Sanderson is a landscape ecologist with the Wildlife Conservation Society, a global squadron of researchers trying of save an imperiled world from itself. At its Bronx Zoo headquarters, Sanderson directs the Mannahatta Project, an attempt to re-create, virtually, Manhattan Island as it was when Henry Hudson’s crew first saw it in 1609: a pre-urban vision that tempts speculation about how a posthuman future might look.
His team has scoured original Dutch documents, colonial British military maps, topographic surveys, and centuries of assorted archives throughout town. They’ve probed sediments, analyzed fossil pollens, and plugged thousands of bits of biological data into imaging software that generates three-dimensional panoramas of the heavily wooded wilderness on which a metropolis was juxtaposed. With each new entry of a species of grass or tree that is historically confirmed in some part of the city, the images grow more detailed, more startling, more convincing. Their goal is a block-by-city-block guide to this ghost forest, the one Eric Sanderson uncannily seems to see even while dodging Fifth Avenue buses.
When Sanderson wanders through Central Park, he’s able to look beyond the half-million cubic yards of soil hauled in by its designers, Frederick Law Olmstead and Calvert Vaux, to fill in what was mostly a swampy bog surrounded by poison oak and sumac. He can trace the shoreline of the long, narrow lake that lay along what is now 59th Street, north of the Plaza Hotel, with its tidal outlet that meandered through salt marsh to the East River. From the west, he can see a pair of streams entering the lake that drained the slope of Manhattan’s major ridgeline, a deer and mountain lion trail known today as Broadway.
Eric Sanderson sees water flowing everywhere in town, much of its bubbling from underground (“which is how Spring Street got its name”). He’s identified more than 40 brooks and streams that traversed what once a hilly, rocky island: in the Algonquin tongue of its first human occupants, the Lenni Lenape, Mannahatta referred to those now-vanished hills. When New York’s 19th-century planners imposed a grid on everything north of Greenwich Village –the jumble of original streets to the south being impossible to unsnarl- they behaved as if topography were irrelevant. Except for some massive, unmoveable schist outcrops in Central Park and at the island’s northern tip, Manhattan’s textured terrain was squashed and dumped into streambeds, then planed and leveled to receive the advancing city.
Later, new contours arose, this time routed through rectilinear forms and hard angles, much as the water that once sculpted the island’s land was now forced underground through a lattice of pipes. Eric Sanderson’s Mannahatta Project has plotted how closely the modern sewer system follows the old watercourses, although man-made sewer lines can’t wick away runoff as efficiently as nature. In a city that buried its rivers, he observes, “rain still falls. It has to go somewhere”.
As it happens, that will be the key to breaching Manhattan’s hard shell if nature sets about dismantling it. It would begin very quickly, with the first strike at the city’s most vulnerable spot: its underbelly.
Alan WEISMAN, The World Without Us, St. Martin's Press, Nueva York, 2007.
