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Some Leeds on finding fossils Aug. 20, 2020

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Some Leeds on Where to Find Fossils

On the Rocks The Woodstock Times

Updated by Robert and Johanna Titus

 

The old stone bridge at Leeds must have been something of a marvel when it was completed in 1792. It really is something to look at, a grand old three-span stone bridge. We imagine it must have attracted many visitors during its first century. Mind you, even in 1792 it was nothing new, the Romans were building better bridges thousands of years ago, but in 18th Century upstate New York it must have been one of the biggest and best around. Once there were a number of similar stone-arch bridges; We have seen several of them up in the Mohawk Valley region. Mostly they were a lot smaller and few of them still operate. This one is big; it must have been planned for a long future. It was rebuilt in the 1930’s and easily accommodates modern traffic. It’s very wide and it’s not only used but still very busy.

The bridge has been the subject of a lot of post cards and, in fact, that’s where we first became aware of it. Recently we decided to go find it and take a look; it was certainly worth the effort. we didn’t have any trouble finding it; it’s on Rte. 23B right at the western access to the Leeds business district. We parked just beyond the bridge and slowly walked across it. We weren’t too surprised at what we found. In fact, we very much anticipated it.

The men who built these bridges very often took a great deal of pride in their work. They didn’t just want to build bridges, they wanted to create works of art. That is certainly reflected in the beautiful curves of the arches, but it is also reflected in the stone itself. If you go there, take a good look; it is made of limestone, which was a good choice for its density and durability. But it’s more; the stone is rich in fossils.

We had little difficulty recognizing the rock unit; it is the Helderberg Limestone, which is common all up and down the Hudson Valley. We have talked about the Helderberg before; it’s from the early Devonian time period, dating back a little more than 400 million years. It’s a sedimentary rock, first formed as deposits of white or pink sand, not silica sand as we have in the north, but a softer calcium carbonate sand as in Florida. It accumulated in a clear, shallow, aqua, tropical sea. There are many units within the Helderberg and two of them are represented here, they are called the Coeymans and the Becraft Limestones.

The Coeymans makes up most of the bridge’s stone. It’s a thick-bedded limestone which probably means that it was deposited by very agitated water, perhaps wave or current swept. Many animals lived in this rugged but hospitable ecology. They were well-adapted to the rough water in that they had thick, heavy shells, good sturdy protection from being batted about. The most common forms are called brachiopods. These were bivalved shellfish, similar in many ways to clams, but of an entirely different group of animals. Most of the other fossils were crinoids, called sea lilies by their common name. We have written about them several times before, they are colorful and beautiful stemmed animals, each with five delicate lacy arms. Beyond that we found a number of other forms, including trilobites, corals, bryozoans and others.

The second unit, the Becraft Limestone, has a fair amount of the mineral hematite in it, and that gives the unit a distinctive red hue. It was also very fossiliferous and the most abundant forms here were remarkably large crinoids. It’s red hue and abundant fossils made this a popular stone, not just for bridges, but, more often, for 19th Century “marble” table tops.

As we said, we saw the handiwork of an able craftsman at work here. This would not just be a functional bridge, but a pleasing and interesting bridge. We have seen a lot of Helderberg Limestone and, while it is a very fossiliferous unit of rock, it is rarely as nice as this. Our bridge maker spent a lot of time looking for and selecting the best slabs. Look, especially, at the capstone that makes up the sidewalk walls east of the bridge and on the bridge itself.

As geologists, we are used to reading and hearing messages from the rocks. Usually, they are sent across hundreds of millions of years and the messages come from ancient ecologies and their long-dead plants and animals. This is one of the few times we have gotten a message from a man of the past. we wonder who he was.

  Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”

Lethal muds Aug. 13, 2020

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Muddying the Record

On the Rocks – The Woodstock Times Dec. 31, 1998

Updated by Robert and Johanna Titus

 

We scientists see hurricanes as lifeless, soul-less entities, and we are right. But there are other viewpoints. Some Animist religions might see them as having souls, the souls of evil spirits of course. In a primitive culture, living on the edge of nature, that can be easy to believe because hurricanes can behave as mean spirits. Few were ever worse than this autumn’s Hurricane Mitch which brought not just catastrophe to central America, but a form of slow, seemingly premeditated catastrophe befitting an evil spirit.

Mitch approached the Coast of Honduras and stalled offshore for three days. That allowed time for the waves and tides to build up on the coasts of that poor nation. It was like a military invasion. After softening up the coasts, Mitch assaulted. For five agonizingly long days the storm meandered across central America, first Honduras, then Guatemala and finally southern Mexico. That ugly hurricane was in no hurry, in fact it was incredibly slow. During its journey, about 50 inches of rain came down, more rain in five days than we get in a year and a half. With its heavy rains and strong winds, this storm’s “mean spirit” was that of a predator, catlike in its killing. Like a cat it slowly, methodically, almost lovingly obliterated some of the poorest communities of the region.

In the highlands Hurricane Mitch’s waters were extremely erosive, scouring out canyons and washing away villages and bridges. Great masses of mud quickly glutted local stream channels. Downstream those many gluts of mud coalesced and advanced as enormous terrifying and killing mudflows. The cold, wet masses rushed down canyons at the speed of an automobile.

No area was worse than the slopes of the Casitas Volcano in Nicaragua. This long extinct Volcano, with its rich soils, had supported agricultural communities for ages. Many villages dotted its slopes, especially along the small stream that flowed south from the summit. At the volcano’s peak there was a large crater. With the heavy rains, the crater filled up and eventually overflowed as a flood. The flood waters rushed down the small canyon and picked up great masses of mud. Soon there was muddy water, then there was watery mud.

From the air, pilots reported that the Casitas mudflow looked like a brown lava flow. It flowed down the canyon and was soon 1500 feet across and eventually ten or more miles long. It flowed across two high mountain villages, one more village farther downslope, and several smaller habitations. Burial was in a matter of a minute or so. In the end about 30 square miles of Nicaragua were under thick layers of mud. In the end, also, about 2,000 people died.

Mudflows are horrible killers. They advance at speeds no one can escape. They engulf villages with little or no warning. Death in a mudflow must be an awful fate. The speeding currents of cold mud strip still-living humans of their clothing and then smother them. Some bodies are contemptuously spit back naked to the surface; most are left buried forever. There is talk of marking the Casitas location as a national cemetery.

These awful events are not confined to far-away places, they have happened here, but only in the very distant past. High in the Catskills you can climb and see what is left. Travel to the Central Escarpment of the Catskills and hike the slopes of Indian Head, Twin, or Sugarloaf Mountains. Below 2,800 feet in elevation, the strata are a mix of red shales and brown sandstones. These are old fossil floodplain soils and river channel deposits. Above 2,800 feet the strata are different. There the strata are thick masses of coarse gray sandstone. Within the sands are many bits of gravel. Not all, but many of these thick strata are old mudflow deposits. Those flows descended the slopes of the old Acadian Mountains of nearly 400 million years ago. The old muds have hardened into fine ledges of rock with magnificent vistas of the wild central Catskills landscape. It is ironic that such awful events of the past should give us such beautiful views today.

We geologists are not Animists, we know that our rocks do not have spirits, but if we are wrong and they do, then there are many evil spirits up there in the higher Catskills.

  Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Stony Clove, Aug. 6, 2020

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Stony Clove

On the Rocks. The Woodstock Time

Updated by Robert and Johanna Titus

 

It can often be difficult to teach a science, even one as interesting as geology. Many people are averse to the sciences. One problem is that a lot of people really would rather not know the technical details behind some remarkable phenomenon. They believe it better to harbor romantic images and not spoil them with harsh factual science. Let’s try this out at Stony Clove.

Stony Clove is a magnificent sight to see. It is a very steep, very narrow notch in the Central Escarpment of the Catskills. It is a remarkably scenic location, especially in the autumn when the leaves are in color and when the lake there reflects their image. A person might very well be tempted to not want to know too much about the notch. How could the science improve upon such natural beauty?

Maybe science is the wrong word to start out with. A better word is mystery. What is this wonderful notch and how did it come to form here? That sounds better, and if the mystery of Stony Clove catches your interest, then it must be the science of the site which will solve that mystery. Certainly no geologist can pass such a landscape feature without wondering how it came to be, and there is quite a story behind the notch, one that takes us back to the ice Age.

When you get a chance, travel to Stony Clove. As you approach the top of the clove, there is a lake to your left. Beyond is the narrow gap in the mountain. Drive to the crest of the hill and stop; in your mind’s eye go back 17,000 years. It’s a time in the history of Catskill Mountain glacial history called the Wagon Wheel Ice Margin. From the Hudson River, valley glaciers have advanced up Plattekill and Kaaterskill Cloves. Some of this ice has turned south and entered into Stony Clove. From the crest of the clove you can picture this glacier; it’s just to the north. Its front is a mess, a jumble of broken blocks of ice. There is a small lake at the base of the glacier. All along the front of the ice, where it bounds the lake, great masses of water are welling upward, and the surface of the lake is churning with turbulence. It’s evident that the climate has been warming and the ice is melting. The glacier is disintegrating and from time to time one or another of those blocks of ice proves unstable and collapses into the lake with a violent crash. With that, a tidal wave radiates quickly across the lake. It’s a big wave in a small lake so the agitation is immense, a lot of that water spills over the crest of the notch.

In your mind’s eye look south, down the valley from the crest. With all that melting, there is only one place for all the water to go and that is in this direction. Stony Clove is a great, loud, cataract of foaming white water racing down the valley. The strength of the flow is manifest in the cracking sound of tumbling, colliding cobbles. Competing currents of water criss cross around boulders and collide with each other sending white fountains into the air. The hissing spray catches the sunlight and forms rainbows.

Many of the powerful currents abut the stream bank. Where this occurs, muddy gravels collapse into the flow and the sediment is rushed away. Beneath the white surface the water is brown with erosion. It’s this erosion that has carved the great notch in the mountain.

On a quiet summer or autumn day Stony Clove can be a site of serene natural beauty, a quiet place to picnic or just sit and gaze. But the serenity is deceptive; there is real violence in the clove’s origins. You can’t really understand Stony Clove unless you understand its past. You have to use your mind’s eye and you need to know its geology to do that.

   Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.: Read their blogs at “thecatskillgeologist.”

Uplift in the Catskills July 30, 2020

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The Uplift of the Catskills?

The Catskill Geologists

Robert and Johanna Titus

 

Late at night in geology bars we get into all sorts of tussles with people over various geological subjects. Recently we were debating the issue of whether or not the Catskill Mountains had ever suffered from the tectonic effects of folding and uplift. Most mountain ranges have endured both and often to a very great extent. So too have our Catskills but these events have been far more subtle and to properly understand them, they need some careful explanation.

Let’s do folding first; that’s the easy part. There is folding in the Catskills but only in its easternmost areas. All Catskills stratified rocks within the Hudson Valley were folded during the Acadian Mountain building event, a little less than 400 million years ago. We think that the Catskill Mountain House ledge has a gentle westward slope to it which brings it down to the shores of South Lake .Beyond that, there is a gentle southwest tilting of the strata throughout much of the rest of our mountains. It’s virtually impossible to see. None of this deformation is all that impressive, especially compared to the Rocky Mountains but it did occur, and it occurred during an important mountain building event.

The uplifting is far more difficult to explain. We are going to have to summon up our clearest writing skills and you are going have to be very perceptive readers. Ready? It all began as the Acadian mountains were rising above today’s western New England. Visit the Mountain House site; look east and you can easily imagine this mountainous uplift on the eastern horizon. Those rising mountains weathered and then eroded. Vast quantities of sediment, most of it being sand, poured onto our Catskills region. Over millions of years, the weight of that sediment pressed down into the crust, causing it to be depressed thousands of feet into the depths. Great thicknesses of sediment that had been deposited at the sea level elevation of a delta, came to lie thousands of feet beneath the earth’s surface.

As long as the Acadian Mountains were rising this process continued and even got worse. Thicker and thicker sedimentary sequences were pressed deeper and deeper into the Earth’s crust. All of it hardened into rock, mostly sandstone. But eventually the mountain building ended in New England. And with this the Catskills stopped being a depositional vicinity and, with more time, became erosional. Over the course of tens of millions of years Catskill sandstones eroded away. This triggered what geologists call a rebound. As erosion stripped rock away, the loss of all that weight resulted in an uplift or rebound from below. Stratified rock, that had long been deeply buried literally rose toward the surface and, in its turn, came to be eroded away. Last week we described the Mountain House Hotel ledge as having been a river channel deposit that had formed at sea level. Now it lies at an elevation of about 2,200 feet. It is a typical example of what we are talking of today. Stand there sometime and look down. These rocks had once been thousands of feet lower and now they are slowly rebounding.

In the end, our main points are that the Catskill mountains were deformed by folding, just not a lot of it. And those same rocks have, indeed been uplifted, just not in the same manner as is seen on other mountains.

Time for another pitcher of beer and another topic to “discuss.”

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”

The Mountain House ledge July 23, 2020

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The Mountain House Ledge

The Catskill Geologists

Robert and Johanna Titus

 

We always like to say that there is a spiritual heart to the Catskill Mountains and that heart is a field called Pine Orchard, lying atop the Catskill Front near North-South Lake Campground. There is a fine ledge of sandstone there and it offers a 75-mile sweeping view of the Hudson Valley. Not surprisingly it became the site of a hotel and that was the famous Catskill Mountain House, first opened in 1824. We frequently find ourselves visiting and we like to sit upon that ledge and gaze into the valley below. Behind us is the image of the old hotel, crowded with its many guests. Back in the 19th Century anyone who was anyone stayed in the hotel. Three presidents visited along the most prominent businessmen, industrialists, artists, writers and so many other celebrities of those times. Now the hotel is gone, but its presence can still be felt here; it was an important place; it still is.

We put our hands upon that sandstone bedrock; it is important too. Human history fills the empty space above the ground but everything below the surface is geological history, and that’s all ours. We can touch it and we can see it. There are miles of sedimentary rock beneath the surface right here and that is a lot of history. That sandstone ledge, for example, is a petrified river deposit. Those sandstones were once sands and they filled a sizable river channel, flowing from out of New England and into the west.

That river flowed across something called the Catskill Delta. It’s an ancient bit of history, well-known and perhaps even well-loved by geologists, and it conjures up quite a story. We look east and see the profile of a rising mountain range out there. Those are the Acadian Mountains and we are looking about 380 million years into the past. Those mountains are in their prime and are very actively rising. They are also actively weathering. Chemical processes are destroying the bedrock of those mountains, turning it into sediment, mostly sand, which is traveling down mountain streams. Where those streams are entering the Catskill Sea, which lies west of the mountains, they are depositing the Catskill Delta.

And, at the Mountain House site, we are sitting in the middle of just one of those streams. It’s not unusual for hundreds of them to make up a large delta complex. But suddenly we realize something important about this river: in its day, it must have been lying exactly at sea level. Such deltas always form at sea level. We, again, gaze into the valley below. The Hudson River flows at today’s sea level and that lies about 2,200 feet below us. Suddenly we have an “aha” moment. This ancient river had once flowed by at a level 2,200 feet lower than where it is today. It has been uplifted all that much. There has to be a story here, a story of tectonic uplift. Let’s continue with this next week.

Contact the authors at randjtitus@prodiy.net. Join their facebook page “The Catskill Geologist.”  Read their blogs at “thecatskillgeologists.com.”

The Abyss at Olana, July 17, 2020

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The Abyss at Olana

Robert and Johanna Titus

 

The great tourist attraction in the middle Hudson Valley is Olana. We went there and stood on the bank in front of the south-facing porch of the old mansion and gazed at its fine view of the Hudson Valley and Catskill Mountain. This is one of the great vantage points from which to see the Catskills. There are days when the atmospheric conditions are just right, and the mountains seem to reach out to you. It’s not just a view; this is also a genuine work of art. Frederic Church intended the porch should have this vista; it is, among many others, one of his “planned views.” For thirty year he was able to enjoy the scene and we envy him that.

But as geologists, we are privileged to see some other views at Olana. On that wonderful site our minds drifted back into deep time. We were at the bottom of the oceanic abyss that was once here. The waters were cold and black, but more than anything else they were still and silent. This was a dead seafloor. Nothing crawled across the mud and nothing swam in the waters. We scooped up some of the mud; it was soft and sticky. It was foul with the remains of dead microbes that constantly rained in from above.

With time the avalanches came. The stillness was abruptly interrupted as the seafloor was jolted by seismic shocks. Shortly thereafter great masses of sediment began tumbling down the slopes. For long minutes there was the rush of dirty water. The torrent boiled as murky clouds billowed upwards all around us. Then the current slowed and gradually the water cleared. The Olana seafloor returned to it silent dead, stillness.

Our mind’s eyes rose through tens of thousand of feet of quiet water until they reached the surface of the sea. We gazed eastward and saw dense black clouds rising above the horizon. The blackness drifted my way and soon it rained volcanic dust into the water all around. Then we looked back eastward again and now a rising landmass had replaced the black clouds on the horizon. The stark profile of volcanic mountains defined this new horizon

The passage of time accelerated. As we watched, this landmass grew taller and its shores swelled out toward us. We were soon lifted out of the sea by the rising gray crust. Occasional, the earth beneath us shook with powerful quakes as the land rose higher and higher. Eventually, we found our imaginary selves high atop a still rising Taconic Mountain range. To the north and south, volcanoes erupted in violent spasms. Below, to the west, what was left of that deep sea retreated away from the rising mountains.

There should have been a great deal of green in this image but there was none. This was a fine range of mountains, but it was a dead landscape that had replaced a dead seafloor. We were in the Late Ordovician time period, and life, especially plants, had not yet managed to colonize the lands. All around us was a bleak, blue-gray landscape. There were not even proper soils, just a litter of gray gravel lying upon bare rocks. Only the dry channels of gullies and ravines broke the monotony of the desolation.

We realized that we had come to the very spot where, 450 million year later, Frederic Church would stand. But we were not seeing what he would see. No, below us and stretching off to the west, a large river delta had formed adjacent to the rising Taconic Mountains. A complex of murky streams crossed the dark gray of that delta. Farther away we could see the retreating waters of the sea. It was bleak and lifeless vista, but there was grandeur in this, Olana’s great unplanned. view.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Hit by a speeding glacier July 10, 2020

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Hit by a speeding Glacier II

On the Rocks, The Woodstock times

March 27, 1997

Updated by Robert and Johanna Titus

 

Around here late winter drags into spring. We get teased by a day or two of warmth and then back comes the cold. It’s depressing and takes its toll on people. But imagine for a moment being teased by some warm weather only to have to face another few centuries of cold. It happened.

Last time we saw the great Hudson Valley glacier advancing from the north, turning into the Woodstock-Ashokan vicinity and flooding the lower Esopus Creek valley. This is sometimes called the Wagon Wheel ice margin and it occurred about 17,000 years ago. That state of affairs lasted for quite some time, maybe centuries. But all bad things must come to an end, and eventually the Arctic cold gave up some of its grip. The ice began to melt, and the glacier retreated from the Esopus. The front of the ice retreated to a line that extended from just south of Overlook Mountain to just north of Kingston. This is quite a time in the history of Woodstock as it conjures up a fine geological scenario. Once again, it’s the mind’s eye that can take us to see an ancient wonder.

It is 16,000 years ago. In our mind’s eyes we are over Boiceville, drifting down the lower Esopus Creek Valley. The valley is a complete mess. It has just emerged from beneath melting ice and is strewn with glacial debris left behind. You know what your backyard looks like in April after a thick snow has melted; this is worse. To the north, behind us, glacial ice is still rapidly melting and that’s feeding enormous amounts of meltwater into the valley. Immediately below us, the Esopus is a swollen white-water stream. Its churning, swirling torrents are cascading down the valley. There are some stretches of the valley which are choked by enormous mounds of sand and gravel, deposits left by the recently retreating ice. These are blocking the valley and small lakes have formed behind the dams. In other locations the valley floor is covered by relatively flat plains of sand. There the Esopus has spread out across the sand and its channel has split up into a myriad of small crisscrossing streams. Geologists called them “braided” streams.

We continue our mind’s journey and leave the Esopus at Ashokan and head northeast toward Woodstock. Below, the landscape continues to be a desolate mess, more heaps of glacial sediment alternating with many small ponds. There are no trees as the climate is still too cold. As we continue drifting eastward, we begin to see a number of much larger pools of water. Beyond them the Hudson Valley glacier rises. The front of the glacier runs north-south right through the present-day location of Woodstock. The front of the ice is very low and behind the front the ice rises at a very low angle. Advancing glaciers loom tall and menacing in a valley, but the low slope of the ice we see is the hallmark of a melting glacier. All along the front of the glacier large springs of dirty meltwater are welling up into those pools of water. From time to time masses of ice collapse into these pools. These are noisy affairs and large waves radiate across the ponds.

All this should be a hopeful sign. There were no people in North America to witness this melting but had there been there would have been grand rejoicing at the retreat of the great ice sheets. Glaciers had filled the lower Hudson valley for the last 5,000 years. Now this awful glaciation seemed about to end.

But sadly, all good things come to an end. Earth history seems to be an endless number of cyclical events. Alas at 16,000 years ago conditions once again shifted in favor of the glaciers. “Spring” would be delayed a few centuries as there was another advance of ice into the Esopus Creek valley. This one is called the Rosendale readvance of the ice and it repeated much of the Wagon Wheel event. Once again, a glacier passed across Woodstock and once again it crossed today’s Ashokan Reservoir. But this time the advance was not quite as far. Once again, the cyclical sequence was repeated. The ice advanced as far as it would and then stagnated. Still one more time the cycle, predictably, swung back from cold to less cold. That favored melting and the glacier retreated the Woodstock area, this time for good. Is “for good” as long as forever? Not likely, but the glaciers have left for good, at least in the way humans measure time.

Oh, the indignity of it all. In effect a glacier ran across Woodstock about 17,000 years ago. Then, a thousand years later, the ice stopped, backed up and ran across Woodstock a second time. Nature means no offence to Woodstock; her endless cycles are just her way.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Boulder Rock July 2, 2020

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Laurels for a Great Big Rock

On the Rocks; The Woodstock Times

June 4, 1998

Updated by Robert and Johanna Titus

 

June is the time to visit North Lake State Park. If you have not been there, North Lake is one of the gems of the New York State park system. There’s not one, but two gorgeous lakes (The other one?  . . .South Lake, of course). More than that, there are several miles of trails running along the great Catskill escarpment. Anywhere along the escarpment trail you can see a grand view of about 70 miles of the Hudson Valley. Beyond that, there are more trails into the woods and up into the mountains.

If you don’t like hiking then you can camp, swim, or picnic.

The park has recently opened for the new season (1998) and among the real draws is the Mountain-laurel which is, right now, in flower. But, year-round, scenery has always been the major attraction at North Lake. Thomas Cole came here in the 1820’s and the canvases he did here helped found the Hudson Valley school of art. The Catskill Mountain House Hotel was, for quite some time, the premier summer resort of America. It was right above the two lakes.

But our main attraction at North Lake has been the rocks and there are some very good ones here. Let’s go look at one of the best. Enter the park (they charge admission by the carload) and drive all the way to North Lake itself and park. Hike south toward the Catskill Mountain House site (follow signs for the hotel site and the blue trail). The hotel is long gone, but the site is still a clear field with a great cliff and magnificent view. You can see the Hudson River and the Taconic Mountains beyond. If you know where to look, you can see the town of Catskill, Frederick Church’s mansion, Olana, and many other sites of the Hudson Valley.

The hotel was pretty expensive so enjoy the view; a century ago you probably couldn’t afford it! Find the signs for the blue trail and follow them up the hill. You will ascend a couple of hundred feet in elevation, and quite steeply at first. Eventually the trail will level out upon one of those great ledges that are so typical of the Catskill Front. Here and there, you will find more vantage points. In June, however, it is the Mountain-laurel that you may want to see; they are at their best now. Soon the trail branches. Follow the signs and take the left branch toward “Boulder Rock.” It isn’t far.

It’s an odd name, but a good one; Boulder Rock is an enormous rock. You can’t miss it; it’s just to the left of the trail. What’s perhaps most remarkable about it is that it is perched right on the edge of the cliff. Yawning out before the boulder is a steep 2,000-foot drop. And if it had been any smaller it would have been pushed over the edge. Alf Evers records that virtually all such boulders, that were small enough and close enough to the edge, did meet such a fate. But this one is much too big for even a small army of very brawny men to dislocate.

So fine, now we know why it is still there, but how did such a boulder get there in the first place? The answer is easy, and it is a good one. Boulder Rock is called by geologists a “glacial erratic.” Our story takes us back about 14,000 years ago to when the last glacier was advancing down the Hudson Valley. The ice age was ending, but ice was still active in the valley. Glaciers are currents of moving ice and they can pick up and move almost anything they want to, including very large boulders. Boulder Rock was swept up in the flow of ice and carried here. The ice then melted and left the boulder behind.

This is commonplace; many displaced boulders are found throughout glaciated regions. We call them erratics because their lithologies do not match the local bedrock. Boulder Rock isn’t all that erratic, however, it probably came from North Mountain, only a few miles away.

Please do make the trip, especially if you have not been to the park before. When you reach Boulder Rock try to imagine it as it was long ago. Imagine the valley before you filled with old gray ice. The ice is melting and wet with pools of water. Up here, water is pouring off the ice and Boulder Rock itself is just emerging from its white shroud. All around, the landscape is still pretty bleak. It will be quite a while before this area recovers from its glaciation, but when it does recover, it will have done it very well indeed.

Contact the authors at randjtitus@prodigy.com. Join their facebook page “The Catskill Geologist.”

 

The abyss at Olana June 25, 2020

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The Abyss at Olana

Robert and Johanna Titus

                          

But the real tourist attraction in the area is Olana. We stood on the bank in front of the south-facing porch of the old mansion and gazed at its fine view of the Hudson Valley and Catskill Mountain. This is one of the great vantage points from which to see the Catskills. There are days when the atmospheric conditions are just right, and the mountains seem to reach out to you. It’s not just a view; this is also a genuine work of art. Frederic Church intended the porch should have this vista; it is, among many others, one of his “planned views.” For thirty year he was able to enjoy the scene and we envy him that.

But as geologists, we are privileged to see some other views at Olana. On that wonderful site our minds drifted back into deep time. We were at the bottom of the abyss that was once here. The waters were cold and black, but more than anything else they were still and silent. This was a dead seafloor. Nothing crawled across the mud and nothing swam in the waters. We scooped up some of the mud; it was soft and sticky. It was foul with the remains of dead microbes that constantly rained in from above.

With time the avalanches came. The stillness was abruptly interrupted as the seafloor was jolted by seismic shocks. Shortly thereafter great masses of sediment began tumbling down the slopes. For long minutes there was the rush of dirty water. The torrent boiled as murky clouds billowed upwards all around us. Then the current slowed and gradually the water cleared. The Olana seafloor returned to it silent dead, stillness.

Our mind’s eyes rose through tens of thousand of feet of quiet water until they reached the surface of the sea. We gazed eastward and saw dense black clouds rising above the horizon. The blackness drifted my way and soon it rained volcanic dust into the water all around. Then we looked back eastward again and now a rising landmass had replaced the black clouds on the horizon. The stark profile of volcanic mountains defined this new horizon

The passage of time accelerated. As we watched, this landmass grew taller and its shores swelled out toward us. We were soon lifted out of the sea by the rising gray crust. Occasional, the earth beneath us shook with powerful quakes as the land rose higher and higher. Eventually, we found our imaginary selves high atop a still rising Taconic Mountain range. To the north and south, volcanoes erupted in violent spasms. Below, to the west, what was left of that deep sea retreated away from the rising mountains.

There should have been a great deal of green in this image but there was none. This was a fine range of mountains, but it was a dead landscape that had replaced a dead seafloor. We were in the Late Ordovician time period, and life, especially plants, had not yet managed to colonize the lands. All around us was a bleak, blue-gray landscape. There were not even proper soils, just a litter of gray gravel lying upon bare rocks. Only the dry channels of gullies and ravines broke the monotony of the desolation.

We realized that we had come to the very spot where, 450 million year later, Frederic Church would stand. But we were not seeing what he would see. No, below us and stretching off to the west, a large river delta had formed adjacent to the rising Taconic Mountains. A complex of murky streams crossed the dark gray of that delta. Farther away we could see the retreating waters of the sea. It was bleak and lifeless vista, but there was grandeur in this, Olana’s great unplanned. view.

   Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.

Fossil corals of the Catskill Mountains June 17, 2020

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Fossil corals of the Catskill Mountains
Robert and Johanna Titus
From chapter 7 of their book The Catskills, A geologic Guide, 4th edition

Corals: Film and still photos of coral reefs portray some of the most vivid and colorful images of today’s seas. Such images are difficult to associate with the Catskills but, as in today’s tropical seas, corals were sometimes quite common in the old Appalachian Basin. While there is nothing in the Catskills that can match the Great Barrier Reef of Australia, there were some fairly decent reefs in those times. Many of the Devonian forms were horn corals (see right figure below; (A) horn coral; B) digitate corals C) honeycomb corals. Courtesy of the New York State Museum) so named because they had skeletons shaped like a cow’s horn, wide and open at one end and curving to a point at the other.
The chamber within was divided into compartments by walls much the way you see in a cut open orange. Other types are called digitate corals (figure 7-2B), that is they grew long slender branches similar to fingers (the digits). A third common group, the honeycomb corals, grew massive honeycomb-like skeletons (figure 7-2C) that are similar to some modern-day corals. Corals are only occasionally found throughout the strata of the Appalachian Basin, but they can sometimes be common in the Onondaga Limestone.

 

Stromatoporoids: The stromatoporoid is a peculiar fossil (left figure above), intermediate in appearance between sponges and corals. They were colonial- and reef-building animals, much like the corals. But they seem to have been simpler creatures, like the sponges. They appear to be entirely extinct, so we know nothing of their soft anatomy, and we will thus never be exactly sure what they were. They grew abundantly in the very shallow, nearshore environments of the Manlius Limestone and are seen within that unit, especially to the east as at John Boyd Thacher State Park (see Chapter Three). We have seen them in blocks of the Manlius that make up the Bronck homestead in Coxsackie.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.com.”

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