Several hundred thousand years ago, a meteor crashed on Earth. But, until now, the location of the impact remained a mystery. Researchers have just found it.
Such an impact necessarily leaves traces. At the time, the cataclysm caused thousands of tonnes of tectite, rapidly cooled pieces of molten rock, to be released into the sky. It is estimated that about 10% of the Earth’s surface was covered with these black fragments, from Indochina to eastern Antarctica.
Due to their wide distribution, researchers have struggled to locate the crater for a century, or even to estimate its size. Some spoke of a structure 15 km in diameter, while others imagined a hole 300 km wide. A team of researchers from the Jackson School Museum of Earth History at the University of Texas (USA) again conducted the investigation.
As part of this work, they carried out geochemical studies and gravity readings at several potential sites. They focused in particular on several eroded craters found in the south of China, in the north of Cambodia and in the center of Laos. But, after analysis, it emerged that all of these structures were much older, formed between 252 million years and 66 million years.
The researchers then made the following reflection: if the crater has so far gone unnoticed, it may be because it is no longer visible.
A crater buried under the lava
Their research then led them to Laos, on the Bolaven plateau. Here you will find a landscape lined with thick layer of cooled lava covering almost 5000 square kilometers. Most of the lava flows in the region were formed between between 51,000 and 780,000 years. In other words, the timing was good.
They got it right. By taking measurements at more than 400 locations, the researchers recorded a gravitational anomaly. In other words, they spotted an area less dense than the surrounding volcanic rock. According to their measurements, there would be under this thick layer of lava an “elongated crater” of approximately 100 meters deep, 13 km wide and 17 km long.
” Together, all of these clues suggest that this thick pile of volcanic rock effectively buries the site of the impact. “, Conclude the researchers. Study details are published in the journal Proceedings of the National Academy of Sciences.
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