00:00We tend to think of Earth's landmasses as being fixed in place,
00:04but in reality, they are attached to moving tectonic plates
00:08that constantly jostle for position and slide over the more viscous mantle beneath.
00:12Case in point, Iceland.
00:16Volcanic eruptions are common on this young landmass, driven by the two tectonic plates
00:20that divide it, and by its location above a hotspot, an upwelling of magma
00:24that protrudes from deep in the mantle up to the crust.
00:28This hotspot fuels Iceland's eruptions today,
00:32but millions of years ago, it was situated beneath neighboring Greenland.
00:36Now, a NASA scientist and her colleagues have used anomalies
00:40in Greenland's crustal magnetic field to derive its geothermal heat flux.
00:44The researchers also analyzed gravity data
00:48and other geophysical information to effectively peer beneath Greenland's
00:52kilometers-thick ice sheet and into the crust itself.
00:56What they found was a thermal track in Greenland's bedrock that records the motions
01:00of a continent over geologic time.
01:04Greenland is part of the North American tectonic plate.
01:08For tens of millions of years, the plate's movement pushed Greenland over the hotspot.
01:12When the hotspot emerged at the Denmark Strait, it began raising the seafloor to form Iceland.
01:16Today, a channel of warm bedrock marks the ancient path of the hotspot,
01:20a reminder that nothing stands still over geologic time
01:24and that even the largest landmasses are constantly being reshaped
01:28by our dynamic planet.
01:32music
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