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In the whole history of the Earth, giant mountain ranges that geologists call supermountains formed only twice: once 2 billion years ago and another 600 million years ago. Each was more than 8,000 km long and more than 1,000 km wide, at least four times longer than the Himalayas, and both coincide with the greatest evolutionary leaps that life has ever taken.
The discovery began in 2006, when geologists studying the geological history of the Earth analyzed zircon grains collected from sedimentary deposits in continents as distant as Australia and Africa. Zircon is a practically indestructible mineral that acts as a geological time capsule: it contains uranium that transforms into lead at a known rate, allowing for accurate age calculation of the grain. The age patterns were strangely similar across different continents, which only made sense if all that sediment came from a single gigantic source: an unprecedented mountain range in the planet’s history.
This source was the Transgondwanan supermountains, formed about 650 million years ago by the continental collision that created the supercontinent Gondwana. The erosion of these mountains was so intense that, according to researchers’ estimates, the volume of sediment deposited would be enough to cover the entire United States with 10 kilometers of depth.
What happens when a giant mountain dumps nutrients into the ocean for millions of years
The supermountains were located near the equator, in regions with heavy rainfall, and at that time there was no vegetation on land to protect the rock.
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Erosion was extreme. Gigantic rivers carried iron, phosphorus, and calcium to the oceans, transforming nutrient-poor waters into a fertile broth capable of sustaining more complex ecosystems than anything that existed before.
The Cambrian explosion, when most major groups of animals appear in the fossil record for the first time, began about 530 million years ago, exactly at the peak of activity of the Transgondwanan supermountains.
Researchers suggested that the massive influx of calcium into the oceans may have been what allowed the evolution of the first skeletons.
Animals built the first rigid bodies in history from dissolved fragments of supermountains.
Why scientists believe it was not just coincidence
To prove that there was a real connection between supermountains and evolutionary leaps, researchers needed a pattern that repeated itself.
More than a decade after the 2006 study, another team found exactly that: by measuring lutetium levels in zircon grains, they identified a second supermountain, much older.
The supermountains of Nuna formed 2 billion years ago, during the collision that created the first supercontinent in history, and also extended over 8,000 km.
And the pattern was confirmed. The first organisms large enough to be seen with the naked eye, spiral filaments called Grypania, appear in the fossil record 1.9 billion years ago, exactly when the sedimentation of the Nuna supermountains would have been at its peak.
The first eukaryotes, organisms whose cells have a nucleus, also evolved during this time. Two supermountains, two evolutionary leaps. The likelihood of it being coincidence dropped drastically.
What happened in the 1 billion year interval between the two supermountains
Almost nothing. Between 1.8 billion and 800 million years ago, life was practically stagnant.
Scientists call this period the Boring Billion because almost no significant evolutionary change occurred during all that time.
And the explanation may be simple: without supermountains to dump nutrients into the oceans and increase oxygen levels, life had no fuel to make the next leap.
The erosion of supermountains not only dumped nutrients that fed explosions of photosynthesizing microorganisms (producing more oxygen), but also buried elements that normally bind to oxygen, such as organic carbon and pyrite, releasing even more oxygen into the atmosphere.
When the supermountains disappeared, this engine stopped, and life remained stuck at the same level for hundreds of millions of years.
We often say that we are stardust, made of elements forged in the hearts of dying suns. But perhaps we are also dust from supermountains. Comment below: did you know that complex life may have arisen from the erosion of mountains that no longer exist?
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