Eons

Around 600 million years ago, a chain of gigantic ancient mountains loomed over a barren, desolate landscape.

And you might be trying really hard to picture the biggest mountain range you possibly can right now, but I think I can confidently say: no, thats too small.

Because these were supermountains at least as tall as the very tallest mountain range today, the Himalayas, but nearly four times as long.

Supermountains were so ridiculously enormous that, as far as we know, theyve only ever formed twice, far back in deep time, and they lasted for just a small fraction of our planets overall history.

And both of the times when Earth had supermountains seem to coincide with some of the most profound evolutionary shifts in the entire history of life.

So its possible that their rise, and in particular, their fall, may be the reason that complex life is here at all.

In 2006, a team of geologists reported that theyd found a strange pattern.

They were studying sediment samples collected from huge deposits across multiple continents.

And they were specifically looking at tiny grains of zircon.

Zircon is an extremely durable mineral that can last hundreds of millions or even billions of years, making it a kind of geological timecapsule.

Now, zircons contain uranium, an element that gradually decays into lead at a known rate.

This allows scientists to date the age of the zircon grains based on the relative amounts of uranium and lead inside them.

And these zircon grains, collected from different sediment piles on continents as far apart as Australia and Africa, all had weirdly similar age patterns, suggesting that they were all deposited from the same source, around the same time.

But how could one source deposit sediment across such a huge geographic range?

Well, it turns out, these small and subtle clues pointed to pretty much the least small and subtle things ever: supermountains.

See, around 650 million years ago, some of the biggest continental collisions in history led to the formation of the supercontinent Gondwana.

And in the process, these researchers suggested, those collisions created a gigantic chain they called the Transgondwanan Supermountains.

Stretching more than 8000 km across and over 1000 km wide, it dwarfed all other known mountain ranges, lasting for hundreds of millions of years.

And with gigantic mountains, came a gigantic amount of sediment.

See, as mountains gradually erode over time, the rocks they brought up from the earths crust crumble into sediment and end up deposited all over the place by river systems, for example.

The bigger the mountains, the more sedimentation you get.

And the Transgondwanan supermountains may have resulted in some of the highest sedimentation rates in history enough to cover the entire United States 10 kilometers deep, according to the researchers estimates.

Not just because of their unprecedented size, but also because they were close to the equator, in areas with high rainfall that helped weather them away.

Plus, this far back, there was no vegetation on land to cover and protect the supermountains, and slow the weathering process.

So the levels of erosion would have been extreme.

And as giant river systems on either side of the range drained into the oceans, they would have carried huge amounts of sediment with them.

And heres where the researchers proposed something pretty radical .

What if dumping all that supermountain dust into the ancient oceans supercharged life on Earth?

See, the Transgondwanan supermountains just so happen to overlap in time with the appearance of large, complex life in the fossil record, during the Ediacaran and Cambrian Periods.

And the Cambrian is well-known for being the period when many major animal groups show up for the first time, during the so-called Cambrian explosion that began around 530 million years ago.

This explosion was during the literal peak of supermountain time, when enormous amounts of sediment would have been flowing into the oceans like never before.

Could this be not just correlation, but causation?

The researchers argued that the massive sediment dumps would have rapidly increased levels of key nutrients in the oceans like iron, phosphorus, and calcium.

This new continuous nutrient supply may have fueled the emergence of more productive and complex ecosystems that could support large animal life for the first time.

And this could potentially explain why we suddenly see so much biological change in the late Ediacaran and early Cambrian Key elements that had once been limited locked up in the Earths crust where life couldn't get them suddenly became abundant in the oceans.

The researchers even suggested that the rapid influx of calcium into the oceans, specifically, is what allowed for the sudden evolution of skeletons around this time, too.

Animals may have been building the first hard bodies on record out of broken fragments of supermountains.

So metal.

Literally, so much metal.

Now, the idea that ancient supermountains influenced a key chapter in the history of life on Earth was pretty tantalizing when it was proposed in 2006.

But it was hard to know for sure that it wasnt just coincidence.

Maybe these were just two strange events in natural history that happened around the same time.

To really strengthen the idea of a direct link between ancient supermountains and ancient evolutionary shifts, wed ideally need to see a repeating pattern.

For example, another ancient supermountain range occurring simultaneously with another big biological jump.

And then, over a decade later, researchers sampling sediment from the planets major rivers noticed another interesting pattern once again in those tiny, nearly-indestructible zircons.

Theyd been searching for supermountains using a particular method that measured the amount of an element called lutetium in their zircons.

If zircon grains are formed under really extreme pressure, they tend to have unusually low levels of lutetium.

Rather than being incorporated into the grains, the lutetium is soaked up by the mineral garnet, instead.

And one of the few ways zircons can be formed under such ridiculous amounts of pressure especially across a wide area is by being at the roots of ancient supermountains.

This time, when the researchers dated their low-lutetium zircons, they found not one, but two periods of supermountain formation.

One matched up with the Transgondwanan supermountains, of course, beginning around 650 million years ago.

But the other supermountain range was both new to science and much, much older.

It dated back two billion years, to a collision that formed the planets very first supercontinent, Nuna.

And much like Gondwana, the continental collisions that formed Nuna came together in just the right way to form a supermountain range over 8000 kilometers long.

The researchers named them the Nuna Supermountains.

Just like their younger Transgondwanan counterparts, the Nuna supermountains the first the world ever saw also coincided with some major evolutionary changes.

The earliest known organisms big enough to be seen by the naked eye appear in the fossil record around 1.9 billion years ago Right as the sedimentation from the Nuna supermountains would have been in full swing.

Theyre coiled filaments called Grypania.

And while we dont know exactly where they fit in the tree of life, they are orders of magnitude larger than the older microscopic fossil species that preceded them.

And the earliest eukaryotes organisms whose cells have a nucleus are thought to have evolved around this time, too a major milestone in early complex life.

So this is all consistent with the hypothesis that, on multiple occasions, supermountains freed early life from the previous constraints on size and complexity.

The sudden massive pulses of nutrients they supplied as they rose and fell may have first fueled the evolution of large and complex cells, and then on the second occasion, large and complex animals.

And the extreme sedimentation of both supermountains may have also helped trigger this biological effect by boosting oxygen levels.

For one, these unparalleled nutrient influxes would have stimulated massive blooms of tiny marine photosynthesizers which would have suddenly produced a lot more oxygen.

And for another, the erosion of the supermountains would have buried a lot of elements and minerals that normally bind to oxygen like organic carbon, pyrite, and iron allowing more oxygen to build up in the atmosphere.

This made yet another vital resource for complex life suddenly a lot more abundant and accessible.

There was also one more coincidence that researchers pointed out that could help bolster this idea.

They noted that the absence of supermountains also matched up with an absence of big evolutionary change.

A famously stagnant period of Earths history unfolded between 1.8 billion years ago and 800 million years ago, called the Boring Billion.

As the name suggests, not a lot seems to have changed during that time and maybe thats because no supermountains seem to have risen to provide the nutrients for another major evolutionary leap.

Now, we still have a lot to learn about Earths ancient supermountains, and exactly how big a deal they were for early life.

But studies like these point to something we do know for sure: from the highest peaks to the smallest cells, geology and biology are deeply intertwined.

And while its often said that we are stardust built from elements forged in the hearts of dying stars in a sense, we also might be supermountain dust.