ABOVE: Photograph of the putative stromatolitic structures in an outcrop (arrows). While most of the structures point upward (yellow arrows), one points downward (red arrow), indicating the structures did not grow upward from the sea floor.
ABIGAIL ALLWOOD
In 2016, researchers found what they interpreted as stromatolites—layered formations made by sediments from microbes—in a 3.7-billion-year-old set of rocks known as the Isua Belt in Greenland. At the time, they were the oldest evidence of life on Earth by about 200 million years. But in a study published today (October 17) in Nature, another research team challenges the claim that the structures are microbe-made, proposing instead that the shapes in the rocks are due to deformations that occurred as the rocks aged.
“At face value, the results of this study provide a reminder that in geology, some observations are scale-dependent [and that] morphological analysis of putative ancient biological forms is also inherently ...
