Inner snow much heavier than any snowflake on Earth
The snow is made of tiny particles of iron—much heavier than any snowflake on Earth’s surface—that fall from the molten outer core and pile on top of the inner core, creating piles up to 200 miles thick that cover the inner core.
Contradictions between seismic data and existing models of our planet’s molten insides have been hard to solve. So geologists are now reconsidering the existence of a fuzzy zone of mineral ‘snow’ gently falling from the bottom of the outer core.
Not only could this tell us a few things about our planet’s geology, but it might also help to explain how other planets like ours form.
“The Earth’s metallic core works like a magma chamber that we know better of in the crust,” said Jung-Fu Lin, a professor in the Jackson School of Geosciences at The University of Texas at Austin and a co-author of the study.
The study is available online and will be published in the print edition of the journal JGR Solid Earth on December 23.
Expert and professor at Sichuan University in China, Say
Youjun Zhang, an associate professor at Sichuan University in China, led the study. The other co-authors include Jackson School graduate student Peter Nelson; and Nick Dygert, an assistant professor at the University of Tennessee who conducted the research during a postdoctoral fellowship at the Jackson School.
Decades of studies on sound waves bouncing around inside our planet show they slow down in a weird way when they pass through the lower layers of the outer core.
Weirder yet, the data suggests there’s a marked difference in how the waves are transmitted on either side of the core, slowing down more across the western surface than the eastern.
It’s almost as if the core is covered in something viscous, and that coating isn’t even all the way around.
The study shows an explanation for these aberrations.
The study proposes the iron snow-capped core as an explanation for these aberrations. The scientist S.I. Braginkskii proposed in the early 1960s that a slurry layer exists between the inner and outer core, but prevailing knowledge about heat and pressure conditions in the core environment quashed that theory. However, new data from experiments on core-like materials conducted by Zhang and pulled from more recent scientific literature found that crystallization was possible and that about 15% of the lowermost outer core could be made of iron-based crystals that eventually fall down the liquid outer core and settle on top of the solid inner core.
And given the core’s influence over phenomena that affect the entire planet, from generating its magnetic field to radiating the heat that drives the movement of tectonic plates, understanding more about its composition and behavior could help in understanding how these larger processes work.
Bruce Buffet, a geosciences professor at the University of California, Berkley who studies planet interiors and who was not involved in the study, said that the research confronts longstanding questions about the Earth’s interior and could even help reveal more about how the Earth’s core came to be.
This article first published in the Journal of Geophysical research