Academic journal article Science Scope

More Evidence of an Ancient Extraterrestrial Impact

Academic journal article Science Scope

More Evidence of an Ancient Extraterrestrial Impact

Article excerpt

Researchers have identified a nearly 13,000-year-old layer of thin, dark sediment buried in the floor of Lake Cuitzeo in central Mexico. The sediment layer contains an exotic assemblage of materials, including nanodiamonds, impact spherules, and more, which the researchers claim are the result of a cosmic body impacting Earth. These new findings are the latest to strongly support a controversial hypothesis proposing that a major cosmic impact with Earth occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas.

Conducting a wide range of exhaustive tests, the researchers conclusively identified a family of nanodiamonds, including the impact form of nanodiamonds called lonsdaleite, which is unique to cosmic impact. The researchers also found spherules that had collided at high velocities with other spherules during the chaos of impact. James Kennett, professor of Earth science at University of California-Santa Barbara and a researcher involved in the study, noted that the lonsdaleite could not have formed through anthropogenic, volcanic, or other natural terrestrial processes. "These materials form only through cosmic impact," he said.

The data suggest that a comet or asteroid--likely a large, previously fragmented body, greater than several hundred meters in diameter--entered the atmosphere at a relatively shallow angle. The heat at impact burned biomass, melted surface rocks, and caused major environmental disruption. …

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