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Manhattan: Island of many hills

JASMIN K. WILLIAMS Special to the AmNews | 11/2/2011, 6:40 p.m.
Manhattan: Island of many hills

Manhattan is an island, meaning that is surrounded by water on all sides. It's the oldest of New York's five boroughs and is home to more than 8 million people. Manhattan is the financial capital of the country and one of the most important cultural epicenters in the world. The name "Manhattan," translated from the language of its original inhabitants, the Lenape natives, means "island of many hills."

Just how did it get to be so hilly? More than a billion years ago, Manhattan was formed by a combination of tectonic movements, the slow joining and breaking away of landmasses and glaciers that sliced through the landmass like a slow-moving razor.

The island is formed by three layers of rock called strata. The first of which is Manhattan schist, found under most of the island. This creates solid bedrock, a perfect anchor for the city's famous skyscrapers. Schist is literally the backbone of the island, from the Henry Hudson Bridge to the Battery. It dips at Washington Square and then begins to rise again at Chambers Street. It also is the reason for the big differences in the uptown and downtown skylines.

The second strata is Inwood marble. It was created from limestone. These beds sit 150 to 500 feet below the Harlem River. The area where the beds are found is known as Inwood Lowlands. Above ground, it forms a great ridge from Dykman Street to Marble Hill.

The third strata is Fordham gneiss. Formed a billion years ago, it comes to the surface forming the Riverdale and Grand Concourse ridges. These three strata are solidly together, but how did this happen?

All of the world's great landmasses have gone through a series of coming together and breaking apart. In fact, if you look at a map or globe, you can see that the continents almost form a giant jigsaw puzzle. Long ago, the so-called super continents of Gondwana and Pangaea were formed by the joining of smaller landmasses that later broke apart. Pangaea consisted of what is now North America, Europe and Asia. Gondwana consisted of South America, Africa, Australia, India and Antarctica.

These shifts are responsible for great changes in the landscape. Glaciers sliced through rock. Rushing waters carved out great valleys. Mountains, once buried below the sea, emerged. Even now, landmasses are shifting beneath us at about the rate that a fingernail grows. In another billion years, the Earth will most likely look much different than it does now, with more or less land above water and new or different continent formations.

It's hard to image Manhattan without its famous landscape, but once upon a time, it was a rich and fertile tree-covered hunting and fishing haven. The island's first residents were the Lenape. In 1524, Giovanni da Verrazzano became the first European to set eyes on what would become New York Harbor. Verrazzano, who had been hired by the French to find a faster route to the Orient, stumbled upon what is now Staten Island. He was also the first European to meet the area's indigenous people.