Uncategorized - page 32

A VIEW FROM THE MOUNTAIN HOUSE PORCH

The Woodstock Times

Oct 3, 1996

Updated by Robert and Johanna Titus

The view of the Hudson Valley from along the Catskill Escarpment is one of the great sights of the east. You can enjoy it anywhere along a ten mile stretch from Overlook Mountain to North Point, but the most famous vantage point is long gone. That was the 130 foot long piazza of the old Catskill Mountain House Hotel. A 70 mile stretch of the Hudson lowlands lay visible below the hotel site. On certain days, when the clarity and humidity are just right, the atmosphere becomes a magnifying glass and that landscape seems to reach out to you.

Mountain House guests commonly arose just before sunrise. With a little luck they got a special treat. The cool morning fogs would enshroud the valley below. Then the Sun would slowly rise above the clouds, illuminating them brightly from above. It’s still a sight to see.

Beautiful as it is, this view thwarted the efforts of artists to capture it. Seventy miles is just too much to put on a canvas and anything less just won’t do. Only Frederic Church solved the problem. In his “Sunrise in the Catskills” he painted the view at dawn. He showed the Sun rising above a valley filled with clouds. That left all these unpaintable 70 miles of valley floor to the imagination of the viewer. It worked; the painting is a gem!

The twentieth century brought something new to the view. With electricity, the nighttime valley gradually lit up. On a clear, dry, moonless night, with the starry sky above and the lights below, the view is another great sight to behold.

The hotel is long gone, but the view remains. The Mountain House site remains a popular goal for the hikers and picnickers at the North Lake area. It’s a popular draw for visiting geologists as well. Our colleagues and we come to see the view just like anyone else. But we get to see two views at North Lake: One is the landscape as it is, and the other is as it was during the Devonian age. To the far east is the low profile of the modern Berkshires. These humble mountains are the erosional remnants of older and very larger mountains. They are the roots of the old Acadian Mountains.

Out there, between 350 and 400 million years ago, a great mountain building event took place. If you sat on the Mountain House piazza for 50 million years or so, the mountains would rise before your very eyes. It was one of the biggest such events to ever occur in eastern North America. At their greatest, these peaks, called the Acadian Mountains, stood maybe 15,000 feet above sea level, and maybe more, even a lot more!

As we look east from the hotel piazza we can still see those old mountains through our mind’s eyes. The jagged peaks are snowcapped. It’s a tropical climate here, 370 million years ago, so only the highest slopes are white. Below the snow, the mountains are a uniform smoky blue. There is enough haze so that the details of the landscape are not clear, but you can see many deeply cut gullies in the upper mountain slopes. It’s common for heavy rains to activate the gullies which then tear into the mountain. Farther downhill, the gullies merge into very substantial and extremely jagged canyons. During rainy times, great cataracts of water plummet down these valleys. The waters are brown with freshly eroded sediment; there is no flood or erosion control in the Devonian.

Toward the base of the mountain range the canyons empty out onto great heaps of sediment. These are beautiful; they have been sculpted into gently sloping fans and their light colored sediments shine brightly in the sun. There is no foliage to cover these fresh sediments.

But there is foliage farther below. In front of the fans is an enormous landscape of swamps, shallow ponds and many streams. It’s a huge delta complex which geologists have come to call the Catskill Delta. The delta is teeming with life, mostly primitive plants. There is an irony here. In looking at this ancient delta environment we are looking at the Catskills of today. That’s because, with time, the sediments of that ancient Catskill Delta spread out across much of today’s New York State. They hardened into rock and are now the sedimentary rocks of the Catskills of today. In the great cycles of time, one landscape is the parent of another.

And so it is that we sit upon the porch of a long gone hotel and gaze at mountains which eroded away 300 million years ago. Such are some special moments in the lives of geologists.

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

Time in Winter: The Catskill Front again

Windows Through Time

Revised by Robert and Johanna Titus

Daily Mail   Feb. 2011

Last year, about this time, we gazed up at the Catskill Front. That‘s a good thing for a geologist to do this season of the year. Winter is when it is so easy to see the ledges of rock that make up the stratigraphy. With all the leaves down we can see a lot more geology, and that is good. But some readers have written and asked us about some of the numbers we cited. We claimed that there are about 9,000 feet of strata up there and some astute readers wondered how that could be. After all, the Catskill Front only rises to about 3,000 feet at the top of places like North Point. “Where are the other 6,000 feet of rock?” they ask. Good question.

Well, fair enough, and the answers to their questions leads us to something important about the whole Catskill sequence.  First, let’s document our estimate. We asked Dr. Charles Ver Straeten, of the New York State Museum, about this and he confirms that there are eight or nine thousand feet of strata in the Catskill Sequence, depending on exactly where you measure. Plenty more strata have eroded away over the eons. These strata begin at the bottom of the Hudson Valley and stretch up to the top of Slide Mountain. Dr. Ver Straeten has spent many years studying this sequence; his opinions carry a great deal of weight.

But, how come all these strata don’t’ rise up higher over the landscape? How come we don’t have Catskill Mountains that tower a full 9,000 feet? The answers to those questions take us back to the processes that created the Catskill Sequence and the Catskill Mountains themselves. We have to travel back about 380 million years of so, to a time when the Catskills first formed. Back then North America had been enduring a great collision with a landmass which you might call part of Europe. The collision led to the uplift of all of Northern New England and the creation of a mountain range called the Acadians. This event is known to geologists as the Acadian Orogeny.

We have talked about this in several columns. Weathering and erosion of the Acadian Mountains produced the sediment that eventually formed the Catskills. But there was a lot more than just sedimentation going on. There was plenty of real warping of the rocks. The notion of deforming rocks may well be a novel one. How, on Earth, can rocks be deformed? They are, after all, pretty rigid materials. And they are very stable too; at least that’s as it would seem.

Well, rocks certainly are rigid, stable entities, at least under the normal circumstances that we are all familiar with. But most rocks have been around a very long time and they have had many long “journeys.” Our Catskill rocks are mostly a little less than 400 million years old and that was plenty of time for them to have gotten into a lot of “trouble.”

By that we mean that our rocks have seen themselves buried under thousands of feet of other rocks–many thousands of feet. Look up at the Catskill Front and imagine that great thickness of strata rising high above it. That rock would weigh a great deal and the weight we speak of is what allows much of the deformation. Imagine how you would feel if several thousand feet of rock were pressing down upon you.  But there is more.

Our rocks suffered deformation in another fashion. They were there when North America experienced the worst of that continental collision. Again we have to use our imaginations. Try to envision what it is like to be “hit” by another continent. If Europe slowly collided with North America the pressure of the impact generated would be truly enormous.

Now we have seen two processes ganging up on our poor rocks: first there was the weight of burial and then there was the shove of a massive continental collision. The effect of each, individually, would be enormous, but we want them to be occurring at the same time. That’s, in fact, what happened. As Europe collided with North America, it generated a massive uplift and tilting within the whole northern Appalachian realm. Those mountains, the Acadians, eroded away and their sediments buried our Catskill region under thousands of feet of sediment. It was compression, however, that had the better of it. “Europe” pressed in from the east, shoved our Catskill sequence, and then tilted the strata into a broad incline. Incredibly, later in time, Africa collided and all this was repeated. It is such monumental tilting that allows about a mile and a half of strata to make a mountains range only 3,000 feet tall. See our illustration.

Tilted strata of the Catskill Front – Courtesy of Alan McKnight

Reach the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Watch for them in the Mountain Eagle, the Woodstock Times and Kaatskill Life.

Clove encounter

On the Rocks

The Woodstock Times

April 10, 1997

Revised by Robert and Johanna Titus

It can often be difficult to teach a science, even one as interesting as geology. Many people are adverse to the sciences. One problem is that a lot of people really would rather not know the technical details behind some remarkable piece of nature. They believe it’s 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 into the ice age.

When you get a chance, travel to Stony Clove. As you approach the top of the clove on Rte. 212 from the south, there is a lake to your left. Beyond that is the clove. Park in the lot next to the lake and hike north to the top of clove. 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. Its waters reach up to your feet. 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 back 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 raging, foaming, pounding white water racing down the valley. The strength of the flow is manifest in the cracking sound of tumbling, colliding boulders. Competing currents of water crisscross around the largest boulders and collide with each other sending white fountains into the air. The hissing spray catches the sunlight and forms rainbows.

Many of the most powerful currents abut the stream bank. Where this occurs muddy gravels collapse into the flow and this sediment is rushed away. Beneath the white surface, the water is brown with erosion. It’s this scouring 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. This is the science of it all.

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

Tafoni: A real mystery, and a local one at that

On the rocks

May 29, 2014

Updated by Robert & Johanna Titus

Phoenicia has been in the news a lot over the years. It is best known as a place that has had serious flooding problems. Various northeasters, along with the occasional hurricane, are enough to fill Stony Clove Creek to overflowing. The creek swells up over its banks and makes a mess of the town. Engineering efforts to improve flow beneath the bridge there have been controversial. Their effectiveness is questioned.

But, that’s not the topic of this column.

We were recently invited to go to Phoenicia and take a look at some very strange geological phenomena. Our host was Paul Misko, of the Catskill 4000 hiking club. As a veteran hiker, Paul can be found just about anywhere in the Catskills and he has a real eye for unusual geology, so we paid attention to his “very strange” claim. He had piqued our curiosity and, when we got there, we weren’t disappointed; we found a real puzzle. Across the street from the St. Francis DeSales Roman Catholic Church, is a small park. If you walk into the park from Main Street and bear toward the right (east), you will soon find a small hiking trail. It’s called the Tanbark Trail (you can run a search and get a map of it). Climb up a steep incline, and towards the top you will find a fairly sizable ledge of sandstone. It’s rather commonplace stuff; it is a very typical Catskills bluestone ledge. We recognized what are called cross beds. That is to say that a lot of the strata here dip in one direction or another. They were not very well defined, but they were there. That is normally the case with bluestone that was deposited in river channel sandstones. This ledge is, in essence, the cross section of a very old stream. It’s, like all rocks in the Catskills, Devonian in age, something a bit less than 400 million years old.

None of this surprised us in the least. It was strictly routine stuff. But that’s where we encountered that mystery. Take a look at our photo and see what you think. The first view shows the entire ledge. Commonplace cross-bedded bluestone makes up the whole lower half of the exposure. Up top are a large number of closely spaced and very strange cavities. The close-up view shows a tightly packed cluster of these cavities in the rock. Their shapes vary considerably, but they all show a sort of boxy nature and they seem to form an interlocking network. We would like to use the term honeycomb here, but honeycombs show a consistent hexagonal shape; we don’t see that with these. The rock remaining in between these cavities is narrow. The cavities do not penetrate too far into the rock, just a few inches. And there is no reason to think that there is another horizon of these cavities under the ones that are visible. Thus, they appear to be surficial features. Nevertheless, these cavities seem to be concentrated. Many of these cavities are spaced so close together that they comprise a bigger compound cavity. Whatever it was that formed them was focused.

All in all, this is the most puzzling phenomenon that we have seen in ages. There is no trouble putting a name on what is here; it is called tafoni. Each individual cavity is a tafone; lots of them are tafoni. And the terminology keeps getting better; when tafoni occur on cliff faces, as at Phoenicia, then it is called lateral or sidewall tafoni. But, putting a name on something is not the same as understanding it.

What are these features? They seem to be weathering phenomena. Somehow, they appear on the rock surface and grow slowly into their observed shapes, but exactly how? And, also, how is it that they grow in size until they abut each other but do not grow into each other? How do they grow in size without intersecting? Those are very puzzling questions and just naming these things does not provide answers.

Tafoni have been weakly associated with poorly defined stratification on the sides of cliffs and that is the case here. But that still leaves a lot unsaid. Why does this “association” occur? What are the specifics? Salt is commonly cited as an agent in Tafoni development. They are sometimes found on coastal outcroppings, splashed by ocean waves. But there is certainly no source of salt here on a sandstone cliff in Phoenicia. And that begs the question: what exactly is different about his cliff? We have literally seen hundreds of similar cliffs, all through the Catskills and all composed of the same type of sandstone, all originally deposited in the same Catskills Delta river channels. Why don’t all of those other cliffs have tafoni? Why isn’t it that none of them do? There must be something here, right in front of us, which we have missed. This is the sort of thing that makes science so much fun.

Do you have any ideas or questions? Have you seen tafoni somewhere? Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Buried alive, the Gilboa Forest

On The Rocks

The Woodstock Times

Oct 10, 1996

Revised by Robert and Johanna Titus

It’s autumn and once again the leaves are in color. This annual event has not always been. Autumn color is a characteristic of today’s advanced deciduous trees, but there was a time when the world’s forests were composed only of the most primitive plants. In fact, there was a time when there were no forests at all. We New York State paleontologists get to see the transition from a world without forests to one with them. We have very old terrestrial deposits here, red sandstones of Silurian age. They formed in habitats where trees should have been common but they have no fossil trees at all. Then there are the Devonian age Catskill red sandstones. They are only about 40 million years younger, but they have a great abundance of fossil trees. During that interval trees evolved and spread out across the Earth as the first and oldest forests.

Fossil trees this old are extremely rare, but you can go see some of them yourself, and enjoy a fine autumn drive at the same time. From Woodstock take Rte. 28 to Rte.42 and drive from from Shandaken to Lexington. Then take Rte. 23A west until you reach Grand Gorge. Take Rt. 30 north 2.8 miles and turn right onto Rte. 990V. Go downhill another 1.2 miles and you will reach Schoharie Creek where it passes through the village of Gilboa. Just beyond the bridge is a little park with some very fine fossil tree trunks. This humble site commemorates one of the world’s most famous fossil locations, the Gilboa forest. After looking at these fossils you can proceed a short distance to the Gilboa Museum. It’s only open on summer weekends but it displays some more very fine fossil trees.

The Gilboa forest was discovered after the terrible Schoharie Creek floods of late 1869. Extensive erosion along the river ripped through soft red shales and exposed a number of fossil tree stumps. The discovery caused quite a stir and well it should have. This was the oldest known fossil forest; before them nobody had ever guessed that trees were this ancient.

It got better in the 1920’s. Excavations for the Schoharie Reservoir revealed about 200 more fossil stumps. The trees in the little park were among these. These famous Gilboa fossils offer us a rare view of what forest ecology was like very early in its history. Gilboa was forest of trees, most of them called progymnosperms. In common terms that means that these were essentially very big ferns with tall wood stems (trunks). In time they would evolve into today’s common cone-bearing trees, called gymnosperms.

Beneath the trees was simple ecology of even more primitive plants. Hiding among them was an animal ecology of simple arthropods. These were an abundance of centipedes, millipedes, and simple insects, along with many truly exotic creatures. One of note is that Gilboa is the home of some of the oldest known fossil spiders. This is certainly a peculiar, but truly remarkable distinction for a small town. Spiders are among the most abundant and successful groups of invertebrates on the planet and some very old ones are right here!

There are ironies in the story of Gilboa. The trees are a metaphor for the great cycles of time. They grew not along the Schoharie Creek, but along some ancient nameless stream of the old Catskill Delta. They were long ago buried in the muds of a long forgotten flood. There must be a story here: What kind of flood was this? How bad was it? There is no answering such questions. For hundreds of millions of years they lay entombed in those flood sediments. During that time they hardened into rock. If it was floodwaters which buried them, then it would be flood waters which would release them. These trees of stone lay in wait for the day when another awful flood would bring them back into the light. The irony came when so many of them were once again submerged in the waters of the Schoharie Reservoir.

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

Cycles of earthquakes?

Windows Through Time

Robert and Johanna Titus

April 14, 2016

A fun part of our job with the Columbia-Greene Newspaper chain is just going out and exploring for some fascinating locations where there is good geology. Recently we were in Saugerties to hear a lecture at the Friends of Saugerties History Group at the town library. Afterwards, we just went exploring. We found ourselves heading south on Partition Street, we crossed the bridge over Esopus Creek, and took the first left onto East Bridge Street. That took us along the Esopus on Ferry Street.

We didn’t expect to see much. You see Esopus Creek, long ago, when it began flowing into the Hudson, formed a pair of peninsulas that pushed out into the larger river. We expected that these would be composed mostly of sand and would be pretty boring stuff. Well, we were wrong.

A little less than a quarter mile down the road we were forced up and over a sizable knob of rock. When they constructed Ferry Street they had to blast through all that rock. And that gave us a beautiful exposure of bedrock.

We recognized the rock unit, immediately. It was the Normanskill Formation. That has some very important and very interesting geology. It dates back about 450 million years and it is big. Much of the middle Hudson Valley is blanketed with the Normanskill. A lot of it is west of the river, but there is more of it on the east side. It’s named after Normanskill Creek where a very large exposure is found. That‘s where Rte. 9W approaches Rte. 787.

It’s a unit that we should be writing about more often. It is composed of a mixture of thick dark gray sandstones and thinly laminated black shales. Way back during the Ordovician that sandstone was sand and the shale was mud. These sediments accumulated at the bottom of what is sometimes called marine trench or an “oceanic deep.” Deep indeed; that’s a stretch of ocean that can be 20,000 feet deep or more. The best known modern deep is the Marianas Trench in the western Pacific. It is more than 35,000 feet deep! Well, you can easily imagine those rocks caught our attention. They took us down to the deepest parts of the sea—to the very abyss.

But there is more—a lot more. Those black shales speak to us of routine moments on the floor of such deeps. They accumulated one lamination at a time. Silt and clay slowly settled to the floor of the ocean. It takes grains of silt and clay months, even years, to sink that far. So these sediments accumulated very slowly. A few inches of this sort of black shale may represent enormous amounts of time. How much time does a foot of shale represent? Well, in truth, we geologists have no idea, but it is a lot of time.

Not so with those sandstones. They are different. They are a special type of sandstone; they are called greywackes. A greywacke is not just a sandstone; it is a “dirty” sandstone. You are probably used to the clean white sands that we see along the Atlantic coast; those are almost pure quartz sands and quartz is almost white.
But these greywackes are different; there is a lot of quartz in them but they also have a large amounts of silt and clay. That’s the dirt in a “dirty” sandstone.

Greywackes are remarkable for how they form. They are often the products of submarine avalanches. Typically an earthquake strikes the deep sea floor and masses of sediment are thrown up into suspension. Such masses of sediment then, slowly at first, begin to flow down the slopes of the deep. Those avalanches are called turbidity currents and they quickly pick up speed. Soon they are thundering down the steep slopes into the abyss. Eventually they reach the bottom and begin to slow down. When they slow down enough, all that dirty sand slows to a halt and deposition occurs. Hence the greywackes we saw—and probably each one of them.

All this gets us back to the Ferry Street outcrop. It has an eye-catching feature; there are six thick horizons of greywacke and, in between them, are those expected black shales. But the shales are thin, only inches thick. That conjures up quite an image.

We walked along this outcrop and counted those six thick greywackes; we realized that we were likely counting earthquakes. And those thin shales indicated to us that those earthquakes and those turbidity currents had come in relatively short intervals. Those earthquakes were occurring in the nearby rising mountains of New England. Those mountains were in full uplift mode and we saw the results—in Saugerties.

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

Bugs in the house

Windows Through Time

Columbia Greene Media

Sept. 23, 2010

Updated by Robert and Johanna Titus

We don’t know how it is where you are, but in Freehold we have had one amazing summer for centipedes. They are all over the place! We find lots of them on the undersides of logs we have been using for firewood. We have also seen them scurrying around all over our property. Unfortunately that includes even inside our house where the little creatures have been making some occasional appearances. One of us, Johanna the biologist, has been controlling her professional enthusiasm very well! We wonder what causes such a biological event.

Centipedes are a large group of creepy crawlers. The word centipede roughly means hundred legs. When we were kids we spoke of “thousand leggers” and “hundred leggers.” Millipedes were the former; centipedes were the latter.  They both belong to an extremely large group of animals called the phylum arthropoda. Arthropods also include insects, crustaceans, and spiders. The centipedes are common members.

So, why are centipedes the topic of a geology column? The answer is that they are part of our Catskills geological history. We have written about our Devonian past in this column a number of times. About 375 million years ago a great delta spread out across that which would become New York State and, growing upon it, was something called the Gilboa Forest. That was a great expanse of tropical jungle. Our Catskills are essentially a petrified delta and these mountains possess the fossil remains of the plants and animals that lived on it. This is the oldest well preserved fossil forest ecology known to science so it is important. Paleontologists long ago learned a great deal about the plants of this jungle, but there were real limits on how much we knew about the animals that had lived in this ecology. There should have been a lot of animals living in the Gilboa Forest but they, for the most part, refused to be found.

Then, a quarter century ago, geologists at SUNY Binghamton found a way to dissolve Catskill sandstone so that the rock disappeared and the remains of tiny creatures that had been in them were separated out.  Hydrofluoric acid does a good job of dissolving the silica of rock, but it leaves the cuticle of arthropods alone. Using this technique, those Binghamton paleontologists quickly discovered bits and pieces of the skeletons of numerous arthropods, including quite a few centipedes. This was important research. Now geologists could start to put together lists of the animals that had inhabited this ancient forest. We were getting our first look at early forest ecology.

That list proved to be pretty much what people had expected. Our Devonian forest was populated by relatively primitive animals, and most of them were arthropods. There were very primitive insects and then a fair number of creatures which would be familiar to you: mostly spiders, millipedes and centipedes.

The point we are driving at is that those centipedes, which have been plaguing us this summer, have been around here for a very long time. And they have evolved, but not so much that you would notice it. We like to say that these creatures are “ambassadors from the Devonian.” When we look at them, we feel that we are looking into the past. If we were ever lucky enough to find a fossil centipede we would be thrilled beyond imagining. But, there they are – not fossils made of rock, but real living, breathing centipedes. To people like us this is a bit of a thrill.

Modern centipedes have to live in moist surface layers of soil because their skeletons lack a waxy coating which would keep water inside them. They have always been like this and, back in the Devonian, they inhabited the duff, or the moist humus-rich surface soils. They all have mean looking pincers, located at the most forward portion of their bodies. These pincers are not just mean looking; they are venomous too. These are used to kill and these little creatures are carnivores. They are the saber tooth tigers of the soils. Nobody is exactly sure what they eat as they are only active at night, but small worms are likely candidates for their meals. The largest fossils of these killers were over three feet long, a very frightening notion. We are not sure if any of our local centipedes are powerful enough to penetrate human skin, but we have made no effort to test that hypothesis, and we hope that you won’t either. Some have been reported to harm humans with their bites, especially small children, so we wouldn’t temp fate with any you see. But do take a good look, maybe with a magnifying glass. You are looking into the Devonian. Contact the authors at randjtitus@prodigy.com. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”

The Schenectady landslide.

The Catskill Geologists

The Mountain Eagle

Feb. 2, 2018

Robert and Johanna Titus

Have you heard about the recent landslide in Schenectady? A mass of mud slid down a steep hill along Nott Terrace road and did major damage to two houses. It injured at least one person and left perhaps two dozen others looking for a home. This is the type of story that we have been covering for more than ten years now. Landslides are frequent geological hazards up and down the Hudson Valley and throughout parts of the Catskills. We think that this threat should be better known by you, the public.

Albany, Channel ten covers the story. Landslide behind red house

We need to give you a little background first. Back in the later stages of the Ice Age, much of the Hudson Valley was submerged in a body of water called Glacial Lake Albany. That included all of the land that is now Schenectady and Rotterdam. The Mohawk River was a powerful flow back then, carrying large amounts of water from melting glaciers. It flowed into Lake Albany and carried huge amounts of sediment, which were deposited into what became a very sizable delta. Those deposits were mostly sand, silt and clay; when wet enough they become mud.

The lake eventually drained and the delta was left behind, literally high and dry. It provided ideal conditions for people to settle. Delta tops are flat and easy to develop. It was simple to lay out roads. Settlers could build homes with deep, well-drained basements. Those homes were high enough above the Mohawk River so they did not have to fear flooding. It’s a remarkable thing to realize that both Schenectady and Rotterdam are where they are because of the Ice Age.

Schenectady lies on the delta.

Over the millennia, rivers cut canyons into the delta and there lies the problem. Those canyons often have steep slopes and, when the delta deposits become wet from rainfall, they turn into mud and that mud can let go and slide downhill as mudslides. That happens from time to time. One of the most recent such events occurred in the spring of 2004. Heavy rain, the previous autumn, had soaked the ground at 1^st Avenue in Western Schenectady. The Mohawk River and an unnamed creek had eroded into the delta deposits there and created a steep slope, 80 or 90 ft. tall. When the slide began, it caused six houses to slowly subside. It is our recollection that they were all condemned. In January of 1996 a similar event occurred on Broadway, near Rte. 890 where Pleasant Valley Creek created a similar steep slope. That landslide, occurring after heavy rains, killed one man. The Nott Terrace slide is an event very similar to these.

As geo-journalists, we have been following this story for years. We have seen similar events in Delmar, Greenport, Rennselaer, Germantown and just a few years ago in New Baltimore. We fear that many more such slides will occur throughout the Hudson Valley, including at historic sites in Hyde Park. All of these slides involved the sediments of Lake Albany. These silty lake sediments soak up a lot of rainwater. When they reach a certain point, they become unstable. Great curved fractures open up and masses of earth slide along the curves of what are called rotational slumps.

All this is important; it is our region’s greatest geo-hazard. This will happen again.

Reach the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.” Watch for their columns in Kaatskill Life and Upstate Life magazines. They are frequently in the Woodstock times.

Bard Rock in the Ice Age

Windows Through Time

Columbia Greene Media

July 4, 2013

Updated by Robert and Johanna Titus

Last week we visited Bard Rock. That’s a large outcropping of sandstone and shale located at the northern end of the Vanderbilt National Historic Site in Hyde Park. The National Park Service operates a number of hiking trails there and you can take one to the Bard Rock site. The rocks here rise to a gentle peak and trees have grown in where soils formed between the rock exposures. It’s a nice location, ideal for picnicking – and for looking at geology.

The two of us were down there filming videos about the geology of the whole Vanderbilt estate and we wanted to include Bard Rock. Last week we wrote about the history recorded in the bedrock. Those sandstones and shales formed in the depths of a very great marine abyss. This week let’s see if we can figure out the ice age history of the same location.

Take a good look at the photo here. You will see horizons of sandstone and shale. The hand is pointing at a fine thick stratum of sandstone while the foot is on a horizon of shale and grass is growing on another shale. The hand is purposely hovering over evidence of the ice age. Notice how polished the sandstone is; that surface, although sloping, is really quite smooth. What happened is that the Hudson Valley glacier, many thousands of years ago, advanced across this outcrop. The glacier carried large amounts of sand, concentrated at its bottom, and that sand did what sand is good at: pressed by all the weight of a very heavy glacier, the sand ground into the bedrock and – sanded it. It smoothed it off into the surface you can see there today. If you visit this site and step back a bit, you can see that this surface extends up and down the outcrop. Or you can look at the photo we published here last week.

You rise up from the outcrop and gaze across the whole Hudson Valley. In your mind’s eye you fill that valley with ice. There is quite a bit of it. It is hundreds and, more likely several thousands of feet thick. We have gone back in time and visited this site at the peak of the Ice Age, changes your perspective on things, doesn’t it?

But there is more. Take another good look at the illustration. Notice that the hand hovers over some scratches in that glaciated surface. These are called glacial striations. The Hudson Valley glacier didn’t just carry sand; it swept along a large number of pieces of gravel and cobbles as well. Every time one of these bits and pieces of rock was dragged across this surface it left a scratch. Most of them have north-to-south compass orientations. That can’t be much of a surprise. Not only do most glaciers travel in a southward direction but the Hudson Valley glacier was confined and funneled within its north-to-south oriented valley.

But there are some exceptions to that rule. A few of those striations trend from the upper right to the lower left. That sounds like it should not be, but there are explanations. Very late in an ice age, it is not uncommon to have one final advance of the ice. That last-gasp glacial advance is likely to be very small and so it is not pushed so much from the north as it is steered by some unknown local feature. Typically glaciated surfaces are like this one; they have a lot of north-to-south striations and a few local exceptions. Those exceptions dress up the exposure and speak of minor events at the very end of the glaciation.

There is nothing all that rare or unusual about this exposure of ice age features. There are a lot of similar sites all up and down the Hudson Valley. In fact there are a lot of such sites all across the northern half of North America. Wherever the glaciers traveled they left features and exposures just like this one. These are among the most widely seen evidences of the Ice Age. They are the sort of thing that all geologists are accustomed to look for and to see. Though common, we never get tired of finding things like this. We like to bring compasses along and measure the compass directions of similar striations. We plot arrows up on maps and thus document the pathways of once advancing ice. What’s special about these striations is the scenic site where they are found and which they helped form.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” The Vanderbilt videos are currently posted there,

Bard Rock – 450 million years ago

Windows Through Time

Columbia Greene Media

June 27, 2013

Updated by Robert AND Johanna Titus

The two of us have been doing some work for the National Park Service down at Hyde Park. We have shot several videos in which we describe the geology of park lands down there. They have posted this on their website. All this included a visit to Bard Rock and we found an interesting story there, actually two interesting stories. Let’s do one this week and save the other for next week.

Bard Rock is just what it sounds like; it is a sizable outcropping of bedrock. It’s located at the northern end of the Vanderbilt Mansion National Historic Site. That’s the old Vanderbilt estate. It is positioned right on the shores of the Hudson River and that helps make it a very scenic location. You will have to do some walking to visit it; it is on the Bard Rock Hiking trail, part of the park’s system of trails. It’s worth the effort as it really is a pretty location.

But it has a lot of good geology too and that’s why we filmed there. We did a little research before going down and that included looking at the local geological maps. We found, as we expected, that the local bedrock belonged to something called the Normanskill Formation. If you want to be technical, the local rocks belong to the Austin Glen Member of the Normanskill Formation. The two of us are quite familiar with the Normanskill, as we have frequently visited outcrops of this unit. It is one of the most widespread rock units in the Hudson Valley.

The Normanskill is a mix of alternating horizons of dark gray sandstone and black shale. When we got to this outcrop we found it to be a very typical one. There were many nice thick sandstones and an equal number of thinner horizons of black shale. The shales are the indents on our photo. They set up the video camera and we went to work hamming it up, Robert clambered up the outcrop’s slope and with each step said things about “sandstone – shale – sandstone.” Then he got serious and started an explanation of what he was seeing and experiencing here.

The Normanskill Formation is Late Ordovician in age. It takes us back a full 450 million years. That’s a long time ago, and you can understand how we geologists expect that things were different back then. Today these rocks lie on the edge of the Hudson River; back then it was very different. There was no Hudson River during the Ordovician and there were no hills such as we see hereabouts today. The sandstones and shales were here but not as hardened rocks. They were soft sands and very soft muds.

It all gets even more unfamiliar, the more you think about it. We were at the bottom of a very deep ocean. This might be called the Normanskill Basin, but we think it would be better to call it the Normanskill Trench. If you know your way around the Pacific’s geography you will know that there are a number of extremely deep places. Long linear trenches exist and they can be 20 to more than 30 thousand feet deep. The best known, and deepest, is the Marianas Trench, located in the western Pacific adjacent to the Marianas Islands. Trenches form when two great crustal plates collide with each other. They are “creases” between the two plates.

But if you are not familiar with plate tectonics then let’s keep it simple and just say that it was a very deep ocean that accumulated the sediments and sedimentary rocks of Bard Rock. Robert stood up and looked at the camera and then turned a full 360 degrees. He described being on the bottom of this Normanskill Trench. All around him the water was totally black, completely still, silent and very cold. This seemed a lifeless seafloor; almost nothing lived here. Beneath were sticky soft muds. Both of us were “experiencing” the origins of those black shales.

But now he had to explain the thick gray sandstones. He described the striking of an earthquake in some nearby region. The seafloor shook violently all around. Soon masses of sediment, high above in shallower waters, rose up as clouds of sediment. They were, slowly, pulled downslope. Then they picked up speed and became a massive submarine avalanche. For a very unhappy period of time, masses of dirty water passed by. Then things slowed down and settled to a halt. Robert looked around and saw several feet of sand, all deposited by that terrible event.

And then, in a flash, he was back at the edge of the Hudson River on a beautiful late spring day. Geologists live such interesting lives.

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” The Vanderbilt videos are currently posted there.