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The geography of our planet is in flux.
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Each continent has ricocheted around the globe on one or more tectonic plates, changing quite dramatically with time.
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Today, we'll focus on North America and how its familiar landscape and features emerged over hundreds of millions of years.
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Our story begins about 750 million years ago.
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As the super continent Rodinia becomes unstable, it rifts along what's now the west coast of North America to create the Panthalassa Ocean.
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You're seeing an ancestral continent called Laurentia, which grows over the next few hundred million years as island chains collide with it and add land mass.
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We're now at 400 million years ago.
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Off today's east coast, the massive African plate inches westward, closing the ancient Iapetus Ocean.
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It finally collides with Laurentia at 250 million years to form another supercontinent Pangea.
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The immense pressure causes faulting and folding, stacking up rock to form the Appalachian Mountains.
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Let's fast forward a bit.
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About 100 million years later, Pangea breaks apart, opening the Southern Atlantic Ocean between the new North American Plate and the African Plate.
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We forge ahead, and now the eastward-moving Farallon Plate converges with the present-day west coast.
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The Farallon Plate's greater density makes it sink beneath North America.
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This is called subduction, and it diffuses water into the magma-filled mantle.
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That lowers the magma's melting point and makes it rise into the overlying North American plate.
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From a subterranean chamber, the magma travels upwards and erupts along a chain of volcanos.
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Magma still deep underground slowly cools, crystallizing to form solid rock, including the granite now found in Yosemite National Park and the Sierra Nevada Mountains.
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We'll come back to that later.
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Now, it's 85 million years ago.
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The Farallon Plate becomes less steep, causing volcanism to stretch eastward and eventually cease.
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As the Farallon Plate subducts, it compresses North America, thrusting up mountain ranges like the Rockies, which extend over 3,000 miles.
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Soon after, the Eurasian Plate rifts from North America, opening the North Atlantic Ocean.
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We'll fast forward again.
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The Colorado Plateau now uplifts, likely due to a combination of upward mantle flow and a thickened North American Plate.
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In future millennia, the Colorado River will eventually sculpt the plateau into the epic Grand Canyon.
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30 million years ago, the majority of the Farallon Plate sinks into the mantle, leaving behind only small corners still subducting.
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The Pacific and North American plates converge and a new boundary called the San Andreas Fault forms.
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Here, North America moves to the south, sliding against the Pacific Plate, which shifts to the north.
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This plate boundary still exists today, and moves about 30 millimeters per year, capable of causing devastating earthquakes.
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The San Andreas also pulls apart western North America across a wide rift zone.
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This extensional region is called the Basin and Range Province, and through uplift and erosion, is responsible for exposing the once deep granite of Yosemite and the Sierra Nevada.
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Another 15 million years off the clock, and magma from the mantle burns a giant hole into western North America, periodically erupting onto the surface.
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Today, this hotspot feeds an active supervolcano beneath Yellowstone National Park.
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It hasn't erupted in the last 174,000 years, but if it did, its sheer force could blanket most of the continent with ash that would blacken the skies and threaten humanity.
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The Yellowstone supervolcano is just one reminder that the Earth continues to seethe below our feet.
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Its mobile plates put the planet in a state of constant flux.
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In another few hundred million years, who knows how the landscape of North America will have changed.
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As the continent slowly morphs into something unfamiliar, only geological time will tell.