A Princeton-led team of geologists analyzed samples of inorganic and organic carbon from the hills of the Trezona Formation in South Australia to document one of the largest perturbations to the carbon cycle in all of Earth history.

Photo: Adam Maloof

Princeton graduate students Catherine Rose and Nicholas Swanson-Hysell stand at the boundary of the Cryogenian and Ediacaran periods, distinguishable by the different colors of the glacial rocks below and the carbonate rock above.

Photo: Adam Maloof

These layered structures called stromatolites from the Cryogenian Trezona Formation were created by biofilms of microbes that formed in a shallow-water tropical environment in South Australia's Adelaide Rift Complex about 650 million years ago.

Photo: Nicholas Swanson-Hysell