Cameron's Line is an

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

suture fault in the northeast United States that formed as part of the

continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at Convergent boundary, convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroy ...

known as the Taconic orogeny around 450 million years ago. Named after geologist Eugene N. Cameron, who first published a description in the 1950s, it ties together the North American continental craton, the prehistoric Taconic island

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...

, and the bottom of the ancient Iapetus Ocean. Cameron himself credited his colleague William M. Agar with the initial discovery.

Location

Cameron's Line winds southward out of

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

through western

Connecticut Connecticut ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the south. ...

. It has been identified in western Connecticut near Ridgefield before it heads into

Westchester County, New York Westchester County is a County (United States), county located in the southeastern portion of the U.S. state of New York (state), New York, bordering the Long Island Sound and the Byram River to its east and the Hudson River on its west. The c ...

, then the

Bronx The Bronx ( ) is the northernmost of the five Boroughs of New York City, boroughs of New York City, coextensive with Bronx County, in the U.S. state of New York (state), New York. It shares a land border with Westchester County, New York, West ...

, along the East River in

Manhattan Manhattan ( ) is the most densely populated and geographically smallest of the Boroughs of New York City, five boroughs of New York City. Coextensive with New York County, Manhattan is the County statistics of the United States#Smallest, larg ...

, through New York Bay,

Staten Island Staten Island ( ) is the southernmost of the boroughs of New York City, five boroughs of New York City, coextensive with Richmond County and situated at the southernmost point of New York (state), New York. The borough is separated from the ad ...

, and into

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

Geology

The basement rocks of the Manhattan Formation located on the western side of Cameron's Line are metamorphosed sedimentary rocks and can be thought of as the remnants of the edge of the North American continent from 1 billion years ago. They were formed in roughly this location ( autochthonous) and have been tectonically stable over a long period. Through New England, generally, the rocks to the west of Cameron's Line are the remnants of an enormous mountain range (the Grenville orogeny), sometimes called the "Crystalline Appalachians", which once stretched from Newfoundland to Mexico, the local remnants of which are exposed and create the Housatonic Highlands, the New Jersey Highlands ( Ramapo Mountains), and the thin Manhattan Prong (including much of the Bronx). In general, to the east of the line are allochthonous rocks formed elsewhere, which have experienced great tectonic movement in a westward direction on top of the underlying bedrock. In the geological past, around 450 million years ago, an ocean similar to the Atlantic began to shrink. As it did, the North American continent began to collide with island chains, which accreted at the edge of the continent and formed the land of what we now call New England. The major exceptions to this directionality are the southerly remnants of these ancient collisions around New York Bay, the serpentinite outcrops that form

Hoboken, New Jersey Hoboken ( ; ) is a City (New Jersey), city in Hudson County, New Jersey, Hudson County in the U.S. state of New Jersey. Hoboken is part of the New York metropolitan area and is the site of Hoboken Terminal, a major transportation hub. As of the ...

, and Todt Hill, Staten Island. These actually lie both east and west of Cameron's Line because it makes a sharp U-turn, heading south from Manhattan into Staten Island and hooking back north into Hudson County, New Jersey. Indeed, near New York City the term "line" becomes less applicable and its position is subject to much debate, because the boundary has been warped and folded into a complex three-dimensional shape by multiple tectonic episodes. After the Taconic orogeny, a collision with Africa (the Alleghanian orogeny) created the supercontinent Pangaea, which was later split by the rifting process that created the Atlantic Ocean, Ramapo Fault, Newark Basin, and the Palisades. The material in Cameron's Line is described as "highly laminated, migmatized, complexly folded and annealed zones of commingled mylonitic rocks".

References

{{reflist Geology of Connecticut Ordovician geology of New York (state) Ordovician geology of New Jersey Ordovician orogenies