The fascinating discovery about the Earth’s mantle and how it operates has been unveiled in a study published in the journal JGR Solid Earth. The findings reveal that the earth’s inner core, once thought to be a solid mass of iron, is layered with a form of ‘iron snow’. This iron snow is made up of tiny particles – much heavier than the snow we typically experience on Earth.
The Core of the Discovery
Researchers have uncovered that this iron-snow falls from the molten outer core and piles up in the Earth’s inner core. These stacks of iron particles can reach up to a staggering 320 kilometers in thickness. This revolutionary information was derived from analyzing signals generated by seismic waves as they traverse through the Earth.
Seismic waves are vibrations caused by activity such as earthquakes or explosions. They can travel within the Earth or along its surface. This ground-breaking study revealed that these seismic waves moved at a slower speed than anticipated when passing through the base of the outer core. Yet, conversely, these waves moved faster than expected when traversing the eastern hemisphere of the top inner core.
Understanding Seismic Behaviors
A substantial factor in these irregular speed changes was the snow pack’s slurry-like semi-liquid composition. This inconsistency of states consequently hinders the velocity of the seismic waves. Also, the differing thickness of the iron snow pile – thinner on the eastern side and denser in the west – also impacted the traveling speed of seismic waves.
Further investigation built upon previous knowledge indicating that a layer of slurry exists between the inner and outer core of the Earth. Data from recent experiments on core-like materials supported this theory. It was found that about 15% of the lowermost outer core could potentially comprise iron-based crystals, also known as ‘iron snow’.
Crystallization within the Core
Scientists discovered that these iron-based crystals could eventually descend through the liquid outer core and accumulate on top of the solid inner core. This process is brand new to the understanding of Earth’s internal operations, providing a fresh perspective on how our planet functions beneath the surface.
Breaking Down Earth’s Internal Structure
Earth comprises three distinct layers: the crust, the mantle, and the core, each with unique characteristics:
| Layer | Description |
|---|---|
| The Crust | This outer layer is constructed from solid rock, predominantly basalt and granite. There are two variants: oceanic (denser and thinner, mainly made up of basalt) and continental (less dense, thicker, mostly composed of granite). |
| The Mantle | Extending from Moho’s discontinuity (the boundary separating the crust and the mantle) to a depth of 2,900 km, the mantle is differentiated into two regions: the lithosphere (including the crust and upper part of the mantle) and asthenosphere (the origin of magma during volcanic eruptions). The lower mantle extends beyond the asthenosphere and is solid. |
| The Core | This section starts from the mantle-core boundary and can be divided into two parts: Outer core (in liquid state) and Inner core (solid state). Predominantly composed of heavy material like nickel and iron, it is sometimes referred to as the Nife layer. |
New Insights on Earth’s Anatomy
Such extensive research brings substantial revelations about Earth’s inner workings, particularly the intriguing concept of iron snow. The findings not only reshape our comprehension of the seismic behavior but also provide pivotal insights into the formation and structure of Earth’s core.
