Did the Earth once completely freeze over? New evidence found in Colorado rocks

New research on unique sandstone formations in the Colorado Rocky Mountains could confirm that Earth experienced a massive, planet-wide freeze known as “Snowball Earth.” About 700 million years ago, the Earth’s surface was covered in ice, creating an extreme climate in which early life forms 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, until now, no solid evidence of the reaching of ice sheets in the equatorial interior of the planet has been obtained. The recent study, published in the Proceedings of the National Academy of Sciences, identifies unusual sandstone deposits called Tava, found in Colorado’s Pikes Peak granite formations. These sandstones likely formed under pressure from ice sheets, supporting the Snowball Earth theory with new geological evidence.

Tava sandstone formation linked to ancient ice pressures

Pikes Peak, a sacred site known to the Ute people as Tavá Kaa-vi, is the origin of these Tava sandstone formations. Researchers discovered that sandstones formed when water-saturated sandy sediments were pushed into rock weakened by the immense weight of ice sheets. The study’s lead authors, Christine Siddoway and Rebecca Flowers, used advanced radiometric dating to determine that the Tava sandstones developed approximately 690 to 660 million years ago, consistent with the Cryogenian period.

Using iron minerals found with the sandstone, Siddoway’s team used uranium-lead dating to confirm the origins of the Tava Sandstone during the Snowball Earth period. The team suggests that ice sheets covering the equatorial landmass of Laurentia, now part of North America, created the pressures necessary for the formation of these sandstone injectites.

Implications for understanding Earth’s climatic past

The discovery strengthens the Snowball Earth hypothesis while shedding light on other geological phenomena, including “unconformities” in which erosion has erased large portions of Earth’s rock records. The Pikes Peak findings indicate that similar unconformities may predate Snowball Earth, suggesting complex erosional processes over millions of years. Scientists hope this knowledge will lead to a better understanding of Earth’s climate history and the processes that have shaped our habitable planet.