July 2020

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

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 19^th 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

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 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.”

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.”