Comment: 15:08 - 16:02 (00:54)
Source: Annenberg/CPB Resources - Earth Revealed - 7. Mountain Building
Keywords: continent, seamount, "island arc", "Western North America", subduction, "Pacific Ocean", lithosphere, "exotic terrane", "suspect terrane", "accreted terrane", "fault zone", collision
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Our transcription: Much of the landscape of Western North America is made up of continental fragments, seamounts and island arcs.
These land masses have attached to the continent during the subduction of Pacific Ocean lithosphere over the past 150 million years.
Such fragments are commonly described by geologists as "exotic, " "suspect, " or "accreted" terranes.
The term "terrane" refers to an area of rocks having continuous strata or structure and a distinctive composition.
The boundary between an accreted terrane and the main body of the continent may be marked by a fault zone or in places by a belt of oceanic rock, which was not subducted but caught in the squeeze between the colliding land masses.
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Geology School Keywords
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