The Tectonic Theory (It’s Not “Just a Theory”)

Earth is a weird little planet. I’m not talking about all the oxygen and liquid water. I’m not even talking about life (although that is really weird). You may not have thought about this before, but there’s another thing that makes Earth strange: earthquakes.

Of all the terrestrial planets and moons in the Solar System, only Earth has active plate tectonics (also, maybe Mars… maybe).

The theory of continental drift was first proposed by Alfred Wegener in the 1910’s with his book entitled The Origin of Continents and Oceans. At the time, the idea was not well received. Though Wegener had plenty of evidence that the continents had moved, he couldn’t explain why. His contemporaries preferred imagining the world as solid and unchanging. They didn’t want to believe continents could move. (Also, it says nothing about continental drift in the Bible.)

A more formal theory of plate tectonics didn’t emerge until the 1960’s, and it has since become the unifying theory of geology. We now know that massive tectonic plates drift about, jostling against each other, pushed and pulled by the rising and sinking of magma in the Earth’s interior.

Where plates meet, they form three types of boundaries:

• Divergent boundaries: two plates move apart, allowing magma to fill the gaps between them.
• Convergent boundaries (a.k.a. subduction zones): two plates collide, forcing one plate beneath the other.
• Transformal boundaries: two plates moving alongside one another scrape against each other. Most earthquake zones, like the San Andreas Fault in California, occur near transformal boundaries.

As we try to understand Earth, especially how life developed and thrived here, we should take note of all of Earth’s weird traits. Water and oxygen are not the only things that make our planet special.

Links

Without Plate Tectonics Life on Earth Might Never Have Gained a Foothold from Daily Galaxy.

Shift Happens: Mars May Have Plate Tectonics from Discovery News.