"I will never kick a rock"

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Robert Titus has 131 articles published.

Ordovician earthquakes 3-7-18

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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 3-1-18

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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 Feb. 22, 2018

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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 1st 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 Part two Feb 16, 2018

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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 – Part One Feb. 28, 2018

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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.

The Haverstraw Landslide – Feb. 1, 2018

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Landslides at Haverstraw

Windows Through Time

Columbia Green Media

Aug. 6, 2015

Updated by Robert and Johanna Titus

 

We continue our series on the landslide threats of the Hudson Valley. Today we head south quite some distance. We arrive at Haverstraw, a town that lies only about 15 miles north of New York City.  Throughout our series we have emphasized that most of the landslides that we see in our region are natural in origin. Usually heavy rains soak into the soft silty clays of something called Glacial Lake Albany. Water pressure, within those sediments, builds up and those deposits become unstable. The clay gives these sediments a brittle component and concave curved fractures open up. Masses of lake sediments rotate downwards, sliding along these fractures and the landslide results. Quite often, a steep slope, cut by the erosion of some nearby river, contributes a great deal to the hazard.

Diagram of a rotational slump

Are these always natural events, or can man play a role? That’s an important question.  There are few, if any, things that we can do to head off natural landslides but, where man is involved, then that is different. At the April 2025 Normans Kill landslide in New Baltimore there is a chance that man’s efforts played a role.  A sizable amount of earth had apparently been dumped at the top of the slope that, soon thereafter, slid. The two of us disagree on whether this led to the slide, but let’s explore the issue in Haverstraw.

Our trip takes us to a location where a terrible landslide once occurred. And, it is among the most undisputed locations where man’s intervention allowed nature to produce a landslide. Haverstraw is located atop a thick sequence of the sediments of Glacial Lake Albany, lying along about three miles of the Hudson’s banks. Lake Albany did extend this far south and more.  A little after the end of the Civil War there was a growing need for bricks to build fire-resistant buildings in New York City. The lake deposits of Haverstraw had been deposited well offshore within Lake Albany and, as a result, they were unusually rich in clay. That made for very good bricks. Not surprisingly, a very substantial brick industry appeared in Haverstraw. As many as 350 million bricks per year were manufactured in dozens of local brickyards. This industry would thrive well into the 20th Century.

This was not a time when there were many refined environmental attitudes. Nor was it a time when there were many carefully thought out strategies to avoid what are sometime called “geo-hazards.” The sprawling brick industry here was sowing the

seeds of its own destruction. The banks of the Hudson had been tall and steep long before the brickyards arrived. Steep slopes, of course, favor landslides. It got worse. To

Haverstraw after the landslide

mine the clays people dug into the deposits and created even taller and steeper, and more dangerous, slopes.

Then it got still worse. The downtown section of Haverstraw, along with the brick yards, came to be developed right up against the land excavated for clay. Take a look at our photo, taken just after the landslide, and see how precipitous the slopes were. Then things got completely out of hand. Tunnels were cut under the downtown area, and the brick yards. They were actually mining clay! This foolishness only made an already unstable landscape even worse.

Our journey takes us back to the winter of 1905 and 1906. Early on, it had been a harsh, cold and snowy winter, but then there were heavy rains. It must have warmed up and the rain is likely to have fallen onto the snows, melting them.  You see the problem; great volumes of water had to have been soaking into the ground, making it more and more unstable. And below those increasingly unstable grounds there were tunnels.  A disaster was about to occur!

This brings us to the night of Jan 7th and 8th, 1906. The collapse began in the middle of the night. A full six square city blocks sank into an expanding pit. There were electricity and gas lines in Haverstraw at that time, and they made things worse. The gas lines broke and sparks set the leaking gas ablaze. Most of the town burned. One pauses and thinks of the San Francisco earthquake and fire which also occurred in 1906.

A modern geologist reads the accounts of this awful event and wants to scream. They broke all the rules in Haverstraw. They cut steep slopes into the glacial clays; we call this over-steepening. The tunnels only made it worse, and we just cannot imagine such a thing being allowed nowadays. Then they brought development of the town and the brick yards so close to that steep slope. We shake our heads in disbelief.

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

I found a rock, Part two 1-25-18

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I found a rock! Part two    Jan. 25, 2018

Windows through time

Dec. 20. 2012

Updated by Robert and Johanne Titus

 

Last week we rose to the challenge. An English professor at Hartwick College had wondered “What could a person ever write about a rock?” It took a while but we found a good story-telling rock on the Titus family home, and last week we devoted a column to describing that rock. This week we would like to continue the story and talk about that rock’s life history. What has it been doing over the course of the last billion or so years? It’s a good story, maybe not as good as Shakespeare, but still interesting.

We needed help so we went to Dr. Eric Johnson, a colleague at the Geology Department at Hartwick College. He has spent most of his career studying similar rocks in New England and the Adirondacks. He understands rocks such as ours. It was his judgment that our rock dated back to the early history of the Green Mountains in New England. There they were incorporated into a mountain building event geologists call the Grenville Orogeny. This very ancient event involved the collision of masses of the earth’s crust resulting in the uplift of very sizable mountains. These were, of course, called the Grenville Mountains.
They stretched along the eastern edge of the early North American continent, from today’s Maritime Provinces of Canada, southwest all the way to northern Mexico. They rose up many thousands of feet above the landscape just west of today’s Appalachian Mountains. Today, our rock is something called gneiss, an intensely baked rock. Back then there is no telling just what it was.

But for a long while this rock lay, quite possibly, miles beneath the surface of those mountains. Under the extreme pressures and high temperatures down there it became “cooked.” Actually geologists use the term metamorphosed to describe the deformation that occurred. All around, the crust was quite active. Of course mountain building was going on but, more importantly, several great crustal masses were colliding with each other to assemble something we call a “supercontinent.” That is a continent composed of other continents all stuck together. This one has a name; it is called Rodinia.

Given time Rodinia would break up into smaller continents, but much more was in store. About a half billion years ago another land mass collided with North America and another great mountain range rose up. This was called the Taconic mountain building event and it formed the early Taconic Mountains. A good fifty million years later all was repeated in something called the Acadian mountain building event. A piece of what you might call Europe collided with North America. Are all these mountain building events starting to make you dizzy? It gets worse; all this happened still another time when Africa collided with North America to make most of what we call the Appalachians. That was about a quarter of a billion years ago.

All this must have been a bumpy ride for our rock but then things settled down. No other great mountain building events would follow over the course of the last couple of hundred million years. During this time all of New England’s mountains gradually eroded away. Our rock broke loose and came close to being exposed as overlying bedrock was weathered and eroded away. Our rock might have been turned into dust, but something intervened. The most interesting history still lay ahead. That was the Ice Age.

An enormous sheet of ice formed in Labrador and gradually expanded southward. It entered into New England and rose up to become thousands of feet thick. It was so thick that it likely overtopped the Green Mountains. On some long forgotten date the ice scraped up our rock and carried it off to the south. The direction was a little west of south and our rock crossed the Taconics and entered the upper Hudson Valley. From there it continued to work its way southwestward until it reached the vicinity of the town of Catskill.

That’s when its odyssey took another strange twist. It was getting late in the Ice Age and, at this stage, a glacier began to rise up the valley of today’s Catskill Creek. Our gneiss came along for the ride. It was so late in the Ice Age that the climate began a serious warming. The glacier had dragged our rock to today’s village of Freehold and then to land that would be owned by us.

There must have been a day when, for the first time in centuries, the rock emerged as ice all around it melted away. Then, with the ice disappearing below, it settled to the ground of our home.

Join “the Catskill Geologist” on facebook and receive notices of events we are involved in. Watch for our articles in Kaatskill Life, the Mountain Eagle, the Woodstock Times and Upstate Life.

I found a rock! 1-18-18

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I found a rock! Part one.

Windows Through Time

Updated by Robert and Johanna Titus

Dec. 13, 2012

Columbia-Greene Media

 

Many years ago, a colleague of ours in the Hartwick College English Department expressed surprise that we could be a geology columnists. We will never forget what he said: “There is no end to what someone can write about Shakespeare, but what can you ever say about a rock?” Well, if you have been reading Windows Through Time long enough then you know what we “can write about a rock.” The answer is a lot of things. Still, we have been waiting to find just the right rock, and we think it has turned up. A few weeks ago we were doing our last yard work of the season. There, just beyond the edge of the grass, we picked up an interesting looking rock. It was a cobble, a little bigger than a very large potato. It was banded with horizons of light and dark minerals, a type of rock called gneiss. That is a rock which has spent a lot of deep within the earth’s crust. During its burial it was “cooked,” heated up to very high temperatures and subjected to enormous pressures. We are amateurs when it comes to such rocks, but we could recognize that the light banding was probably the minerals quartz and feldspar while the dark bands were probably amphibole and or pyroxene. We saw some crystals of garnet in there too. All this mineralogy had originated during the time the rock had been cooking. Geologists call this metamorphism of a rock. There was also a pair of broad light colored horizons at one end. They lay parallel to all that other banding. The single most interesting thing about it was that it simply did not come from around our Catskills. It was not a native rock; it was an exotic, alien sort of rock. It came from far away. But from where and how did it get here?

 

We knew that it had been dragged onto our property by a glacier, probably about 15,000 years ago. It is something we call a glacial erratic: it simply does not match the local rocks or belong in the local stratigraphy. It was carried to where we found it by a slowly moving glacier. After the ice melted away, it was left behind, waiting many thousands of years for us to find it. Now we had and wer wanted to write a column about it. We needed help.

We brought my gneiss to a Hartwick College colleague Dr. Eric Johnson. Eric has spent his career studying rocks such as these throughout New England. We wondered what he could tell me. Eric liked the rock and pronounced it to be something called a tectonite. That is a rock which had long been involved in a lot of crustal (tectonic) activities. It was an old rock which had experienced a lot of mountain building events, and all the volcanic eruptions and earthquakes that come with them.

He agreed that it was a metamorphic rock but had a lot more to say. One thing that impressed us was that he was sure that this rock had once lain miles beneath the peaks of some ancient mountain range. We asked him if he could tell me where it had come from. He couldn’t be sure, but guessed that our gneiss had once been part of the Green Mountains of today’s Vermont, coming from the deep innards of taller and very ancient versions of those mountains. It was then that the rock had come to be metamorphosed.

But there was more. Those two light colored horizons had been volcanic intrusions. The Green Mountains, way back when, had been volcanically active and injections of molten rock had penetrated the older gneisses.

We was intrigued by the history that was emerging. When had all this happened? Eric thought that had been more than a billion years ago. That was when a great mountain building event had occurred in an early version of North America. Our continent was then called Laurentia and it was colliding with other landmasses. Such collisions have occurred throughout geological time and each results in a mountain range; this one was called the Grenville mountain building event.

This was just a single humble rock. Bit what a story it had to tell! It had been caught up in the core of a rising mountain range when two land masses had collided. It had been cooked by the heat of the deep crust and penetrated by volcanic intrusions.  Over the course of millions of years it had grown the crystals that it now displayed. It was a very venerable rock. Is that what you can say about a rock? It’s a start. To be continued. Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

Wall of Manitou in Winter – Part two

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Time in winter, part II

Windows Through Time

Columbia/Greene Media – Feb. 11, 2010

Updated by Robert and Johanna Titus

 

Last week we drove along Rt. 32, pulled over to the side of the road and gazed up at the Catskill Front. We found that, at this time of the year, we could look through the leafless forests and see the rocks so clearly. We became philosophers as we contemplated the millions of years of geological history rising before us.

Let’s look into all this again, and this time let’s understand some of the mechanics of this passage of time. Our key to understanding the rocks comes from understanding the City of New Orleans! Does that surprise you? Read on.

Many of us learned a lot of geology when Hurricane Katrina struck. One of the most remarkable things was that most of New Orleans currently lies below sea level. How could that be? Were people idiots when the city was first founded? Of course not! Three centuries ago, when New Orleans was settled, it lay above sea level. During those centuries it was slowly sinking and now most of it is below sea level. It would have been flooded decades ago except for the construction of manmade levees.

Ironically, the levees may have caused more damage than they were worth. Obviously they weren’t up to the job when the hurricane struck; the city flooded anyway. But there was something else equally important. Floods bring sand down the river and deposit it, spread out across the delta top. That can’t happen if levees get in the way. Sediment was spread out all across the delta, but New Orleans, being surrounded by levees, did not frequently experience flooding. The city never received the sand that floods would have brought. The city continued to subside, but the sand, which would have kept it above sea level, never got there. That’s an irony!

Our point here is that great deltas slowly subside under the weight of their own sediments. As thousands and then millions of years pass by, enormous thicknesses of sand and mud accumulate on them: first hundreds of feet and then thousands. That’s what we are looking at when we gaze up at the Catskill Front. Had there been a city of Old Orleans on the Catskill Delta, back during the Devonian time period, then this fossil city would still be up there somewhere.  And it would likely be buried beneath many feet of sedimentary rock. What a strange thought!

But, this is science, and that is where the evidence leads us. When we look up there and see all those ledges of sand, we realize that these are the deposits of great flooding rivers. We see countless cities of Old Orleans and we see countless Hurricane Katrina’s. We go back into time and watch as the old Catskill Delta slowly subsides, and we see all that sediment piling up. Eventually all of these strata sink into the depths. Thousands of feet of new sediments bury the old. The weight of all this is stupendous. And given still more time, and a lot of it, these sediments begin to harden into rock.

Eons of time are now flying by in our mind’s eye and we are nowhere near the end of it. We still have to contemplate the erosion of the Catskill Front to create the wall of rock we see here. No giant can do that for us. Only Nature can do that through the weathering of rock, turning it back into sediment and then the erosion of that sediment. Nature must be very patient. But for a person to stand along the side of the road, to look at the strata above, and see all this is a marvel. These are awesome notions; no wonder a geologist becomes philosophical.

But where did all that sand and mud come from? Now we must stop looking west at that ancient delta and I turn around to look to the eastern horizon. There, in front of us, is the ghostly silhouette of a long lost mountain range. It rises above today’s Taconic Mountains and it dwarfs those puny peaks. The sediments and the sedimentary rocks of the Catskills came from the weathering and erosion of that towering range of mountains, called the Acadians. These may have risen to elevations of about 30,000 feet. We instinctively look up, but they are not there . . . anymore.

We look east to west, then west to east. We see 30,000 feet of old mountains (east) having been converted into about 9,000 feet of modern Catskills (west). Old mountains were turned into new mountains. And Nature presents us with a cycle here. That conversion of old mountains onto new mountains will all probably happen again – and then again. It was the English naturalist James Hutton who first understood things such as this. He marveled about time, saying “We see no vestige of a beginning, no prospect of an end.” With his thoughts geology became a philosophical science.

Reach the authors at randjtitus@prodigy.net.  Find more at their facebook page “The Catskill Geologist.”

 

The Wall of Manitou in Winter 1-4-18

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Looking at Time in winter: Part One

Windows Through Time

Modified by Robert and JohanneTitus

Columbia Green Media Feb. 2, 2010

 

Winter is not always the best season to be a geologist. We do greatly prefer the warm months when we are better able to get out and explore. But there are some compensations. This is the season when, with all the leaves down, we can see so much that will be hidden come next summer. We have in mind a good look at the great Wall of Manitou, the Catskill Front. From numerous sites down in the Hudson Valley you can gaze up at this massive wall of sandstone and shale and see details that are usually hidden.

We stopped along the road down in Palenville and did exactly that, and we were soon able to wax poetic about one of our favorite topics in geology. That would be the enormous lengths of time that we see recorded in the strata. We geologists routinely travel back hundreds of millions years into “deep time.” Much of our own work involves Devonian age rocks which are mostly a bit less than 400 million years old. Much of the rest of our work takes us to ice age deposits which are a mere 15 to 20 thousand years old. We geologists get to be a little jaded with all this. What’s a couple of hundred million years in a universe that is more than 14 billion years old? Still, sometimes it is nice just to go and “look” at all that time. That’s what we did in Palenville.

If you get the chance, please do the same. Follow Rt. 32 and pull over someplace where you can get a good view of the Catskill Front. We picked just south of the intersection with Rt. 32B. Gaze up at wall of rock and really appreciate what is before you. There are about 2,000 feet of stratified rock up there and all of it was, originally, sediment. The strata that you can see clearly are layers of sandstone; they make up those many horizontal strata. That’s sturdy stuff and it has held up well in the face of eons of weathering and erosion.

What you can’t see is what lies in between the sandstone ledges. That would be mostly red shale. Shale was mud to begin with and that makes it pretty soft stuff. Nature has little trouble with shale; she likes to erode it away and she is good at that, turning it into soil. So you rarely get to see shale in steep slopes like this. They are there, but they are buried in their own soils.

So, we have a pattern here. There appear to be countless horizons of sandstone, interbedded with equally countless horizons of shale. All were once soft sediments. Layers of sand alternated with layers of mud. And there before us are about 2,000 feet of all this, all deposited one stratum at a time. How long did it take? Well, that’s our main point today: it took a very long length of time!

Geologists estimate that the Devonian time period stretched from 419 to 359 million years ago. What we are looking at here is perhaps about a fifth of the whole. That suggests that what we are looking at are about 11 million years. Our estimate is very rough so we will ask you pay it little heed. But we are certainly dealing with millions of years of time, and in Palenville you are looking at all of them.

For all of those millions of years our region witnessed the steady accumulation of layers of sand and layers of mud. Many of these sediments are red and that indicates that they were terrestrial in origin. The red is the mineral hematite and that forms only on land. The sands accumulated in stream channels; the mud of the shale formed on floodplains. This was a great delta, called the Catskill Delta.

You stand along the road, you gaze up, and you are looking at the cross section of something akin to the Mississippi Delta. Imagine if some enormous creature could slice 2,000 feet into the southern reaches of the Mississippi delta. If that giant then peeled away the earth, it would expose a cross section of the sediments of that delta. Those sediments are probably all still soft; they have not yet hardened into rock. But, in every other respect, our slice of Louisiana would look exactly like what we see here.

We spoke of waxing poetic before, and we guess that a person can actually get that way when he contemplates such thoughts. We could have spoken of waxing philosophical and that might be appropriate. We geologists do find all of this very spiritual and maybe that is the best word of all. Reach the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.”

 

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