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Drumlins: pretty little hills

Windows Through Time

Robert Titus

Sept. 10, 2010 in Columbia Greene Media

I would like to introduce you to a new geological topic today, one which is very important throughout the Hudson Valley. That is the drumlin. Drumlin is a Gaelic work for hill, but these are very special hills with very special origins. Hills come in all shapes and sizes; they are found everywhere. What makes a drumlin different is its particular shape and the particular type of place where it is found.

A drumlin is said to have the shape of an upside down spoon bowl, so we can start by having you take out a typical spoon, turning it over, and looking at it from what would normally be below. You will see a very nice symmetrical oval shape to the spoon bowl. It is wider at the handle end and tapers to a narrow front. Now turn your spoon sideways, but still upside down and look at it from this angle. The handle end is steep but the angle, again, tapers towards the front.

       A teaspoon bowl, shaped like an upside down drumlin.

   These are exactly the forms we see in a drumlin; you just have to scale it all up in size  . . . a lot. Drumlins can be a mile long, up to 150 feet in height and they can be more than 1,500 feet wide. Most are a good bit smaller, but they are large. They are like potato chips; you can’t just have one. It is very unusual to just see one of them; typically they occur in drumlin fields where they can number in the scores and sometimes many more. And those drumlins fields are, as I said, only found in particular landscapes: areas that had been glaciated.

                                                                    A drumlin field, arrows show direction of glacial movement.

Drumlins display compass directions and those directions speak to us of their origins. Typically drumlins are parallel to each other, and parallel to the long ago flow of the glaciers that formed them. In the Hudson Valley they are commonly oriented north to south.

But how, exactly, did the glaciers form them? Late at night, in geology bars, that issue has been debated for decades. It is not easy to describe the origins of drumlins without using the word sculpting. It would seem that glaciers pass across large masses of coarse glacial sediment and sculpt those materials into the forms we see, but more explanation is needed. The big problem is that nobody has ever been to the bottom of a glacier that was sculpting a drumlin so we can’t go and observe the process.

It may be that drumlins formed late in the Ice Age, when the climate had been warming up. Water would melt out of the glacier and soak into the sediments below. That would make them soft and very pliable and speed up the sculpting process. But, again, nobody has been there to see this happen.

But, for our purposes, something that is very important is that drumlins are scenic and make for very nice landscape. Recognizing them is important to appreciating our Hudson Valley landscapes. You need to see one.

We will, in the future, visit a lot of drumlins and a number of drumlin fields, but today I would like to just recommend a visit to just one, a good one. That would be in the Hudson Valley Hamlet of Viewmonte, along the northern edge of Clermont. Take Rte. 9G south from the Rip Van Winkle Bridge about five miles. Watch on the left (east) for Cemetery Road. Take that left and, less than a mile down the road, you will see a cemetery on the right. If you are not careful you will pass by its inconspicuous entrance so watch it. Drive up that narrow driveway. You have not only entered a cemetery, but you have entered onto a drumlin and a very good one. You are driving up the north end of the hill and this is the steep side. When you reach the top, you will appreciate just how symmetrical a drumlin can be, Steep, but very smooth slopes, form the two, east and west, sides of the drumlin. At the back of the cemetery the driveway forms a turnaround and there you have reached the tapered downstream end of the hill.

                                                                          The top of the cemetery drumlin at Viewmonte

This is a very good drumlin; it has all the morphology that you would expect to see. Being a graveyard, the landscape has been kept open; there are few trees or shrubs to block the view. So this is a very good “introductory” drumlin. We will, in the future, see many more and we will learn about drumlin fields and see what they have to tell us about the ice age history of our region. They, if fact, have much to say.

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

A few moments in time

Windows Through Time

Robert Titus

Like many paleontologists, I can well remember the first time I visited a dinosaur. My parents took me to the American Museum of Natural History in New York. There was the magnificent full skeleton of a Brontosaurus. I can remember looking up at it. I was about seven, so that beast looked pretty big to me. So too did a nearby Tyrannosaurus. It’s an experience that helped lead me, like many other youngsters, to a career in the study of fossils.

Every child should have a moment like this. But as an adult, I am often more impressed by things other than size. I am more philosophical now. Time means more to me now than back then; after all, I have known so much more of it. And one type of fossil that impresses me the most is called the trace fossil. That’s something you might well not be familiar with so let me explain. Most fossils, such as those towering dinosaur skeletons, are body fossils; they preserve parts of the original creatures. They are bones, shells or teeth and have lasted so long because they are composed of resilient materials. They are great fossils, but not the only kinds we see.

Trace fossils are different; these preserve the activities of ancient organisms. You can be forgiven if you ask how activities can be preserved in rocks. It does not seem intuitive, does it? But let’s begin with the best known of the trace fossils: the dinosaur footprints. They illustrate what I have in mind. The sizable three toed footprints of dinosaurs are actually quite common. The old monsters walked around in mud and left footprints which eventually petrified to make the most wonderful fossils. Walking is an activity and so these are trace fossils. There are quite a few locations where these can be seen in the Connecticut River Valley of Connecticut and Massachusetts. Someday I will describe one of them for you to go visit.

Dinosaur footprints from the Connecticut River Valley

But, what I have in mind are the traces of creatures that are a lot more modest. These fossils are so humble that they don’t even have a proper name. These are the traces of animals that burrowed across marine sediments almost 400 million years ago when our region was beneath the waves of the ancient Catskill Sea.

Take a look at my illustration and see what I am talking about. This is a slab of local sandstone. It is from near the top of an outcrop that lies along Rte. 23, just east of Five Mile Woods Road, just east of the town of Cairo. That outcrop was overrun by a glacier back during the Ice Age, and that glacier polished this surface, bringing those traces into sharp detail. This sandstone was once lying upon the bottom of the sea and that seafloor was alive with living creatures. Often I see the shells of ancient invertebrates on such sandstones, and a number of such fossils have been found at this outcrop.

            The burrows on Rte. 23

Notice the back and forth motion displayed with these traces. Some sort of creature was moving in this fashion, probably right on the floor of the old sea. There is a series of small “wiggles” inside of the larger ones (the third photo). This is pretty complex behavior from what must have been small and simple animals. These lines are the traces. Once, long ago, some sort of a simple invertebrate animal was mucking about across the sediment at the bottom of that sea. Today, lot’s of animals live in this sort of habitat. They dig across the mud. They actually travel, and in so doing, they leave their burrow traces behind.

Close up of same burrows

What kind of animal was it? I don’t know. If you force me to answer the question I would first guess that it was some sort of a worm, but I really don’t know. Some of our readers have observed snails producing these sort of movements. Where was this creature going? Here I can only guess that it was just wandering and it did not know itself where it was going. Worms and snails don’t carry maps you know; they have no idea where they are going.

What was this creature doing? Here I can come up with a reasonable answer: it was very likely looking for food. That’s the motivation for a lot of animal activity. It is even possible that, if it was a worm, then it was eating the very mud it was digging through. Modern earthworms do that and there is no reason to suppose and ancient worms did not. Snails make these motions as they scrape algae off of the sea floor.

In the end, however, what is so remarkable about this fossil is how ordinary it is. This is not the skeleton of a towering dinosaur; it only records the very existence of a humble invertebrate animal; there was nothing remarkable about what that creature was doing. It was simply going about its daily routine on the floor of an ancient sea. It is the extraordinarily everyday nature of this that makes it of note. When we look at this fossil we are sharing a few minutes or so in the life of an invertebrate animal. I find that astonishing. Contact the author at titusr@hartwick.edu or find more at the facebook page “The Catskill Geologist.”

Our reader’s rocks: the submarine avalanche

Windows Through Time

Robert Titus

   Dear Professor Titus: I found this peculiar looking rock at my son’s new home. This rock came from an outcropping along the Mohawk River near the Twin Bridges of the Northway. What are the markings on the surface? What can you tell me about them? Mrs. Deborah Teator, Greenville.

Dear Mrs. Teator: Yes, this is a very interesting rock and I can tell you a great deal about it. The state geological map indicates that your rock is from the Normanskill Formation and that is a unit that I have been meaning to write about anyway so I am glad that you asked about it. The Normanskill makes up much of the bedrock in the Hudson Valley and it is a very important unit of rock in that region. It has quite a story to tell, when you look through a window of time.

The rock is a very dark type of sandstone which is called graywacke. We geologists sometimes call it “dirty sandstone.” The “dirt” is a large amount of silt and clay which is mixed with the sand. Graywacke is a special type of sandstone which generally forms in a special type of environment. That is the bottom of a great marine trench.

If you know your way around the bottom of the Pacific then you will know what a marine trench is. If not, take a look at most any globe and find the dark blue stretches out there in the middle of the Pacific. The best one is the Marianas Trench, adjacent to the Marianas Islands. A trench is just what it sounds like; it is a long deep crease in the floor of the ocean. I am not kidding about the deep part; the Marianas Trench is about 36,000 feet deep, deeper than Mt. Everest is tall!

The slopes of a trench are, not surprisingly, very steep. Because of that, the soft sediments that accumulate on those slopes are very unstable. If anything jars those slopes, then it triggers a submarine avalanche. Great masses of sediment are kicked up into big smoky looking plumes of dirty water.  These sediment laden plumes are denser than surrounding seawater and thus they, slowly at first, start moving downhill into the depths. These “density currents’ soon pick up a lot of speed and they become submarine avalanches. These are, like their snowy counterparts on land, very dramatic events and they reach speeds of 30 to 50 miles an hour.

They can be destructive events as well, just like the ones on land. These fast moving masses of dirty water are very erosive. They sweep across the muddy deepwater slopes and pick up more sediment and carry it away. That makes the current bigger, heavier and even more powerful. Eventually these avalanches reach the bottom of the trench and the slope flattens out. That’s when the currents slow down and, with time, come to a rest. That is also when the sediment is deposited. The event has a technical term; it is called turbidity current. The resulting sedimentary deposit is called a turbidite.

Toward the end, when the masses of dirty water are slowing down, they press into the soft sticky mud below, and they create some very recognizable features. These are called sole marks and it is sole marks that adorn the surface of Deborah Teator’s rock. What I am saying is that this is a “petrified avalanche!” That might, at first, seem impossible, but my description is of something that marine geologists have observed in the modern Atlantic Ocean. We simply know that these things happen.

So, all this speaks volumes about the Twin Bridges vicinity. Back in time, during the Ordovician Period, about 450 million years ago, this was a very different place. This was a deep marine trench. How deep? I don’t know but 20,000 feet seems reasonable. It was a very quiet, very dark seafloor. But, every once in a while, an awful catastrophic submarine avalanche swept by. After it was over, things quieted down again. The next time you are crossing the Twin Bridges, please remember to think about all this. It really rearranges your sense of reality. Doesn’t it?

Do you have an interesting rock, an interesting outcrop or some puzzling landscape feature? Then e-mail the author at titusr@hartwick.edu or write him at Dept. Geology, Hartwick College, Oneonta, NY, 13820. Send photos if you can.

Time in Winter, part three

Windows Through Time

Robert Titus

The outcrop on Rte. 23. Dark stratum in middle marks boundary between 2nd and 3rd cycles.

We have been philosophers, contemplating time itself these past few weeks. We’ve been gazing up at the Catskill Front. There, before us, were millions of years of history: petrified into the strata of the Catskills. Rip Van Winkle spent 20 years sleeping up there, but those rocks have slept for nearly 400 million. I’d like to take you up there to see those venerable lithologies, but it’s winter and not a very good time to climb up into the mountains. Fortunately, we won’t have to wait for spring; there is a better strategy.

The Catskill sequence, happily for us, begins in the Hudson Valley. You can go and see its strata, up close and right along the highway. No climbing is needed. Find your way to the intersection of Routes 32 and 23 near Cairo. Then travel just the shortest distance east on Rte. 23. There, alongside the west bound lane, is a fine outcropping of strata. These are mostly sandstones, but there is some shale as well. This is the Catskill sequence up close. These are virtually the same rocks that make up all of the Catskill Front. We have been gazing up at them, but here we can look them right in the eye.

And maybe it is time to stop being philosophers and start, once again, being geologists. Pause and survey the whole outcrop. You will, I hope, be able to see that it is broken up into three separate horizons of stratified rock. In other words there seem to be three “packages” of strata here, laid out, one atop the other, in a vertical sequence. As geologists, we always start at the oldest layers of rock and those are the ones at the bottom of the outcrop at its western end. That first package of strata is the least well exposed but let’s start there. You will see a sequence of thickly bedded, light colored sandstones. Above them the stratigraphy grades into finer grained, thinner bedded material. This has a greenish gray to brick red color.

Red strata at very bottom are overbank floodplain sediment. Gray sandstones, above, are river deposits. Notice some river strata dip to the right. These are typical river cross beds.

This stratigraphy is repeated in the next package and in the third. In other words we are looking at cyclical events in a cyclical stratigraphy. In the second package you can see that many of the thick sandstone strata are inclined to the west (left). This is typical of river channel sediments. Each of the three cycles begins with this sort of river channel sandstone. The overlying, finer grained materials are petrified soil profiles, literally fossil soils. So, if you follow all this, each cycle represents the presence of a Devonian age Catskill Delta river channel, overlain by a floodplain soil. And it happened three times.

So, what was going on here and how does it relate to an ancient delta? There were two sedimentary dynamics back in Catskill Delta days. First those ancient rivers were what we call meandering streams. They formed beautiful, sinuous channels that literally snaked back and forth across their delta floodplains. This process, called river meandering, is a very slow one but it is effective over time and it can still be seen in many modern rivers. But it is slow and that gets us to the second dynamic.

Remember, from those earlier columns, how the sediments of the Mississippi Delta are sinking and that the sinking is slow? Well, our Catskill Delta was sinking slowly too. Gradual river meandering was matched with slow crustal subsidence. The rivers had a back and forth motion. First the river would meander one way for quite a long time and then it would return. Meandering “back” was easy, but, by the time a river meandered “forth” the crust has already sunk quite a good bit. A new river channel/ floodplain “forth” sequence would be laid down on top of the old “back” one. If meandering continued, and it would, then a third horizon (cycle) would be deposited on the same subsiding delta.

That’s what deposited the three cycles we see on Rt. 23. Did one meandering river deposit all three cycles? I don’t know. Did one or several rivers meander across this site? I don’t know, but it doesn’t much matter. The important thing is that we can look into one outcrop and recognize very typical chapters in the history of the whole Catskill Delta. It was subsiding, its streams were meandering, and all of it behaved very much like the Mississippi Delta of today. The Devonian Catskill Delta was the virtual twin of today’s Louisiana; only time has changed. Now: look at the outcrop and then up at the mountains again and appreciate that these were the kinds of processes that formed all the rocks of all the Catskill Front.

Reach the author at titusr@hartwick.edu and find more at the facebook page “The Catskill Geologist.”

Time in winter, part II

Windows Through Time

Robert Titus

Feb. 11, 2010

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 has slowly sunk until 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. New Orleans, being surrounded by levees, did not frequently experience flooding, but 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!

My 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 along the Catskill Front.  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 I look up there and see all those ledges of sand, I realize that these are the deposits of great flooding rivers. I see countless cities of Old Orleans and I see countless Hurricane Katrina’s. I go back into time and watch as the old Catskill Delta slowly subsides, and I 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 my mind’s eye and I am nowhere near the end of it. I still have to contemplate the erosion of the Catskill Front to create the wall of rock we see here. 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 I must stop looking west at that ancient delta and I turn around to look to the eastern horizon. There, in front of me, 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. I instinctively look up, but they are not there . . . anymore.

   Profile of Acadian Mountains against profile of modern Catskills, Hudson Valley and Taconics

   I look east to west, then west to east. I 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 to younger 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 author at titusr@hartwick.edu  Find more at the facebook page “The Catskill Geologist.”

Looking at Time in Winter: Part One

Windows Through Time

Robert Titus

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. I 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.

I stopped along the road down in Palenville and did exactly that, and I was soon able to wax poetic about one of my 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 my own work involves Devonian age rocks which are mostly a bit less than 400 million years old. Much of the rest of my work takes me 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 I 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. I 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 my 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. My estimate is very rough so I 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.

I spoke of waxing poetic before, and I guess that a person can actually get that way when he contemplates such thoughts. I 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 author at titusr@hartwick.edu  or at https://thecatskillgeologist.com

Colonel Pratt’s Pyramid

Windows Through Time

Robert Titus

Columbia/Greene Media

July 23, 2009

Prattsville, along the banks of the Schoharie River, is steeped in Catskills’ history. It’s emblematic of the most progressive aspects of the area’s history, and at the same time, it represents many of the mistakes people made as our region developed.

Zadock Pratt was the towering personality in the town’s development. Even today his influences permeate the village. Pratt was a founder of the Catskill tanning industry. From 1833 to 1846 his Prattsville tanneries turned out shoe leather for the New York City market. His tanneries, however, were dependent on the bark of the hemlock tree, and when all of those trees were cut down, the industry closed.

We frown upon the wanton destruction of the Catskill hemlocks that characterized the 19^th Century, but our collective wisdom is based up a history of trial and error. It was men such as Pratt who provided the errors.

But Pratt is also remembered for progressive attitudes toward urban planning. His Prattsville was a pioneering effort in the field. He laid out the streets, built the Greek Revival style homes and planted the 1,000 trees that lined the village streets. Pratt founded churches and the town’s academy as well. Prattsville today is still truly Pratt’s town.

Zadock Pratt was a great man, but I suspect history would have mostly forgotten him except for the one singular act of vanity he was responsible for. Pratt, the Rameses II of the Schoharie Creek Valley, is remembered for Pratt Rock, his would-be tomb.

Pratt Rock consists of a series of stone carvings on a glacially cut cliff along State Route 23, just east of town, and overlooking the old Pratt farm. The site is now a town park and open to visitors. You can hike the winding path up the steep slope toward the main carvings. If you tire along the way, you can sit up stone seats thoughtfully carved into the rocks of the mountain.

The main level of carvings displays images and symbols of Pratt’s life; there are carvings of the hemlock tree, a horse which hauled the bark to the tanneries, a strong arm to do the work, along with other emblems of the great man’s life. There is a poignant carving of his only son, who died in the Civil War. Then there is the Pratt burial chamber, the point of it all.

                                                         Pratt Rock

   Unlike the pharaohs, Pratt was never buried in the grotto carved out for him. One story is that the chamber was rendered unsuitable for burial by the fact that its roof leaked when it rained. The chamber is still there, and when I looked it over, I found there may be some truth to that tale, along with a good geological story about Pratt Rock.

Pratt Rock is carved into sedimentary strata from the old Catskill Delta. Deposited nearly 400 million years ago, the sediments here record the coastal regions of a delta similar to that of the Mississippi River today. This was once the coastline of the old Catskill Sea. Rivers flowed, back and forth, across this location and emptied their waters into the old ocean.

There is thus a lot of geological history here. I had little trouble finding bits and pieces of the old Gilboa Forest, and I could picture its foliage along the old stream banks. But the most interesting horizons I found were those at the burial chamber.

The ceiling of the chamber is made up of inclined strata. These horizons of rock formed on the sloping floor of an old stream channel. The beds slant down to the right, away from which was once one side of a river, and farther along the outcrop, they rise up again onto the river’s other shore. When I looked at the chamber ceiling I found a horizon rich in a hash of broken plant remains. This stratum is likely porous and it’s quite possible that accounts for the leakage that caused the burial project to be abandoned. The pharaohs of arid Egypt faced no such problem.

                                           The burial grotto, at bottom

   And so it is that this in one of the many ironies of geology. The great Zadock Pratt is buried in a nearby graveyard with all the common folk of old Prattsville. That indignity may be because about 380 million years ago some inconspicuous river made a wrong turn. It’s not Pratt buried in Pratt’s tomb, but the sands of an ancient river! Contact the author at titusr@hartwick.edu Join his facebook page The Catskill Geologist.

The lengths of time

Windows Through Time

Robert Titus

Columbia/Greene Media

July 9, 2009

One of the most scenic wonders of our region is Kaaterskill Clove. It is a breathtakingly beautiful canyon cut right into the Catskill Front. It is the sort of landscape feature that one normally associates with the great American West, but it is right here.

Kaaterskill Clove from the air

The clove from Poet’s ledge

There are trails which navigate hikers around the rim of this canyon, but for most, the easy way to enjoy the views is to drive Route 23A, up or down the canyon. It is a grand experience, any time of the year.

You have probably driven the highway, but I don’t imagine that you put much thought into the bedrock cliffs that line the road. They are pretty; they contribute so much to the scenery, but think about them? Not many do that. Too bad, there is much to ponder here.

Let’s take a ride up the clove.

Our trip starts out at the western edge of Palenville. The highway crosses a bridge there and we get our first glimpse of the rocks. I would like it if you paid attention to your driving, so just give those rocks a few glimpses. You will quickly note large ledges of sandstone and that is about all you need to see here for now. You will very soon pass another huge cliff and then cross More’s Bridge. A quick look at the cliff will reveal, again, a sequence of red shale and brown sandstone. Now is the time to begin pondering what we are actually seeing.

Keep heading up the canyon. Not too much farther up the road there are a couple of places where you can pull over, get out, climb down and take a more leisurely look at the rocks. Just across the canyon from the highway is something called the “Red Chasm.” Its name is well chosen because it is a very handsome shade of red. Take a good look and you will see thick layers of red shale. These were, long ago, formed as floodplain deposits. Then too, there are a large number of thick ledges of gray and brown sandstone. These were once the deposits of river channels. What you are looking at is an ancient delta. It’s called the Catskill Delta and back during the Devonian time period it boasted numerous rivers flowing across its surface.

                                                                                                         The Red Chasm

Floodplains and river channels; you have just learned about 90% of what there is to know about Catskills geology. As you travel throughout mountains, it is red shale and brown sandstone that make up most of the bedrock that you will encounter. And that will prove true for the rest of our drive up the clove.

Each stratum of this sedimentary sequence represents a short chapter of time. Each had its turn being the surface of the Catskill Delta. The top of each red shale stratum was once the surface of the ground. If you could travel back through time then you could walk on that surface and leave footprints there. You could return to the present and go searching for your own fossil footprints. Too bad we can’t time travel, but we can’t. Not literally.

Let’s continue our drive uphill. We will pass more outcrops of sandstone and shale. We gradually begin to appreciate how much time is involved here. Each horizon of rock really was the surface of the Catskill Delta for a brief moment, so long ago. Each of those landscape surfaces would have, back then, had the look of permanence about it.

But that look of permanence would have been deceptive. It is by driving up the canyon that we begin to “see” the passage of time. The strata, as we pass them by, record the history of the deposition on the Catskill Delta. They record time itself, a lot of it, and we are traveling through that time.

Our journey up the canyon will eventually take us into Haines Falls, passing many more strata of sandstone and shale – and a lot more time. We will have passed by a thickness of about 1,200 feet of strata. Try to imagine, for a moment, how long it took for all that sediment to be deposited on the Catskill Delta. It must have been many hundreds of thousands of years and, quite possibly, millions – I do not know.

But just how thick is the whole Catskill Sequence? I asked Dr. Charles Ver Straeten, research geologist of the New York State Museum, and he told me that he had just made that calculation. From the bottom of the Devonian sequence, in the Hudson Valley, to the top of Slide Mountain, there are about 9,000 feet of stratified Devonian sandstones and shales. I asked him how much time was involved in this same sequence and he gave me a chart that showed that, if we read it right, a bit more than 60 million years had passed while those strata were being deposited. Our journey through Kaaterskill Clove seemed to have taken us through an enormous length of both rock and time, but it is perhaps only approximately one seventh of the Catskill sequence! Time, it would seem, is very long.

Contact the author at titusr@hartwick.edu  Join his facebook page The Catskill Geologist. Or visit his blog site thecatskillgeologist.com

                               The Hyde Park Deltas – Part two

thecatskillgeologist.com

Robert and Johanna Titus

Nov. 2016

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This is the second of two new articles about the Hyde Park deltas.

Last time, we began investigating the Hyde Park Deltas. These ice age features have been recognized by glacial geologists for decades and they are seen on the New York State Museum’s map of New York State glacial geology. That map recognizes two deltas.  But we have found something remarkable and, we feel, revealing. Those two deltas represent two chapters of delta formation. That needs to be explained. So – we are going to, herein, record the sequence of events that we have deduced to, we hope, explain all this. We are, in short, going to record a sequential history of the formation of the Hyde Park Deltas – and thus Hyde Park itself.

1) It all began sometime close to the end of the Ice Age. The Hudson Valley glacier had been melting and vacating the valley, and it left behind a sizable lake. That has long been recognized as Glacial Lake Albany. The lake stretched across the Hudson Valley and, at Hyde Park, it was nearly two miles wide.

   2) Crum Elbow Creek was flowing south by southwest, east of, and parallel to, the lake. This took it across a newly deglaciated landscape. We suspect that, at least at first, it was a far more powerful stream than it is today. It does not amount to much today, but back then, it may have been swollen with very dirty meltwater. It, we think, it (must) have been a very erosive stream.

Crum Elbow Creek today, upstream.

3)  If so, then Crum Elbow Creek had to have carried a very substantial load of sediment which came to be deposited in Lake Albany. Most of that sediment formed what we are calling the Roosevelt Delta (see yellow on our map). The waters of Lake Albany, at that time, reached a level of 180 feet in modern elevation. The delta’s topset was, likewise, at today’s 180 feet.

The Hyde Park deltas; Roosevelt Delta in yellow; Vanderbilt Delta in brown.

4) We conclude that, back then, Crum Elbow Creek did not turn sharply to the west as it does today. Instead, it continued its southwest path which took it past today’s Wallace Center and onward, just a little north of the Roosevelt mansion, Springwood. Its old channel can still be seen adjacent to the parking lot at the Wallace Center (see map and see photo). This is the time when the stream deposited the Roosevelt Delta (again, see our map).

“Old” Crum Elbow Creek, highlighted in red. “New” Crum Elbow Creek (blue) extends off to the west.

Now dry channel of “Old” Crum Elbow Creek, just north of Wallace Center. “Old” Crum Elbow Creek once flowed at the bottom of this small valley.

   5) Next, there came a time when Lake Albany (suddenly?) drained down to a level of 170 feet. We do not know why, but with that lowering, a remarkable event ensued. A small stream, one that had just begun flowing along the northern edge of the Roosevelt Delta, became quite erosive and, by headward erosion, it worked its way up along that northern flank of the Roosevelt Delta. Stream piracy was now occurring. The path of this stream, “New” Crum Elbow Creek, can be followed along East Market Street (aka County Route 41). It can be seen that this stream had been erosive enough to cut down into the bedrock there (see our photo) and create something of a canyon.

East Market Road follows canyon of “New” Crum Elbow Creek. The creek is just out of sight on the far right; it presumably cut the steep slopes of this canyon.

6) With time, this growing creek would intersect “Old” Crum Elbow Creek and divert its waters into the present-day path of “New” Crum Elbow Creek.  Also, a new delta, our “Vanderbilt” Delta, began to form. This younger episode of delta building apparently did not last as long as the previous one, and the new delta never got to be as large as its predecessor. The old Roosevelt Delta leveled off at 180 feet; the new Vanderbilt one at 170.

7) During the period of stream piracy, “Old” Crum Elbow Creek continued flowing in its old path. But that path was about ten feet higher above the new level of Lake Albany. This higher level promoted active erosion of the “Old” Crum Elbow channel. This old channel is the one visible just north of the Wallace Center parking lot. More of the old channel can be traced through Hyde Park.

More channel of “Old” Crum Elbow Creek (left center) on the Yellow Trail at the Winnakee Nature Preserve, just north of Rte. 9.

8) After stream Piracy was complete, the “Old” Crum Elbow channel was left high and dry as is seen at the Wallace Center today (our photo, above). Another dry channel can be seen immediately north of the old Roosevelt family stables. (See our photo below). That had been a tributary of Old Crum Elbow Creek.

Dry canyon of a tributary of Old Crum Elbow Creek, just north of Roosevelt family stables on the Cove Trail.

Sometime later, Lake Albany dropped the remaining 170 feet, down to its present level. Today’s “New” Crum Elbow Creek came into its modern form by eroding those 170 feet. This is best seen where the bridge crosses the creek at the south end of the Vanderbilt Estate.

Crum Elbow Creek at the Vanderbilt Estate.

We believe that this history accounts for pretty much all the landscapes we see, today, at Hyde Park. It is an account that describes the very origins of Hyde Park itself and is thus a fascinating history. We invite you to tour the town and see the geologic sites that we describe here. Then, take Rte. 9, north and south of Hyde Park, and see what the vicinity would have looked like if the deltas had never formed.

We have long been impressed with how ice age events explain so much of what we see in our scenic Hudson Valley. This is a fine example.

            The Hyde Park Deltas – Part one              

   Thecatskillgeologist.com

Robert and Johanna Titus

   Nov. 2016

Most of the time we are re-running old newspaper columns on this site. But we expect to do some original work as well. That is the case here today. We are publishing the first half of a study we recently did on the geology of the Hyde Park ice age deltas. We hope that you will be able to go to Hyde Park and see what we have seen. We are publishing this again because we have new photos for Part Two

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The town of Hyde Park is built upon a broad flat platform. It’s a natural landscape feature and it needs to be understood. When you drive into the town, we want you to take note of it. From the north, you pass the Vanderbilt Estate with its endless front lawn. Then the highway passes through the urbanized part of the town. That area is just as flat. Farther south is the Roosevelt Library and Museum. See its expansive and, again, very flat grounds. All this flatness begs to be understood. There is a pattern here, and we always say “when Nature presents scientists with a pattern, she demands an explanation.”

We like to bring a barbeque skewer along with us wherever we go. When we want to investigate this sort of flatland we try to drive it into the ground. If there are rocks, which there usually are, we have little luck. But – if the skewer slides in easily – then we have likely found a glacial lake bottom. That is the case at Hyde Park. Take a look at our map. All the yellow is flatland where there are few, if any, rocks in the ground.

Yellow on map is delta flatland. Base map courtesy of US Geological Survey

But, is this a simple lake bottom or is there more to the story? Notice that, on our map, the yellow flatlands lie at the downstream end of a stream with the unlikely name of Crum Elbow Creek. Long ago, glacial geologists recognized that that all these flatlands comprised an ice age delta, sometimes called the Hyde Park Delta, the delta of Crum Elbow Creek. The New York State Museum map of ice age features actually portrays two deltas here, one north of Crum Elbow Creek, with a second and larger one, just to the south. This is important, and we should name the two deltas. Let’s call the northern one the Vanderbilt Delta (brown) and call the other the Roosevelt Delta (yellow).

Roosevelt Delta in yellow; Vanderbilt Delta in brown.

Back during the Ice Age, there was a sizable lake flooding all of this part of the Hudson Valley. It has been called Glacial Lake Albany. Crum Elbow Creek is a long flow of water and, back then it was likely carrying a lot of sediment. Most of that sediment was deposited as the delta where the creek flowed into Lake Albany. The top of a delta is always flat and it roughly corresponds with the old lake level. That’s called the topset of the delta. That would have been at about 180 feet in today’s elevation.

The front of a delta is typically a steep slope called a foreset. That explains another landscape feature that we see throughout Hyde Park. Take a look at our photo from the Vanderbilt mansion. The mansion was located at the top of the steep foreset slope. That offered the Vanderbilt’s a nice view of the Hudson River. Walk north and south from the mansion and enjoy this view.

The Vanderbilt Mansion from the south. Below it is the foreset slope.

Foreset slope, north of the Vanderbilt mansion, with its view of Hudson.

Now we have learned a lot about Hyde Park. You are not likely to be able to pass through town without envisioning yourself in a very different landscape, an ice age one. With your mind’s eye look west and see Glacial Lake Albany spread out before you. It extends all across the Hudson Valley. The lake was almost two miles wide here. That’s about four times as wide as today’s river is.

But, the more we worked the area, the more we saw problems that needed to be explained. For starters, we thought the flow of Crum Elbow Creek was a bit odd. The stream has its head about ten miles north of Hyde Park. It flows in a remarkably straight line, just a little west of south, all the way to Hyde Park. Much of the way, it follows Rte. 9G. But then, at the village of East Park, it turns sharply to the west and flows directly into Hyde Park and, from there, into the river (see our maps).  Back during the Ice Age, that took it right into Glacial Lake Albany. We wondered if there was a story to that sharp westward turn. We are scientists; again, we are supposed to wonder such things.

Then it began to bother us that Crum Elbow Creek did not match the delta all that well. It certainly did a good job of explaining the northern part of the delta, the Vanderbilt Delta. But how was it that the delta spread out so far to the south? How could delta sediments extend a full two miles, south of Crum Elbow Creek? In short we just did not think that Crum Elbow Creek was accounting for the Roosevelt part of the delta complex. Again, we are scientists.

That’s when another problem appeared. We were now looking more carefully at the map and we suddenly noticed that, while there were two deltas at Hyde Park, they were also of two different elevations. The Roosevelt Delta, south of Crum Elbow Creek, had a topset at about 180 feet in elevation, but the Vanderbilt Delta, north of the creek, lay at just about 170 feet. We were, clearly, looking at two separate events.

This is when it started getting exciting. We soon had a flash; all of a sudden we saw what had happened, and that was a genuine epiphany. We will be back next Thursday with the solutions to these problems, but in the meantime we want you to have a chance to ponder them, and see if you can come up with the solution yourself. We leave you with a blown-up version of our map, focusing on the southern part of the Roosevelt Delta. Take a good look and see if you can solve these problems without our help.

Do you have some ideas? Write to our facebook page “the Catskill Geologist.”

Close-up of the southern delta.