Was the Earth once completely frozen? New evidence found in Colorado rocks

New research on unique sandstone formations in the Colorado Rocky Mountains may confirm that Earth experienced a massive, planet-wide cold snap known as “Snowball Earth.” About 700 million years ago, the Earth’s surface was covered with ice, creating an extreme climate where early life not only survived but later evolved into complex multicellular organisms.

For decades, the Snowball Earth hypothesis was supported primarily by coastal sedimentary rocks and climate models. However, concrete evidence of ice sheets reaching the planet’s equatorial interior has so far remained elusive. The recent study, published in the Proceedings of the National Academy of Sciences, identifies an unusual sandstone deposit, called Tawa, found within the granite formations of Colorado’s Pikes Peak. These sandstones probably formed under the pressure of ice sheets, providing new geological evidence supporting the snowball Earth theory.

The Tawa Sandstone Formation is linked to the pressure of ancient ice

Pikes Peak, a sacred site known to the Ute people as Tawa Ka-wi, is the source of these Tawa sandstone formations. Researchers discovered that the sandstones were formed when the heavy weight of ice sheets pushed sandy, water-saturated sediment into weaker rock. The study’s lead authors, Christine Siddoway and Rebecca Flowers, used advanced radiometric dating to determine that the Tawa Sandstones developed approximately 690 to 660 million years ago, corresponding to the Cryogenian period.

Using iron minerals found with the sandstone, Siddoway’s team used uranium-lead dating to confirm the origin of the Tawa Sandstone within the Snowball Earth time frame. The team suggests that the ice sheets covering the equatorial Laurentia landmass, now part of North America, created the pressure necessary to create these sandstone injections.

Implications for understanding Earth’s climatic past

The discovery strengthens the Snowball Earth hypothesis, while also shedding light on other geological phenomena, including “unconformity”, where erosion has removed large portions of the Earth’s rock record. The findings at Pikes Peak indicate that similar unconformities may predate Snowball Earth, suggesting complex erosion processes over millions of years. Scientists hope that these findings will lead to a deeper understanding of Earth’s climate history and the processes that shape our habitable planet.