New research on unique sandstone formations in the Colorado Rocky Mountains may confirm that Earth experienced a massive, planet-wide freeze known as "Snowball Earth." About 700 million years ago, Earth's surface was encased in 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, solid evidence of ice sheets reaching the planet's equatorial interior has remained elusive—until now. The recent study, published in the Proceedings of the National Academy of Sciences, identifies unusual sandstone deposits called Tava, found within the granite formations of Colorado's Pikes Peak. These sandstones likely formed under the pressure of 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 source of these Tava sandstone formations. Researchers discovered that the sandstones formed when sandy, water-saturated sediment was forced into weakened rock by the immense weight of ice sheets. The study's lead authors, Christine Siddoway and Rebecca Flowers, used advanced radiometric dating to determine that Tava sandstones developed around 690 to 660 million years ago, aligning with the Cryogenian Period.
Using iron minerals found with the sandstone, Siddoway's team employed uranium-lead dating to confirm the Tava sandstone's origins within the Snowball Earth timeframe. The team suggests that the ice sheets covering the equatorial Laurentia landmass, now part of North America, created the pressures necessary to form these sandstone injectites.
Implications for understanding Earth's climatic past
This discovery strengthens the Snowball Earth hypothesis while also shedding light on other geological phenomena, including “unconformities” where erosion has removed large portions of 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 these insights will lead to a deeper understanding of Earth's climate history and the processes that shaped our habitable planet.
