Staten Island - Geology

Geology

During the Paleozoic Era, the tectonic plate containing the continent of Laurentia and the plate containing the continent of Gondwanaland were converging, the Iapetus ocean that separated the two continents gradually closed and the resulting collision between the plates formed the Appalachian Mountains. During the early stages of this mountain building known as the Taconic orogeny, a piece of ocean crust from the Iapetus ocean broke off and became incorporated into the collision zone and now forms the oldest bedrock strata of Staten Island, the serpentinite.

This strata of the lower paleozoic (approximately 430 million years old) consists predominantly of the serpentine minerals, antigorite, chrysotile, and lizardite, it also contains asbestos and talc. At the end of the Paleozoic era (248 million years ago) all major continental masses were joined into the supercontinent of Pangaea.

• The Palisades Sill, designated a "National Natural Landmark" being "the best example of a thick diabase sill in the United States." underlies a portion of northeast Staten Island, with a visible outcropping in the Travis section of Staten Island, off Travis Rd. in the William T. Davis Wildlife Refuge. This is the same formation which appears in New Jersey and Upstate New York along the Hudson River in Palisades Interstate Park. The sill extends southward beyond the cliffs in Jersey City beneath the Upper New York Harbor, and resurfaces on Staten Island. The Palisades sill date from the Early Jurassic period 192 to 186 million years ago.

• Glacier: Staten Island has been at the southern terminus of various periods of glaciation, the last of which, the Wisconsin Glacier ended approximately 12,000 years ago. The accumulated rock and sediment deposited at the terminus of the glacier is known as the terminal moraine present along the central portion of the island. The evidence of these glacial periods are visible in the remaining wooded areas of Staten Island in the form of glacial erratics and kettle ponds.

At the retreat of the ice sheet, Staten Island was connected by land to Long Island as The Narrows had not yet formed. Geologists' reckonings of the course of the Hudson River have placed it alternatively through the present course of the Raritan River, south of the island, or through present-day Flushing Bay and Jamaica Bay.