Posted on 11/19/2024 10:43:36 AM PST by Red Badger
New findings from Colorado’s rock formations provide physical evidence supporting the Snowball Earth theory, which suggests Earth was once frozen entirely, down to the equator. This study offers insights into a key phase of climate and life evolution. Credit: SciTechDaily.com Evidence from Colorado suggests glaciers once covered Earth to the equator, supporting the Snowball Earth theory. This discovery provides insight into early climate shifts and the evolution of life. Geologists have discovered compelling evidence in Colorado that hundreds of millions of years ago, enormous glaciers blanketed Earth as far as the equator, turning the planet into an icicle drifting through space.
The study, led by the University of Colorado Boulder, is a coup for proponents of a long-standing theory known as Snowball Earth. It posits that from about 720 to 635 million years ago, and for reasons that are still unclear, a runaway chain of events radically altered the planet’s climate. Temperatures plummeted, and ice sheets that may have been several miles thick crept 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,” said Liam Courtney-Davies, lead author of the new study and a postdoctoral researcher in the Department of Geological Sciences at CU Boulder.
Tava Sandstone
Dark brown bands of Tava sandstone cut through other rocks. Credit: Liam Courtney-Davies
The team published its findings on November 11 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 University of California, Berkeley.
The study zeroes in on the Front Range of Colorado’s Rocky Mountains. Here, a series of rocks nicknamed the Tavakaiv, or “Tava,” sandstones hold clues to this frigid period in Earth’s past, Courtney-Davies said.
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 that these rocks had been forced underground between about 690 to 660 million years ago—in all likelihood from the weight of huge glaciers pressing down above them.
Courtney-Davies added that 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.”
Searching for snow
The term “Snowball Earth” dates back to a paper published in 1992 by American geologist Joseph Kirschvink.
Despite decades of research, however, scientists are yet to agree whether the entire globe actually froze. Geologists, for example, have discovered the fingerprints of thick ice from this time period along ancient coastal areas, but not within the interior of continents close to the equator.
Which is where Colorado enters the picture. At the time, the region didn’t sit at the northern latitudes where it does today. Instead, Colorado rested over the equator as a landlocked part of the ancient supercontinent Laurentia.
If glaciers formed here, scientists believe, then they could have formed anywhere.
Going deep
The search for that missing piece of the puzzle brought Courtney-Davies and his colleagues to the Tava sandstones. Today, these features poke up from the ground in a few locations along Colorado’s Front Range, most notably around Pikes Peak. To the untrained eye, they might seem like ordinary-looking yellow-brown rocks running in vertical bands less than an inch to many feet wide.
But for geologists, these features have an unusual history. They likely began as sands at the surface of Colorado at some point in the past. But then forces pushed them underground—like claws digging into the Earth’s crust.
“These are classic geological features called injectites that often form below some ice sheets, including in modern-day Antarctica,” Courtney-Davies said.
He wanted to find out if the Tava sandstones were also connected to ice sheets. To do that, the researchers calculated the ages of mineral veins that sliced through those features. They collected tiny samples of the minerals, which are rich in iron oxide (essentially, rust), then hit them with a laser. In the process, the minerals released small quantities of the radioactive element uranium. Because uranium atoms decay into lead at a constant rate, the team could use them as a sort of timekeeper for the planet’s rocks.
It was a Eureka moment: The group’s findings suggest that the Tava sandstone had been pushed underground at the time of Snowball Earth. The group suspects that, at the time, thick ice sheets formed over Colorado, exposing the sands to intense pressures. Eventually, and with nowhere else to go, they pushed down into the bedrock below.
“We’re excited that we had the opportunity to unravel the story of the only Snowball Earth deposits that have so far been identified in Colorado,” Flowers said.
The researchers aren’t done yet: If such features formed in Colorado during Snowball Earth, they probably formed in other spots around North America, too, Courtney-Davies said: “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.”
Reference:
“Hematite U-Pb dating of Snowball Earth meltwater events”
by
Liam Courtney-Davies, Rebecca M. Flowers, Christine S. Siddoway, Adrian Tasistro-Hart and Francis A. Macdonald, 11 November 2024, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2410759121
PinGGG!.................
They used to teach this in sixth grade science class.
But then cars came along.....and there was an unstoppable warm up...the earth puked up hostile gases...and then...in the distance...a garden....with an apple tree, a fig tree and a hard wood tree...you know the rest....
Then the Flinstones got SUVs and warmed the planet.
Good thing the aliens showed up with their SUVs to warm things back up.
It was called Snowball Earth.
I have, yet another, dumb question. Doesn’t this mean there was more water back then?
Now it’s Pickleball Earth............
There are videos on youtube that talk about the age and development of the earth. One stated that the Earth was once an “ice planet” during one period and overrun with fungiform life in another. In a different video, a team used (LED?) lights on a dry lake bed to describe the age of the earth in a straight line. The lights stretched for about a mile. Human history (IIRC) could measured between two out-stretched arms at the end of the same line.
More ice, less water..................
I have heard a similar comparison, where the Empire State Building height represents the Earth’s timeline, and a postage stamp place atop the building represents the entirety of human history...............
Not necessarily... Same water... just frozen and piled up in places. The weight of the glaciers actually deformed the crust in some points so much that when the ice melted, the magma pushed the crust back up... This is how some rock at the tops of mountains was once sea bed...
Well, that and crustal boundary layers, obduction and subduction zones, etc...
I’m going to say no. It was just taken out of the loop in the form of ice. Sea levels were far lower at the time.
It has been a theory for 30 years, that now has some empirical support. Interesting.
Amazing what a few cow farts can do.
And big hairy elephants with long tuskusses would wander across the glaciers.
Exactly. You can today go to the top of mountain ranges in the American West and other places and find the marks of glaciers as they moved across the continent when these mountains were young pups.
“ice sheets that may have been several miles thick crept over every inch of Earth’s surface.”
How would that work? As the ice sheets grew larger and larger, there was less and less ocean surface for evaporation needed to create snowfall. When the ice sheets covered half of the ocean surface, evaporation would be reduced by half and snowstorms would be greatly diminished.
One would think that would be a self-limiting phenomenon, that you could not get to more than 50% or 75% of ice coverage of the oceans before there simply would not be enough snowfall to continue glacial growth.
But the glacial the ice sublimates (goes directly from solid to gas without passing through the liquid phase). So the water cycle could continue due to atmospheric water originating from sublimating glacial ice rather than evaporating ocean water.
In the case of glaciers, sublimation can occur when the air temperature is below freezing and the air is very dry (as the oceans got covered in ice, the air would become drier and drier). Under these conditions, ice at the surface of a glacier can turn directly into water vapor and be carried away by the wind. This process can occur even when the air temperature is below freezing because the heat required to sublimate the ice comes from the ice itself, which cools as it sublimates and can keep the surface below the air temperature.
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