660 million years ago, glaciers covered even the equator: new rock discovery confirms it

660 Million Years Ago: Was Earth the Real Winter Wonderland?

Forget about the eternal debate around global warming for a second and picture this: some 720 to 635 million years ago, our good old Earth wasn’t just chilly—it was locked in one of the deepest freezes in planetary history. And by deep freeze, we mean glaciers stretching not just to the tips of the poles, but hugging the equator too. Recent revelations, published in Proceedings of the National Academy of Sciences and highlighted by The Conversation on November 11, 2024, confirm this icy scenario thanks to a humble rock high atop Pikes Peak, Colorado. Grab your scarves (and maybe an ice pick) as we dive into this frosty tale!

The “Snowball Earth”: Ice, Ice, Everywhere

Scientists believe that during this ancient period, virtually the entire surface of Earth was draped in a thick, continuous sheet of ice, oceans and continents united. This glacial age, evocatively named Snowball Earth (or “Iceball Earth” if you really want to underscore the chill), is thought to have lasted tens of millions of years. This was not your average cold snap—it was an epoch-spanning glaciation with only the hardiest forms of life eking out an existence beneath the planetary ice blanket.

What happened when all this ice eventually thawed? A surge of multicellular life emerged, giving way to the vibrant forms we’re somewhat more familiar with today (give or take the odd trilobite). But how do we really know all this happened, especially at the equator, where perpetual summer is practically mandatory?

The Colorado Connection: Solving the Equatorial Glacial Puzzle

Evidence of this glacial era has popped up across various regions globally—but until now, signs had been missing from the innards of continents positioned near the equator during the era. Enter new research from Pikes Peak, Colorado (yes, where there’s more than just marathons), which may finally fill in this critical gap. The study, led by Liam Courtney-Davies, has shed light on curious sedimentary rocks unearthed on the mountain.

Known as Tava—a name given by indigenous American peoples—these yellow-brown sandstones are more than just picturesque. According to Courtney-Davies, they are jam-packed with clues from this glacial period. The rocks appear to have formed when immense pressure from a gigantic ice sheet squeezed sand-rich sediments mixed with meltwater into the underlying bedrock. Basically, mother nature’s way of leaving a calling card from the ancient freezer.

• Dating the chill: To make sure they weren’t jumping to icy conclusions, researchers zapped the minerals with lasers (a high-tech version of melting the ice?), using a method called “laser radiometric dating.” 
• The result? The Tava rocks formed about 690 to 660 million years ago, matching the era when massive glaciers would have weighed down the bedrock—right at the equator’s doorstep.

Deep Freeze Mysteries: Why Did It Get So Cold?

As for what sparked this wild cold snap, the scientific consensus is…not quite consensus. Competing ideas jostle for the spotlight:

• Tectonic shifts: Some say tectonic changes released light-reflecting particles into the air, shielding Earth from the Sun’s warmth.
• Volcanic CO2: Others point to volcanic eruptions pumping the atmosphere with CO2, which, after the deep freeze, could have reversed the process and set the stage for warming.
• An asteroid? Because nothing says drama like a space rock meddling with the climate.

Back then, the land we now call Colorado wasn’t skipping through Rockies meadows; it was nestled right on the equator, as part of the ancient supercontinent Laurentia. The fact that such glaciers existed there suggests, as the researchers believe, they must have formed practically anywhere on Earth—no region was spared from the planetary snow day.

Why the Snowball Earth Still Matters Today

Liam Courtney-Davies emphasizes the significance: “Better characterizing this period lets us understand how we and the planet evolved together. If such features formed in Colorado during Snowball Earth, they probably also appeared elsewhere in North America.” It’s a small leap from combing the heights of Pikes Peak to re-imagining geology across a continent.

The quest is far from over. Scientists hope the secrets buried in those elusive Colorado rocks will lead to more discoveries, tracing the frosty fingerprints of Snowball Earth around the globe. So next time you complain about the cold, just be glad you weren’t around when even the equator was wrapped in ice.

Lesson learned? Our planet definitely has a flair for the dramatic. And when scientists say Earth moves in cycles, don’t be too quick to reach for your swimsuit.