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We tend to think of Earth's
landmasses as being fixed in

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place, but in reality they
are attached to moving tectonic

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plates that constantly jostle
for position, and slide over the

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more viscous mantle beneath.

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Case in point: Iceland.

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Volcanic eruptions are common on
this young landmass, driven by

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the two tectonic plates that
divide it, and by its location

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above a hotspot - an upwelling
of magma that protrudes from

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deep in the mantle
up to the crust.

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This hotspot fuels Iceland's
eruptions today, but millions of

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years ago it was situated
beneath neighboring Greenland.

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Now, a NASA scientist and her
colleagues have used anomalies

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in Greenland's crustal magnetic
field to derive its geothermal

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heat flux.

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The researchers also
analyzed gravity data and other

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geophysical information to
effectively peer beneath

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Greenland's kilometers-thick ice
sheet and into the crust itself.

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What they found was a thermal
track in Greenland's bedrock

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that records the motions of a
continent over geologic time.

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Greenland is part of the
North American tectonic plate.

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For tens of millions of years,
the plate's movement pushed

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Greenland over the hotspot.

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When the hotspot emerged at the
Denmark Strait, it began raising

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the seafloor to form Iceland.

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Today, a channel of warm bedrock
marks the ancient path of the

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hotspot - a reminder that
nothing stands still over

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geologic time, and that even
the largest landmasses are

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constantly being
reshaped by our dynamic planet.

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[ Music ]

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[ Churning lava ]

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[ Satellite beeping ]