00:01We tend to think of Earth's landmasses as being fixed in place,
00:04but in reality they are attached to moving tectonic plates
00:07that constantly jostle for position and slide over the more viscous mantle beneath.
00:12Case in point, Iceland.
00:15Volcanic eruptions are common on this young landmass,
00:18driven by the two tectonic plates that divide it,
00:20and by its location above a hotspot,
00:23an upwelling of magma that protrudes from deep in the mantle up to the crust.
00:27This hotspot fuels Iceland's eruptions today,
00:31but millions of years ago it was situated beneath neighboring Greenland.
00:35Now, a NASA scientist and her colleagues have used anomalies in Greenland's crustal magnetic field
00:41to derive its geothermal heat flux.
00:44The researchers also analyzed gravity data and other geophysical information
00:49to effectively peer beneath Greenland's kilometers thick ice sheet and into the crust itself.
00:55What they found was a thermal track in Greenland's bedrock
00:58that records the motions of a continent over geologic time.
01:02Greenland is part of the North American tectonic plate.
01:05For tens of millions of years, the plate's movement pushed Greenland over the hotspot.
01:10When 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 by our dynamic planet.
01:29The End
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