BACKGROUND – Why I wrote this

Drive east on Route 173 (East Seneca Turnpike) out of Manlius, New York and you’ll slowly rise in elevation up to a peak at the intersection with Palmer Road. Turn right on Palmer, go up a short hill to the top, called “Top of the World,” park your car, get out and look back, to the north. What immediately strikes you is the beautiful view of flat farm land, punctuated in the middle with Oneida Lake, which runs east-to-west for about 21 miles. High school students would gather on this hill at the end of the day to catch this view and to watch the sun set to the west; I’m not sure if that tradition has continued.

Shortly after returning to Manlius, after having lived in Philadelphia since 1987, I visited this spot to, once again, take in the beautiful view. But in so doing, and perhaps due to the fact that I didn’t recall anything I was taught in 8th grade Earth Science and was inspired to make up for it, I found myself asking, “how did this view happen?” I didn’t understand why the flatness to the north, the elevation rise I was on, and the existence of Oneida Lake, especially given the east-west direction as opposed to the north-south direction of many other lakes in the region, and especially the Finger Lakes, came into being. And as I started wondering about this, I started also wondering about many of the other geographical structures in upstate NY, both above ground, e.g., Finger Lakes, Lake Ontario, Ontario Lowlands, Niagara Falls, St. Lawrence River, Mohawk River, Hudson River, Tug Hill Plateau, etc., and below, e.g., limestone, shale, salt, coal, oil, natural gas, etc. It didn’t take long for all of these questions to inspire me to find the answers.

It was in this context that I set out to educate myself on the geological origins of upstate New York and to then share what I learned. To this end, 1) I reconnected with an old friend (here), retired (and since deceased) S.U. professor Pat Bickford, former Chairman of the Department of Geology at Syracuse University from 1990 to 1997, 2) I read Stephen Marshak’s excellent geology book EARTH – Portrait of a Planet, which my wife serendipitously discovered on a hallway table outside a cleaned-out office at Hamilton University, and 3) I read John McPhee’s long, dense, and wonderful Annals of the Formal World. I also enjoyed a very educational discussion with one of Pat’s colleagues in SU’s Geology Department, Scott Samson. Below is my brief summary of what I learned. Any errors are due solely to me.

GEOLOGICAL TIME – numbers and thoughts to consider

Age of Earth = 4.6 billion years  =  4,600 x 1 million years

1 million years = 10,000 x 100-year lifetimes

Homo sapiens have existed for around 300,000 years = 3,000 x 100-year lifetimes

Tectonic plates – move about 2 inches per year (32 miles every 1 million years)

Glaciers – move about 100 meters per year (Laurentide Ice Sheet)

People think in five generations—two ahead, two behind—with heavy concentration on the one in the middle.  Possibly that is tragic, and possibly there is no choice.  The human mind may not have evolved enough to be able to comprehend deep time.  It may only be able to measure it. // A million years is a short time – the shortest worth messing with for most problems.  You begin tuning your mind to a time scale that is the planet’s time scale.  For me, it is almost unconscious now and is a kind of companionship with the earth. // If you free yourself from the conventional reaction to a quantity like a million years, you free yourself a bit from the boundaries of human time.  And then in a way you do not live at all, but in another way you live forever. – McPhee, p. 90

It makes you schizophrenic.  The two time scales—the one human and emotional, the other geologic—are so disparate.  But a sense of geologic time is the most important thing to get across to the non-geologist: the slow rate of geologic processes—centimeters per year—with huge effects if continued for enough years.  A million years is a small number on the geologic time scale, while human experience is truly fleeting-all human experience, from its beginning, not just one lifetime.  Only occasionally do the two-time scales coincide. – Eldridge Moores in McPhee, p. 458

PRELUDE

Before putting the spotlight on upstate New York, I first share the history of the larger system, Earth, starting with those who figured it all out, the geologists who hypothesized what must have happened in the past to bring us to where we are in the present.

THE GEOLOGIST

Geologists make better intelligence officers than physicists or chemists, because they are used to making decisions on faulty data – Eldridge Moores in McPhee, p 564

All science involves speculation, and few sciences include as much speculation as geology – Kenneth Deffeyes in McPhee, p. 133

It is the natural and legitimate ambition of a properly constituted geologist to see a glacier, witness an eruption, and feel an earthquake – G. K. Gilbert in McPhee, p. 299

The slow steady march of geologic time is punctuated with catastrophes.  And what we see in the geologic record are the catastrophes – Anita Harris in McPhee, p.171

To geologists, Earth is like a crime scene with their job being to figure out what happened and when by searching for and interpretating the evidence scattered around us, some hidden, some not, the task made extremely challenging due to what Pat Bickford called “the veil of time.”  There are certain things that we simply won’t be able to know because they occurred too long ago and the evidence simply disappeared.  But such complicated crime scenes occur as invitations to the geologists as well captured in this section of McPhee’s book:

Geologists are famous for picking up two or three bones and sketching an entire and previously unheard-of creature into a landscape long established… Long case histories are constructed and written from interpreted patterns of clues.  This is detective work on a scale unimaginable to most detectives, with the notable exception of Sherlock Holmes … Geologists, in their all but closed conversation, inhabit scenes that no one ever saw…If some fragment has remained in the crust somewhere and something has lifted the fragment to view, the geologist in his tweed cap goes out with his hammer and his sandwich, his magnifying glass and his imagination, and rebuilds the archipelago. – MePhee, p. 64 

Their evidence?  The shapes of everything—hills, mountains, valleys, flat lands, basins, ranges, large rocks in the middle of nowhere, rivers, lakes, oceans, and so much more—and the rocks they contain.  The age and location of each rock, as determined by radioactive decay and fossil dating, composition, magnetic field[1], etc., at the time of its solidification play crucial roles in the geologists’ work.  As McPhee wrote (p. 156), “Rocks are the record of events that took place at the time they formed.  They are books.  You have to learn how to read them.”  If you want to know more, check out both Marshak’s and McPhee’s books.

IN THE BEGINNING (4.6 billion years ago)

Earth began as a collection of dust and gas particles that orbited the young Sun and eventually stuck together to form larger particles and then bodies, which eventually became the building blocks of our planet.  This process involved high-speed collisions of enough kinetic energy to melt the merging bodies, turning early Earth, at least partially, into a liquid mass.  Heavy elements like iron and nickel sunk through the liquid and eventually formed the core while the lighter elements remained behind in the liquid, and the even lighter elements and compounds, primarily nitrogen, carbon dioxide, water vapor, and smaller amounts of methane, ammonia, and hydrogen, remained in the atmosphere above.

As I shared previously (here), geologists estimate that early Earth formed about 4.6 billion years ago, and that it took about 600 million years for the Earth to cool enough for its surface to solidify, this assumption based on discovery of a 4-billion-year-old rock formation in northern Canada.

RAIN, RAIN, RAIN (3.8 billion years ago)

About 3.8 billion years ago, as the Earth continued to cool, water vapor began to condense, filling Earth’s low points.  A lot of water, enough to cover the entire planet to a depth of about 1.7 miles if Earth were completely flat.  The resulting liquid water absorbed certain gases, such as carbon dioxide, and certain minerals, such as a variety of salts. Oceans formed, water evaporated, clouds formed, rain fell, rivers formed, erosion occurred, salts dissolved, salts precipitated, and the up-and-down, endless cycle of water began.

While there is a fixed amount of water on Earth, the sea level changes constantly.  The reason?  Ice.  When glaciers form, sea level goes down, and vice versa.

TECTONIC PLATES (3 billion years ago)

While the solidification of Earth’s surface is thought to have been complete, this didn’t mean that all was quiet beneath the surface.  Indeed, Earth’s subsurface was not (and is not) rigid.  A circulating fluid-like state existed that created an inner convective energy and thus caused motion in and break-up of the outer solid region, resulting in the formation of early “tectonic plates.”  These plates, currently totaling about 15 to 20, depending how you classify them, evolved into different sizes and shapes, some up to 100 miles thick, some almost entirely land, some covered with ocean, and did not (and do not) remain stationary.  It was their motion relative to each other and the collisions that resulted, together with the water-induced erosion, that led to our mountains, valleys, volcanoes, and other topographical features.

Development of the tectonic plate theory during the 1960s was very exciting.  So too was the preceding history, and a good book on the topic is Martin Schwarzbach’s “Alfred Wegener.  The Father of Continental Drift,” (1986).

THE GREAT OXIDATION EVENT (2.4 billion years ago)

Life in the form of microscopic organisms (microbes) began about 3.7 billion years ago.  Lacking atmospheric oxygen, they relied upon anaerobic metabolisms for life.

About 2.4 billion years ago, a new form of bacteria, cyanobacteria, named for their bluish-green color, evolved and set the stage for a remarkable transformation. Being Earth’s first photo-synthesizers, they relied on water and the Sun’s energy to take in carbon dioxide (CO2), keep the carbon, and release the oxygen. This was the Great Oxidation Event.  The sudden rise in oxygen catalyzed the transformation of iron from soluble (ferrous +2) to insoluble (ferric +3), which precipitated out into iron-rich sediment layers of “banded-iron” on the ocean floor.  This increase in oxygen also eventually catalyzed the evolutionary explosion of life.

OROGENY (timeline pause)

orog·​e·​ny ȯ-ˈrä-jə-nē :  the process of mountain formation especially by folding of the earth’s crust

When tectonic plates collide or move relative to each other while in direct contact, they interact at plate boundaries.  The most common interaction is convergent.  Such an interaction, called an orogeny, is really more like a slow-motion collision that causes rock layers to fold, fault, uplift into mountains (Himalayas from India-Asia collision), steadily shedding sediment along the way due to water erosion, and subside (subduction) into deep trenches (Mariana Trench).  The two other interactions involve diverging to form ridges (Mid-Atlantic Ridge) or sliding past each other (transform) to cause earthquakes (San Andreas Fault).

 From Pat Bickford’s presentation at the Erie Canal Museum on 12-13-10

THE RISE OF SUPERCONTINENTS (timeline pause)

Because of their constant contact and the resulting orogenies, tectonic plates are not flat.  Parts remain above the seawater, and parts remain below.  While their movement may be slow (2 inches per year) and seemingly random, there are times when the above-water parts all come together to form one large landmass known as a supercontinent.  While not all orogenies lead to a supercontinent, all supercontinents result from orogenies.

Geologists estimate that at least seven such supercontinents have occurred during Earth’s history.  While the process involved seems random, statistical analysis, as summarized by the Wilson Cycle, revealed a formation/breakup regularity of about once every 300-500 million years.  Of relevance to this post and discussed later are the last two supercontinents, Rodinia (1.1 billion to 750 million years ago) and Pangaea (335 to 200 million years ago).  The next supercontinent is predicted to occur within the next 200-300 million years.

The plate movements, collisions, supercontinent formations, breakups, ocean realignments, water-induced erosions, and glacier-driven land shifts have shaped our current geological features.

ZOOM-IN ON UPSTATE NEW YORK

With this background behind us, we now start zooming in on New York State’s history, starting with the earliest known relevant orogeny and the supercontinent it led to.

From Grenville Orogeny (1.3 to 1.1 billion years ago) to Rodinia Supercontinent (maximum assembly 1.0 billion years ago)

The Grenville Orogeny was a mountain-building event that occurred roughly between 1.3 and 1.0 billion years ago when a large land mass called Laurentia, the ancient core of North America which included upstate New York, collided with other land masses.  Out of these collisions was born the beginnings of eastern America and a mountain range along eastern and southeastern North America, including the foundation for the Blue Ridge Mountains and the formation of the Adirondack Mountains, the oldest geological feature of New York State, potentially 10,000–20,000 feet tall, and eventually the supercontinent Rodinia. Erosion has since removed much of the size of these mountains.

A hypothesized, by some at least, important additional consequence of the Grenville Orogeny concerned the MidContinent Rift, a massive event that attempted, unsuccessfully, to split the North American continent apart along an 1,800-mile-long arc of rocks across what is now central United States.  The fact that this occurred around the same time as the Grenville Orogeny, 1.1 billion years ago, suggests a possible connection (or a pure coincidence) in which the collision that occurred to the east prevented the rift from completing the job to the west. While the rift failed to split apart our country, it did succeed in leaving a large crack in the land that eventually became Lake Superior and additionally influenced the formations of Lake Michigan, Lake Huron, and likely Lake Erie.  Subsequent shaping of the Great Lakes was completed by advancing glaciers.

Rodinia’s breakup started around 850–750 million years ago and accelerated between 750–600 million years ago.  As the lands split apart, water rushed in, forming new ocean basins including the Iapetus.

Laurentia – origin of the future New York State (as it occurred from 540 to 360 million years ago) 

Before moving toward the Taconic Orogeny and the formation of Pangaea, I wanted to share some information about one of the key actors, the former land mass known as Laurentia, mentioned above and included in the illustrations.

As the land mass that was to become eastern North America and Greenland, Laurentia played a central role in the geological history of New York State.   Laurentia first began forming around 2 billion years ago and long after, from 540 to 360 million years ago, largely occurred as an island, located near the equator, surrounded by shallow ocean seas, less than 200 meters in depth, which allowed sunlight to penetrate.   The combination of sunlight and rising oxygen levels enabled the evolution of shell-forming invertebrates (animals without backbones). These organisms extracted dissolved calcium (Ca²⁺) and carbonate (CO₃²⁻) ions from seawater and combined them to form insoluble calcium carbonate shells. After death, these shells accumulated on the ocean floor, eventually creating the limestone rock formations that are a dominant feature of the greater Syracuse region.

These same conditions, especially from 358 to 299 million years ago, promoted the explosive growth of plants, trees, and organic material that eventually formed significant deposits of coal, oil, and natural gas in western and southern New York.

Last but not least, salt!  During this same time period, evaporating inland seas deposited layers of salt, ranging from 80 to 5,000 feet thick (!), particularly in western New York and states west – Pennsylvania, West Virginia, Ohio, Michigan.  Needless to say, salt mining is a major industry in these regions.  Syracuse bears the nickname “Salt City” due to its rich history of salt production, especially during the 1800s.

From Taconic Orogeny (470 t0 445 million years ago) to Pangaea Supercontinent (maximum assembly around 300 to 250 million years ago)

Long before the Taconic mountain-building pulse was felt, the scene was very different.  A subdued continent, consisting of what is now the basement rock of North America, stood low with quiet streams, collecting on its margins clean accumulations of sand (which became sandstone) – McPhee, p. 186

Violence occurred once again as a volcanic island chain (Iapetus Arc) in the Iapetus Ocean smashed into the eastern section of Laurentia and remained permanently attached to North America.  Note that future-Scotland was part of Laurentia at this time, attached to Greenland.  This collision, named the Taconic Orogeny, gave us the Taconic Mountain range along much of what is now the eastern seaboard of North America, e.g., Vermont, eastern New York, Massachusetts (Berkshires), Connecticut.  Once formed, these mountains were estimated, based on the discovery of vast amounts of sediment, to have reached elevations of 15,000 to 20,000 feet (!!!), comparable to the highest peaks of today’s Himalaya’s, Andes, and Rockies.  Today’s absence of these huge mountains makes it difficult to envision what once was.  Their disappearance indicates the power exerted by rain-water erosion over hundreds of millions of years, erosion that was “tearing down mountains even as they rise,” (McPhee, p. 44) with the fresh rivers running in a westerly direction.

The Taconic Orogeny collision began the building of the Appalachian Mountains that run from current Alabama to Maine and into Canada and subsequent orogenies completed the job.  (Yes, the eastern seaboard got hit multiple times!).  The Acadian Orogeny (400-350 million years ago), involving the future Ireland and England, came next and helped form the Catskill Mountains.  Then came the grand finale, the Alleghanian Orogeny (325-260 million years ago) involving the collision of Laurentia with Gondwana, an almost supercontinent in-and-of-itself, comprised of the future Africa and South America, to form Pangaea around 335 million years ago.  These orogenies created and re-arranged the mountains in the northeast, including formation of the Allegheny Mountains in western Pennsylvania (that’s how intense the collision was), and also squeezed out the Iapetus Ocean water between the future N. America’s northeast and Ireland/England.

The elevation of Central New York south of Syracuse is primarily due to its location on the Allegheny Plateau, a region uplifted during the Alleghanian Orogeny.  While this region consisted of sedimentary rock resistant to erosion, more so than the lowlands north of Syracuse, sufficient weather over a long time carved valleys into the plateau, which eventually became the tracks on which the glaciers traveled. 

Pangaea broke up around 175 million years ago – North America separated from Africa

Pangaea’s breakup began around 175 million years ago when North America began separating from Africa and ocean water began flooding into the resulting gap, thereby creating the North Atlantic Ocean[2]; the South Atlantic Ocean wouldn’t be created until South America separated from Africa around 120 million years ago.

Glaciation & Upstate New York

Alien boulders, directional scratches, unsorted gravels, cobbles, and sands.  The signature of glaciation is as bold as John Hancock’s and as consistently recognizable wherever ice has moved across the solid earth – McPhee, p. 252

The evolution of Laurentia to North America prepared the above-ground topography and the below-ground geology for subsequent sculpting by glaciers.  Before getting to those details, here’s a short course on glaciers.

For glaciers to form, a consistent and adequate supply of snow must fall on land located in a region that prevents melting during the warmer seasons, making far-north and far-south regions and high elevations favorable.  An additional criterion is the need for the glacier to have sufficient thickness to flow under its own weight.

Ice sheets and glaciers first formed around 2.4 billion years ago, after Earth’s surface cooled sufficiently, and have since sculpted the landscape in recurring cycles. These cycles, particularly over the last few hundred million years, were partly driven by the Milankovitch cycles—variations in Earth’s orbit around the Sun. Glaciers formed, advanced, and retreated in a rhythmic pattern, causing sea levels to rise (with melt) and fall (with freeze) in sync with each cycle.

When glaciers advance, they push, pick up, move, and drop most everything in their paths, resulting in situations in which “Pieces of the Adirondacks have been found in Pennsylvania.” (McPhee, p. 161) And then when they’re done advancing, they melt, releasing tremendous volumes of meltwater, creating rivers that sort and smooth miscellaneous sizes of rock, “moving cobbles farther than boulders, and gravels farther than cobbles, and sand farther than gravels, and silt grains farther than sands.” (McPhee, p. 152)

In eastern United States, the ice has come and gone at least a dozen times, in cycles that seem to require about a hundred thousand years.  We are currently in an interglacial period, a warmer interval between colder glacial periods.   The next advance of a glacier into the north east could happen, per current cycle analysis, in another 20,000 to 50,000 years, when it will be possible that a glacier two miles thick “plucks up Toronto and deposits it in Tennessee.” (McPhee, p. 148)

Note that during the most recent ice advance, which spanned from approximately 26,500 to 19,000 years ago, sea levels fell by about 120 meters, creating a land bridge between Alaska and Russia that provided the migration route for animals and people from Asia into North America.

Wisconsinan Glaciation and the Laurentide Ice Sheet (from 110,000 to 11,700 years ago)

During the Wisconsin Glaciation (110,000 to 11,700 years ago), “three-fifths of all the ice in the world was on North America, another fifth covered much of Europe, and the rest was scattered.” (McPhee, p. 254)  Several major ice sheets existed across the Northern Hemisphere, with the largest and most dominant, called the Laurentide Ice Sheet, covering much of Canada, the northern U.S. (down to Illinois and New York), and parts of Greenland.  This ice sheet reached a thickness of up to two miles at its peak during the Last Glacial Maximum (LGM, 26,500–19,000 years ago), eventually melting away approximately 11,700 years ago. [3] 

The LGM shaped many of the topographical features of greater upstate New York region. Below are some of the highlights.

Great Lakes

• The MidContinent Rift cracked open or otherwise softened the land currently occupied by Lake Superior, Michigan, Huron, and Erie in a way that enabled subsequent glacier advances to carve out the final deep lake basins.  As the glaciers retreated (20,000 to 12,000 years ago), meltwater filled these basins, forming the Great Lakes.  Naturally, the survival of these lakes required continual sources of incoming water. 
• Note that the Great Lakes are not that old.  Who knows how long, in geologic time, they’ll last.  As McPhee pointed out (p. 410), “Lakes are so ephemeral that they are seldom developed in the geologic record… Lakes fill in, drain themselves, or just evaporate and disappear.  They don’t last.”

Great Lakes Illustration (reference here)

Lake Ontario

• While Lake Ontario’s basin was formed by glacial scouring like the other Great Lakes, there was a fundamental difference.  The Midcontinent Rift played a significant role in preparing the formation of the upper Great Lakes (Superior, Michigan, Huron, and to some extent Erie) but had little to no direct influence on the formation of Lake Ontario’s basin.
• The issue that enabled the carving out of Lake Ontario’s basin was the fact that it was located on softer sedimentary rock.
• Lake Ontario started as a much larger lake known as Glacial Lake Iroquois, which formed ~13,000 years ago at the end of the last ice age, ~100 feet higher than the current lake level. The lake formed when an ice sheet blocked the natural drainage northeast via the St. Lawrence River, diverting water southeast through the Mohawk River Valley to the Hudson River. When the ice dam melted, the lake rapidly dropped to its present level.

Glacial Lake Iroquois Illustration (reference here)

Niagara Falls

• Niagara Falls formed due to a regional land tilt. Lake Erie sits on the uplifted Allegheny Plateau, elevated during the Alleghanian Orogeny. As the land slopes northward, elevation drops—Lake Erie is about 570 feet above sea level, while Lake Ontario is about 240 feet. This 330-foot difference explains the 170-foot drop at Niagara Falls, with the rest of the drop occurring downstream along the Niagara River.
• The transition from plateau to lowland created a strong river flow capable of eroding the downstream landscape, forming the Niagara Escarpment—a steep slope where erosion-resistant rock (under Lake Erie) meets softer sedimentary rock (under Lake Ontario). Over time, the river carved deeper into the softer rock, steepening the slope and giving rise to Niagara Falls.

Niagara Falls Illustration (reference here)

Ontario Lowlands

• In my opening, I described the view north from the “Top of the World,” where flat land stretches nearly to Lake Ontario—just out of sight, but marked by the visible steam plume rising from the Nine Mile Point Nuclear Station.
• Known as the Ontario Lowlands, this flat land of rich soil was once the bottom of the aforementioned Glacial Lake Iroquois.

Tug Hill Plateau

• When moist winter air flows due east off of Lake Ontario, it rises up the Tug Hill Plateau, cools, and dumps up to 25 feet of snow per year on average, more than double what we get in Syracuse.
• This plateau owes its formation largely to what the glaciers didn’t do—erode it away. Uplifted sometime after ~200 million years ago, the plateau’s elevation reduced sediment accumulation and preserved a cap of erosion-resistant sandstone. As a result, advancing glaciers carved deeply around it but left the plateau itself largely intact.

St. Lawrence River

• The formation of the St. Lawrence River involved multiple events, the dominant being the creation of a break or rift in the Earth’s surface caused by the assembly and breakup of Rodinia (around 1.1 billion years ago) and also Pangaea (around 200 million years ago).  This rift became a natural lowland that would later guide the flow of water, both in and out.
• During the last Ice Age, the advancing Laurentide Ice Sheet scoured and deepened this rift, carving a broad valley across what is now eastern Canada and northern New York. The massive weight of the ice sheet also depressed then land below sea level such that when the ice began to retreat around 13,000 years ago, the depressed crust quickly flooded with the inflow of Atlantic seawater, forming the Champlain Sea.
• Over the next several thousand years, with the ice weight melted away, the land began to rise, causing the Champlain Sea to drain away. As it receded, freshwater melt and runoff from the Great Lakes flowed out through the same valley, forming the modern St. Lawrence River.
• In summary, the St. Lawrence River flows along a path shaped by ancient tectonics, carved by glaciers, and briefly submerged beneath a postglacial sea.

Mohawk River

• The Mohawk River Valley likely originated as a structural low point between the Adirondack uplift and the Appalachian Plateau, which provided a path for water flow and further deepening via erosion.
• Early east-west rivers may have flowed in this valley in response to the rise of the huge Taconic Mountains ~450 million years ago. These rivers would have drained westward, carving channels and depositing sediments along the way.  Although the exact courses of these rivers are lost, their presence is inferred by the erosional evidence behind the valley’s underlying shape.
• During the last Ice Age, as the Laurentide Ice Sheet retreated 15,000 to 13,000 years ago, massive volumes of meltwater rushed through the Mohawk Valley. This tremendous discharge established the modern Mohawk River and carved key portions of its channel.
• The Mohawk joined the Hudson River and created the only major natural corridor through the Appalachians in the Northeast. This path became geologically critical and historically vital, especially with the construction of the Erie Canal, linking the interior of North America to the Atlantic Ocean.

Hudson River/Lake Champlain/Lake George

• As shared previously, our northeast coast was the target of multiple orogenies and breakups, the net result being the creation of multiple cracks in Earth’s crust.
• The origins of Lake Champlain, Lake George, and the Hudson River were in these cracks.
• All three of these structures formed from pre-existing fault zones followed by glacial sculpting during the last Ice Age.
• Because of their low elevation and their depth, they persist as natural drainage basins for the neighboring mountains, the Adirondacks to the west and the Green Mountains to the east.

Long Island

• The last glacial advance of the Laurentide Ice Sheet reached New York City between 22,000 and 20,000 years ago.
• As it slowly flowed down the Connecticut and Hudson river valleys and spread from New Jersey to Long Island, the glacier pushed and piled up rock, sand, and clay at its front edge, and when it retreated, it left it all behind.  The resulting ridge of debris became the backbone of Long Island.

Finger Lakes

• The Alleghenian Orogeny created the Alleghany Plateau in Central New York.  The uplift caused rivers to flow from high elevation to low, which cut into the bedrock and formed deep V-shaped valleys.
• The advancing glaciers followed these pre-existing river valleys and deepened and widened the valleys into the characteristic U-shaped valleys of the Finger Lakes.
• After glacial retreat (12-20,000 years ago) meltwater filled the glacially deepened valleys. 
• The Finger Lakes continue to hold water because they lie in deep valleys that act as natural collection basins for precipitation, groundwater, and stream runoff.

Oneida Lake

• The formation of Oneida Lake differed from that of the Finger Lakes, even though both were influenced by glacial activity.
• Compared with the intense glacial scouring that creating the Finger Lakes’ basins, much less intense activities involving glacial deposition and meltwater dynamics created Oneida Lake’s basin.  The difference in intensities is manifested by the difference in lake depths:  22 feet for Oneida Lake and 187 (Keuka Lake) to 618 (Seneca Lake) feet for the Finger Lakes.  The difference is also manifested by the fact that Oneida Lake runs east-west as opposed to the north-south direction of the Finger Lakes, which was the direction of the advancing glaciers.
• Oneida Lake formed during the same postglacial period as Glacial Lake Iroquois and lies just east of its former shoreline.

Clark Reservation/Green Lake

• Two New York State Parks just outside of Syracuse, Clark Reservation and Green Lakes, provide wonderful puzzle pieces for geologists to study in their attempt to explain what happened.  The impact of glaciers, meltwaters, and past lakes that are no longer, is observed in Clark Reservation’s “plunge pool,” created by the erosive force of falling water on the bedrock, and in Green Lakes’ steep cliffs surrounding two deep lakes.
• The geological history of these two parks and many other topographical features in upstate New York is beyond the scope of this post.  Having said this, I encourage you, the reader, to visit these wonderful parks.

WRAP UP

And so concludes this post, dedicated to Pat Bickford.  I miss my one-on-one lessons with Pat and loved the journey he inspired me to take. I am naturally an amateur in this world. If you want to take a much deeper dive into all aspects of geology, not only regarding upstate New York but also regarding the entire Earth, I encourage you to check out Stephen Marshak’s Coursera course, Planet Earth…and You!

Epilogue – Marshak, p. 422

Earth will likely exist for another 5 billion years, assuming we are not struck by large body from space beforehand. The key determining factor is our Sun.  As a mid-sized star, the Sun has an average lifetime of 10 billion years, so about 5 billion years from now the Sun will run out of nuclear fuel, collapse inward, temporarily heat up, and then expand greatly into a “red giant” with a diameter that will come close to Earth’s orbit, heating up Earth, boiling the oceans dry, then evaporating the planet itself, as our atoms mix with the gases from the Sun, thus ending Earth.

REFERENCES

[1] As magma crystallized and turned solid, certain iron minerals within it lined themselves up like compasses, pointing toward the magnetic pole (McPhee p. 21).  Since the late Miocene, the earth’s magnetic field had reversed itself twenty times and the dates of those reversals had by now become well established. (McPhee, p. 114)

[2] When Africa broke from North America, it apparently left a large piece of Florida (southern) behind (McPhee, p. 558)

[3] The Ice Age hasn’t totally stopped yet.  While ice is in recess in most areas, it has not totally gone away.  Greenland is 85% capped with ice that is more than two miles thick.  McPhee, pp. 254-260.

ILLUSTRATIONS

Cover image from: http://www.vidiani.com/detailed-topographic-map-of-new-york-state/

Grenville Orogeny Illustation

Extent of the Grenville orogenic belt in North America and Scotland from https://en.wikipedia.org/wiki/Grenville_orogeny#cite_note-1 and these two specific references:

Tollo, Richard P.; Louise Corriveau; James McLelland; Mervin J. Bartholomew (2004). “Proterozoic tectonic evolution of the Grenville orogen in North America: An introduction”. In Tollo, Richard P.; Corriveau, Louise; McLelland, James; et al. (eds.). Proterozoic tectonic evolution of the Grenville orogen in North America. Geological Society of America Memoir. Vol. 197. Boulder, CO. pp. 1–18. ISBN 978-0-8137-1197-3.

Darabi, M. H.; Piper, J. D. A. (2004). “Palaeomagnetism of the (Late Mesoproterozoic) Stoer Group, northwest Scotland: implications for diagenesis, age and relationship to the Grenville Orogeny”. Geological Magazine. 141 (1): 15–39. Bibcode:2004GeoM..141…15D. doi:10.1017/S0016756803008148. S2CID 140614712.

Rodinia Illustration

From Brittanica: https://www.britannica.com/place/Rodinia

Formation of Iapetus from the breakup of Rodinia Illustration

From: https://www.sciencedirect.com/science/article/pii/S0012825221002920

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