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The Hoogebergs

Updated by Robert and Johanna Titus

On the Rocks – The Woodstock Times

We often use lots of words without having a precise notion of what they mean. English is designed for that as sometimes its words need to have just a touch of (appropriate) vagueness. For example, just what does the word “mountain” mean? There are many good answers to that and each one is different from all of the others, and each one may still be correct. Similarly, what exactly does the word “hill” mean? It gets worse. What does “foothill” mean? Hills don’t have feet, so let’s pursue the issue and do it with a good local example.

The Catskills are often called mountains although many debate that heatedly. Our Catskill Mountains have foothills and some of those are very close to Woodstock. The foothills that we are speaking of are the hills of the Hoogeberg Range. If you have never heard the term that’s quite excusable, the Hoogebergs are not great or famous peaks.

The Hoogebergs are a series of small hills lying parallel to the Catskill Front, the great eastern escarpment of the Catskills. They are found just a few miles east of the Catskills and rise to only 600 or 700 feet in elevation. That’s merely a third of the elevation of the Catskills themselves. Thus, they are adjacent and parallel to Catskills, but just not very elevated. They are like a practice run before the big mountains, hence the term foothills. You can see the Hoogeberg Range if you drive north on the Kings Highway (Rt. 31), south of Saugerties and Rt. 32, north of Saugerties. The ridge looms to your left (west). It forms a fairly impressive horizon.

            Hoogebergs – lower right

You can easily go and see the rock that makes up the Hoogeberg Range. There are several locations where there are gaps in these hills, and they let you drive right through the bedrock. Rt. 212 cuts through at the village of Veteran, Rt. 32 cuts through at Quarryville and the Glasco Pike cuts through at the village of Mt. Marion. In each of these locations there are fine exposures of the bedrock right along the road.

What is the Hoogeberg and why is it here? Visit the Rt. 212 exposures and you will observe some very fine, thick, rugged sandstones. These are tough rocks and they have resisted the efforts of weathering and erosion. To the east and west, softer rocks have eroded away, and as they did the Hoogeberg came to be sculpted into a series of hills. These sandstones belong to a geological unit called the Mt. Marion Formation. It is mostly sandstone, and it makes up the Hoogeberg Range. Park along Rt. 212 here and poke around for a bit and look the sandstones over. You may find the fossils of some marine shellfish. That tells us a lot. The Mt. Marion sands accumulated at the bottom of an ocean, sometimes called the Hamilton Sea. The sands once made up the floor of that sea.

At the Glasco Pike exposure you will learn more about the Mt. Marion and the Hoogeberg. This outcropping is at the bridge which crosses Plattekill Creek. The lower levels of the exposure are mostly black shale. Up above, however, those sandstones make their appearance. We talked about this in an earlier column. This sequence of strata records a transition from an offshore, deep water setting to a nearshore, shallow ecology. The offshore accumulated muds that hardened into the shales while coastal sands would eventually harden into the Mt. Marion sandstones.

If you look carefully, you may notice that the strata at these locations are not perfectly horizontal; they dip gently to the west. These rocks were all here during the late Devonian time period and they were involved in crustal tilting that was part of a mountain building process, then going on in New England. The tilting of these resistant strata raised those sandstones and exposed them to erosion. They responded by eroding into the hills we see today. The tilting accounts for much of the form of the Hoogeberg. Its west-facing side is generally a gentle slope, reflecting the original tilting, while the east-facing front was eroded into a steep slope, often a cliff.

Crustal tilting, shallowing seas, ancient shellfish, there’s a lot of history in these pretty little foothills and they do make up a significant feature in our local landscape, even if they are just foothills.

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

A winding river

On the Rocks; The Woodstock Times

Robert and Johanna Titus

Congressman Faso has introduced a resolution in Congress that recognizes the natural resources and economic importance of the Upper Delaware River watershed. It was supported by something called the Coalition for the Delaware River Watershed. As       much as anything, the resolution is looking to improve the area’s tourist trade and we are in full support of that. This picturesque region is well worth visiting. Have you spent much time there? Well maybe we can give you a good reason to visit.

We have often enjoyed driving west on the valley of the East Branch of the Delaware. It passes through a largely rural region which presents us with a very scenic drive. What you are bound to notice very quickly is how the slopes on each side of the river are so steep. The valley is narrow here and its slopes rise up and tower over the river itself.

That’s unusual in the Catskills region. Our river valleys typically slope down far more gently. The story becomes more interesting when you get a good map out. Take a look at our first picture.

It traces the river from Corbett to Linden. Notice the broad sinuous curves that the river follows. These sorts of curves are commonplace among rivers but, not with this sort of river. These river bends have quite a story to tell.

This is properly called a meandering stream and the derivation of the word meandering is obvious; it refers to our sinuous curves. The problem is that meandering streams are supposed to be found on rivers that flow across enormous wide floodplains but there are virtually no floodplains here. The Mississippi is very good at meandering. And the other problem is that meandering streams are not supposed to be found at the bottoms of canyons. We geologists have a lot of explaining to do.

The story goes back to the 1930’s when a New York State Museum geologist named Rudolf Ruedemann began looking at these rivers and did some deductive thinking. Ruedemann knew that meandering streams had to have formed on broad floodplains and so he, in his mind’s eye, traveled back in time and saw our western Catskills as they may have been during the Cretaceous Time Period, about 100 million years ago. Ruedemann deduced that the western Catskills region must have been flat at that time. No hills or mountains rose up as they do today. That flat landscape, he reasoned, was ideal for the production of meandering streams. And so it was that rivers which would become our modern East and West Branches of the Delaware, found themselves flowing in those broad sinuous meanders. And they were flowing across an enormous flat landscape.

Then things changed. The crust of our whole region began a long slow uplift. The East and West Branches found themselves in a rising landscape. Their meanders had no choice but to begin eroding into that rising land. The meanders were trapped as, above them, were those rising slopes. That is how our distinctive landscape came into being.

All this speaks of the East Branch occupying a very old river channel. It could be that the banks of the river date back to the Cretaceous, 100 million years ago – or more. If you get a chance to go out there, and can climb down to the edge of the river, then think about all this. During the Cretaceous the river was right where it is today. There were dinosaurs in abundance during the Cretaceous. Stand on the edge of the river and look to your left and then to your right. There once were dinosaurs there, drinking the waters of this stream!

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

The Widow Jane Mine

Windows Through Time; The Register Star 201

Robert and Johanna Titus

We have been spending a lot of time in Rosendale lately. (Early spring, 2016) There is a lot of good geology there and some pretty good tourist attractions as well. Things will soon be opening up for the season at the Century House Museum and the Widow Jane Mine. These are parts of the Snyder Estate Natural Cement Historic District. They are operated by the Rosendale Historical Society. They all commemorate the natural cement industry that flourished here during the nineteenth and early twentieth centuries. Last year we did an article in Kaatskill Life magazine about all this and recently we also did a column on the production of lime. So maybe you would like to go and visit Rosendale and see what happened down there. Now is the time.

Natural cement is made from a form of rock called dolostone. It is a close cousin of limestone, but differs in that it has a lot more magnesium in its crystal structure. Natural cement was made from a unit of rock called the Rondout Formation. That is found abundantly in Rosendale. During the peak of the cement industry, the Rondout was extensively quarried. Its stone was crushed and then cooked in large industrial kilns. The resulting lime was just of the right composition to make a very high quality form of cement. It was real durable material. It held up better than other forms of cement. Just as important, nobody had to mix sand or any other additives with it; it came with just the right recipe of silt and clay already in it. So not only was it good stuff but it must have been relatively inexpensive as well.

Not surprisingly, a sizable industry grew in Rosendale by the turn of the 20^th Century. There had been a great rush of building in the Northeast and quality materials were sorely needed.  As you wander around the town you can still see a lot of remnants from those mining days. There are relic kilns and a number of old mine openings. The Widow Jane Mine was a typical operation. Miners cut into the bedrock and excavated what are called “pillar and room mines.” They cut into the dolomite but left sizable pillars to support the mine as it expanded. These can be visited and explored and it is fun to do so. The mines can be seen at two stratigraphic levels. The lower Rondout was called the Whiteport Dolostone and the upper part of the unit was the Rosendale Dolostone. Each was just the right composition, so each was excavated extensively. In between the two dolostones was a pure limestone of no economic value. It’s the Glasco Limestone and, if you can get close enough to it, you will find a large number of fossils, many of them corals. We enjoyed seeing them. The Glasco is an outdoors museum.

We would like you to get used to watching for pillar and room mining. That is because you are likely to encounter it from time to time as you wander around Ulster County. This sort of mining was once very widespread and all the old caverns are still around. Sometimes you can even get into some of them.

The value of the Rondout Formation was first appreciated in the middle 1820s. By the 1840s extensive quarrying was underway. The American economy was fast growing and there was a real need for cement. Rosendale satisfied much of that need. Rosendale cement came to be used for some historical sites. It was ideally well suited for large foundations. It was used in the construction if the Statue of Liberty, parts of the Capital Building and the Brooklyn Bridge.

There were problems with natural cement and eventually history was not kind to this industry. It took a very long time for natural cement to fully harden and that made it unpopular. If you made a highway of it, it took a month to cure and be useable. Portland cement was discovered, or invented if you prefer. It’s an artificial sort of cement that is made of commonplace limestone but requires the addition of sand and other ingredients. By the early 20th century Portland cement was gradually replacing the natural form. The last Rosendale plant survived into the 1920s

The Century House website says that things will be open daily for self-guided tours from 10:00 to 4:00. The Museum will be open Sundays, 1:00 to 3:00, from Mother’s Day through September. You will want to keep up with their events listings. They do hold occasional concerts in the old mine. We are most curious to find out what the acoustics are like.

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

The Present is a key to the past

On the Rocks; The Woodstock Times, 2018

Robert and Johanna Titus

We are always happy to see the opening of a new land preserve anywhere in the Hudson Valley or the Catskills. We get out to see them as soon as we can, always hoping that there is some good geology. After all, we always need things to write about. Recently, Scenic Hudson opened a new preserve near where we live. It is called the Mawignack Preserve and it is off Snake Road in Jefferson Heights, just west of Catskill. Mawignack, we understand, means where two rivers come together. Kaaterskill and Catskill Creek are joined nearby.

We have always enjoyed the many landscapes found along Catskill Creek. Our home lies just (safely) above the Creek. So, we were most eager to see Mawignack. But when we found an aerial photo online, we were a bit disappointed. The preserve seemed to be little more than a very large field with a trail circling it. The trail did pass right along a thousand feet or so of the creek and that boded well, but–it just didn’t seem like all that much; this was not the Grand Canyon. But we went and looked for ourselves. It turned our pessimism was not justified. There as some very interesting geology there.

Google Earth will quickly help you find your way to Snake Road in Jefferson Heights. The Preserve parking lot is near the end of the road. You follow orange trail markers a short distance until there is a split in the trail. Take the right branch. That’s where we found that things got interesting.

We saw something that we imagine few others would notice. Take a look at our first photo, look carefully. Do you see what sort of resembles a stream channel – it trends right to left in the far distance and then left to lower right in the middle of the photo. It looks like something that geologists call a stream meander. It’s dry so it is not an active river, but it was, long ago, late in the Ice Age. How do we know that?

We use something that is fundamental to geology. It’s called uniformitarianism. Briefly that means that when we find a problem in the geological past, something that we can’t figure out right away, then we search the modern world for something similar that we can use to find the solution. We like to say that “the present is a key to the past.” Let’s do that right now. We would like to take you to the “present” at a location you are likely to be familiar with. That’s the Thorn Preserve at its intersection of Zena and John Joy Roads. The southeast corner of the Preserve overlooks a bend in the river, the Saw Kill, exactly the same as we suggest used to be at the Mawignack preserve

Well, what happened at Mawignack? Why is that bend in the river high and dry? We think we know that too. First things first though; the Mawignack Preserve, back then, was indeed a river meander. It lay atop the old floodplain of an ice age version of Catskill Creek. But today’s Catskill Creek flows about ten feet lower that the old floodplain. How could that be? Yep, we think we know that too.

You see, at the end of the Ice Age, when a lot of glacial ice was melting, the ground was rising. As the ice melted away, weight was removed, and the ground simply expanded and rose—about ten feet. Catskill Creek eroded down into those ten feet, to establish its modern channel while abandoning its old floodplain. That floodplain, with its old meander, is still there, perched those ten feet above the river. But the meander can only be seen by the trained eyes of modern geologists.

So, we propose that the two preserves be considered as twins, twin landscapes separated by time. Visit the Thorn Preserve and see a modern floodplain with a modern meandering stream and then go to Mawignack and see an old floodplain with an old meander. Mawignack looked just like Thorn, perhaps 10,000 years ago. Thorn may well look like Mawignack—10.000 years from now.

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

Herbert Hoover–at Prattsville?

On the Rocks; The Woodstock Times 2019

Updated by Robert and Johanna Titus

Herbert Hoover doesn’t get much good press these days. He is largely remembered for not being able to end the Great Depression. Not enough people remember that, earlier in his life, he was able to feed and save the lives of millions of people in Belgium during World War I. He did the same in the Soviet Union soon after that war. He, it has been argued by some, saved more human beings from death than any other person in history. Hoover was a conflict of terms–a brilliant bureaucrat. We are fond of him, and his wife Lou too, for another reason. They were both trained in geology–at Stanford University (for Lou, an extraordinary accomplishment for a 19^th Century woman). Herbert called himself a mining engineer, but he was, first of all, a geologist.

Can we do a little bragging? Geologists typically are given to have very good spatial relationship skills. We need them in our everyday functioning with the structures of rocks. We see through time too; we have to when we are dealing with millions of years of earth history. We geologists develop very structured ways of thinking and the two of us think we see that in Herbert Hoover’s biography.

For us, the best and most geological part of the story takes us back to the horrible flooding on the Mississippi in the year 1927. There had been extremely heavy rainfall over the winter of 1926-1927. By April the waters of the Mississippi were rising over the river’s levees at scores of locations. Hundreds of thousands of people were flooded out of their homes (largely poor and black). The highway and railroad infrastructures were being destroyed. It can be called the worst flood in the Mississippi’s history; it was a rampage.

There had, hitherto, been no real history of federal assistance for such emergencies, but federal help was needed. The governors of six southern states called for Herbert Hoover’s help. The engineer, Herbert Hoover was, after all, the world’s foremost disaster relief specialist. Somewhat reluctantly, President Calvin Coolidge appointed him chairman of a special cabinet committee. The committee had its first meeting – two hours later – and Hoover was in Memphis early the next morning.

Hoover assembled an enormous fleet of boats and airplanes to work the flooded river. He put together an army of military and volunteer civilian personnel to carry out what needed to be done. He built 154 refugee camps to house those displaced by the flood. He provided those refugees with health care, particularly the immunizations they would need. What Hoover did not have was federal money. But working with the Red Cross, Hoover directed a very successful fundraising effort. His emergency relief was, more than anything else, a volunteer effort. And it was a resounding success.

When we read the story of Hoover and the Mississippi, we thought back to our experiences at Prattsville, just two weeks after the Hurricane Irene flooding. We wanted to cover the story as both journalists and geologists but when we got to the Rte. 23 bridge at the eastern edge of town, we found the National Guard there. We were not welcome to enter Prattsville that day, especially as “journalists.” Well, we won’t tell you how, but we snuck in. But then, unfortunately, we still had to walk about a mile to get to where the cleanup action was going on. The Federal Emergency Management Administration (FEMA) was there in force and had been for most of those two weeks. It didn’t take long before we saw evidence that an experienced team who knew what they were doing, had been hard at work. Each house we passed had been marked with a red X to indicate there were no people, especially dead people, inside. We passed a field filled with derelict cars. All had been towed there to get them out of the way. Another field was piled high with the flotsam and jetsam of flooding. Again, nothing was going to get in the way of FEMA activities.

When we got to the center of town, we found it buzzing with activity The National Guard was there too, in large numbers. And busloads of volunteers were arriving every few minutes, or so it seemed. People who had been hard at it for a while were covered with mud. We found a food service area with a sign that said they would feed anyone, any time, day or night–free.

We were most impressed.
Well, you probably see where we are going with all this. The ghost of Herbert Hoover was there in Prattsville. He had been something of a Teddy Roosevelt type of progressive Republican. Give the government a problem and watch and see if it can’t solve it. FEMA came long after Hoover (1978), but we think we saw his approach to the Mississippi floods at Prattsville. We speculate that Hoover’s 1927 efforts were, at the least, inspirational to today’s FEMA.

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

THE CATSKILL GEOLOGISTS BY ROBERT AND JOHANNA TITUS

When Cow Slip Rock Slipped.

Most of our field studies consist of pretty serious science, but sometimes we just like to go out and have some fun. We love to chase down geologies that we find on old postcards. Recently we found a good one. Take a look at our first photo; it’s a post card mailed in 1934. It shows something called “Cow Slip Rock” on Basic Creek at the south end of Hempstead Lane in Greene County’s Freehold. On the postcard, Cow Slip Rock was the big, tilted boulder lying upon four slightly smaller ones. We like big rocks so of went to look for it. We thought there might a good story there and we were right.

Take a look at our second photo. There it is, Cow Slip Rock at least 87 years later, and things have changed. It is still in the same location and still tilted as it was long ago. But those other boulders are gone. What happened; where did they go? The answer is fairly obvious; there had to have been a terrible storm in the not too distant past. It generated a streamflow that was powerful enough to sweep away those smaller boulders but not strong enough to move the heavier Cow Slip Rock itself. We stood at this site and let our mind’s eyes take over. We soon were able to experience that flood. There was a very heavy rainfall. We knew that the flow of water had risen considerably. It must have overflowed the stream banks, including where we stood, in a full-fledged flood. The two of us were soon up to our necks in the cold flow. We felt raging, foaming, pounding torrents all around us. White caps speeded by. We heard the loud roaring noise of this flood, and that roar was punctuated by the cracking sounds of fast-moving boulders smacking into each other. We looked across the stream and saw Cow Slip Rock quickly dropping down. All those other boulders were being swept away.

It was an incredible moment; perhaps something that only geologists can hope to experience. We had been privileged to witness an important instant in the history of Basic Creek. should have feared for our lives, but we were the mind’s eyes, and nothing can harm the human imagination.

But when did this actually happen? We don’t know; it’s an event lost to time. But our best guess is that this was hurricane Irene in the August of 2011.

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

The Sinking Coast

The Devonian of Greene County Part Ten

Updated by Robert and Johanna Titus

We usually think of environmental disasters as great, awful catastrophic events. What could be worse than a sudden earthquake or volcanic eruption? But sometimes these disasters proceed quietly, even stealthily with almost nobody taking notice until the worst of the damage has been done. People are alarmed about catastrophic events, but it is easy for them to remain blissfully unaware of those more subtle, downright sneaky problems.

One of those today is the sinking coastline of the Mississippi Delta in southern Louisiana. There, the great mass of earth that is the delta has been subsiding, very slowly so that coastal regions have sunk into the Gulf of Mexico. Homes and villages, right on the shore, have had to be abandoned to the advancing waves. Millions of acres of coastal land have thus been lost over the decades and centuries. But have you ever heard about this? Quite possibly not, it is such an inconspicuous process, who notices?

Why is the Louisiana coastline sinking? Many of the reasons are quite natural. Over the millennia, as the Mississippi has carried sediment to this coastal realm it has piled this material up in increasingly thick masses. Just the weight of all this sediment has pressed down on the crust and caused subsidence. Then too, there is the normal process of compaction. The sediment has simply settled and that causes still more sinking.

It probably won’t surprise you to learn that man has interfered with Nature’s balance. Normally the Mississippi replenishes most of the land that has been lost. Floods rise up over the banks of the river and carry new sediment to fill in and replace volumes of sediment that have been lost to subsidence. The land surface is maintained. Sadly, that important process has been halted; over the past three centuries man has built levies along the banks of the Mississippi in a successful effort to thwart flooding. Now there are many fewer threats from flooding, but the benefits have also been lost. It is impossible for floods to carry new sediment onto sinking landscapes. Ironically man’s efforts to control riverbank floods have helped let coastal flooding get out of control. It gets worse; over the past century so many oil wells have been drilled in the region and so much oil has been pumped out of the ground that this has hastened the rate of subsidence. The oil had helped buoy up the ground, and now where it is gone the land is sinking.

Well, for these and other reasons, much of coastal Louisiana has been condemned to sink beneath the waves. It will take decades or even centuries, but a lot of Louisiana is doomed. Some have decried this as one of the greatest looming environmental disasters of our time.

It couldn’t happen in Greene County, could it? Well, no, but it has happened and of course that was back during the Devonian. In the recent installments of this series, we have watched Greene County rise out of the sea as a great expanding delta, the Catskill Delta, advanced westward across much of New York State. For a considerable length of time Greene County lay along the front of that delta and, just like the Mississippi Delta of today, it was subject to the natural effects of subsidence. There were no Devonian age levies or oil wells, but Nature herself caused just the sort of sinking that we see today in Louisiana. And, of course, we have the rocks to prove it.

Take Rt. 32 south from Freehold until you arrive at Rt. 23. Turn left and travel east a quarter mile, or so. There on both sides of the highway are some fine outcroppings of what is mostly Devonian age sandstone. It is the north side of the road where you can see the best exposures so find a good place to turn around and park at the outcrop.

Pause and survey the whole outcrop. You will, we hope, be able to see that it is broken up into three separate layers of stratified rock. In other words, there seem to be three packages of rocks 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.

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 cycle you can see that many of the thick sandstones are inclined to the west (left). This is typical of river sediments, and we have found, in recent columns, that such sandstones are, indeed, river channel deposits. That’s the case here; each of the three cycles begins with river channel sandstone. The overlying finer grained material is a petrified soil profile, literally a fossil soil. So, if you follow all this, each cycle represents the presence of a Devonian age Catskill Delta river channel overlain by a floodplain soil.

So, what is going on here and how does it relate to today’s Louisiana? There were two dynamics going on here 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 how Louisiana is sinking and that the sinking is slow? Well, our Catskill Delta was sinking slowly also. Slow river meandering was matched with slow crustal subsidence. There was a back and forth motion. First the river would meander one way and then it would return. “Back” was easy, but, by the time a river meandered “forth,” the crust has already sunk quite a distance. A new river channel/ floodplain “forth” deposit would be laid down on top of the old “back” one. If meandering continued, and it would, then given time a third deposit (cycle) would be deposited on the same sinking delta.

That’s what we see on Rt. 23. Did one river deposit all three cycles? We don’t know but it might have been. Was one river or several rivers meandering across this site? We don’t know but it doesn’t much matter. The important thing is that we can look into the stratigraphy here and recognize chapters in the history of the Catskill Delta. It was sinking and its streams were meandering, and it behaved very much like the Mississippi of today. And that is because Greene County, back during the Devonian, was very much like the Louisiana of today. Only time has changed.

Let us add a note about the names of these geological units. This Devonian sequence has been classified and reclassified over the decades. Different names have been applied to the several units of rock described in this series. The rocks described in this installment are probably the upper portion of the Ashokan Formation. Those outcrops probably belong to the lower Ashokan Formation. To the average reader these will not be very important issues but to professional geologists they are the subjects of often heated debate.

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

The Present is a key to the past

On the Rocks – The Woodstock Times

Robert and Johanna Titus

We are always happy to see the opening of a new land preserve anywhere in the Hudson Valley or the Catskills. We get out to see them as soon as we can, always hoping that there is some good geology. After all, we always need things to write about. You folks have helped quite a bit; the Woodstock Land Conservancy has long kept us busy and we are glad of it. Fortunately, there are also other groups. Recently, Scenic Hudson opened a new preserve near where we live. It is called the Mawignack Preserve and it is off Snake Road in Jefferson Heights, just west of Catskill. Mawignack, we understand, means where two rivers come together. Kaaterskill and Catskill Creek are joined nearby.

We have always enjoyed the many landscapes found along Catskill Creek. Our home lies just (safely) above the Creek. So, we were most eager to see Mawignack. But when we found an aerial photo online, we were a bit disappointed. The preserve seemed to be little more than a very large field with a trail circling it. The trail did pass right along a thousand feet or so of the creek and that boded well, but–it just didn’t seem like all that much; this was not the Grand Canyon. But we went and looked for ourselves. It turned our pessimism was not justified. There as some very interesting geology there.

Google Earth will quickly help you find your way to Snake Road in Jefferson Heights. The Preserve parking lot is near the end of the road. You follow orange trail markers a short distance until there is a split in the trail. Take the right branch. That’s where we found that things got interesting.

We saw something that we imagine few others would notice. Take a look at our first photo, look carefully. Do you see what sort of resembles a stream channel – it trends right to left in the far distance and then left to lower right in the middle of the photo. It looks like something that geologists call a stream meander. It’s dry so it is not an active river, but it was, long ago, late in the Ice Age. How do we know that?

We use something that is fundamental to geology. It’s called uniformitarianism. Briefly that means that when we find a problem in the geological past, something that we can’t figure out right away, then we search the modern world for something similar that we can use to find the solution. We like to say that “the present is a key to the past.” Let’s do that right now. We would like to take you to the “present” at a location you are likely to be familiar with. That’s the Thorn Preserve at its intersection of Zena and John Joy Roads. The southeast corner of the Preserve overlooks a bend in the river, the Saw Kill, exactly the same as we suggest used to be at the Mawignack preserve. See our second photo.

Well what happened at Mawignack? Why is that bend in the river high and dry? We think we know that too. First things first though; the Mawignack Preserve, back then, was indeed a river meander. It lay atop the old floodplain of an ice age version of Catskill Creek. But today’s Catskill Creek flows about ten feet lower that the old floodplain. How could that be? Yep, we think we know that too.

You see, at the end of the Ice Age, when a lot of glacial ice was melting, the ground was rising. As the ice melted away, weight was removed, and the ground simply expanded and rose—about ten feet. Catskill Creek eroded down into those ten feet, to establish its modern channel while abandoning its old floodplain. That floodplain, with its old meander, is still there, perched those ten feet above the river. But the meander can only be seen by the trained eyes of modern geologists.

So, we propose that the two preserves be considered as twins, twin landscapes separated by time. Visit the Thorn Preserve and see a modern floodplain with a modern meandering stream and then go to Mawignack and see an old floodplain with an old meander. Mawignack looked just like Thorn, perhaps 10,000 years ago. Thorn may well look like Mawignack—10.000 years from now.

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

How far away is the Devonian?

The Woodstock Times – On the Rocks; Feb. 15, 2018

Robert and Johanna Titus

   If you have been longtime readers of “On the Rocks” then you will know that we almost always write about geology that we have gone out to the field and seen for ourselves. We would like to depart from that in this issue. In fact, we are going to step out of Geology, itself, altogether. It all began when we were pondering the Devonian time period. That’s the geological chapter that extended from 419 to 359 million years ago. It’s an important unit of time here in the Catskills. All of the bedrock you see hereabouts was formed during the Devonian.  But what, we wondered, was going on in the universe that surrounded the Earth during that time? That got us pondering some more. We were being typical scientists and we were doing typical science thinking.

We realized that when you are looking into space, you are always looking into the past. When you are looking at the moon, you are looking at an image of light that departed it a short time ago. We asked our cell phone, and it told us that the image of the moon, that we see, left it 1.3 seconds ago. Our cell phone went on to tell us that light from the Sun is Eight minutes and 20 seconds old. We can’t actually see the Moon or the Sun; we can only see them as they were in the past. Do you think thoughts like this? Then you are a bit of a scientist.

We realized that there must be something out there that emitted light during the Devonian, but our cell phone was of no help. Our “smart” phone might have been stumped, but the Physics department at Hartwick College was not. We posed our question, by email, to the faculty of that department and in just a few minutes we got a very good answer. Living, breathing PhD physicists do these things all the time; they are very bright people. Dr. Kevin Schultz, Associate Professor of Physics, looked into NASA records and found a galaxy, poetically named UGC 12591. It lies just a little less than 400 million light years away from our Earth. That makes its light just a little less than 400 million years old. That light has been traveling toward the Earth all that time. When it reached the halfway point, Dinosaurs were just getting themselves started (that’s more science thinking). In short, that galaxy’s light was shining during the Devonian; it was there during the Devonian.

Would you like to see this Galaxy? Well, you need to look into the westernmost region of the Pisces-Perseus Supercluster. That is an enormous chain of galaxy clusters which extends across some 250 million light years of space. It is regarded as one of the largest “things” found in the cosmos. UGC 1259l is big; it is four times the size of our Milky Way Galaxy. That makes it four times bigger than everything you can see in the night sky. Think about that for a moment. The bad news is that you won’t be able to actually look at UGC 12591; it’s too far away. Our photo was taken by the Hubble Space Telescope. If you don’t have access to the Hubble, you won’t be able to see it yourself.

That galaxy is out there; it is that far away. But Hubble is not just looking far into space; it is looking far into the past. This column’s photo is of the galaxy as it was when lower Devonian tropical seas were invading New York State. Our local limestones are as old as the image you see in this column. That light was in transit while the trees of the fossil Gilboa Forest were growing. That light was geologically ancient at the very times when all the rocks you see around here were forming. We scientists ponder such things.

We should specify that we are not that smart; we paraphrased much of this article from a NASA publication. Dr. Schultz helped. We hope that Bob Berman will forgive our trespassing.

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

What is in limestone?

Windows Through Time; The Register Star

Robert and Johanna Titus

Last week we introduced you to a special type of rock– the fossiliferous limestone. It is largely composed of fossil shells and fragments of fossil shells. We showed you a very fine example of a shelly limestone, something called the Glenerie Limestone. It is exposed in an outcropping along Rte. 9W, south of the bridge at Glenerie. It is simply an extraordinary rock, absolutely packed with marine shellfish fossils. It is so much fun to explore an outcropping like this.

But how was it, exactly, that a pile of broken shells turned into a rock? That’s an important question. But how can we answer it? After all, nobody was there while it was hardening. Nobody saw it happening. And what can you learn from just looking at such a limestone rock anyway? These might seem like tough questions, but let’s tackle them today.

Turns out that there are different ways of looking at a limestone. One way is to make something called a thin section. That is a slice of rock so thin that you can look right through it. But now, still another question, how do you make such a thing?

You start by cutting your piece of limestone in half. Pretty much every geology lab has a rock saw. It has a turning blade that slices right through rock. You cut your rock into two small pieces and then you pick one and grind it down to a smooth shiny surface. And pretty much any geology lab can do that. We put grits onto a large piece of plate glass and grind the rock. When it is smooth enough, we cement it to a small slide of glass. We cut as much as possible off the limestone so that there is a relatively thin sheet of rock cemented to the glass. If this is done right, and it takes practice, you will already be able to see through the rock. But there is more that needs to be done.

In fact, now comes the hard part. We go back to that plate glass, clean it, and sprinkle it with a very fine grit. Then we grind, and grind, and grind. That bit of limestone keeps getting thinner. And, with practice, geologists can make it very thin. Then a sheet of cover glass is cemented onto it and the result is (drum roll) a thin section! You take it to a good microscope and now you can look right into the rock.

And what you can see is its innards. Take a look at our photo. It shows a thin section view from a piece of Ordovician aged limestone called the Trenton Limestone. One of us (Robert) spent 25 years studying this unit and its fossils. What you see are cross section views of several fossils. On the right center you will see a piece of a creature called a trilobite. We have written about trilobites in Windows Through Time several times. They are marine creatures that might remind you a little of horseshoe crabs. This is a thin section view of one of the creature’s skeletal elements. See the white holes in it? Those housed sensory hairs in life. In the upper left center and lower left there are fragments of crinoid skeletons. Again, we have written about these distant relatives of starfish.

There are several smaller bits of fossil debris in this view. It’s a good image; it shows just how abundant shell fragments are in a limestone. Few of these would be visible to the naked eye so this thin section image is important.

The rest of the view is all white; what is that? It’s cement. It’s a mineral called calcite which is calcium carbonate (CaCO₃). That’s the stuff that “glues” all the other grains together to turn the whole thing in a rock.

Calcium carbonate is a very soluble mineral and there is a lot of it in sea water, especially in tropical seas. It readily crystalizes and can quickly, by geological standards, harden a limestone. All those shell fossils are also composed of calcium carbonate and that means that nearly everything you see in this thin section view is CaCO_3.  Calcite reacts with hydrochloric acid; it effervesces, sometimes very actively. Many geologists carry an eye dropper, filled with this acid, into the field. If they think they have limestone, but are not sure, they just do the “acid test” and see. This acid is marketed as muriatic acid and you can get some and test rocks yourself.

Thin section analysis is hard work, so we don’t recommend that you learn, but we hope you enjoyed reading about it.

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