Nevadan orogeny
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The Nevadan Orogeny was a major mountain building event that took place along the western edge of ancient North America between the Mid to Late Jurassic (between about 180 and 146 million years ago). The Nevadan orogeny was the first of three major mountain building episodes to transform Western North America between the Late Mesozoic and Early Cenozoic Eras, the latter two being the Sevier and Laramide orogeny, chronologically. Much like the two orogenies that followed, the Nevadan was caused by the subduction of oceanic lithosphere at a subduction zone running along the edge of the North American continent. This resulted in relatively cool oceanic crust descending into the lithosphere very quickly, and steeply beneath the edge of the continent. Due to the melting of the subducted plate, magma rose from the subducted crust producing a chain of volcanoes. Due to the steep angle of the subducted plate, these were located relatively close to continent's edge. This volcanic activity over the course of several million years would form what is today the Sierra Nevada of California.
