We often think of the ground beneath us as solid and unchanging. But deep under the surface, Earth is constantly shifting and evolving.
New research now shows that a strange and quiet process is taking place right below parts of the United States. And scientists are just beginning to understand it.
According to a recent study published in Nature Geoscience, parts of the Earth's crust in the central United States are slowly sinking, according to WP.
This is not something visible to the naked eye. But deep underground, rock is melting and forming heavy droplets.
These droplets eventually get so dense that they fall deeper into the Earth’s mantle.
Researchers say this is happening below a large, stable chunk of Earth's crust called the North American craton.
Cratons are ancient and normally very stable. They are the base of entire continents. But something unusual is going on here.
Junlin Hua, a seismologist from the University of Science and Technology of China, led the research.
He worked alongside scientists from the University of Texas. They believe that parts of an old oceanic plate called the Farallon Plate are causing this change.
That plate has been sinking under North America for millions of years. It now lies far below but is still influencing the area.
As heat builds up under the craton, the lower parts of the crust start to melt and become unstable.
The melted rock forms drips that slowly fall deeper. Scientists compare it to a very slow version of the tar drop experiment.
They discovered all this by using seismic waves. These waves travel differently through solid and melted rock.
By measuring them, researchers could map out what’s going on deep below.
Right now, there is no danger to people living on the surface. The sinking is extremely slow.
But the discovery gives scientists a rare look at how continents are shaped and changed over time.
It may also help them understand what could happen to other parts of the planet in the future.
