The international team of geologists showed that traces of animals in a quartzite found in Australia 1.7 billion years old were left after the formation of rocks. The article of scientists has been published in the journal Proceedings of the National Academy of Sciences.
More than 50 years ago, the find in the form of “moves”, similar to those left by animals, in the quartzite detected in the West, a quartite – mineral, formed under high pressure and temperature from sand deposits – became a riddle for researchers. The sand sediments arose 1.7 billion years ago in Paleoproterozoy, after another 500 million years old have become a solid quartzite, where it is not easy to leave traces, and the evidence of the existence of the first animals in the fossil chronicle appeared 0.6 billion years ago.
Researchers from Australia, China, the United States and Sweden measured the age of sand in the “moves” themselves, and it turned out to be almost a billion years of less than the age of the surrounding quartzite. After examining the samples under the microscope, scientists found that the traces were left in Eocene about 40 million years ago. Weathered turned the surface of quartzite into loose sandstone, in which the traces of animals left. The subsequent quarz deposition again turned the material of the “moves” in quartzite. According to scientists, traces were most likely left crustaceans during a short-term sea level.