to an understanding of geology needs to have a vivid imagination: To stand, for example, on Route 156 between Voorheesville and Altamont and look at the Helderberg escarpment rising above you and envision it 20,000 years ago buried under the mile-plus-thick continental glacier. Or to project your mind farther back into the Devonian Period 400 million years ago when this part of New York lay under a warm shallow sea dotted with low coralline islands that, through the fantastic processes of plate tectonics, would rise up into the looming, fossil-rich plateau we see there today.
Over the past decade, I have made several trips to Chaco Canyon in New Mexico, a spectacular preserve about a hundred miles northwest of Albuquerque off of Route 550, but often described by visitors as being “a hundred miles west of Nowhere.”
The highway passes through some of the bleakest terrain in the United States, though some of it is starkly beautiful, as arid landscapes tend to be, bordered by miles of desert plants: sagebrush, cactuses, and cholla, towered over by angular mesas and buttes formed of dusty, pastel-colored rock.
Chaco is then accessed by a truly horrendous 13-mile-long washboard-surface dirt road, which surely is intended to discourage all but the most determined of visitors. Although designated as a National Historical Park, Chaco has no facilities beyond a campground that offers rather primitive camping (though it does feature flush toilets), and a visitor center, which is, as they say, “under renovation.”
It is air-conditioned and has a small shop selling a variety of books that theorize about Chaco’s human history, but had — as of this past June — no exhibits at all, which is a shame considering that a few years back it had a museum featuring fascinating displays and presenting information about Chaco’s spectacular Anasazi ruins and the ancient people’s stunning architecture and pottery.
Mystery and miracle of water
In June of this year, I was again hiking in Chaco with a friend, Mike Whalen, who is a filmmaker living in Boulder, Colorado. The temperatures were somewhat lower than we had expected: mid-80s in the late afternoons but relatively cool and dry early in the days, and so we chose one particularly clear morning for a hike to a pueblo ruin known as “Penasco Blanco,” the most remote in the immediate vicinity of Chaco and one that we had never managed to visit on previous trips.
It lies atop a mesa at the end of a relatively flat three-and-a-half mile trail that leads out over the dusty floor of Chaco Canyon through vast stretches of sagebrush and cactuses, some of which were late blooming in exuberant shades of red and yellow and orange in the wake of the spring rains. The path at first follows the base of the canyon’s North Mesa and has some shady stretches, but the last mile-and-a-half or so are out in the open.
Frequent examples of honeycomb weathering may be found in the boulders at the base of the cliffs. This phenomenon — fairly common in extremely arid environments — seems to occur when salts within the rock migrate toward the surface and form crystals that shatter it. The shady recesses undoubtedly provide respite from the blistering sun for desert birds and reptiles. Though the temperature was still in the 70s, the high sun shining through a cloudless sky soon became oppressive and we found ourselves gulping down our water faster than we had planned.
And it is true that, among the great mysteries of Chaco Canyon, one of the most perplexing revolves around the subject of water.
The people of many ancient cultures thought of water as something spiritual — even sacred. Temples were built over springs, which must have been regarded as connection points between the world of the gods and that of humans.
It is not hard to see why and it is on the subject of water that this essay ventures into geopoetry. Consider the appearance of the landscape on the road from Albuquerque to Chaco: Much of it consists of plateaus and mesas composed largely of shale and siltstone but capped by hard sandstone forming steep escarpments above the crumbly talus slopes.
The situation is rather comparable to the stratigraphy of the Helderberg plateau, where the shale- and soft-sandstone talus slopes towering above Voorheesville and Altamont are capped by the hard Manlius and Coeymans limestone layers that form the vertical cliffs of Thacher Park. But the Helderberg area is a very wet climate and the slopes — and indeed, every fissure and hollow in the cliffs — are green with massive amounts of vegetation. As the song says, “The hills are alive….”
The New Mexican talus slopes show signs of the occasional turbulent movement of water — but then, so does the surface of dry and dusty Mars. Yet, aside from pinyon pines and junipers on the valley floor that somehow manage to find enough moisture to thrive, the slopes in the New Mexican scene are nearly devoid of life, whether plant or animal, and the changes brought by abundant water verge on the miraculous.
Doors to nowhere
The trail to Penasco Blanco crosses a small dry wash just before it makes the final steep ascent of the mesa, and in a sheltered alcove above the trail is an ancient pictograph — one of the most remarkable ever discovered. It seems to record the appearance of a crescent moon and next to it a supernova that was observed in other parts of the world as well in 1054 A.D.
Clearly, the ancient inhabitants of Chaco Canyon took a keen interest in the stars and one of them made the effort to record the stellar explosion; the handprint may well be that of the artist.
On this mid-June day, the wash was indeed very dry and probably had not had any flow since the sparse spring rains following the melting of whatever light snow cover had fallen on the canyon. Beyond the wash a series of exposed switchbacks led to the top of the mesa, and, as we climbed up to the crest, we were presented with a view of the Penasco Blanco ruin a thousand or so feet away.
The ruin is immense; ovular and greater in area than a football field, it was subdivided into hundreds of rooms and passages and courtyards — home, it is believed, to perhaps many hundreds of puebloan people.
A dozen or more of the sunken, circular pits known as kivas — which served as places of worship and socialization — are scattered about it. The ruin is mostly unexcavated, so the tumbled-down walls and doors to nowhere stand picturesquely on the windy mesa as they have for centuries, and in places the ground is littered with fragments of the Anasazi people’s beautifully decorated pottery.
The low hills around it reveal the partially exposed walls of other, smaller “satellite” pueblos that were built as Penasco Blanco grew and expanded.
Surveying the ruins, built so deftly from millions of rock fragments, we were confounded by a number of questions. The first had arisen a year ago when Mike and I hiked to another ruin called Pueblo Alto, remotely situated on Chaco’s North Mesa: What was the source of all the rock fragments from which the ancient pueblos were constructed?
The landscape around the ruins is covered with shattered rock, though it is likely that the vast majority of these have weathered from the walls of the ruins themselves. Undoubtedly many more lie buried in the dry soil, but excavating them in that sometimes scorching heat would have been agonizing.
The bases of the various mesas are littered with innumerable fragments of the needed sizes — but transporting them up the cliffs to the building site in the thousands of tons needed would be an appalling task even with modern technology. From all evidence, the ancients had nothing to rely on but arm- and leg-muscle power — and this fact is one of the major aspects of the Chaco Canyon mysteries.
But, as we stood there draining our canteens under the glaring New Mexican noon sun, another even more provocative question arose in our minds: How did the ancient people supply the builders with water?
We tried to envision great teams of workers engaged in construction activities that in some ways must have posed many of the same challenges that faced the builders of the Egyptian pyramids. But the pyramid builders had the Nile River at their feet — an endless supply of water for drinking, cooking, washing, and probably bathing when the heat became unbearable.
Southwestern museums often display hollowed-out gourds and huge ceramic pots that are believed to have been used by the ancient people for water storage. But to store water, one must first obtain it, and, here in the vast dry stretches of Chaco Canyon, the only source of water other than rare precipitation is the Chaco Wash — a narrow streambed incised into the compacted soil of the canyon floor that, except for brief periods in spring and the occasional August gulley-washer, is never more than a sluggish, muddy trickle, and it is over a mile from Penasco Blanco.
Clearly, it could never have provided enough water for this pueblo’s builders let alone the construction teams raising the other pueblos of Chaco Canyon.
And that fact raises another major question: How were the workers and the inhabitants of the pueblos fed?
The builders of the great Egyptian monuments had the well-watered and incredibly fertile fields of the Nile Valley to provide their food. But, although for millennia the inhabitants of the Southwest have been expert at what is called “dry farming” to raise the “three sisters” crops of corn, beans, and squash, one can only wonder how the ancients managed to produce enough food for the teams of workers building Penasco Blanco as well its inhabitants — and one must keep in mind that Chaco Canyon holds over a dozen other large pueblos and innumerable smaller ones.
But even “dry farming” requires essential amounts of water, so once again the question arises: What was its source? And how was it transported to the top of the mesa in sufficient quantities to allow Penasco Blanco to expand and flourish?
A survey of the literature both popular and more technical on the subject of Chaco Canyon shows researchers with wildly differing interpretations of the reasons for the construction of the pueblos of Chaco Canyon, of estimates of its population, and of the enormous problems that revolve around the source and quantities of food and water.
But one fact is critical: Water is life.
Hence, scientists today are excited by the discovery that, in the far reaches of our solar system, the moon Europa, orbiting Jupiter, and the smaller satellite Enceladus, orbiting Saturn, show evidence of being the repositories of gigantic quantities of water in both liquid and solid states: beckoning targets for future exploration.
And yet here in one of the most hostile environments in the United States, a thousand years ago a great culture grew and flourished, reaching startling technical and artistic heights that evoke admiration and even awe today.
What made it possible was water. But where that water came from and how the ancient people obtained and transported it are questions that science is nowhere near answering. “Geopoetry” indeed!
A point I have always tried to make with my students or participants in one of my field trips is that geologists have a name for absolutely every natural process involving the rocky sphere that is Planet Earth. And one of the wonderful things that has happened in recent decades is that scientists have sent robot probes to examine the surfaces of other planets, as well as asteroids and comets, and have found not only that many of the same processes occur on worlds as alien as the Moon, Venus, and Mars, but have discovered exciting evidence of other geologic phenomena unknown on Earth and waiting to be explained.
Over the past few days, the Internet has been sizzling with reactions to a rock photographed by the Curiosity Rover that has a passing resemblance to a thighbone. Given the fact that not one of the robots sent there has yet found persuasive evidence that anything as large as a microbe ever lived on Mars, the curiously shaped rock is unlikely to be anything but that: a curiously shaped rock.
But the various chat rooms that dwell on such things are buzzing with charges that NASA (the National Aeronautics and Space Administration) is once again concealing evidence of macrobiotic life on Mars and those who disagree are denounced in vitriolic (and often hilariously ungrammatical) language.
Yet the fact is that the natural processes which change the shape of Earth’s surface are sometimes capable of producing very curious results: hence, the chess-piece shapes of the rocky towers of Bryce Canyon, the elegantly sculptured mesas and buttes of Monument Valley, and the granite profile of New Hampshire’s Old Man of the Mountains that collapsed ignominiously some years ago into a heap of rubble due to frost-wedging.
A few weeks back, on emerging from a trip with some students through one of the caves near the village of Clarksville, I noticed some odd, miniscule features on a pile of muddy debris at the cave’s entrance. The debris was glacial drift, deposited on the Clarksville area by one of the streams pouring off the melting Ice Age glaciers thousands of years ago: hundreds of penny-sized and smaller pebbles in a matrix of packed clay.
But many of the pebbles stood atop a small, thin column of that clay, forming tiny structures geologists call by the French term “damoiselles”— which loosely translates as “little maidens.” Evidently, to the French-speaking geologists who coined the name, the pebbles resembled broad bonnets perched atop the slender structures below.
This happens when rain water or melting snow cascades down an exposure of soft sediment, washing away anything that is not protected by the tiny pebbles; their weight has slightly compressed and hardened the materials on which they sit.
In many places in the world, these structures appear on a much larger scale. Chimney Bluffs State Park on Lake Ontario features enormous examples, which are often given the name “hoodoos” when they form such massive structures. A somewhat smaller display of hoodoos appears on the mysteriously named “Ghost Fire Bend” of the Normanskill, though these are currently not accessible by car with the closing of Grant Hill Road due to road work.
In June of this year, while on a hiking trip to New Mexico, I had the opportunity to visit Tent Rocks State Park on the reservation of the Cochiti Pueblo, southwest of Santa Fe. The preserve was originally given the Keresan language name Kasha-Katuwe, which is usually translated as “rocks that resemble teepees.”
Here, between 6 million and 7 million years ago, the land was buried under the debris from an incredibly violent volcanic eruption that formed the Jemez Caldera, a giant bowl-shaped depression to the north. Layers of the soft, spongy-looking rock known as pumice, compacted rock fragments called tuff, and volcanic ash buried the region in layers hundreds of feet thick.
The weight of all of that air-borne sediment compacted the strata into a crumbly matrix rock that weathers easily due to the wildly varying seasonal temperatures and is poorly resistant to erosion by the occasional rainfall or melting snow. But mixed in with the smaller rock fragments are boulders, some the size of an automobile, and these had the effect of compressing and compacting the sediments that lay beneath them. Thus the sediments were protected from the raging, highly erosive waters that flow during those occasional periods in arid climates when sudden torrential rains fall.
The results are the hoodoos of Kasha-Katuwe, and they are marvels to behold.
Those found near the parking area for the preserve’s trailheads gave Tent Rocks its name. There are a dozen or more of them, ranging in height from a couple of yards to 20 or 30 feet, but these represent the last stage in the erosion cycle of the hoodoos. They have lost their protective boulder caps and, in respect to geologic time, they are not long for this world.
Though this part of the Southwest is currently experiencing a severe decade-long drought, every drop of rain that does fall is washing them down to ground level, the eventual fate of all hoodoos.
To get a better idea of nature’s inventive sculpting talents, one must hike up one of the two major trails that head into the park. They are easy for the experienced hiker, though the lack of shade and the unforgiving summer sun make it mandatory to carry a couple of quarts of water. In addition, signs warn of poisonous snakes lurking in the underbrush — sufficient cause for those inclined to bushwhack to stay on trail.
A textbook example of the formation of the hoodoos lies on the edge of the eroding mesa around which the trail meanders. Rising some 20 feet from the middle of a dry wash, the structure is crowned by a large boulder of pumice.
Farther along the trail, the hoodoos become larger and more varied in shape and one particularly steep slope offers a view of their entire life cycle: some eroded down to mere stubs, some proudly displaying their protective caps, and others just beginning to emerge from the eroding cliffs.
They derive their weird shapes from the varying hardness of the rock strata from that they form. A slot canyon cut into the rock by raging waters offers a shady respite from the heat and climaxes in a hair-raisingly steep and exposed series of switchbacks leading to a jaw-dropping view out over the canyon to Sandia Mountain above Albuquerque.
The American Southwest — particularly in New Mexico and Arizona — features some spectacular geology due to its diverse rock types; its wildly varying elevations; and its climate, which tends to be arid but is subject to sudden intense flooding.
Terms such as “weathering,” “erosion,” “resistance,” “strata,” “frost wedging,” and other prosaic expressions may seem lifeless on the page of the textbook. But, in an environment such as Tent Rocks State Park, these dry words describe nature’s endlessly varied talent to create wonders in the rock from which Earth is made.
Acadia National Park on Maine’s “Down East Coast” is a place of mystical wonders: sheer granite cliffs rising from the sea, washed in the salt spray of enormous waves crashing against them; barren mountain peaks that seem much loftier than they really are, climbing upward from sea level and splashed with the colors of flowers normally found hundreds of miles farther north; spectacular stone bridges in the most unlikely places in the Acadian forests, gifted by John D. Rockefeller and looking like leftover sets from The Lord of the Rings films; and miles of fir and hemlock coastal forests, the dark green boughs hanging with the lichen called Old Man’s Beard, wreathed in fog and dripping in a silence broken only by the haunting cries of gulls and the clanging of buoys.
But Acadia is also an enormous outdoor natural history classroom, and educational institutions such as the College of the Atlantic in Bar Harbor frequently use its features for courses in geology, marine biology, botany, and environmental chemistry, among others.
The mountains of Acadia and other even higher summits in interior Maine must have been among the last places in the northeastern United States to have had glacial ice when the vast Wisconsinan glacier — the most recent continental glacier — retreated as Earth warmed over the last 15,000 years. U-shaped valleys, the odd asymmetrical mountains called “roches moutonnees” (which translates as something like “sleeping sheep”), bedrock showing the striations (scratches) caused by the advance of the glacier, and immense deposits of glacier-borne rock material all testify to the recent — in geologic time — Ice Age.
Glaciers are immensely powerful agents of erosion, and much of the upper part of the continental United States is covered in the debris they left behind.
The poet Robert Frost wrote frequently of the hardship of being a New England farmer — not the least of whose problems was the immense quantity of rock left behind in the landscape presenting an appalling challenge to the horse-drawn plough. His poem “Mending Wall” deals with the boulders — “some like loaves and some…nearly balls” that are ubiquitous in fields and which farmers for generations have used for stone walls and house foundations and churches.
The beaches of the Acadian Coast are famous for the almost infinite variety of types and colors of rocks found on them, many of which may have been transported for hundreds of miles from their point of origin: For it is a rule of glacial geology that an advancing glacier acts as a bulldozer, scraping away loose sediment and vegetation right down to the bedrock and then proceeding to abrade it, too, away; but a melting or evaporating glacier acts as a dump truck, leaving behind all sizes of rock particles from tiny clay and silt to huge cobbles and boulders in one heterogeneous mess called glacial drift.
The larger particles — the cobbles and boulders — are known by the quaint name glacial erratics. The high summits and slopes of Acadia are dotted with thousands of erratics, and on many of the peaks such as Cadillac Mountain, the highest mountain on the East Coast of the country, they sit in rugged isolation, often looking like the remnants of the mysterious rocky circles found in Ireland and England.
One of them is a famous landmark for visitors to Acadia: It is called Bubble Rock and it perches picturesquely on the steep slope of the summit of a small mountain known as South Bubble. It is an enormous chunk of the Lucerne Granite, a beautiful black-and-white speckled stone with large crystals that forms the bedrock some 40 miles north of Mount Desert Island
The sight of it challenges credibility: The slope appears to exceed the physicist’s “angle of repose” and it looks as if the slightest touch would send it careening noisily into the valley below it, smashing rocks and trees as it went.
Many visitors to Acadia National Park have appeared in the apparently obligatory photograph in which they attempt to dislodge it. Legend has it that, on a Halloween night some years ago, the entire football team of a local high school hiked up and attempted to push it off South Bubble. But there it stands.
A charming children’s book (now, alas, out of print) attributed the precarious position of the rock to Acadian trolls. But it must be remembered that on what is now the coast of Maine, the continental ice sheet was greater than a mile in thickness and thus had immense power to transport rocky materials: Retreating, it left this erratic and many others behind, sometimes in the most unlikely of locations.
Our own Helderberg hills and the Adirondacks also feature vast numbers of erratic cobbles and boulders, but, given the thickness of the forests that grow on them, erratics are often hard to spot, except when they are exceptionally large.
A relatively low mountain to the west of the Great Sacandaga Lake has a ridge running from its summit that features dozens of fairly large boulders of gneiss and anorthosite, transported from the High Peaks of the Adirondacks. Just below the mountain’s summit is a gigantic erratic, split down one side by frost wedging and the action of tree roots.
Far larger than Bubble Rock, it sits on a much gentler slope, and, located as it is in some fairly remote wilderness, it has likely had few visitors. Doubtless, hundreds more like it are scattered throughout the Adirondack fastness.
But we in the Albany area do not have to look far to find glacial erratics. Anyone who lives outside of the city of Albany — especially in the Altamont and Voorheesville area on the west side of the Hudson and in the Wynantskill and East Greenbush area on the east side — has found the same problem as the New England farmer in attempting to dig on one’s property: the enormous quantities of rocks in the soil.
They may have many different points of origin, of course, but one that is very common is a purplish rock often found as a smooth cobble or boulder, deposited directly by the ice or perhaps rounded and polished in a vigorous stream pouring off the melting glacier. These are samples of what is called the Potsdam sandstone and they originate far to our north near the border with Canada.
The fact that erratics’ points of origin can be determined with precision is useful to glacial geologists, who sometimes refer to deposits of such rocks as boulder trains. Appearing in more or less straight lines that strike roughly north-to-south, they allow the directional motion of the glacial ice to be determined very accurately.
When I am conducting geologic field trips, I usually toss out this question to participants: Just how long ago was the Ice Age?
Unless respondents are exceptionally knowledgeable, answers are usually accompanied by a shrug of the shoulders: “A million years ago?”
That is not a bad answer as a million years ago the ice was, indeed, in control of much of this part of the world.
But people are often unaware that even 10,000 years ago there was glacial ice on some of the highest peaks in the Northeast, and that we are living in what geologists call a glacial interlude.
But aren’t we in a time of global warming? Yes, there is evidence of that assertion. But all evidence is that the warmest Earth has been in the last 20,000 years occurred 7,000 years ago in a time geologists call the “hypsithermal,” and the glacial ice is poised for its return in a few thousand years.
In a few weeks, we will be entering the first stages of fall, and the average day-to-day temperatures will begin to drop. From time to time, we may see exceptionally warm days — we can all remember days in October and even November when the thermometer incongruously hit 80. But no one is foolish enough on such days to think that summer is coming back.
We are living in a geologic period of continental glaciers and the little purple stones in your backyard not only tell us that the last glacial advance was not so long ago; they may be harbingers of cold, cold days to come!
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.
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