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Pangaea’s Edge

Reporting for this piece was made possible by the Ed Bennett III Memorial Fund.

Illustration by Julia Hedges.

At the summit of East Rock Park in New Haven, Connecticut, marked by the Sailors and Soldiers war monument, the view extends for miles and miles –– across tall green trees, over downtown buildings that look like miniatures from a distance, and all the way to the blue waters of New Haven Harbor.

Turn back the clock 200 million years, and this view is completely different. The land is covered with marshy shores and turquoise lakes and steaming volcanoes. A twenty-foot-tall crested Dilophosaurus prowls in search of prey, leaving three-toed footprints. North America, Africa, and South America are joined together as the supercontinent Pangaea. Walking across Connecticut, the dinosaur might step into what is now Rhode Island –– or southern Morocco.

About 175 million years ago, as Pangaea broke apart, the continental plates spread and allowed magma to emerge from deep within the Earth. Lava flows, volcanic eruptions, and glacial events continued to shape the landscape –– molding Connecticut by fire and ice.

From the top of East Rock today, these dramatic events are hardly apparent. Visitors to East Rock and West Rock, the rocky ridges that flank New Haven, or Sleeping Giant mountain in neighboring Hamden only see a stable landscape covered in greenery. Hikers are likely unaware that these parks once stood at the borders between continents, or that they’re tracing the footsteps of prehistoric dinosaurs. 

Though the community relies on the parks as local hubs of exercise and leisure, most people know very little about the stories of these landmarks –– stories that have shaped the human history of Connecticut for centuries. 

For geologists, East Rock and West Rock aren’t weekend hangout spots –– they’re ground zero in a dramatic story about how the earth under our feet has shifted ever since the planet first formed. Geologists investigate how continental collisions and lava flows shaped the landscape of Connecticut, uniquely positioned at the fault lines of Pangaea.

To understand why Connecticut’s landmarks fascinate geologists, I met with Professor Charles Merguerian from Hofstra University, a leading expert on geologic structure and plate tectonics in Connecticut and New York. He had come to New Haven to visit the Yale Peabody Museum’s geology collection, and asked me to meet him there. Dressed in jeans and hiking boots, Merguerian showed me his collection of rocks in the back rooms of the museum, stored from his graduate school research projects. 

“Geologists are like detectives,” he told me as he opened a drawer, revealing tagged slabs of rocks about the size of my palm. The rocks seem unremarkable at first glance –– they’re what Merguerian calls “ugly rocks,” chunks that can be seen at the side of any road –– but these are often extremely valuable to scientists. These rocks, which Merguerian collected from construction sites around Connecticut and New York, carry the record of geologic events that occurred in New England hundreds of millions of years ago.

Lava flows, volcanic eruptions, and glacial events continued to shape the landscape –– literally molding Connecticut by fire and ice.

In his research, Merguerian uses a special saw blade to cut the rocks into paper-thin slices. He analyzes the slices to figure out what minerals are present. “These minerals…tell you how deep the rocks were, how old they were, under what temperatures and pressures they formed,” he explained. Since certain minerals can only form at precise temperatures, pressures, and locations, he uses this information to piece together the story of continental-scale collisions and breakages that shaped Connecticut.

As Merguerian recounted to me, Connecticut’s story began as Pangaea formed. Around 450 million years ago, the continental plates began to crash together to form Pangaea. North America and Africa collided in an event called the Taconic Orogeny, where the earth’s crust wrinkled, building mountain ranges that make up the present-day Appalachians.

Then, 275 million years later, Pangaea started to break apart. Magma seeped out from the crust as gaps between the plates opened up. The peeling apart of the North American and African continents created the Hartford Basin, the jagged rift basin spanning across Connecticut and Massachusetts today.

“[The basin] marked the fracturing of the edge of North America, when Africa as a continental landmass started to spread away from North America,” explained Merguerian. Around this time, Merguerian said, the coastline would have resembled what the East African Rift looks like today, a massive trench running across the continent.

East Rock, West Rock, and Sleeping Giant all formed 175 million years ago when Pangaea broke apart. Magma cooled underground and was pushed to the surface by continental movement to expose igneous rock. In the following hundreds of millions of years, these rocks were shaped into their present form. The rocks contain mainly diabase and basalt with a high iron content, explaining the dark brownish-reddish color. The stair-like appearance of these ridges led to their technical name, “trap rock” ridges, from the Swedish word “trappsteg,” meaning “stair.”

Like these landmarks, most of the rocks New Haven residents see and walk on today all came from deep within the earth. “The surface of rock that you drive on and look at in Connecticut, along the highways and walking through the wood –– [the] bedrock that’s now exposed to the surface –– was exhumed from depths of at least twenty to twenty-five miles beneath the earth’s surface today,” said Merguerian.

Finally, starting around two hundred thousand years ago, a series of glaciers added the finishing touches to our modern landscape, sprinkling boulders across the land and remodeling the Connecticut River Valley. These events –– from the formation and breakage of Pangaea to the most recent glaciation –– shaped the environment where we walk and live and breathe every day. 

Merguerian feels that his scientific understanding of the area allows a deeper connection with the landscape. “There are people that like to drive cars without knowing anything about how the cars work,” he said. “Others take great pleasures in knowing the inner mechanical secrets of how cars work, because it enhances the driving experience. Same thing with the earth’s surface.”

But the story of Connecticut is incomplete as only a geologic tale. As humans became a part of the landscape, they too began to shape it. To understand the role of humans in Connecticut’s natural history, I met with Julie Hulten, the community outreach chair at Sleeping Giant State Park. We spoke in the History Room at the Hamden Library, which was filled with documents, pictures, and models that showed what the town looked like throughout the ages. She sifted through black-and-white photos of Sleeping Giant, with families posing proudly in front of cabins on its rocky head. 

Ten years ago, Hulten, a Hamden resident and former teacher, started regularly hiking Sleeping Giant and decided to help with its preservation. She now both contributes to the upkeep of the park and the documentation of its history. Hulten picked up the story of the landscape for me, now on a human, rather than geologic, timescale. 

The Quinnipiac nation, which has inhabited this part of New England from long before European contact, has a legend explaining how Sleeping Giant was formed. The Quinnipiac tell stories of the giant Hobbomock, a powerful spirit who had taught all people and animals to speak the same language. When they drifted apart and lost this ability, he was enraged. He started ripping up trees, and, with one stomp of his foot, created a bend in the course of the Connecticut River.

In order to stop Hobbomock from wreaking havoc on the landscape, his brother Keitan cast a spell on him to get him to fall asleep. Hobbomock has yet to wake up today. For the Quinnipiac, the place exists as a living, breathing part of the Earth.

When British colonists arrived in Connecticut, they settled around trap rock ridges like East Rock, West Rock, and Sleeping Giant, where they found rich construction materials like brownstone for their houses and churches. As the tale goes, in the 1660s, several judges had sentenced King Charles I to death during the English Civil War, and sought refuge in the New Haven wilderness. They hid in a cave now called Judges Cave in West Rock, and spent several months there until being chased out by a mountain lion. 

Society’s relationship with the landscape began to change with industrialization in the 1800s, when for the first time, interested naturegoers had to actively seek out natural spaces. As the transcendentalist movement took hold, more people grew interested in nature as a respite from industrial daily life. East Rock and Sleeping Giant became popular tourist destinations.

The wealthy of New Haven and Hamden built cabins along the ridges of Sleeping Giant and would stay there during the summers. A local named John Dickerman constructed a carriage road and a pavilion on one of the ridges, and held an ice cream social to celebrate its completion; such projects ushered in a new age of outdoor recreation.

At the same time, these natural spaces were not outside the influences of industrialization. In 1911, the Mount Carmel Traprock Company began to quarry the Giant’s “head” for its valuable building materials. Successive companies joined in on the quarrying as America developed its love for the automobile, and years of blasting and stone removal left deep scars on the Giant’s head. Locals complained about the noise and worried that quarrying might destroy the landscape. In 1924, under the leadership of Yale professor James Toumey, citizens formed Sleeping Giant Parks Association to manage a donation of two hundred acres from a local landowner. In a remarkable environmentalist community effort, they turned the land over to the state for the creation of Sleeping Giant State Park.

This effort might have gone even further, as local residents had long played around with the idea to create a park spanning from New Haven to Hamden. The park would have joined East Rock and extended all the way up north to Sleeping Giant, but residential and commercial interests prevented this effort. While Hulten would have appreciated having such vast space set aside for nature, she laughed and admitted that if the plans were completed, her house wouldn’t be there today. 

Parks like East Rock and Sleeping Giant continue to play an important role in the community, from organized hikes to outdoor classrooms. In the summer, students toss Frisbees at the East Rock summit; in the winter, when the ground is covered in snow, some Special Olympics participants have used the flat open spaces around Sleeping Giant for ski training. “It’s a place for recreation and re-creation,” said Hulten. “Any folks will say that’s my sanctuary –– that’s where I go to clear my head. We all need natural places, away from noises and people.”

Robert Thorson is a professor at the University of Connecticut who describes his work as “cultural geology.” He studies how humans might impact the natural landscape’s future, and educates the public about their stake in the environment. “When you take someone outside in a real setting, away from a desktop and away from a classroom and away from a laboratory, when you take them into some place they could have been a hundred thousand years ago, I think they feel differently about it…there’s a Paleolithic sort of power at heart.”

Thorson thinks that at the end of the day, people are inspired by this same feeling when they encounter geological features, whether hiker or geologist. “Geologists are in the field because there’s this visceral sense of being outdoors somewhere looking at something,” he said. “Even if they spend ninety percent of their time in the lab sorting microfossils, they’re still really interested in the place. It’s the lakes, the river valley, the up-faulted block that interests people.”

While we use these natural spaces to “get away” from society, it’s impossible not to bring human influences with us into these environments.  Thorson advocates for greater public awareness of natural history, so that Connecticut residents can make informed decisions about the future based on the past.

In a shift to what he calls “exit-ramp culture,” cities and roads have cut across the landscape, replacing birches and pines with gas stations and highways.

Thorson believes that humans hold the power to bring about great positive or negative impacts on the landscape. Columbia researcher Peter LeTourneau describes parks like East Rock, West Rock, and Sleeping Giant as valuable “sky islands,” contained ecological areas in a largely urban landscape. Thorson laments how the increased urbanization of Connecticut threatens these spaces. In a shift to what he calls “exit-ramp culture,” cities and roads have cut across the landscape, replacing birches and pines with gas stations and highways. He wants more places like East Rock, West Rock, and Sleeping Giant, which serve as refuges both for people who seek nature, and for nature itself.

In the effort to protect our natural spaces, Thorson thinks that geologists play a key role in understanding the human impact on the environment. “I think the most important thing is to evaluate the ways in which human beings in the last four hundred years have modified the landscape,” said Thorson. “It’s only fair to talk about human beings as geologic agents.” While human beings have only appeared for a sliver of a second on the geological clock, they’ve modified the landscape with impunity, from the quarrying of the colonists to the ambitious construction projects taking place today.

Merguerian offers a slightly different perspective. He’s contributed to the construction of highways and subway tunnels, for instance, by researching rock types suitable for drilling. His work represents a source of contention among geologists, who have often felt conflicted about their knowledge being used for development rather than preservation.

Merguerian thinks such a conflict is unnecessary. He believes we should continue using our natural resources, while developing judicious ways to make use of our environment without exhausting it. When he helped with the construction of the Queens Tunnel in New York, he thought, ‘Why not just leave the rocks instead of paving them over with concrete, so people can appreciate their natural beauty?’ His idea was dismissed, but he hopes that more people can understand that the relationship between humans and the environment is not an issue of two extremes, but rather of compromise.

In his writings, Thorson references a quote from Thoreau: “The earth is not a mere fragment of dead history, stratum upon stratum like the leaves of a book to be studied by geologists and antiquarians chiefly, but living poetry like the leaves of a tree, which precede flowers and fruit –– not a fossil earth, but a living earth.”

Throughout history, people have found their own ways to understand and interact with Connecticut’s landscape, from the Quinnipiac to geologists like Thorson. The lens through which people have interpreted these geologic landmarks has changed based on the era. But through it all, these natural landmarks have continually captivated the public’s interest and imagination.

While human beings have only appeared for a sliver of a second on the geological clock, they’ve modified the landscape with impunity, from the quarrying of the colonists to the ambitious construction projects taking place today.

Now, more than ever, humans exert great control over their environments, shaping and re-shaping them at their whim –– as powerfully, in some senses, as continental plates. By recognizing this power, humans may begin to reconsider their relationship with the landscape.

The New Haven community has done so by striving to co-live with natural spaces –– not only co-existing, but interacting with nature on a personal and daily level. The city of New Haven is nestled between the natural sanctuaries of East Rock and West Rock. Residents in the East Rock neighborhood live walking distance to the landmark. From organized hikes and runs to the Rock to Rock Earth Day bike race, community events show that New Haven would not be the same city without these parks.

It is impossible to predict what the landscape will look like in 200 million years, or even in two hundred years. But geologists, historians, and residents alike all hope that these remarkable natural spaces will continue to be an integral part of New Haven’s identity.

From the twelve-storied Kline Biology Tower on Science Hill of Yale’s campus, the view extends across the city. Looking out, one can see East Rock far in the distance, marked by the Sailors and Soldiers monument at its peak. Its tall and impressive cliffs seem unintimidating when looking at it from this height. Yet it’s impossible to forget what it feels like to stand at the base of the park: gazing upwards, at jagged rock against a blue sky. One human looking up at this towering structure made by the Earth. Small, but part of something bigger.

Christine Xu is a senior in Saybrook College.

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