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The Farallon plate subducted under North America from the late Mesozoic, while spreading between the Pacific and Farallon plates was initiated 190 Ma and lasted until the break-up of the Farallon plate 23 Ma. During the Cenozoic the Farallon plate broke up along the eastern Pacific margin into the Kula, Vancouver/Juan de Fuca, and Cocos plates.
The Pacific plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km 2 (40 million sq mi), it is the largest tectonic plate. [2] The plate first came into existence as a microplate 190 million years ago, at the triple junction between the Farallon, Phoenix, and Izanagi plates. The Pacific plate subsequently grew ...
Relative velocity vectors of Pacific, Farallon, and Kula plates 55 million years ago (Black represents present-day land area). The Pacific-Farallon Ridge was a spreading ridge during the Late Cretaceous that extended 10,000 km in length and separated the Pacific Plate to the west and the Farallon Plate to the east.
The Pacific Plate began forming when the triple junction at the center of Panthalassa destabilized about 190 million years ago. Panthalassa , also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek πᾶν "all" and θάλασσα "sea"), [ 1 ] was the vast superocean that encompassed planet Earth and surrounded the ...
Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction. [citation needed]
The Pacific plate changes its direction of motion from north to northwest. 35 Ma Eocene Rio Grande Rift begins to form. 20 Ma Miocene: San Andreas Fault comes into being as the North American plate begins splitting the Farallon plate in two. 17 Ma - 14 Ma Miocene: Columbia River Basalt Group forms. 8 Ma Miocene
About 25 million years ago, the southern part of Zealandia (on the Pacific Plate) began to shift relative to the northern part (on the Indo-Australian Plate). The resulting displacement by approximately 500 km (310 mi) along the Alpine Fault is evident in geological maps. [ 20 ]
Most of the region began forming about 200 million years ago as the North American Plate started to drift westward during the rifting of Pangaea. Since that date, the western edge of North America has grown westward as a succession of island arcs and assorted ocean-floor rocks have been added along the continental margin.