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