Cameron's Line is a Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 suture fault in the northeast United States which formed as part of the continental collision

Continental collision

Continental collision is a phenomenon of the plate tectonics of Earth that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together...

 known as the Taconic orogeny

Taconic orogeny

The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States...

 around 450 mya. Named after Eugene N. Cameron, who first described it in the 1950s, it ties together the North American continental craton

Craton

A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...

, the prehistoric Taconic Island volcanic arc

Volcanic arc

A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...

, and the bottom of the ancient Iapetus Ocean

Iapetus Ocean

The Iapetus Ocean was an ocean that existed in the Neoproterozoic and Paleozoic eras of the geologic timescale . The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia...

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Location

Cameron's line has been identified in western Connecticut near Ridgefield

Ridgefield, Connecticut

Ridgefield is a town in Fairfield County, Connecticut, United States. Situated in the foothills of the Berkshire Mountains, the 300-year-old community had a population of 24,638 at the 2010 census. The town center, which was formerly a borough, is defined by the U.S...

 before it heads into the Bronx, along the East River

East River

The East River is a tidal strait in New York City. It connects Upper New York Bay on its south end to Long Island Sound on its north end. It separates Long Island from the island of Manhattan and the Bronx on the North American mainland...

 in Manhattan

Manhattan

Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

, through New York Bay

New York Bay

New York Bay is the collective term for the marine areas surrounding the entrance of the Hudson River into the Atlantic Ocean. Its two largest components are Upper New York Bay and Lower New York Bay, which are connected by The Narrows...

, Staten Island

Staten Island

Staten Island is a borough of New York City, New York, United States, located in the southwest part of the city. Staten Island is separated from New Jersey by the Arthur Kill and the Kill Van Kull, and from the rest of New York by New York Bay...

 and into New Jersey

New Jersey

New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

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Geology

The basement rocks of the Manhattan Formation located on the western side of Cameron's line are metamorphosed sedimentary rocks. They were formed in roughly this location (autochthonous) and have been tectonically stable over a large period of time. The other side of the line has allochthonous rocks formed elsewhere, which have experienced great tectonic movement in a westward direction on top of the underlying bedrock

Near New York City, the eastern side of the line is the Hartland Formation, the remains of the volcanic island arc underneath Cretaceous and Pleistocene layers. The nearby Newark Basin

Newark Basin

The Newark Basin is a sediment-filled rift basin located mainly in northern New Jersey but also stretching into south-eastern Pennsylvania and southern New York. It is part of the system of Eastern North America Rift Basins.-Geology:...

in New Jersey is similar to a layer underneath the Cretaceous period rocks in this region.

The position of the line in New York City and especially in Manhattan is subject to much debate and contradictory data. Due to the violent nature of the Taconic Orogeny, the line has been folded and eroded several times. The material in the line is described as "highly laminated, migmatized, complexly folded- and annealed zones of commingled mylonitic rocks".