February 2017

The birth of Manorkill Falls

Windows Through Time

Robert Titus

Columbia Greene Media

Nov. 4, 2010

A lot of our Catskills landscape is owned by the New York City reservoir system and is administered by the city’s Department of Environmental Protection (DEP).  You can pretty much always tell where these lands are; the roadsides are festooned with no admittance signs. They will let you in if you have a proper fishing permit but, if you don’t, they will chase you away. I should know! But, even if most of us cannot get in, not everything is out of sight. One good example is Manorkill Falls. It’s located on DEP property, but it is still visible from the highway (Schoharie County 39, AKA the Prattsville Road). A highway bridge crosses the Manor Kill itself and you can park, walk out on it and see the falls. The upper falls are visible on the upstream side and, just below the bridge, and almost out of sight, are the lower falls.

The local stratigraphy accounts for the two falls, or so it would seem. They tumble over sturdy and resistant sandstone ledges. But, when I visited, I thought there must be more to it than that.  I looked at the upper falls, then crossed the road, looked down and to the west. I pondered the origins of these falls. When a scientist is faced with a problem and spends some time thinking about it, then he or she is likely to come up with possible solutions. We call these potential solutions “hypotheses.” That’s a fancy name for educated guessing, but it is an important step in the “scientific method” of problem solving.

Off to the west was the Schoharie Reservoir and it lies quite some distance below the falls. I wondered about that as I began to do some serious hypothesizing. I knew that there had once, long ago, been a sizable glacier down there. In my mind’s eye I could see it. It had slowly advanced south from the Mohawk River Valley and filled the entire Schoharie Creek valley, passing through Middleburgh and Blenheim. From there it would continue past Prattsville, almost reaching Hunter. That’s a lot of ice and a big glacier. I was watching it passing north to south, which was my right to left.

What a vision I witnessed! The glacier was mostly gray except where fresh snow lay. It was fractured by great curved crevasses, all of them reflecting the stresses that build up within brittle ice as it moves forward. Above it, the hills were bare; there were no forests in this ice age vista. My vision was a brief one, when I looked again, it was autumn and the season’s dense foliage displayed its rich leaf colors. It was the very same view but at a very different moment in time. Geologists are such sightseers!

This large Schoharie Valley glacier would certainly have been a very erosive phenomenon. It must have, as it advanced, cut into the Schoharie Valley floor, deepening it and widening it. I realized that this would give me some more help in my effort to explain Manorkill Falls. I looked west once again and, in my mind’s eye, I watched that glacier more carefully, as it slowly passed before me. It was, indeed, erosive and it did work to carve the sizable valley that eventually would form the basin of the Schoharie Reservoir. As such a glacial valley, it was, in fact, steep walled and deep. That helped me some more. I looked to the west and saw that deep valley under the waters of the modern reservoir. Then I turned east again, returned into the past, and saw a post ice age stream emerging from that direction. That stream would have been forced to tumble down the steep valley walls to get to the bottom of old Schoharie Creek Valley. I was looking at the earliest origins of Manorkill Falls.

Now I put together a more complete story. That Schoharie glacier had first advanced down the valley. It deepened and widened it, but mostly made its slopes steep. The ice filled the valley for a very long time but, eventually, the climate warmed and the ice began to melt back to the north. A sizable lake replaced the glacier. Its waters filled the valley, matching in so many ways the view of the reservoir, the one we see in modern times. That old lake must have been ten time larger than the modern reservoir!

It was about then that Manorkill Creek came to be born. That creek began to flow out of the valley to the east and it was forced to tumble down the newly formed steep slopes of the greater valley. Today’s canyon, behind Manorkill Falls, is deep and speaks of a very strong flow of water, way back then. You can see it as you drive east toward Conesville on Rte. 990 V. I pulled over and got out. I watched, and felt, the flow rising in this canyon. Soon it was a far more powerful and even thunderous flow than we see today. Raging, foaming, pounding torrents raced by. Below all that whitewater, the flow was carving the modern canyon. I, the geologist, had been privileged to go and see its birth. You can go there and do the same.

Reach the author at titusr@hartwick.edu. Join his facebook page “The Catskill Geologist.”

A Different Kind of Protest

On the Rocks

Robert and Johanna Titus

The Woodstock Times

Jan. 22, 2015

Perhaps you have read the news of the recent rehabilitation of the Gilboa Dam at the Schoharie Reservoir near the village of Gilboa. The city of New York, which owns the dam, has been spending hundreds of millions of dollars to upgrade its structure and to render it ready to survive any potential future flood events. It is said that the dam is now engineered to endure a flood two and one half times worse than the one it survived during Hurricane Irene, just a few years ago. That’s a big win for a local civic group named “Dammed Concerned Citizens” (DCC). But, it is also a big win for New York City. That’s our story today.

This story began about ten years ago when an engineering report found that the dam did not meet “. . . safety standards associated with modern engineering practices . . . “. These understated words set off alarms. People were aware that there had been a surprisingly large number of “hundred year” floods in the recent past. Such floods had struck in 1955, 1987, and 1996. Now they feared that the impact of one more awful flood would cause the dam to lurch forward, just a bit, and then give way altogether.  The threat was truly frightening; after all, almost 20 billion gallons of water were pressing against the aged dam. People couldn’t help but to imagine the dam fracturing and breaking up, as masses of water burst through it, and exploding into the valley below. The result of such a total destruction would be a tsunami, rushing for hours down the Schoharie Creek Valley. The horrible wave would pass across Middleburgh and then Schoharie. It would continue into the Mohawk River Valley and then turn east, heading for Schenectady. It was estimated that some 8,000 people might lie in the path of this deluge. Read all that again – slowly –  and just think about it for a moment!

The Gilboa Dam had been constructed during the 1920’s, so it was, by then, a little more than 80 years old. It was, reportedly, designed to last only 50, so it was old. Below the dam, the spillway had seriously deteriorated, with holes eroded into its cement by decades of plunging waters. The bedrock beneath was cut by numerous fractures. The face of the dam itself had been weathering, over all those decades, until it was reported that about seven percent of the original structure had been eroded away. It all looked unstable; it all looked dangerous; it was, all of it, neglected.

The long and the short of it was that any sizable flood might take out the whole dam and result in thousands of horrible deaths. It was estimated that if waters rose to 1,138 feet in elevation, then the pressure would be so great that the dam might just let go.  Dam Concerned Citizens was damned concerned!

Imagine for a moment that we are talking about an old dam, and an old reservoir that lies along the Saw Kill, a bit upstream from your Woodstock, How would you react? We monitored some of the internet chat about all this and found a lot of people felt vehemently that the Gilboa Dam should just be drained and shut down. Close it and be done with it! We are guessing that a lot of you would band together to form something called CDD, “Close the Damned Dam.”

But the people of Schoharie County are not like that. They took a more pragmatic approach. It was not reasonable to demand a closing of the dam. There would be no “occupy Gilboa” here. They would come up with a different sort of protest, a softer, quieter, but unrelenting protest. They aimed at an achievable goal, of infrastructure improvement, aimed at maximizing the safety of the dam.  They knew how important New York City is to the whole of the state and its economy. And they rather thought it would be better to fix the dam than close it. A closed dam would benefit them, but a fixed dam would help everybody.

But they were under no illusions; they faced very serious hazards, and they understood that fact. Lives were, after all, at stake.  Dam Concerned Citizens went to work. They opened a website, which became a public advocate on issues of regional dam safety. For these reasons, they recruited experts on dam engineering and stream flow. They never confronted New York City or its Department of Environmental Protection (DEP), but always kept up a conversation. They quietly, even softly, maintained a pressure to get things going. And they continuously monitored what was going on. Their experts were always quite able to judge whether or not things were being done right.

We, who drive by the dam frequently, began to notice that things were happening. A five foot deep notch was cut into the top of the dam; it would make it very hard for water to rise to that fearsome 1,138 foot level. Siphons appeared; they would drain the dam if things got dicey. Importantly, time had been purchased. Later the dam face was worked on and restored to a youthful appearance – and function. The dam was being fixed. And DCC was closely following the progress.

Gilboa was far enough along, so that when Hurricane Irene struck in August of 2011, it held. There were, indeed, very frightening moments on that very frightening day, but the dam stood firm. Since then, it has only gotten better. And, just recently, the dam has been declared safe. An observance was held, and waters from the reservoir were ceremonially poured onto the dam face. Members of DCC were present.

It could have been so different. DCC could have dug in its heels, resolving to shut down the dam and its reservoir. And maybe they could have pulled it off. But that would have deprived New York City of one of its major sources of fresh clean water. What would have resulted from that? It is probably very good that we will not find out. But there is something else. The city is world famous for the high quality of its water and it is from the Catskills that most of it is derived. Catskill residents take quiet pride in being the source of that water. They want that to continue; they are good neighbors.

We won’t be subtle in stating that the two of us support everything that DCC has done. But, there are lessons to be learned here: First, it is better for parties, with problems like this, to work together. More importantly, it is even better to have a can-do attitude, and to work to solve those problems in a way where both sides come out winners.  Perhaps Schoharie County residents could have been the sole winners – had they really wanted that. But they resolved to find a different kind of protest.

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

Top of the falls, bottom of the river

Windows through time

Robert Titus

Kaaterskill Falls is one of the scenic centerpieces of the Catskills. To stand atop these falls and to gaze out at the gorge below is a grand Catskills experience. The stream which makes the falls can, at times, be a powerful flow. This is the creek that drains North and South Lakes so it witnesses a lot of water flowing by. Sometimes it is a thunderous and very loud flow that tumbles over the falls. That adds to the experience. People have been coming here for almost two centuries now. Many have left the names or initials carved in the rocks here. The oldest inscription in the rocks that I have seen carries the date of 1810. Thomas Cole did some of his early work here.

But I am a geologist and when I am at the top of the falls, which is often, I see inscriptions that Nature herself has left here. And these are a lot older, hundreds of millions of years older. I know how to read those inscriptions even though they are not in English.  And when I read the rocks I see into them. I see not just one stream here but two. And both of those streams are flowing in the same direction and their two channels are almost identical in size. Left banks match left banks; right banks match right banks. But that second stream is as old as the rocks themselves, perhaps 375 million years old. You might dismiss my observations as tainted by hallucinations but I am quite literal in what I report to you. There are two streams there. Let me explain.

If you visit the top of Kaaterskill Falls please notice the rock ledge that rises above the modern flow of water. Notice the stratification within those rocks. Beds of sandstone lay there, all of them inclined in the direction of the falls. These sandstone beds and their patterns of stratification make what is called planar cross bedding. That is a sedimentary feature which we associate with the channels of rivers. Essentially, these strata were part of a sand dune which formed within the channel of the old stream and grew with time as it also migrated down the stream.

Aha! Now you too can see my second stream; it is composed of rock. Planar cross stratification occurs when powerful river currents are sweeping sand along in a downstream direction. As long as the current stays strong the sand will continue on its journey. But, just as the current is starting to slow down which has to occur eventually, then deposition begins. The sand slows down too and that dune begins to form and then it grows one stratum at a time. That growth continues the dunes migration as it is now growing in a downstream direction. Look carefully and that is what you can see here. Those strata of rock are inclined to the right which is roughly to the southwest. That’s the direction that the old stream was flowing. And, it is also roughly the direction that the modern stream is flowing.

What happened to that sand and its dune is that it finally stopped advancing downstream and never moved again. The stream was probably diverted to a new path, rivers do that. Then, with time, the sands came to be buried under so much more sediment that they were hardened into rocks. This became a petrified dune in a petrified streambed.

And so it is that I really do see two streams here. One is modern, the other is very ancient. Both display the same direction of flow, to the southwest. It is so odd to see two streams, so similar to each other but separately by hundreds of millions of years. But it is the nature of my science of geology to discover such things.

   Kaaterskill Falls is a wondrous place, but it can be a dangerous place too; a number of people have fallen to their deaths at Kaaterskill Falls, you must be careful there. Wait for dry and warm times before you visit. Contact the author at titusr@hartwick.edu  or visit the facebook page “The Catskill Geologist.”

Tilted Strata

Windows Through Time

Robert Titus

This column is focused on allowing you to see things that have always been right there in front of you. That’s something we geologists are good at. We travel to outcroppings of rock and look into them and see things that we never saw before. We survey landscapes and find meanings in them that we could never before have perceived. That is the nature of a geologist’s life; we are always looking through those windows through time and we are always seeing such wondrous visions, visions of the past.

Let’s take a drive down Rte. 23 near Leeds and see what we can see. Where Rte. 23B enters onto Rte. 23 there is a very fine outcrop. The strata here are of the Helderberg Limestone. This is pretty much the same rock sequence that makes up the cliff at John Boyd Thacher State Park. It is limestone and that means it formed at the bottom of a very shallow tropical sea. I can’t drive past these rocks without seeing images of the Bahamas. I find myself snorkeling in that beautiful sea.

                 Tilted strata along Rte. 23 near Leeds.

   But there is something else, and you have to look twice and think about it before you take notice. All those strata are tilted.  Take a look at my picture. Those strata tilt steeply to the right. That’s just exactly the sort of thing that people don’t normally notice. You do have to think about it to appreciate it. Strata form, originally, on the flat bottoms of the ocean. The seafloor never dips on one direction steeply as we see here. Something must have happened to these rocks.

Geologists recognize a concept called the “principle of original horizontality.” Simply stated that means that seafloors are flat and, because of that, strata accumulating upon them must also be flat. But what if they aren’t? Then we have to figure out what happened to them. Tilting is a good word, a verb which implies that the once flat strata have come to be tilted from the horizontal. But how on earth could that have happened?  Stop and think about it. Those rocks are heavy, very heavy. How could they have ever have become tilted. One end of the outcrop must have been lifted, and how on earth can such a thing happen?

Now you see what is happening. We have stopped and actually looked at an outcrop and all of a sudden we have a lot of very interesting questions. It was about 300 years ago that early geologists first paid attention to this sort of thing and you can just imagine how perplexed they must have been. What could have caused such phenomena? Back then, they could not even guess.

Today, it’s different. We have scientific theories to explain such things. Today we understand a lot about what is called mountain building. We can look to the east and we recognize that once, long ago, something collided with North America. That collision squeezed the rocks throughout what we call the Appalachian realm. The compressed rocks acted like the folds of an accordion; they were squeezed and deformed just as an accordion is.  A lot of that deformation consisted of simple tilting of the sort we see here.

That something that collided with North America was essentially a very large portion of Europe. Just as India is, today, colliding with Asia, once Europe collided with North America. When you stop and think about that, then you can appreciate that this sort of thing is capable of lifting and tilting such enormous masses of rock. This is big time geology. This is mountain building and that makes it important.

But, you might ask, where are those mountains? The answer to that question makes this outcrop still more interesting. Look up into the air above it – thousands of feet up – actually a mile or so. There used to be mountains up there; they have all eroded away.

Now it is fitting to take a few steps back and look, now more deeply, into this outcropping. Using your mind’s eye you can see the aqua colored waters of an ancient tropical sea. Then you watch as thousands of feet of sediment pile up upon this site. Slowly those sediments petrify; they become brittle masses of rock. Then, the ground starts lurching and rising to form a great range of mountains. The old ocean quickly drains away. Those mountains reach great elevations and tower above the horizon. Now wrenching motions are contorting the strata within; this is the chapter which witnesses the tilting we first came here to ponder.

Then all becomes silent; the mountain building is over. For millions upon millions of years the old mountains slowly decompose; they weather and erode away. Eventually, they build a highway here.

Contact the author at titusr@hartwick.edu or find visit his facebook page “The Catskill Geologist.”