Weekend, December 26/27, 2020 – STEPHEN BLANK EXPLORES THE PRE ISLAND HISTORY
246th Edition
December 26-27, 2020
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LEAPIN’ LIZZARDS… DINOSAURS ON MAIN STREET!
Dinosaurs on Roosevelt Island!
Stephen Blank
Well, actually there were no dinosaurs on Roosevelt Island. But read on – explore the very early history of our Island.
First of all, I have learned, we have to think of two different time frames when we explore our deep history. First is the long term – from the beginning (say a billion years ago) to around 50,000 years ago. Then second, the more recent era of the last Ice Age.
In the first period, New York City was shaped and reshaped by enormous transformations in global geography. Turns out we were right on the edge of several of these profound changes – the creation of the supercontinent Pangaea around 300 million years ago and the dissolution of Pangaea when North America and what became Africa separated. The land on which we now live has drifted and changed, been uplifted, folded, submerged, frozen, and melted countless times. These events pushed up and dragged out the bedrock that underlies the New York region.
This bedrock – “schist” – was formed between 450 million and over a billion years ago. But being New York City, it has to be complicated. The City rests on three different strata, formed at different periods over millions of years – Manhattan Schist, Inwood Marble, and Fordham Gneiss. These three strata shape the topography of Manhattan. They aren’t arranged in simple layers like the leaves of a book but are complexly interfolded. It’s still more complicated: Continents drifted – and at some points we were much to the south – and climate changed many times.
A personal moment: Why was I interested in all of this? Answer is that I wondered why our Island existed. It appears to be a little hill (mountain?) of schist sticking up out of what became the East River, which remained as the River deepened and broadened. (This stuff sticking up out of the River was what was quarried here by Blackwell’s Island prisoners for many of the buildings on the Island.) I assumed we were related to Manhattan – same sort of bedrock. But not quite: Roosevelt Island is near the boundary of several of these bedrock regions. But we’re different. While the bedrock making up other nearby East River Islands (i.e. Randall’s or Ward’s Islands) represents their proximity to these various regions, Roosevelt Island is underlain only by Fordham Gneiss, characteristic of much of the south Bronx. This rock dates to the Lower Paleozoic and/or Precambrian Eras, formed approximately 500 to 4500 million years ago, and Roosevelt Island represents one of only a few isolated exposures of Fordham Gneiss in New York City. Who knew?
But while these vast movements over millions of years created the foundations of New York City, the landscaping we recognize was carried out by glaciers. In the second, more recent period (the Pleistocene or “Ice Age” from 1.8 million years ago to 8,000 years ago), glaciers spread southward from eastern Canada. Between 17,000 years ago to 11,000 years ago, large ice sheets bulldozed the landscape. Around 17,000 years ago, the part of Wisconsin glacier covering the New York City was about 985 feet thick (the Empire State is 1250 feet high, not counting the aerial). Rocks with the glaciers scrapped and scratched the bedrock of Central Park, producing long linear striations and grooves. Long Island is composed of rubble that glacier left behind as it melted, and the channel of East River was formed by the retreating/melting of the glacier and advancing of the Atlantic Ocean.
GLACIAL LANDSCAPE IN CENTRAL PARK
So what about dinosaurs? As I said, there weren’t any. Not here at least. But not far.
We had some big, mean critters. A little over 400 million years ago, much of North America, including New York State, was under water. The Eurypterus, a type of marine invertebrate, a giant sea scorpion, lived in this period – and in case you don’t already know, it is the official state fossil of New York. Eurypterus was one of the most feared undersea predators before the evolution of prehistoric sharks and giant marine reptiles. They colonized much of the supercontinent of the time, and are one of the first animal groups to venture from sea to land.
EURYTERUS
Dinosaurs seem to have roamed around not far from New York City. In 1972, dinosaur footprints were found in what is now Rockland County, dating to the late Triassic period, about 200 million years ago. The footprints belong to a type of lizard known as a Grallator. This beast was probably coelophysis, a slender, bipedal carnivore that lived throughout the east coast of what we call North America. It’s also found in other parts of the world, because back then, there was no North America. There was no New York, no Hudson River, no Westchester or Rockland Counties. There was only Pangea.
Coelophysis
And New Jersey! The first nearly complete dinosaur skeleton in the world was found in Haddonfield in 1858. Sediments from the Cretaceous period revealed a 75-million-year-old fossil of a Hadrosaurus foulkii, the first known duck-billed dinosaur, which have become the most plentiful dinosaur finds from this period on the East Coast. Specimens of giant dinosaurs like Dryptosaurus, a tyrannosaur six feet tall at the hip that may be a cousin of the fearsome T Rex was found in Ellisdale.
So we didn’t have dinosaurs. But we still had some pretty great creatures.
For 64 million years following the great extinction of the dinosaurs and much of life on earth, our region was warm, moist and conducive to the evolution of many of the plants and animals we see today (and more than a few we don’t see anymore). Periodic ice ages brought glaciers that covered the state and then retreated, each time reshaping the landscape, carving rivers and lakes and mountains and killing off many of animals.
As temperatures increased, a variety of flora and fauna spread through the region. At this time, large open forests of spruce, fir, pine, and other tree species expanded across the Northeast, interspersed with open meadows and marshland. Creatures like mammoths, mastodons, giant beavers and sloths, musk oxen, and the giant short-faced bear roamed the land. In 1866, during the construction of a mill in upstate New York, workers discovered the near-complete remains of a five-ton American Mastodon dated to about 13,000 years ago. The “Cohoes Mastodon,” as it became known, testifies to the fact that these giant prehistoric elephants roamed the expanse of New York in thunderous herds
OK, no dinosaurs. But we’ve got Mastodons, Woolly Mammoths and Giant Beavers. What about people?
The earliest “Paleo-Indians” seem to have arrived here between 13,000 and 10,000 years ago. Because of the close proximity of any of their sites to the coastline, few have been preserved in the New York City area. As the glaciers continued to melt, sea levels rose and much of what was once adjacent to the water line became submerged. Only one Paleo-Indian site has been discovered in the entire New York City area—that of Port Mobil, on Staten Island. Some paleoanthropologists believe that the large mega-mammals, like mammoths, were still here when the earliest folks arrived. Some feel that these folks – together with climate change – were responsible for killing off the local plus-sized mammals. Seems like they were tough New York City types – taking on a mastodon with bare hands.
That’s the story. From here on, just 10,000 years ago, we’re practically home.
Stephen Blank
RIHS
December 23, 2020
AKRF, CornellNYC Tech Roosevelt Island Campus
https://hvmag.com/life-style/history/hudson-valley-dinosaurs/
https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-new-york-1092090
https://www.geocaching.com/geocache/GC27ENH_east-river-a-tidal-strait-in-new-york-city
https://www.newyorknature.us/new-york-geology/
https://www.nytimes.com/2018/06/05/science/how-the-ice-age-shaped-new-york.html
WEEKEND PHOTO
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FRIDAY PHOTOS OF THE DAY
Plaque that was at foot of the Lighthouse
commemorating the Asylum inmate who had
“constructed” a fort where the Lighthouse was
situated. The plaque vanished in the 1970’s.
JAY JACOBSON CLARA BELLA GOT IT RIGHT.
EDITORIAL
It is Christmas morning and a rather bleak day outside. We (Pat and I) will gather to watch a video of the NYC Ballet Nutcracker video. Then I will make a pork roast and macaroni for dinner.
Last evening my friend Jeong and I feasted on King Crab Legs. I have never had them and they were delicious and a real treat. In Jeong’s homeland, Korea, crab are a New Year’s tradition and we celebrated early this year.
We spoke to my brother last evening and discussed our two dinners. He has more wine and champagne in contrast to my cider.
Our celebrations are not grand this year. Some friends are gone, times have changed but we will be in our pod of neighbors and friends.
HAVE A SAFE AND HEALTHY 2021
JUDITH BERDY
Text by Judith Berdy
Thanks to Bobbie Slonevsky for her dedication to Blackwell’s Almanac and the RIHS
Thanks to Deborah Dorff for maintaining our website
Edited by Deborah Dorff
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