V

IN WHICH MANNAHATTA LIFTS OFF

COLUMBUS DAY MORNING 2003 was clear, sunny, cool, not cold. Eric W. Sanderson was walking east on 42nd Street, heading toward the assembling annual parade. He carried a small GPS unit, not much larger than a cell phone. Wearing blue jeans and a light coat and shouldering a heavy green backpack, Sanderson looked ready for a hike in the woods—which he was. As he approached Fifth Avenue, Sanderson paused. “So probably here was oak and chestnut forest,” he said, pointing at Bryant Park. He then gazed southeast at the swell of Murray Hill. The Murray family buildings and the shaded rise of the hill can be seen on Randel’s 1811 map and on farm map 18. “There is a legend that Mrs. Murray entertained the British general to try to delay him,” Sanderson said. “What seems more likely is that the general was under orders to stop at Murray Hill. But if he had just walked down the hill and blocked this road, that would have been it. Instead, a mile away, the American troops got away again.” He stood a few seconds, entranced by what his mind’s eye could see.

On Fifth Avenue, bagpipes and motorcycles surged. Parade-goers brandished Italian and American flags. “A lot of primates,” Sanderson noted. “Needless to say, it would have been a lot quieter.” He turned north onto the west side of Fifth and descended into the cool air of a steep 30-foot-deep ravine. Brooks and birds were soon the only sounds beneath beech and hemlock trees. Sanderson began walking the valleys, hills, and forests of an earlier, less noisy Manhattan.

A quarter of a mile later, Sanderson stopped to listen to a stream coursing down a slope under what had become the J. R. Cigar Store on the northwest corner of Fifth Avenue and 46th Street. (The store is no longer there.) He crossed it—“probably a very nice little stream, babbling brook as it were”—and turned west, down Diamond and Jewelry Way on 47th Street, past more hemlocks, some wild turkeys, a spring (the source of the stream), and a small pond, ideal for duck and beaver. The block became the heart of the diamond trade in the early twentieth century, as merchants moved north with the unfolding grid; the diamond district was originally based in the Bowery, near Canal Street. As Sanderson gazed at the pond, a woman pushed past him to gaze at diamonds in the window of a jewelry store. She too was peering into the past, across millions of years when, miles beneath the crust, carbon was pulverized into tightly bound cubed lattices and then pushed upward in eruptions of magma. The carbon crystals cooled and sat until they were cut out, cut up, and caratized. The woman may not have appreciated the reach of time as she looked at the flickering rocks. Eons are hard to fathom. Even the changes across four hundred years are hard to imagine. Nevertheless, Sanderson has devoted more than a decade to getting New Yorkers—and, by extension, city dwellers anywhere—to see the past alive in the present.

Sanderson is the author of Mannahatta: A Natural History of New York, a best-selling book many New Yorkers and others came to know well during the four hundredth anniversary of Henry Hudson’s arrival in his flyboat, Half Moon. In the book and an ongoing web-based project, Sanderson presents a vision of Manhattan in 1609, the year Hudson arrived and the year marking the beginning of European transformations of the land, of species composition, and of native people’s way of life. Informed by scientific information and imagination, Mannahatta (the Lenape’s word for their “island of many hills”) is the first computer model seeking to render a four-hundred-year-old landscape in an approximation of its full ecological splendor. Sanderson hopes Mannahatta will enable New Yorkers to layer transparencies of the past atop the present, and to imagine future layers, future possibilities.

To create Mannahatta, Sanderson had to lift the grid, which connected him to the man who set it down. Randel’s topographical data proved crucial to Sanderson’s ecological restoration. Sanderson loves thinking about storms, trees toppling to create space for saplings, marshes rich with birds, fry, and mollusks. Randel enjoyed eating oysters but was plagued by thickets, storms, and mosquitoes swarming from the island’s profusion of wetlands and marshes. Across the expanse of two centuries, the two men have met, perfect foils in their double vision. One walked a verdant island, seeing right angles and the streets of a great invisible city. The other walks a great gray gridded metropolis, seeing green hills.

REMOVED FROM A WILDERNESS CONDITION

The idea of ecological restoration—of recreating a landscape—arose in the United States at the tail end of Randel’s era, during the full throttle of railroad construction and industrialization. As the New York City grid extended up Manhattan and the federal land ordinance grid extended across the West, as canals and then railroads linked states and the vast interior, the American relationship to land and nature changed. Infrastructure transformed landscapes and fostered greater economic security; the nation grew less skittish about its future. Americans increasingly came to reflect on the transformation of familiar landscapes and on the loss of wildlife. They had hunted, farmed, and “improved” the land for more than two centuries, and the forces making settlers vulnerable—the chaotic forces Gouverneur Morris feared in 1806 might “unhinge the intellect”—were no longer so viscerally troubling. By the mid-nineteenth century, more than 60 percent of New England’s old-growth forests had been felled and many animals were long gone. Americans were becoming nostalgic, appreciating wild nature, wild land—the particular American landscape—now that they no longer felt threatened by it and the possibility of depleting the nation’s ample resources loomed. “Although there were a few exceptions, American frontiersmen rarely judged wilderness with criteria other than the utilitarian or spoke of their relation to it in other than a military metaphor. It was their children and grandchildren, removed from a wilderness condition, who began to sense its ethical and aesthetic values,” writes historian Roderick Frazier Nash.¹

The shifting sensibilities were captured in the early and mid-nineteenth-century by authors such as Washington Irving, James Fenimore Cooper, and Henry David Thoreau, the philosopher Ralph Waldo Emerson, and the painters of the Hudson River School, among them Asher B. Durand, who had worked with the master engraver Peter Maverick during the time Randel designed his 1821 map. These writers and artists depicted nature as sublime and essential to the health of the human spirit, and they celebrated the distinctive American landscape. Central to their Romantic or transcendental views was a conviction that nature existed in a harmonious equilibrium and that humankind could disrupt the balance of nature and increasingly did so through the use of technologies. The railroad rapidly became “the machine in the garden,” as literary critic Leo Marx calls it. A tension between industrial progress and the preservation of essential nature—for some the pastoral, for others the wild—emerged.²

How fully, and to what end, humans could alter nature became more widely clear to Americans in 1864, when scholar, linguist, and diplomat George Perkins Marsh published Man and Nature; or Physical Geography as Modified by Human Action. Marsh’s popular book used science and history to argue that humans unintentionally as well as intentionally destroyed natural processes, creating disastrous consequences for themselves. They wrought devastating floods and lethal droughts: “. . . man is everywhere a disturbing agent. Wherever he plants his foot, the harmonies of nature are turned to discords.”³

The idea that changing the landscape changed human experience was not new to many Americans. “Most New England naturalists agreed by the 1790s that deforestation and agricultural cultivation had the effect of warming and drying the soil, making the surface of the land hotter in summer and colder in winter. Temperatures in general fluctuated more widely without the moderating effects of the forest canopy to shade the ground and protect it from winds,” notes University of Wisconsin environmental historian William Cronon. But Marsh’s book reached an extensive and diverse audience: it was read not only by naturalists, scientists, and historians but by the general public. And Marsh’s argument was global, rooted in resonant historical examples. Environmental destruction could do more than change local weather—it could destroy civilizations. He linked deforestation and erosion to the fall of the Roman Empire and to the emergence of vast deserts.⁴

Marsh’s detailed, rigorous, highly footnoted, and digressive treatise advocated for human intervention on nature’s behalf for the mutual benefit of man and nature. Having observed efforts to replant forests and stabilize mountainsides in Europe, Marsh argued that nature needed humans in order to heal. Man “is to become a co-worker with nature in the reconstruction of the damaged fabric which the negligence or the wantonness of former lodgers has rendered untenantable,” he urged. His call for environmental restoration appears to be the first made in America.⁵

It was to be many decades—indeed, more than half a century—before ecological restoration was formally pursued as a discipline and before the full significance of Marsh’s arguments was appreciated, but Marsh’s influence was far-reaching in his own time as well. Some scholars credit him with launching the U.S. conservation movement, contributing to the mindset that led to the establishment of the first national and state parks. And although Marsh did not advocate for parks in urban areas, his ideas about the human relationship with nature resonated in aspects of Frederick Law Olmsted’s projects. Olmsted repaired damaged land in Boston’s fens and along the Muddy River, reclaiming a polluted urban wasteland. As scholar Anne Whiston Spirn notes, the project seems to be the first effort in any country to “construct a wetland.” Olmsted built water purification and flood control into this wild-looking, nonpastoral landscape. By dredging, draining, recontouring, and planting native and nonnative plants, he made an ecosystem. “The thing is to make it appear that we found this body of water and its shores and have done nothing to them,” he wrote.⁶

With Central Park, which predated the Boston Fens and Riverway by several decades, Olmsted was not seeking to construct a sense of wild Manhattan. Although he advocated for the protection of Yosemite and for the preservation of nature in untrammeled form in other places as he worked on Central Park, he wanted a pastoral, rural experience for New York City dwellers. Central Park, as noted in Chapter III, is landscape architecture—an artfully engineered Romantic setting, an idealized, human-friendly nature.

The Mannahatta idea is a Central Park for its time. It is a form of restoration ecology, not landscape architecture. It is virtual, physically aspirational, not actual. Yet both the park and Mannahatta celebrate the value of nature in an urban environment. Both seek to connect people to a lost or inaccessible landscape. Both remove the grid and by so doing criticize the grid for evicting nature from the city. Both are informed by a Romantic sensibility. Both posit a stark opposition between “nature” and “city,” the garden versus the machine. Both use the cutting-edge technologies of their time to create and evoke “nature.”

ON-THE-GROUND TRUTH

Maps, particularly historical maps, stir the individual imagination of viewers. The mapmaker selected what was important to him or to his sponsors. Europeans portraying the New World wanted enticing maps, as did Simeon DeWitt and Randel. But the cartographer’s chosen details can elicit vivid and unexpected images in the viewer. Personal experiences converge with seemingly universal referents; the viewer’s idea of mountains (for some the Berkshires, for others the Himalayas), the viewer’s expectations, hopes, prejudices, sense of way-finding, and fantasies all come to bear. Which is why beautifully made and historical maps are such treasured objects—treasured as much for what they evoke as for their artistry.

Mannahatta was inspired by just such a map. Sanderson moved to New York City from California in 1998 to work as a landscape ecologist for the Wildlife Conservation Society at the Bronx Zoo. Part of his job would be to create computer maps of habitat, of resources, of animal territories. One weekend a few months after moving, he visited the Strand Bookstore and discovered Manhattan in Maps. He starting paging his way forward from the lost Maggiolo Map of 1527—the first depiction of the area that was to become New York City. Whereas Reuben Rose-Redwood had been captivated by Randel’s farm map 27 from 1819, Sanderson stopped short several pages and decades earlier, at the British Headquarters Map, circa 1782.

The map, drawn at a scale of 1 inch to 800 feet, had not been reproduced since 1900. Robert T. Augustyn and Paul E. Cohen, the authors of Manhattan in Maps, were the first to publish the British Headquarters Map in full color, the first to introduce it to modern audiences. The map portrays the many hills of Manhattan shaded, inked in beautiful relief so they seem to rise above the page. As the authors note, occupation of the island between 1776 and 1783 meant that British surveyors, engineers, and “the cream of English cartographic talent” were in long-term residence; as a result, “New York, which was one of the most poorly mapped American cities before the war, became by its end the most thoroughly mapped urban area of the United States.” Based on the landscape presented in the map, Augustyn and Cohen describe what a “rich and varied visual experience a carriage ride” around the island would have offered during that era.⁷

The images the map conjured for Sanderson were at less a remove than a carriage ride. The meticulously rendered landscape, woven with so many waterways that “island of many streams” would have been an equally apt Lenape name, conjured images of vegetation, insects, amphibians, reptiles, mammals, and birds. As a landscape ecologist, Sanderson knew topographical information and details about watercourses could yield clues about what the island’s ecosystems had been before they were covered in cobblestone, asphalt, and concrete. “Why is some place forest, some place wetland? It is the geomorphology, the topography, the hydrology, the shoreline,” he said. Perhaps, he thought, relevant information from the map might be combined with historical and contemporary records of flora, fauna, climate, and soil to understand—or at least reasonably hypothesize about—what used to live where on the island. Sanderson bought the book. And the more Sanderson examined the British Headquarters Map, the more he became convinced it could unlock the island’s ecological past. Maybe he could create a computer model and produce historical ecological images that could, ideally, show any New Yorker or tourist what the corner he or she was standing on used to look like. Perhaps he could induce New Yorkers to “identify with the nature that used to be here as much as they identify with Times Square today,” he mused. “And when they think of New York, they don’t just think of Times Square and taxis, but they think of forests and wetlands and deer and wildlife.” He paused. “Maybe not deer; there are too many of them. Bears and elk or something.”⁸

The first step to building the model would entail scanning the map into his computer so he could manipulate it. To scan it, he had to slice apart the pages. This act proved to be one of the most difficult of the entire project. It took him six months. “It is hard to cut open a book. Was it worth it to cut the binding of a fifty-dollar book?” he asked. Finally, one Sunday afternoon, “I was like, goddammit, I am going to do it! I got out my X-Acto knife and cut it open and scanned the map and assembled it with a program I had.”

Sanderson then planned to position the scanned map over a contemporary digital city map, and for that he needed control points. In the same way that Rose-Redwood required the datum so he could relate the height of a hill in Randel’s terms to the height of that same hill in today’s terms, Sanderson needed to correlate landmarks on the British Headquarters Map with the GPS coordinates of those landmarks today. Such landmarks are like pins holding together the back and front of an unfinished garment. The process of connecting one map to another through those points is called geo-referencing or—a lovelier term of art—ground-truthing. In 2001, Sanderson and a crew of two began traveling the island to look for some fifty landmarks that had probably survived since 1782: the hill in Highbridge Park where Fort George had stood, old walls around Fort Tryon, Mount Morris in Marcus Garvey Park, the steps of Trinity Church at Broadway and Wall Street, St. Paul’s Chapel on Broadway and Fulton. Sanderson’s team consisted of his newborn son, Everett, and his wife, Han-Yu Hung, a horticulturalist and educator at the New York Botanical Garden. “The field crew is in good condition and high spirits despite the early hour,” Sanderson narrated in one of the home videos taken during the early fieldwork. “It is so different from being on a field trip in Gabon. You can stop and get a cappuccino,” he noted. “I sat in a café downtown with the map and looked outside and tried to reconcile this in my head. This pond is gone. That hill is gone. That rise is gone. Remarkable how much it has changed. It blows your mind.” About twenty-five landmarks were shared by the two maps after those early forays.

But when Sanderson tried to align the British Headquarters Map with a contemporary one, affixing the two together at the landmarks in common, “there was a big problem.” He found that the 1782 map was peculiarly out of register with his current one. Overall, the discrepancy was about 100 meters, which didn’t bother him greatly. He felt he could work with that degree of error, and over time he reduced it to an average of plus or minus 40 meters. For a surveyor, a discrepancy of 100 or 40 meters would be akin to looking at a 3-D movie without the funky glasses: blurred edges, no focus, distraction, a powerful headache. For a virtual ecological reconstruction that was to be in large part inference and artistry, that fuzziness was acceptable. Much more troubling to Sanderson was the fact that the two islands were quite dissimilar to the south. “It looked fine for most of Manhattan, but the lower tip of [the British Headquarters Map] jutted out into the Hudson River.” After days of consternation and frustration, he noticed a faint dotted line on the old map. He returned to his computer scans and shifted pieces, reassembling the two southernmost sections along the faint line. The 3-foot-by-10.5-foot map had been misassembled in the National Archives in London, where it is kept and where Sanderson visited it, still misaligned, in 2001 and in 2006.

Once the British Headquarters Map overlapped the island of today, Sanderson could start to add the components of lost ecosystems. But which ones? Those present in 1782, during the British occupation? Those present at the birth of the modern city in 1811? Sanderson needed, as all restoration ecologists do, a baseline. “People think of the Commissioners’ Plan as being the big thing,” he reflected. “I am not so sure about that. If you think about biological changes, when the biggest changes occur, I think it was when the Dutch came in the 1620s to settle and introduced agriculture, pigs and cows. They just let them loose in the woods. Those things have a massive effect on ecosystems in terms of competition, introduced disease, and pests. And on plants. Those were all huge things. By the time you get to actually laying down roads and buildings there had already been so many modifications.”

During the seventeenth century, the Lenape relationship with and impact on the island—burning, hunting, gathering—ended as well. “The Native Americans abandoned Manhattan after a really nasty war,” Sanderson noted. Under the combative and harsh policies of governor Willem Kieft, the Dutch of New Amsterdam were exhorted to fight the Lenape, a conflict triggered not solely by Kieft’s reportedly blustering and bloodthirsty nature, but by the colony’s decreased reliance on the tribe for trade and increased demand for tribal land. (Kieft was ultimately recalled to Holland and replaced in 1647 by Peter Stuyvesant.)

Sanderson eventually settled on 1609. The year represented the liminal moment between Native American and European effects on the land. It also offered an evocative moment in the city’s history. Most New Yorkers, history buffs or not, know of Henry Hudson, and the four hundredth anniversary of Hudson’s arrival was only a few years off. Sanderson had a built-in deadline and the potential for citywide engagement if he linked the project to the quatracentennial. He was ready to recreate the ecosystems of 1609, to bring Mannahatta back to life.

“Landscapes are among one of the most intricate and fascinating historical documents that we have, and too few see it that way. Most people take the landscape for granted,” commented William Cronon when Sanderson embarked on the project. “But for people who have eyes to see, you can see that the entire past exists as ghost layers. It is palimpsest. You can peer down through those different descriptions of the record of human dwelling and all the natural systems and creatures. Arguably, what better place to do that than Manhattan, where people don’t think nature exists?”

MEASURE FOR COUNTERMEASURE

The surveyors who set Americans along their paths to ownership and nationhood, who staked out grids small and large, who sought the shape of the earth, unwittingly provided an antidote to their own actions. For centuries their documents have provided crucial legal information about provenance and property lines. That legal value persists, but another value has emerged in tandem: surveyors’ records and maps provide vital information about former landscapes, permitting ecological rewind—permitting us to assess what shape the earth was and is in. Many historical and restoration ecologists celebrate their luck in that they have several centuries of survey data containing details about trees, vegetation, water, and soil in locations that can be identified today. The land ordinance of 1785 led to the creation of more than 6,500 volumes of survey notes kept by the U.S. General Land Office (which was formed in 1812 to manage the surveys and settlement) and more than 100,000 township maps. Additional state and town records, such as those Randel made, supplement the wealth of federal records. A few ecologists began using these records in the 1920s to understand the land’s history, particularly in Ohio and Indiana. Their efforts, which culminated in manuscript maps and dissertations, were little known, and had largely wound down by the 1960s. But the emerging field of GIS revitalized the practice.

In Randel’s day, a typical map showed the general features of landscape and property. Cadastral or census information might be printed around the edges, as in Randel’s 1821 map of New York City and the northeastern states, or in an accompanying pamphlet. Or a map might be thematic, portraying one kind of information, as in William Smith’s 1815 geological map of Great Britain. The hallmark of a GIS map is multiple layers of information. For that reason, physician John Snow’s famous 1854 map tracing cholera cases in London to public water pumps is credited as a kind of GIS precursor: his map revealed a connection between contamination, exposure, and disease. In essence, GIS enables mapmakers to layer various kinds of information on a landscape or geographic region and present it in different combinations. These associations ideally give rise to insights about an area or an issue. A GIS map might show a city’s Zip Code zones and then add strata of data about population, air pollution, disease, and income. It might combine vegetation cover with average mean temperature. The overlaps might yield connections significant for policy or research, such as showing an association between the number of asthma cases and proximity to bus depots.

GIS arose in the late 1950s and early 1960s in different settings for different ends, including the depiction of land use, transportation patterns, census data, ocean depths, urban planning, and natural resource management. Although it was not initially used for historical recreation, historians and ecologists are increasingly employing it in creative ways. Among the first historical ecologists to use nineteenth-century surveying records in such a model was David J. Mladenoff of the University of Wisconsin. The idea of documenting the state’s original landscapes had been considered for a long time, “because Wisconsin was so heavily transformed,” Mladenoff explains, and because the Wisconsin Historical Society in Madison held the field books and maps of about one hundred surveyors who had walked and staked out the state’s townships and ranges. Mladenoff started a project to do so in the 1970s, but abandoned it because the GIS was too cumbersome. In 1994 he tried again. Working with GIS expert Ted Sickley and an “army of undergrads,” Mladenoff began recording every detail the surveyors noted or marked on maps as they set markers or scratched signs into bark every half-mile. The marked trees were called bearing trees or witness trees.

The surveyors’ accounts are virtually identical to those Randel, Charles Brodhead, and others made in upstate New York for Simeon DeWitt. “Land first half level prairie last half hilly stony timber oak,” reads an October 1832 entry by John H. Mullett. The entries also show surveyors’ woes to be universal: “During four consecutive weeks there was not a dry garment in the party, day or night . . . we were constantly surrounded and as constantly excoriated by swarms or rather clouds of mosquitoes, and still more troublesome insects; and consider further that we were all the while confined to a line; and consequently had no choice of ground . . . and you can form some idea of our suffering condition. I contracted to execute this work at ten dollars per mile . . . but would not again, after a lifetime of experience in the field, and a great fondness for camp life, enter upon the same, or similar survey, at any price whatsoever.”⁹

For five years Mladenoff and his team entered the information into a database. When they were finished, the records enabled them to create statewide maps of soil and vegetation, of prairie and woodland. Unlike contemporary satellite images, which can reveal only whether vegetation is evergreen or deciduous, the images created with the nineteenth-century survey data provide species-level information, identifying white cedar, tamarack, spruce, black ash, white pine, sugar maple, yellow birch. With such fine resolution at their fingertips, the team discovered important details about the older landscape. “People in Wisconsin used to think an area of conifer forest along Lake Superior was boreal forest,” notes Mladenoff, meaning that one of the predominant tree species would have been balsam fir. “Actually, it was predominantly white pine. That was new information for them and led them to reevaluate what they were doing.” The Wisconsin Department of Natural Resources, which helped fund the project, uses the data to make management decisions and to prioritize land for protection. The Nature Conservancy has used the maps for a restoration project.

Mladenoff knows of similar statewide efforts in Michigan and of many other historical ecologists using surveyors’ data. But the most ambitious project he is familiar with is Charles V. Cogbill’s. It transcends states or a particular forest.

Since the early 1980s, Cogbill, a freelance ecologist based in Vermont, has been traveling the Northeast gathering surveying and planning information for 1,350 early towns in nine states. He recalls learning about an old map for a town in New Hampshire where he was studying a forest, tracking down that map, and having “a Eureka moment, if you will.” The trees standing in the corner of each lot—the witness trees—were labeled with species names. Cogbill realized he could recreate the exact location of specific types of trees all over the Northeast with such town maps, noting valuable information about the early landscape and its flora. Since that cartographic encounter, Cogbill has compiled information about well over 200,000 witness trees. He has used only one Randel survey in his set so far, which provided information for part of the Onondaga Salt Springs Reservation—although “DeWitt is on my horizon, to see if there are some geographic holes that I have that he might be able to fill in.” Every data set, of course, has its caveats. Cogbill says bias exists in the surveyors’ reckoning of what the land was best suited for—in how they described its utility. Tree names are not standardized and not always easily recognizable, and so Cogbill has developed a lexicon for state-specific colloquialisms. The project is ongoing: “If you could tell me what Cockburn’s rose bloom was, I would be forever grateful.” And sometimes surveyors recorded only genus, not species. Yet, Cogbill says, “almost every surveyor was a very good natural historian. They were very good botanists, I am convinced. The interesting thing is how consistent and accurate they really were.”

Cogbill’s findings have altered ecologists’ understanding of the Northeast’s pre-European landscape. Most previous studies took the remaining 1 percent of old-growth New England forest as a baseline, extrapolating conclusions about the original forest from those few stands of remnant trees. But Cogbill and his colleagues contend that those patches survived precisely because they were atypical. Using them to inform understanding about the original landscape is akin to looking for keys under a lamppost. He has shown how pivotal topography is for the balance of species, and that pine, hemlock, and chestnut were not as extensive as ecologists previously thought. Instead, beech and oak were more dominant: beech to the north, oak to the south. The findings have implications for how GIS programs model the forest, for management, and for restoration. “We are just scratching the surface,” Cogbill says. “The material is voluminous, and the types of information are multidisciplinary.”

SCIENCE WITH A DASH OF POETRY

No witness trees existed for Mannahatta. The surveyors creating the British Headquarters Map were interested in forests for fuel and the features of the land for military maneuvers. To find information, such as Cogbill’s, about what types of presettlement forests grew on the island, Sanderson had to infer soil types from geology and hydrology. And he extrapolated tree species from those inferences as well as from elevation and slope. Some trees like more dampness, some less; some like to live higher up, some lower. Some are fine with sandy soil, others not. Some prefer a southern exposure; for others, north or east or west is best.

Sanderson felt confident about the hydrology, because he had combined the British Headquarters Map with Egbert Ludovicus Viele’s famous 1859 water map. Viele, a civil engineer and rival of Frederick Law Olmsted for the Central Park design, mapped the island’s water systems to make the case that diseases such as cholera and malaria, still rampant in mid-nineteenth-century New York, could be curbed by drainage and grading. “It is a well established fact that the principal cause of fever is a humid miasmatic state of the atmosphere, produced by the presence of an excess of moisture in the ground, from which poisonous exhalations constantly arise, vitiating the purer air and carrying into the system of those who inhale it a virus,” he wrote in an 1865 pamphlet, The Topography and Hydrology of New York. “Let us hope the time is coming when we shall do some credit to the higher intelligence and broader philanthropy which characterize the age in which we live, and shall adopt those measures which are so clear and so imperatively necessary . . . In this money-making money-wasting generation, let us not be deaf to the lessons of the past.”¹⁰

Some of Viele’s recommendations did come to pass. But water is not easily dominated. Today, when flooding occurs on a construction site or when a foundation sinks, engineers and architects consult Viele’s gemlike green-and-blue map. There they often see the thin green line of a stream gone underground. Unbeknown to many of them, they are largely relying on the research of another cartographer. Viele consulted Randel’s farm maps to determine where the island’s watery features lay.¹¹

Inevitably, Sanderson came to rely on Randel too. He needed precise elevations, not evocative shadings capturing a hill, a bigger hill, a really big hill. Unless he knew heights, he could not plant tree species or other flora in the right places on his map. And without the vegetation characterizing the ecosystem, he could not add the animals associated with those particular ecosystems. Sanderson enlisted the aid of a Columbia University biology student. During the summer of 2003, just as Rose-Redwood was finishing his first digital elevation model and readying it for publication, William T. Bean, who is now a doctoral student in ecology at the University of California at Berkeley, started gathering elevation data from Randel’s records. Settling in with the field books at the New-York Historical Society, Bean recalls, “was exciting because it was the first real primary data that I was working with, the first time it seemed like I was doing something that someone hadn’t done before. And that was really thrilling.” But it wasn’t clear that it was going to work. “There was the risk that I was collecting all this data and that we weren’t going to get anything from it. It was not well organized, and incomplete.”

Sanitary and Topographical Map of the City and Island of New York by Egbert L. Viele. Courtesy of the David Rumsey Map Collection, www.davidrumsey.com.

Bean could discern distance and temperature, but he was not sure how to decipher some of the other figures. It wasn’t until he went home for winter break and showed the numbers to his father, a computer programmer, that it all came together. With his father’s help, Bean realized that Randel had been recording angles of ascent and descent for every rod or chain measure he made. So a cross street and an avenue had complete and, most importantly, decipherable elevation profiles—angles of rise or fall every 10, 30, or 50 feet. Bean first tried using these elevation data in his senior paper, on the burning patterns of the Lenape in Harlem plains—elevations Randel had gathered when he lived in Harlem, tending his garden in a former grassland.

To create their elevation model for Mannahatta, Sanderson and Bean printed out a version of the British Headquarters Map and added all the elevation data they had collected: Randel’s farm map elevations and field book data, elevations recorded on Viele’s water map, and elevation figures from Sanderson’s and others’ GPS recordings at enduring landmarks and rocks—more than 7,000 points, including the initial 25 Sanderson and his family had collected. Then they correlated some of the elevation data to hill shadings on the British Headquarters Map, drawing contour lines by hand, which took nearly four months. “That was the only way we could integrate the map and an elevation model,” Sanderson says. Bean entered the fruits of their effort into a software program called ArcGIS, and Mannahatta’s digital elevation model was born.

Bean currently studies the biology of giant kangaroo rats, endangered burrowing rodents that have lost 99 percent of their habitat. He has spent months at Carrizo Plain National Monument, 100 miles or so from Los Angeles, figuring out where the kangaroo rats thrive so he can predict the best habitat to preserve. Randel has stayed with him across the hot empty desert. “A large portion of my research is fieldwork, and I do keep a field notebook. I don’t think I realized it, but having access to Randel’s notes had a huge impact on how I think about keeping records. Something I thought about constantly while I was digitizing his notebooks was the fact that he must have had no idea (1) what New York would turn out to be, and (2) how his surveys would be used (e.g. the Mannahatta project),” Bean reflected in a recent e-mail. “I call myself an ecologist, but of course ecology is deeply entwined with natural history. And while I hope that my research is important right now, I also suspect that what will be valuable one hundred years from now is not some computer model that I developed for kangaroo rats, but my notebooks—the natural history that I’ve recorded at this time, in this place. That is, I really think ecologists are historians of the land. I hadn’t realized how much I believe that, and how much of that must be due to Randel.”

AND A RAYE AS GREAT AS FOURE MEN

To the skeleton of Mannahatta—to the elevation, soil, hydrology, and to some solid temperature data—Sanderson now introduced species and flux. Many travelers and residents had chronicled New York City’s natural history. “The Land they told vs were as pleasant with Grasse and Flowers and goodly Trees, as euer they had seene, and very sweet smalls came from them,” wrote Robert Juet, Henry Hudson’s first mate, in September 1609, amid his many notations about magnetic variation and how far off true north the compass needle strayed. “So wee weighed and went in, and rode in fiue fathoms, Ozie ground, and saw many Salmons, Mullets, and Rayes, very great. The height is 40. degrees, 30. minutes . . . Then our Boate went on Land with our Net to Fish, and caught ten great Mullets, of a foot and halfe long a peece, and a Ray as great as foure men could hale into the ship.” Juet noted chestnut and walnut trees, pumpkins, grapes, and bear and otter skins. A director of the East India Company recorded Lenape words for many animals, so Sanderson also knew that the island had deer, elk, cougars, skunks, turkeys, partridges, loads of toads, and tons of turtles. One of his favorite Dutch records read, “The most wonderful are the dreadful frogs.”¹²

Some early chroniclers were scientific in their orientation, using Linnaean classification and avidly corresponding with other natural historians of their era. Others were less exact. But all captured abundance. “Boats crossing the bay were escorted by schools of playful whales, seals and porpoises. Twelve-inch oysters and six-foot lobsters crowded offshore waters, and so many fish thrived in streams and ponds that they could be taken by hand. Woods and tidal marshlands teemed with bears, wolves, foxes, raccoons, otters, beavers, quail, partridge, forty-pound wild turkeys, doves ‘so numerous that the light can hardly be discerned where they fly,’ and countless deer ‘feeding or gamboling or resting in the shades in full view,’ ” write historians Edwin G. Burrows and Mike Wallace in their review of those early accounts.”¹³

While Sanderson compiled accounts of plants and animals, he reached out to several dozen archaeologists, anthropologists, historians, paleobotanists, biodiversity mavens, herpetologists, invertebrate experts, foresters, and botanists, who contributed their wealth of knowledge about the island’s physical, biological, and human history. Many scientists Sanderson spoke with in those early days were intrigued but skeptical. “The project as an idea is a very exciting and excellent one,” mused seismologist Klaus Jacob at the time. “My concern is, can he really extract enough hard data? He has a good model into which he feeds all the physical environment, and he thinks he can reconstruct total ecology from spare data. That is a tough nut to crack.” Sanderson’s fusing of a rigorous scientific approach with scant data might produce a historical myth—of which plenty already abounded.

This is the challenge of restoration ecology: the distance between what we truly know about the past and what we want for the future, tempered by our truly inadequate, ever-shifting ecological understanding. One of the earliest, if not the first, U.S. restoration projects is now seventy-five years old. Curtis Prairie—which John Curtis, Aldo Leopold, and others decided to restore in the 1930s—remains a work in progress. Controlled burns, which help grass seeds germinate and keep woody plants from thriving, are not dissuading enterprising shrubs and invasive species. The webs of interactions between members of a community—from the microorganisms populating the soil and root systems to the relationship between a plant, a pollinator, and a particular bird—are dizzyingly intricate, still mysterious today, when the planet has been so mapped and scrutinized. As E. O. Wilson notes in Biophilia, “. . . the naturalist’s journey has only begun and for all intents and purposes will go on forever . . . it is possible to spend a lifetime in a magellenic voyage around the trunk of a single tree.”¹⁴

And when Leopold started his prairie restoration, the ecological paradigm was balance of nature and equilibrium. The idea that the Romantics and the transcendentalists, that Marsh and his cohorts honored seemed to find scientific support with the work of a biologist named Frederic Clements. At the turn of the century, Clements had devised a technique that allowed him to show that plant communities moved through distinct phases, called stages of succession, until they reached a stable or climax state. Imagine a meadow first colonized by shrubs and then filling into forest. Clements’s breakthrough technique, which did much to establish ecology as a modern quantitative science and which remains the predominant field technique today, was the grid. By plotting a study site on a grid and counting and characterizing species within 1-meter-square frames called quadrats, the technique made ecology mathematical, statistically robust. The harmonious proportions of the mathematical grid seemed to capture a harmony of a kind: the balance of nature. Quadrats revealed to Clements and other researchers that over time, ecosystems reached a state of equilibrium—an endpoint, a climax, a mature stasis.¹⁵

That endpoint vanished in the mid- to late twentieth century. In the 1950s, John Curtis, R. H. Whittaker, and other biologists showed that there was no equilibrium. Individual plants were not working together to create some preordained community; they were all out for themselves. This idea had been put forth in Clements’s time by rival botanist Henry Gleason, but during that era the scientific community was not ready for it—flux was anomaly, equilibrium was the dominant paradigm. By the 1970s researchers were building on the work of Curtis, Whittaker, Gleason, and others, characterizing ecosystems as undergoing constant disturbance, as being “chaotic” and, then, “complex.” Chaos has no order, whereas complexity suggests, as environmental historian Donald Worster points out, that there “might not be any large overarching order inherent in nature, but there was plenty of evidence of conditions of change giving way to those of order, of order dissolving into change.” In short, nothing stays the same, ecosystems included. Although the ideas of equilibrium and of a climax community endure—they remain central to many people’s thinking about wild nature—and have their place in biology, the ideas of flux and disturbance are just as essential.

Today Clements’s quadrats capture flux, whether in the rocky intertidal zone of Prince William Sound or on a survey of botanical diversity deep in the Amazon. Ecological GIS programs model and incorporate that flux as well—a tree fall, a lightning strike, hailstorms, hurricanes, fire.

SANDERSON ACKNOWLEDGES ALL of Mannahatta’s scientific shortcomings. The information he amassed with the help of Jacob and many others and through his reading was, as all had anticipated, uneven. Completeness in the species lists: improbable. Completeness in the Lenape records: improbable. Accuracy in the computer models of flux, plant succession, and human impact: highly unlikely. “So what I say is that we use science to the extent that the science can help us. And then we admit when we don’t know,” Sanderson says. “But we don’t have to be afraid because we don’t know. I am not saying it is going to be easy. And I am saying maybe it is crazy. But I totally think it is worth trying.”¹⁶

Mannahatta has brought engagement with restoration and historical imaginings to a wide audience because of its storytelling, scale, format, ambitious artistry, and because it explicitly muses about the future. The centerpiece of the project and the book are several stunning computer renditions by artist Markley Boyer of different areas of the island. Sanderson and his team’s years of research and software tweaking and orchestration and Boyer’s graphical talents culminated in sweeping bird’s-eye views of a lush, verdant isle thick with forests, woven throughout with blue streams, home to bears, eagles, and egrets. Photographs taken above the Amazon rainforest seem the most apt modern comparison. Informing the images are Sanderson’s Manhattan tallies: the island had 21 lakes or ponds, 66 miles of streams, 10,000 or so species (not including insects, molds, mosses, and microorganisms), and 55 ecological communities—among them sandy beaches, eelgrass meadows, red-maple hardwood swamps, vernal pools, grasslands, and pitch pine–scrub oak barrens. He estimates that between 300 and 1,200 Lenape lived on the island; faint spirals of smoke attest to their presence in several images.

Sanderson’s hope has always been that once New Yorkers saw visions of Mannahatta dancing in their heads, they would think of their city in new ways. If they stepped into the past and appreciated the biological diversity of the island four hundred years ago, residents might want to preserve remaining ecosystems—of which there are many, and Sanderson includes photographs of examples taken in and around the city. Residents might embrace the creatures repopulating the city: the raccoons, red-tailed hawks, great horned owls, peregrine falcons, the occasional coyote. They might support ecological restoration or lobby for more parks and green space. “I guess my hope is that people fall so much in love with Mannahatta that they want to do those kinds of things. Not because they feel forced to, but because they want to,” Sanderson says.

The final chapter of Mannahatta offers readers another thought experiment. Sanderson invites them to imagine the city they want in the future. His last line makes explicit his own desire: if the city makes thoughtful choices about transportation, energy consumption, food production, architecture, and green space, “Mannahatta will be back for all of us, a land as pleasant as one can tread upon, a city that all the people have created, connected by a thousand invisible cords, the fresh, green breast of a world that will thrive for another four hundred years, and then some.” His closing illustration shows New York City 2409. Three greenbelts extend from Central Park, flowing down to the rivers; a stretch of Chelsea has gone to park. The Bronx, Queens, Brooklyn, and Staten Island have largely lost their human inhabitants and regained an agrarian past.¹⁷

Perhaps through the medium of information technology—through the quadrat of the computer screen or, if Mannahatta the app materializes, the phone or the handheld or the pad or the pod—a wired generation will imagine Manhattan wild. And if they do, they will be engaging an idea that was virtual before it played out in computers. “This is all about the virtual. The idea that nature is this trope we take to be our ultimate icon of the authentic or the real is profoundly human. Whether that idea finds its ideal in a Mannahatta computer program or a Hudson River School painting by Frederick Church or a book like Uncommon Ground, all are human constructs,” notes William Cronon. “Mannahatta is very much an expression of wilderness thinking in American culture, of a greater historical consciousness of changes in the landscape, and a sense of the human embedded in a natural matrix. Mannahatta is an invitation to mull on how a landscape can be both profoundly natural and human at the same time. Not that the two are not the same, but the way we tend to think of them is in opposition, as counterpoints.”

THE GARDEN IN THE MACHINE

Randel’s survey of the Delaware & Raritan Canal was part of the national movement to lay down the country’s infrastructure; it was to be, as Albert Gallatin intended, part of the necessary network of internal improvements. Canals cut through land, some of it farmed, some of it wild, bringing with them settlement, commerce, and industry. They were among the agents bringing the machine to the garden. Today the Delaware & Raritan Canal is a blue meander, a stretch of welcome water traveling across a suburban and industrialized landscape. It has become, as Howard Green of the New Jersey Historical Commission has noted, “the garden in the machine.” Many early canals similarly have become significant recreational routes, the Erie and the Chesapeake & Delaware among them.

Many old railroad lines have become quiet bike paths, trails through the woods, refuges from highways, cars, and urban living. The High Line, which clattered and shed soot between factories and warehouses in lower Manhattan, transporting raw materials and produce, has become an aerial refuge, a long thin bridge of architectural and botanical beauty curving above the darting energy of the streets and sidewalks below. It too is a garden in the machine, one that explicitly honors its industrial history and its resurrection as a carefully cultivated landscape.

The High Line was built in the 1930s. By then many elevated lines wound above New York City, most of them carrying passengers. The possibility of traveling quickly above the streets, avoiding crowds and carriages, omnibuses and refuse, seemed a wild visionary scheme when presented to public audiences in the mid-nineteenth century. It reached those audiences alongside another wild visionary scheme: the elevator. Once adopted, the elevated railway permitted New York to expand and fill itself out, to ink in the pencil lines of the grid. The elevator permitted New York City to expand up and out of the grid, in a direction the street commissioners never described, doubtless never dreamed of. Disfavored natural hills and slopes found rebirth in the air as buildings brought people to new elevations. Manhattan remains an island of wild topographical variation—an island of layers.

Layers of time beguile us. In unfamiliar places, the present often crescendos while the past and future take a step back. There is no personal past to recall in a new place, no memory of an event that occurred at this corner or in that park. History may be explicit all around you—in the architecture, in stories of the place, in the landscape—but it is not your felt history. The present, however, necessarily grips you. You notice what is the same or different from where you live. You notice details along routes so you can find your way. You can see freshly because no habit or routine has yet dulled your senses, as it often does in familiar places.

If you return to a place you visited before—say it is Paris, but it might be Nairobi, Philadelphia, the house your grandmother lived in; it might be anywhere—you pass spots now quasi-familiar. You might remember that the last time you visited, you never imagined you would be back. You can see your younger self, your expectations, ideas, purposes, walking along a street unaware of your future self walking down that same street with different expectations, ideas, and purposes. Layers of experience can make that place feel nostalgic and magical, as though it has special significance. Time there feels less linear, more a looping, a backstitching. You wonder if you will be back this way again. In fanciful moments, you wonder if the place knew you would be back; if your future return was already set. And in this way you can feel the past, the present, and the future woven together. An experience of simultaneity arising from rare visits and memories evoked by place.

If you have lived a long time in one place, your personal history lays itself down more thickly, many strata in many places. The past is never far from the present. You see accumulations of your own experience, you feel flux, you see change. The layers of time we can experience in such a familiar place are for many of us an approximation, a hint, of what is experienced by ecologists, cosmologists, geologists, paleontologists, and others who explore the earth through time. The layers they see in a place can be centuries or eons thick. They can see the story of the earth’s ever-shifting dynamo in the magnetic pull of a boulder. They can see the story of the earth’s orbit and our solar system in the changing thickness and composition of ancient sediments making up the 222 million-year-old rock jutting out behind a New Jersey mall, where, just a stone’s throw from Lowe’s, fossil coelacanths can be hammered out of a hillside.¹⁸