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Name your poison Mar. 12, 2020

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Name your poison
On the Rocks
Oct. 24, 1996
Updated by Robert and Johanna Titus

Black sedimentary rocks are occasionally seen in the Hudson Valley. Recently, we described some along Rte. 209, south of Saw Kill. The dark appearance of these strata makes them remarkably eye-catching and, when they make up tall cliffs, they loom, dark and menacing, over the landscapes.
It’s the shiny, jet-black shales that we are talking about. They are often rich in undecayed organic matter; it’s the carbon that makes these rocks black. This generally suggests to the geologist that there were low-oxygen conditions in the sea waters at the time of deposition. Without oxygen, most decay bacteria cannot function; they die before they can completely destroy the organic matter. But why low oxygen? That takes us back in time.
Back in the early Devonian Period, these shales were accumulating in a deep sea, immediately adjacent to the rising Acadian Mountains of western New England. Thick soils formed on the rapidly weathering mountainsides. The soils were easily and rapidly eroded and provided sediments that were eventually transported into the nearby Catskill Sea. This material was rich in dissolved nutrients, such as nitrates and phosphates. They fertilized the water and that led to the next step in what was to be a complex chain of events.

The fertilized waters were ideal for algae; they experienced algal blooms, great population explosions in the surface waters of the Catskill Sea. A whole ecology became established as dense mats of floating, or planktonic plants and animals grew, somewhat similar to that of today’s Sargasso Sea. While all this was great for the plankton it was deadly for just about every other category of marine organisms. As the plankton died, they were attacked by decay bacteria; the algae bloom led to a bacteria bloom. But the decay process consumed so much oxygen that the seas soon became oxygen depleted. The hapless bacteria had, in effect, poisoned their own habitat, because they needed oxygen too. Their numbers quickly plummeted and very soon, all types of animals, as well, suffocated in the oxygen depleted sea. But the algae just kept on proliferating in the surface waters where there was plenty of oxygen, diffusing in from the air above. Soon, large masses of undecayed biological material were sinking to the floor of the ocean. The climate was tropical, and the nearby coastal lowlands provided lots of vegetation, much of which drifted into the basin, adding more organic matter to the black shales. Almost all of these organics accumulated as thinly laminated, shiny black shales.
Back then, the Catskill Sea was largely isolated from other deep bodies of water; it was nearly surrounded by land or very shallow water. To its east, mountains blocked weather patterns and shielded the basin from most storm activity. All of these conditions promoted what are called stagnant, thermally stratified waters. The sunbaked surface layer was hot, while deeper water remained cool. Depth stratification and a dense planktonic mats combined to prevent agitation and mixing of the waters, causing stagnant seafloor conditions to develop. Virtually nothing could live in this sea, except at the surface where there was always plenty of oxygen. This was truly the poison sea.
Many of the earliest Catskill shales are jet black, and they form the Bakoven Shale at the base of what is called the lower Marcellus Group. As we have seen, they are the record of the Catskill poison seas. The upper beds of the Marcellus Group are similar looking but very different deposits. These are fossiliferous black shales and dark gray sandstones. They sometimes have rich assemblages of brachiopods, clams and even corals. These were still mud-bottomed seas, but they were deposited at times when there was a fairly large amount of oxygen in the water, at least enough to allow marine shellfish to survive and even flourish. These can be fun rocks to poke through as they are occasionally richly fossiliferous, and the preservation of those fossils can be very good.
See the Bakoven Shale on Rte. 23A where it crosses Kaaterskill Creek east of Kiskatom. Go visit that large outcrop along Rte. 209, between Kingston and Saw kill. The far south end is the real poison sea. As you travel upwards and north from those bed you are looking at shallower waters which had more oxygen.

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

Your Godawful geology. Mar. 6, 2020

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Your most Godawful geology
The Catskill Geologists
Robert and Johanna Titus
The Columbia Paper, January 2020

We haven’t properly introduced ourselves, have we? We are Robert and Johanna Titus. We will, from time to time, be writing for The Columbia Paper. One of us, Robert, has worked with editor Parry Teasdale off and on since 1996 and now we are going to resume. We call ourselves “The Catskill Geologists” and that is because we work for a number of newspapers and magazines across the river from you
So, if we are the “Catskill Geologists,” then why are we writing in Columbia County? Good question, and we have been wondering about that ourselves. You see, you folks have some of the most Godawfully difficult geology anywhere that we know of – perhaps just anywhere at all. Take a look at the map we include here. It is the Columbia County part of the New York State Museum’s geological map. Its production was a big event back in the 70’s. That was supervised by then State Museum geologist and our friend, the late Dr. Don Fisher. Maybe you knew Don; after retiring from the museum he opened up a rock and mineral shop in Kinderhook.
Don’s map shows the distribution of the major rock units that make up the bedrock here in Columbia County. If you can’t make sense of the map, don’t worry about it; we just want you to see how difficult it is. One unit, in gray, stretches through the middle of the map from the south center of the county and then on toward the northeast. That’s the Elisaville Formation which is mostly a black shale. You can see outcroppings of it exposed along the Taconic Parkway in the southern part of the county. Look around the map; there are a lot of other rock formations, aren’t there? Each records a moment in geological time. And they all seem to make up a very complex jumble. That’s the Godawful part of all this.


How on Earth did all this come about? Well, we think we know – sort of. We read about this in Don Fisher’s book “The Rise and Fall of the Taconic Mountains,” which was published in 2006 by Black Dome Press. Don’s book recounts the geological history of the county and it is broken up into a number of chapters defined by their plate tectonics. Each tectonic event witnessed North America colliding with another tectonic plate, one was a collision with Africa, two others involved Europe. Columbia County was in the heart of all this. Each collision saw the rise of mountain ranges, here and in western New England. Sediments, eroding off of those new mountains, would be the makings of each new rock unit. All of the county’s rocks, both new and old, were compressed, folded, fractured and metamorphosed in the heat of the collisions. Does this sound Godawful? It is, and that’s what you see on the map, perhaps all you can see!
It only gets worse; hundreds of millions of years later came the Ice Age. Glaciers, thousands of feet thick, flowed down the Hudson Valley and swept across the rest of the continent. You can imagine the complexity of the geology left behind by that event? The two of us don’t have to imagine it; we have seen it and worked with its geology.
Our job at the Columbia Paper will be to explain all his in a fashion that can be understood by you, the average general reader. We think we can do that; we look forward to it.

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

Tafoni: a mystery at Pratt’s Rock Feb. 27, 2020

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A real geological mystery, and at Pratt’s Rock
The Catskill Geologists
The Mountain Eagle May 31, 2019
Robert and Johanna Titus

We were invited to speak at the Pratt Museum recently. Our topic was the glacial geology of the Schoharie Creek Valley. After that, a group of us went to Pratt Rock and climbed up the trail there. We took a good look at Colonel Pratt’s carvings and continued on to see some nice ice age features. But, along the way, we ran across one of those mysteries we have long struggled with.

We were first alerted to this particular mystery by Paul Misko, a veteran Catskills hiker. Paul told us of some “very strange structures he had found in Phoenicia. Paul has a real eye for unusual geology, so we paid attention to his “very strange” claim. We saw his Phoenician structures and now we have found more of them at Pratt’s Rock. Take a look at our photo and then climb up the steep incline at Pratts Rock and keep an eye out. Towards the top you will find sizable ledges of sandstone. This is rather commonplace stuff: very typical Catskills bluestone ledges. These ledges are, in essence, the cross sections of a very old streams. 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 but that’s where we encountered that mystery. Take another look at our photo and see what you think. See the cluster of closely spaced and very strange cavities just above the hand. 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. 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 one of the most puzzling phenomena that we have seen in the Catskills. There is no trouble putting a name on what is here; these structures are called “tafoni.” Each individual cavity is a tafone. And the terminology keeps getting better; when tafoni occur on cliff faces, as here, then it is called lateral or sidewall tafoni. Names are great but putting a name on something is not the same as understanding it.
What are these features? They seem to be chemical weathering phenomena. Somehow, they appeared on the rock surface and grew 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: sort of. 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 Prattsville, and certainly no waves. And, why do only a few Catskill Cliffs display these? That begs the question: what exactly is different about his cliff? Why don’t all cliffs have tafoni? Why isn’t it that none of them do? There must be something here, right in front of our eyes, 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.”

Fossil tree roots in the Catskills feb. 20, 2020

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Fossil tree roots in the Catskills
The Catskill Geologists
Robert and Johnna Titus
The Mountain Eagle, Aug 5, 2017

If you are accustomed to reading our columns then you might like to get out and do some geology on your own. Let’s give you a good project to work on. We are hoping that you might make some discoveries that might help us. We would like you to take a look at our photo. It’s a horizon of reddish Catskill sandstone. It’s a stratified sandstone and, especially at the top, you can see strata that range from a half inch to a full inch in thickness.
That red color, here in the Catskills, tips us off as to what kind of environment these strata formed in. Red is the color of terrestrial deposits. These strata formed on dry land. This was on the floodplains of the Catskill Delta and we have written about it before in this column.

 


But what is special about these strata are the petrified root systems that were preserved within them. You can see one root system on the far left, another just a little left of center and the third to the right. What a remarkable thing this is; we are looking at the fossilized root systems of three plants that, long ago, grew on the surface of the Catskill Delta. All of the foliage that once rose above the ground is now gone but there are the roots.
These plants were part of what is called the Gilboa forest. That’s the oldest known fossil forest known to science, so these are important. They date back to the Devonian time period and are probably about 380 million years old. Potentially these fossils might tell us something about what early forests were like.
Paleontologists sometimes call these fossils “rhizomorphs.” That roughly translates as “root morphologies” – structures that preserve the forms of ancient plant roots. What kinds of plants were these? Well, that is the important question – we really don’t know. Given the modest size of these root systems we expect that they would be called shrubs, but what kinds of shrubs were they? Again – we do not know.
Shrubs of this sort can be considered to be small trees. Most of the trees that are known to have grown in in the Gilboa forest have well known and easily identifiable root systems. They don’t look like these ones. So – you can see why we are interested in them. These may be something new.
We found these fossils along the dirt road that ascends Mt. Utsayantha in Stamford. We parked our car at the bottom of the hill and walked to its top. We hoped we might find something of interest in one the many outcrops that we found along the way. It’s easier to drive to the top, but you are more likely to find something interesting if you walk. These specimens were in an outcrop that lay about halfway to the top of the mountain.
Well, here is the main point of all this. It seems likely that there may be many more specimens like these scattered perhaps throughout the Catskills. There are only two of us, but there are many more of you. Once you have seen our photo you will have a good idea of what to look for. Once you know what to look for it’s easier to find things. Maybe you can tell us where some more of these are.

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

Those looming eastern mountains (186) Feb. 13, 2020

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Those looming eastern Mountains
Windows Through Time
Robert and Johanna Titus
Register Star

Look east from any high vantage point in the Hudson Valley and what is it that you see out there? Are those the Berkshire Mountains? Many, if not most people think so. And they go on to think fond thoughts about them. The Berkshires conjure up images of grand New England scenery. Many thousands of summertime tourists are drawn to those landscapes every year. The low-lying hills and the dense forests make a wonderful vacation destination. The serenity is both scenic and spiritual.

  T – Taconics; B – Berkshires

It gets better. Those pretty mountains are historic; they were the sometimes homes of many great American writers. Nathaniel Hawthorne and Herman Melville lived and worked there during the 19th Century. Edith Wharton and Edna St. Vincent Millay made homes there during the 20th. They all found the Berkshires an inspiring location for their writing. Likewise, musicians have found the same scenic landscape equally stimulating to their endeavors. Leonard Bernstein rarely missed a summer’s visit to Tanglewood.
We too have spent a lot of time in the Berkshires, developing stories for a number of our columns. We have followed in the tracks of many of those fine writers and we have been to Tanglewood as well. And, like so many before us, we have found those mountains to be inspiring, just in a different way. But, here’s the rub. Those are not the Berkshires that you look east and see on our near horizon. Those are the Taconics.
The whosits!? The whatsits!? What on earth are the Taconics? What images do they inspire? Great scenery? Great writing? Great music? No; they just conjure up images of an over the hill, mostly worn out state parkway. How dare does a set of second-rate hills get in the way of such awe-inspiring, historic BERKSHIRE scenery. There is a lot of explaining that needs to be done here.
For starters, the Taconics are, in fact, very pretty. Have you been to Taconic State Park? Well then, enough said. Also, nobody should be berated for confusing the two mountain ranges. They run parallel to each other, and each has a very clear north to south lineation. It’s not easy for the average person to tell when they are leaving the Taconics or entering the Berkshires; there are just no sharp boundaries. We have never seen a state highway sign that announces that we were leaving or entering either one. It just isn’t very important to people – except people like us.
So, why are they different; why are there two mountain ranges recognized? The answers to those questions lie in their geological history. The two of them formed in different geological time periods. The Taconics are late Ordovician in age; that makes them about 450 million years old. The Berkshires are younger; they are Middle and Late Devonian in age and started rising only about 400 million years ago. Each records a separate episode of mountain building.
The Taconic Mountains formed when a sizable volcanic terrane collided with North America. Imagine what would happen if the islands of Japan drifted westward and crashed into Asia. A very large mountain range would result in the collision zone. We have seen this volcanic terrane go by various names; it has been called Vermontia, and Taconica. The names matter little; it’s the collision that was important; it created a mountain range. Late at night in geology bars the sizes of those mountains are debated. They may well have once been 15,000 feet tall.
The Taconics were more than 50 million years old before the early Berkshires even began rising. They too, formed as a results of a plate tectonic collision. A landmass called Avalonia advanced toward and collided with North America. Another comparison is called for; imagine what would happen if Madagascar drifted westward and collided with Africa. Avalonia was a very sizable peninsula that extended off to the southwest as an appendage of Europe, then called Baltica. In fact, it collided with the Taconics while they were still there. The result was the rising of another and probably larger chain of mountains. Those mountains, early on, were called the Acadians.
The debates about how tall those mountains were are even more heated. Many think they too were about 15,000 feet tall, but others insist that they were twice that, and competed with today’s Himalayas! Think about that notion every time you look east.
In the end, we hope you now appreciate that there is a lot of history out there on our eastern horizon. Look that way and see that, twice, great mountains rose up and towered over our region. What a thing to imagine. But, it’s just another one of those things that the rocks tell us.

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

A trip through Grand Gorge (185) 2-6-20

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A trip through Grand Gorge
The Catskill Geologists
Robert and Johanna Titus
The Mountain Eagle July 2017

We remember our first drive through the town of Grand Gorge. We both wondered where the gorge was. It didn’t take long before we headed south on Rte. 30 and discovered that gorge. The highway passes right through a fine canyon down there, and its walls tower above the highway. You can’t get around in the central Catskills without frequently passing through the gorge, but have you ever wondered how it got there.
It’s so easy to just take things like this for granted: the gorge must have just always been there- right? Well – not right. We are geologists and it is our business to not only ask questions like this, but to answer them as well. Let’s give that a try.


When studying landscape features in the Catskills, we always think of the Ice Age first. The two of us knew a lot about the ice age history of the Grand Gorge vicinity, and we came up with a good explanation quite quickly. We knew that there had been a sizable glacial lake extending from just north of Grand Gorge all the way to the Mohawk River Valley. If you drive north on Rte. 30 you will usually be driving on the bottom of that lake. We wrote an article about this a couple of weeks ago.

 

We would like you to make this into a nice “Sunday drive.” It will be leaf peeping season before you know it, and maybe you could do a little geology peeping too. Head north on Rte. 30 and watch for all the flat landscapes left and right of the highway. That’s the old lake bottom. (You learned this a couple of weeks ago; now it’s time to go out and see it). The lake has a name; geologists call it Glacial Lake Grand Gorge. And that lake had a lot to do with how Grand Gorge came into existence.
All lakes have waters which, if possible, will flow into the nearest ocean. Lake Grand Gorge was no exception. Its waters rose up and passed through some sort of early Grand Gorge gap up in the mountain. The flows involved enormous amounts of water and those flows were erosive – very erosive. Over a period of time that erosion cut at least the lower third of the gorge.
When we are driving through the gorge, we always give our mind’s eyes complete freedom. We imagine that enormous flow passing by above. Those currents are brown with sediment; but more than anything else, they are powerful. We see eddies in the surface of the flows. Sometimes these graduate into full-fledged vortices. Curiously, there isn’t all that much noise. There is something of an electrical hum that we feel as the waters pass by beneath us.
We have been describing an experience that is one of the great privileges that come with being geologists. We appreciate our scenic landscapes just as much as anyone else, but we are privileged to be able to travel through time and see the landscapes as they were forming. Keep reading our columns and you can soon start doing this too.

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

Glaciers of Hunter Mountain (184) Jan. 30, 2020

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Skiing at Hunter – its ice age origins.
The Catskill Geologist
The Mountain Eagle. July 7, 2017
Robert and Johanna Titus

This week we welcome new Mountain Eagle readers in the town of Hunter. Hunter is famed for its skiing and we wondered if there was a geologic explanation that would account for this town’s important industry. Currently skiing on Hunter Mountain is confined to the “Colonels Chair” which lies on the slopes of Shanty Hollow. There are six more similar hollows which are arrayed around the top of the mountain. All these have origins which date back to the ice age when they were occupied, not by skiers but by Alpine glaciers.
Not all that many people realize the important role that glaciers played in making our Catskill landscapes. The story takes us back about 20,000 years to a chapter in glacial history described as the Wisconsin glaciation. Catskill glacial history is complex, but geologists simplify it into two very different phases. First, there was a time when something called the Laurentide Ice Sheet swept across our mountains. The Catskills then resembled the ice plains covering most of today’s Antarctica.
By about 16,000 years ago, however, the Catskills had escaped the worst grip of this phase. The great thick ice sheet was gone, but all was not over yet. Glaciers were still found in the shaded valleys. There were more in high mountain hollows; these are called Alpine glaciers. If you are familiar with the images of today’s Swiss Alps then you know that, high up in the Alps, large glaciers form in pre-existing hollows (also called niches). These are nourished by snowfall and with cold conditions, these picturesque Alpine glaciers descend the slopes and flow into the valleys below. That was the case with Hunter Mountain
As time went by these glaciers modified their own Alpine hollows. Glacial ice forms a sticky bond with the rock beneath it, and as the ice moves downhill, it plucks loose large amounts of this rock. Alpine ice is thus a very effective agent of erosion. Given enough time, this expanded the niches and enlarged them into beautiful, bowl-shaped features called “cirques.” See our photo.
There are a lot of cirques in the Catskills, but few of them are as well developed as those of the Alps. Our glaciation was too short for Swiss-like landscapes to develop. Warmer conditions returned and the Alpine glaciers melted. Nevertheless, Hunter Mountain displays some of the best cirque landscape seen in the Catskills. Each of these once harbored a glacier.


You can see some of this Alpine landscape. From West Kill Valley take the Blue Trail southeast and up the western slope of Hunter Mountain. There is a fine ledge at the top of the trail. The cliff below drops off into an Alpine glacier’s niche. Look west into the valley of West Kill. The beautiful U-shaped valley you see is the product of that glacier’s erosion as it flowed down the valley.


But if you are not all that physical and would like an easier way to see some of these cirques, we recommend that you simply drive west into town on Rte. 23A. To the left you will find an entrance to the ski resorts. Find a place to park and get out and look up. You will see two of these cirques (again, see our photo). One contains the ski slopes. In between is a very steep hill. Geologists have a name for hills like these that once lay in between adjacent Alpine Glacier. They are called aretes.

So – to a great extent, the town of Hunter is there because of its skiing industry. And all that skiing is because of the Ice Age. We like to say that it is “a gift of the Ice Age.”

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

Cold snaps and the jet stream, (183) 1-23-20

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Cold snaps?
The Mountain Eagle, Nov. 22, 2019
The Catskill Geologists
Robert and Johanna Titus

We have seen some pretty cold weather lately. November 12th and 13th witnessed what was called “historically cold weather.” Forecasters warned that this may be repeated, perhaps many times this winter. Specifically, they predict that cycles of cold Jet Stream air masses will pass slowly across North America during this year’s winter. Each pass is expected to bring similar “cold snaps.” Each cold episode can be an alarming event. How many times have you heard people say, “What happened to climate warming?” That’ a fair question, so we would like to give answering it a try in today’s column. Our argument is that there is, indeed, an explanation for this weather, and it may actually be that has been caused because of, not despite global warming. Obviously, we have a lot of explaining to do.
Let’s begin with a short overview of what the jet stream is. In North America the jet stream is a massive, high-altitude eastward flow of air lying at the boundary the Arctic and the Mid Latitudes. The stream typically undulates up and down through broadly prominent ridges and troughs. See our first illustration. It’s the temperature difference between the cold Arctic and warmer Mid Latitudes that drives the jet stream; the greater the difference, the faster the jet stream. That difference drives the cold troughs and warmer ridges across America. That brings a lot of weather to us, especially as it did in what came to be called “Novembruary.”

Normal jet stream, Illustration courtesy of Wikimedia Commons.
In recent decades there has been a consistent and pronounced warming of Arctic realm climates. That’s something we remember that climate scientists predicted at least 30 years ago. At the same time the mid latitudes have only warmed a little, so the differences have been greatly reduced. That has, as would be expected, slowed down the movements of those ridges and troughs. What results is a lot like what happens to auto traffic when it is slowed down. The cars behind catch up with those in front. The ridges and troughs become slower and more closely spaced. But there is more; in order to keep all those air masses moving, both the ridges and troughs must become more expansive. See how, in our second illustration the ridges and troughs are so accentuated. We call this a higher amplitude.

High amplitude jet stream. Courtesy US Geologic Survey
Each trough is a mass of slow moving very cold weather. Just what we saw in middle November. Each trough becomes at least a few days of very cold weather. Each expands far to the south and spreads across a vast expanse of our continent. We all, especially in the south, find this most unsettling. But, as you can see, it’s all a very explainable phenomenon. We think it is something that you should understand.
In the end we are hoping that you will pay more attention to the jet stream part of your local weather forecasts and have a better understanding of what they have to tell.

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

Lake Schoharie at Vroman’s Nose (182) 1-16-20

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The top of a nose, the bottom of a lake?
The Catskill Geologists, The Mountain Eagle 2018
Robert and Johanna Titus

We certainly hope to be writing large numbers of columns for the Mountain Eagle. And, over and over again, we plan to take you on journeys into the past. Our strategy is simple; in each column we will be looking at a modern landscape somewhere, and at the same time, gazing into that location as we think it was thousands, and even hundreds of millions of years ago.
Let’s start today. We would like to take you up the trail that ascends Vroman’s Nose in Middleburgh. It’s a moderate climb and most of you can do it. In fact, we are guessing that most of you have done it. We want you to be watching for exposures of bedrock along the way. If you find a good enough one, then you are likely to see flat lying strata. Each stratum was once a horizon of sediment that had been deposited at the bottom of an ocean called the Catskill Sea. It’s flat because sea floors are almost always perfectly flat. Those sediments are about 375 million years old; that’s how long ago the Catskill Sea existed. Reach out and touch one of those strata; you are literally touching the bottom of that ancient sea!


That’s some pretty interesting geology all by itself, but it’s not the main focus of our story today. Keep going up the trail. When you get to the very top, you find yourself on a great flat ledge of bedrock; it’s called the “dancefloor.” This cliff overlooks the valley of Schoharie Creek. We want you to look south, down to the bottom of the valley; that’s where our story is. It is awfully flat down there. It’s even flat as set by the standards of river floodplains. But it is not a floodplain. It is, in fact, the bottom of an ice age lake.
Now, our journey into the past has begun in earnest. We still stand atop Vroman’s Nose, but we have traveled about 15,000 years into the past. We are witnesses to the final phases of the Ice Age. There had recently been a substantial glacier filling the whole valley. Look down there and, in your mind’s eye, fill the valley with ice. But now the climate has been warming and that ice has been melting away; the valley glacier has been melting back to just about where Middleburgh is today.
All that ice fills the valley and acts as a dam, plugging the Schoharie Creek Valley. That dam has blocked the flow of Schoharie Creek and the valley below us has filled with water – creating a lake. The lake has a name; geologists call it Glacial Lake Schoharie. It stretches out before us, extending as far as we can see to the south.
That makes it a very large lake and it is a deep one too. The bottom of the lake is at 600 feet in elevation and the top of Vroman’s Nose is at 1,200. We are looking down 600 feet into the deep, dark bottom of a very substantial lake. We promised you, right at the start, that we would be looking into the past. We think we have kept our promise.
When you get a chance, why not climb Vroman’s Nose and see it as we do.

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

Glacial Lake Albany 181 1-9-20

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Glacial Lake Albany
The Greenville Press; Mar. 20, 2003
Updated by Robert and Johanna Titus

The upper Hudson Valley is a very picturesque region. Most of us take at least a little time to wander around and just plain enjoy the scenery. That includes us but, as geologists, we have the privilege of seeing the world around us in more than just one way. Just like you we see the scenery all around as it is today and, as we said, that is very nice around here. But there are two other landscapes that we are very fond of enjoying. One of those is the landscape preserved in the rocks. Whenever we see an exposure of the local bedrock, it takes us back to a Greene County of long ago. And we mean very long ago; we are witness to the landscapes and seascapes of hundreds of millions of years ago. These rocks are time machines that really can transport us, in our mind’s eye, to those distant eons. Then there is still another vision of the past, that’s the one preserved in today’s landscapes. We geologists call the science of landscape geomorphology and when we study our landscapes, we see the scars of the past. When you learn to read landscape, you learn to read history. It’s a history just a little less ancient than that preserved in the rocks, but just as fascinating.
Here in Greene County, if you know what to look for, there is a fine record of a wondrous geological event of the recent past. That event is one of the most remarkable discoveries in the history of geology: The Ice Age. A mere 20,000 years ago the whole Hudson Valley, including Greene County, was in the grips of a great glaciation. Thousands of feet of glacial ice lay upon our landscape, and that certainly includes right where you are today. The best evidence for that event is in the lay of the land, and you might be surprised to learn that it is in the most inconspicuous part of the landscape. A great deal of eastern Greene County is made up of very flat land. That’s the swath of land lying within five miles of the Hudson River. That’s pretty much everything east of the New York Thruway, much of it is traversed by Rte. 9. we are not talking about a flatness to rival Iowa, but we are talking about a reasonably widespread flat landscape. Pay attention as you drive around just east of the Hudson and see if you notice this yourself.
A level landscape may seem monotonous, but we have to be careful here. What does all that monotony represent? The answer is that this is the floor of an old lake. It was a very big lake and it dates back to the end of the Ice Age. Wherever you are, we would like you to go outside and look north. In your mind’s eye we would like you to see a great glacier in that direction. It towers hundreds of feet above the horizon and stretches off to the east and west. It dominates the landscape, but this is the end of the Ice Age and it is melting. Great volumes of meltwater are cascading off of it.

     
Glaciers are heavy, so heavy that they actually press down on the land and cause the crust to sag beneath them. Back then our Greene County had been glacially depressed by about several hundred feet. That created a basin and that basin was kept filled with the very cold waters flowing out of the melting ice. That’s our lake. It’s called Glacial Lake Albany and back its waters stretched south most of the way down the Hudson Valley.
Lakes accumulate sediments, mostly clay, silt and sand, and our lake was no exception. In fact, our lake accumulated very thick sequences of sediment at a very rapid rate. The sediments here are at least scores of feet thick and probably even more than that. Lake sediments are spread out by lake currents and that makes for flat lake bottoms. When the waters drain away, those old lake bottoms are left, high and dry, as flat landscapes and that is what you will see throughout eastern Greene County.
How deep was the lake? Geologists can’t help but ask that question. We found that the bottom of the lake in Leeds was at an elevation that is today 150 feet. The shoreline of the lake can be determined where the flat lake bottoms disappear. The shorelines appear to be at about 220 feet and therefore the lake must have been about 70 feet deep. That’s a preliminary figure; we have a lot more research to do here, but that’s a lot of lake.
There were islands in this lake as well. They are hills now, rising above the flat old lake bottoms. The western side of the city of Catskill is an old island. So too is Flint Hill, a site famous as the site of an Indian flint making industry. You should try to get used to this as you travel around eastern Greene County. You will soon become comfortable with the flat old lake bottoms and, after that, you should soon find it easy to “see” the old islands. It makes a difference in how you see this region.
Lake Albany did not last all that long, perhaps only for centuries; we are not sure. With time the glaciers melted away to the north. With their weight removed the landscape rebounded; it physically rose upwards a couple of hundred feet. With that, the waters of Lake Albany were unceremoniously dumped down the Hudson and into the sea. Eastern Greene County returned to its normal condition as a dry landscape. But it had been changed, as the old lake bottoms were left, mostly undisturbed. In the thousands of years that have passed by since then, local rivers have carved their valleys into the old lake bottom and a lot of that flatness has been lost, but much or most of the lake bottom is still here to be seen.
Again, we would like you to notice this. Please do watch for those long flat stretches of landscape as you drive around. We like the stretch of Rte. 9 for the five miles south of Coxsackie. You will notice a lot of flat land here. Pick a good place and then stop, get out of your car, look up, and return to the past. High above, you can see the Sun’s rays shining through the surface waters of the lake. As waves pass by above you, the sunlight sparkles in the choppy waters. Here and there, you can observe the undersides of small drifting cakes of ice, tiny icebergs, searching vainly for tiny Titanic’s. Now look around you and see the ancient lake bottom as it was. The muds lie silently at the bottom of the lake. There are few currents this far down. It is mostly very cold and very dark down here. Our journey to the bottom this glacial lake is merely a fleeting journey of the imagination, but it should give you a very different impression of eastern Greene County, and take you, perhaps for the first time, into the geological past.

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

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