Researchers have analyzed grains of ancient quartz crystal from Australia and made a surprising discovery: while scientists believed that the entire Earth was covered in water 4 billion years ago, the researchers have found that this may not be the case, CNN reports.
Analysis of the chemicals in the crystals revealed that the lava in which they formed was in contact with fresh water, which the study found indicates that at least part of the Earth was once covered by dry land. CNN.
“By examining the age and oxygen isotopes of microscopic crystals of the mineral zircon, we found an unusually light isotope signature that dates back 4 billion years,” lead study author Hamed Gamaleldien said in a press release, according to CNN. “These light oxygen isotopes are typically the result of hot freshwater altering rocks several kilometers below the surface.”
The lead author explained that the presence of ancient freshwater can only be explained by the presence of land. “We know two important things here: we’ve found the oldest known evidence of freshwater and the most representative evidence of land above the ocean,” Gammalerdien said. (Related: Study: Science may have been wrong about the origin of life on Earth)
The find not only indicates the presence of land, but also suggests that life may have emerged less than 600 million years after Earth was formed, the report said.
“This discovery not only sheds light on the early history of Earth, but also suggests that land and freshwater systems provided the foundation for life to thrive within a relatively short time frame – less than 600 million years after Earth’s formation,” said study co-author Hugo Orioluk.
Gamalerdien explained that they can’t confirm whether any large land masses existed during this time, but according to CNN, it does indicate that there was at least some dry land above sea level. Additionally, fresh water likely occurred as rain, providing the conditions for the origin of life on Earth.
“The main novelty of the new paper is that it concludes that rainwater means the rocks were on land, not on the ocean floor,” John Valley, professor of geological sciences at the University of Wisconsin-Madison, said in a press release.
