Earth’s oldest soil could be tucked away in an ancient rock outcrop in Greenland, according to new research. Dating back some 3.7 billion years, the suspected soil—exposed underneath a retreating ice cap—could potentially contain fossilized traces of primordial life. The new study, published this week in the awkwardly named science journal Palaeogeography, Palaeoclimatology, Palaeoecology, opens thusly: “Soil formation is a combination of physical, chemical, or biological processes important for regulating planetary atmospheres, and the ultimate source of essential nutrients such as phosphorus for the nutrition and origin of life.” Indeed, soil—unlike sterile bits of rock or sand—serves as a natural medium for the growth of land plants. Identifying our planet’s oldest soils, therefore, is of critical importance to scientists who study Earth’s formative period and the emergence of our planet’s first organisms. The new study, led by University of Oregon geologist Greg Retallack and Old Dominion University geologist Nora Noffke, describes a tantalizing new rock outcrop in the Isua Greenstone Belt of southwestern Greenland that, quite possibly, contains our planet’s oldest dirt, and by consequence, the oldest traces of life on the planet. It’s not actually dirt—it’s a substance known as paleosol, former soil that’s been packed tightly into solid rock. During a recent helicopter survey, Noffke saw the outcrop sticking out from underneath a receding ice cap. After collecting the rocks and analyzing them in the lab, the researchers dated the samples at 3.7 billion years old—which, if confirmed, would make it the oldest known dirt on the planet. Prior, the… [Read full story]
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