At Lyndhurst’s Hudson River Fest June 7 I saw a presentation about the Mannahatta Project, examining what Manhattan’s ecology was like when Henry Hudson showed up in 1609.

The island’s habitat of 400 years ago is now the subject of a web site, a school curriculum, a museum exhibit and a book. Author Eric W. Sanderson was at Lyndhurst’s Hudson River Fest for one of the many Quadricentennial events this month.

So how do you research a place that’s been paved and blasted and buried for four centuries? Sanderson, an expert on animal habitats, described using a British topography map from the Revolutionary War to begin charting Manhattan’s long-buried hills and streams. He stood atop rocks in Central Park to begin gauging the elevations drawn on the map. Computer modeling helped flesh out the picture of soils, wildlife, vegetation and other elements. And the research is ongoing.

The Lenape Indians probably had settlements around the freshwater pond where Foley Square now stands, he said. The Lenape spoke Algonquin and were known as the ancient ones, or forbears, of that group. To illustrate what various parts of Manhattan looked like, he showed photos of Marshlands Conservancy in Rye and Cranberry Lake Preserve in White Plains.

The historical narrative continues with an exhibit and celebration Saturday Sunday June 21 at the Hudson River Museum — “Dutch New York: The Roots of Hudson Valley Culture.” Journal News writer Georgette Gouveia has this story about the display.

The Dutch presence helped set the tone for New York as an immigrant gateway, according to historians. Below is a story I wrote about a presentation on the subject by historian Kenneth Jackson.

Oct. 14, 2007

KATONAH – A long time before Lady Liberty appeared, New York was welcoming immigrants like no other American city.

And the reason dates back centuries, historian Kenneth Jackson said in a lecture Friday night. While other cities were established by groups looking to protect their religious beliefs, New Amsterdam began as a center of trade. Founded by the Dutch in 1624, the city quickly attracted diverse nationalities. The driving force, then as now, is a pursuit of prosperity, Jackson said. The prevailing attitude: “We don’t care who your grandfather was. Can you get this job done for me?”

More than its size and density, its wealth and industry, that outlook is Gotham’s true distinction, Jackson said.

“The ultimate unusual characteristic of New York,” he said, “is that it’s never had a majority culture.”

Jackson, a Columbia University professor and editor of “The Encyclopedia of New York City,” gave the first in a series of three fall lectures that will raise money for the Neighbors Link center in Mount Kisco. The center replaced its usual fall gala with the three events featuring Northern Westchester neighbors. The “Latin Links” series is meant to generate discussion about the influence of immigrants over time. Jackson spoke at the Katonah Museum of Art.

His discussion drew connections between an early spirit of religious tolerance and a modern multiculturalism that other cities lack.

In Puritan Boston in 1637, Anne Hutchinson was put on trial for heresy and banished for her religious beliefs.

“That action would have been incomprehensible in New Amsterdam,” Jackson said. (Hutchinson later died in an attack by Indians in what is now Westchester. The river and later the parkway were named for her.) In 1654, a group of Jews fled Portugal and settled in New Amsterdam. When the English took over in 1664, the city’s name changed, but the tradition of openness did not.

That’s not to say that the mixing of cultures is always seemless.

When Quakers began meeting in modern Queens, Gov. Peter Stuyvesant deemed them fanatics and ordered a halt. But other residents stood in their defense by signing the “Flushing Remonstrance,” a declaration that religion and government should remain in separate spheres.

The immigrant waves continued in the mid-1800s, from Germany and Austria-Hungary. The peak year at Ellis Island was a century ago, in 1907, when more than 1 million immigrants came through.

Jackson argued that immigrant entrepreneurs were the reason why New York managed to survive the collapse of its two major employment sectors during this century: the port, where dock workers were replaced in the 1950s with the advent of container shipping, and manufacturing, which once thrived with breweries, printing and garment-making.

Dominicans are the largest nationality among immigrants in New York City, but they make up only 13 percent of the foreign born.

In proportion with the rest of the U.S. population, “immigration is a smaller deal now than it was a century ago,” he said.

But there are differences. “They weren’t passing judgment on your ancestry when you came to Ellis Island, until 1924 and it changed,” Jackson said. “But it’s clearly a different system now that these people are illegal, and can be arrested just for being here.”

Until the 1920s, the only restriction against immigrants was an exclusion of Chinese and Asians. Then a set of quotas aimed to curtail the Italian and Jewish arrivals from Europe. Since the quotas ended in 1965, most legal immigrants to the United States have been admitted through family ties.