Remnants of the Farallon Plate, deep in the earth's mantle.

The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic period. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other The North American Plate is a Tectonic plate covering most of North America, Greenland and part of Siberia. The State of Utah (ˈjuːtɔː or) is a western state of the United States. Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in The Jurassic is a geologic period and system that extends from about Ma (million years ago to  Ma that is from the end of the Triassic to the beginning It is named for the Farallon Islands which are located just west of San Francisco, California. The Farallon Islands, or Farallones, are a group of Islands and rocks found in the Gulf of the Farallones, off the coast of San Francisco, The City and County of San Francisco is the fourth most populous city

Over time the central part of the Farallon Plate was completely subducted under the southwestern part of the North American Plate. The remains of the Farallon Plate are the Juan de Fuca, Explorer and Gorda Plates, subducting under the northern part of the North American Plate, the Cocos Plate subducting under Central America and the Nazca Plate subducting under the South American Plate. The Juan de Fuca Plate, named after the explorer, is a Tectonic plate arising from the Juan de Fuca Ridge, and subducting under the northerly The Explorer Plate is an oceanic Tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada. The Gorda Plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon Plate. The North American Plate is a Tectonic plate covering most of North America, Greenland and part of Siberia. The Cocos Plate is an oceanic Tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic Tectonic plate in the eastern Pacific Ocean basin off the west The South American Plate is a Tectonic plate covering the Continent of South America and extending eastward to the Mid-Atlantic Ridge.

It is thought that much of the plate initially went under North America (particularly the western United States and southwest Canada) at a very shallow angle, creating much of the mountainous terrain in the area (particularly the American Rocky Mountains). Mountain peaks of the Rocky Mountains The Rocky Mountains, often called the Rockies, are a Mountain range in western North America. A large fragment of the subducted plate is believed to presently be in the mantle under eastern North America. It is also speculated that the associated spreading center was also subducted and may be responsible for the rifting which has created the Basin and Range geologic province. Basin and range is a geologic term for a type of Topography characterized by a series of separate and parallel mountain ranges with broad valleys interposed extending

The Farallon Plate is also responsible for transporting old island arcs and various fragments of continental crustal material rifted off from other distant plates and accreting them to the North American Plate. These fragments from elsewhere are called terranes (sometimes, "exotic" terranes). A terrane in Geology is a fragment of crustal material formed on or broken off from one Tectonic plate and accreted — " sutured " Much of western North America is composed of these accreted terranes.

See also

• Kula Plate
• Izanagi Plate

External links

• Reconstruction of Farallon Plate
• USGS diagram
• Pictures and animations of the subduction of the Farallon Plate at NASA's Goddard Space Flight Center:
  • Animation of the Farallon subduction, with special emphasis on the effects on the surface of western North America