Many people have heard the term 'Snowball Earth', a theory suggesting Earth was covered nearly or completely in ice and snow 700 million years ago.
Now, geologists have uncovered strong evidence from rocks in Colorado that massive glaciers covered Earth down to the equator and transformed the planet into an icicle floating in space.
The study, led by the University of Colorado Boulder, and its proponents posit that from approximately 720 to 635 million years ago, Earth was a 'Snowball Earth', researchers from CU Boulder said in a release Monday.
According to the study, and for reasons still unclear, a runaway chain of events radically altered the planet's climate, including temperatures plummeting and ice sheets forming several miles thick, creeping over every inch of Earth's surface.
"This study presents the first physical evidence that Snowball Earth reached the heart of continents at the equator," Liam Courtney-Davies, lead author of the new study and a postdoctoral researcher in the Department of Geological Sciences at CU Boulder said.
The team will publish its findings this week in the Proceedings of the National Academy of Sciences. Co-authors include Rebecca Flowers, professor of geological sciences at CU Boulder, and researchers from Colorado College, the University of California, Santa Barbara, and the University of California, Berkeley.
Colorado's connection to the study focuses on the Front Range Mountains, in particular one southern Colorado fourteener, aka, America's Mountain.
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Today, these features poke up from the ground in a few locations along the Front Range, most notably around Pikes Peak.
"On the slopes, a series of rocks nicknamed the Tavakaiv, or "Tava," sandstones hold clues to this frigid period in Earth's past," Courtney-Davies said.
To the untrained eye, they might seem like ordinary-looking yellow-to-brown rock running in vertical bands less than an inch to many feet wide.
For geologists, these features have an unusual history.
To study the history, the researchers used a dating technique called laser ablation mass spectrometry, which zaps minerals with lasers to release some of the atoms inside. They showed these rocks had been forced underground between about 690 and 660 million years ago -- likely from the weight of huge glaciers pressing down above them.
Courtney-Davies said the study will help scientists understand a critical phase in not just the planet's geologic history, but also the history of life on Earth. The first multicellular organisms may have emerged in oceans immediately after Snowball Earth thawed.
"You have the climate evolving, and you have life evolving with it. All of these things happened during Snowball Earth upheaval," he said. "We have to better characterize this entire time period to understand how we and the planet evolved together."
Research isn't done either. If such features formed in Colorado during Snowball Earth, they probably formed in other spots around North America too.
"We want to get the word out so that others try and find these features and help us build a more complete picture of Snowball Earth," Courtney-Davies said.
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