What are terranes? How are they recognized? What role did accretion of terranes play in the growth of western North America?
Small accreted lithospheric blocks, called terranes, are found in many mountain systems. They are composed of such different fossils, stratigraphy, structural trends, and paleomagnetic properties from the surrounding rocks and craton that geologists think that they were carried great distances as parts of other plates until they collided with other terranes and continents. More than 100 different-sized terranes were added to the western margin of North America during the past 200 million years.
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