Deep under the Atlantic, separating Africa and South America, magma below the ten thousand mile ridge marks the boundary of the delicate tectonic plates. Just below the plates lies a whole world of chaos. The extreme temperature inside the core deprives magma of its magnetic properties. Left with no other choice, it succumbs to the heat, melting its life away. Earth then takes the molten iron in it on a roundabout chase around its axis until it feels giddy. Chained to Earth’s gravity and sat upon by Earth’s crust, it has little to no choice about its movements. Every now and then, it bubbles up in anger, wobbling the slab of solid rock floating above it. Gravity dominates its force and it watches unhappily as the plates regain their composure, closing the tiny gap between them. Outraged, it spins even faster, disrupting the balance. It rotates along with the earth, only at a greater speed. This time, it hits the ridge with all its force, widening the gap to several kilometers. It marvels at its own sight, bright and restless, gushing out onto the seabed, its ferocity reflected in the rising fumes around it. Eager to cover the world, it starts flowing out in all directions, only to be rooted in its spot by the sudden drop in temperature around it.
Willink, Cai. Lava Lake of the Nyiragongo Volcano in Virunga National Park. 2011. wikimedia.org. Web. 27 Apr. 2017.
The iron in the lava finds itself orienting along the direction of Earth’s magnetic field before turning itself into dull brown color. Marking a new layer of Earth’s crust, it settles down to wait for hundreds of thousands of years for its secret to be unlocked. The drastic change in the temperature freezes the iron in it, and along with it, the direction of Earth’s magnetic field.
Every new layer of crust sees the alternate orientation of iron, indicating the reversals of Earth’s magnetic field. Only after thousand such eruptions and hundred such magnetic pole reversals did the species on Earth finally begin to understand what Earth was up to.
Deep inside the core, molten iron rotates in harmony with the earth, its symmetrically fluid motion generating humongous magnetic fields extending above and beyond Earth’s surface. The rotation and temperature are just right for the field to orient itself like a bar magnet. It aligns its magnetic north and south poles roughly along the geographic ones, enabling accurate navigation for the inhabitants living on the surface of the Earth.
Novella, Bob. Earth’s Magnetic Field. 2014. theskepticsguide.org. Web. 27 Apr. 2017.
And sometimes, just sometimes, when the harmony is disturbed, the poles turn upside down.
- Magnetic Field Reversals- www.youtube.com
- Plate Tectonics- www.livescience.com
- The Mid-Atlantic Ridge- www.youtube.com