Thursday, March 10, 2011

Mannahatta, by Eric Sanderson

I must confess I was intimidated when Mannahatta, by Eric Sanderson, (Abrams Books, 2009, 352 pages) first appeared in our house. The hardcover measures 7.5 x 10.25 inches and the shipping weight is 4.2 pounds, according to Amazon. But once I opened it, I realized that only 70% of those pages are text, and a lot of those are (extremely beautiful) illustrations. The paper is very heavy. And then I started reading.

What a story Sanderson has to tell! Using Geographic Information Systems (the same technique that brings us Google maps), modern statistical techniques, a detailed Revolutionary War map, and the modern street grid, Sanderson recreates the island of Manhattan as of September 12, 1609, the day Henry Hudson sailed the Half Moon up the estuary that would one day be named for him. Sanderson does a magnificent job explaining the methodology, the research, the mapping software, and the tradeoffs that went into developing this study. With its careful maps, archival photos, and clear writing, the book is at once a fascinating story and a wonderful example of how to present complex data clearly.

In 1609 Manhattan was a hilly island created by glaciers, full of streams. Now the hills are flattened and the streams run underground. Manhattan is at a climate crossroads; summers were nearly tropical, and winters, cold (well, that part is unchanged), and had as a result a wide variety of habitats: woodlands, grasslands, salt marshes, sandy beaches, rocky shores, 55 ecological communities in all -- more than the average coral reef. The island was once home to 30 varieties of orchids, and countless beavers, squirrels, river otters, and birds. (Insects too, but there are too many of those to try to account for.)

Beavers were more than a numerous inhabitant -- Sanderson shows how they were a key component of the island's ecology. They dammed streams, creating pools, which attracted deer and supported amphibians. The pools eventually filled and became marshes and then grasslands, creating new habitats that attracted yet more plants, insects, and animals.

Because a Revolutionary War map prepared by the British planning a defense of the island exists, Sanderson and his team were able to match the modern streetscape to the original topography. East 74th Street was once a brook, and Minetta Lane was named for the footbridge that once crossed Minetta Water, now Minetta Street. Harlem Meer was a tidal inlet.

Sanderson also projects what Manhattan will be like, ideally, 400 years from now. In his vision, cars will have given way to bicycles and pedestrians; our successors will use the subways to deliver freight and food. Roofs and buildings will be green. Our great-great-great-great-great-great-great-great-grandchildren will live densely, in a smaller area as rising seas will take back some of the island. Many of the surrounding neighborhoods will revert to farmland and streams so that residents can eat locally. It's a hopeful vision. May it come to pass.

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