Massive Crater Found Under Greenland Ice Sheet

Kai Huang - 2A Computer Engineering
Posted on: November 28, 2018

In 2015, Kurt Kjær, a geologist from Denmark’s Natural History Museum, was studying the contours under Greenland’s colossal ice sheets when he discovered in the topography a hint of a hole underneath the Hiawatha Glacier. He was intrigued at the possibility, but needed further research with radar technology in order to see through more than a kilometer of ice.

Kjær and his team began to work with NASA glaciologist Joseph MacGregor, who had found that NASA aircraft often flew over the Hiawatha when on their way to survey conditions in the Arctic. In a stroke of luck, they found that the instruments were often turned on while in the flyby, and indicated what looked like the rim of a crater. However, the results were still somewhat inconclusive, with no revelation of what the center looked like. A rim could merely indicate an ancient volcano, but a crater has telltale signs as the debris forms rings surrounding the epicenter. The scientists knew that future dedicated missions must be taken.

Kjær reached out to the Carlsberg Foundation for funding, while MacGregor utilized his NASA connections to allow them to work out of the USAF Thule Base in northern Greenland. Using a new radar system mounted on a Basler aircraft from the Alfred Wegener Institute, they flew three flights in May of 2016. Their data revealed a central peak rising roughly 50 meters high, and a surprisingly jagged crater bottom. The latter fact is particularly interesting as it indicates a relatively young crater; had the impact been more than 100,000 years ago, the erosion from the end of the ice age would’ve smoothed it off.

Knowing that their results would be scrutinized by the entire scientific community, the team conducted further analysis on the Hiawatha, directly above the crater. They collected sediments that gave further credence to their meteor impact theory. There were glass grains that would’ve required temperatures higher than a volcanic eruption to forge, as well as quartz crystals that contained a distinctive pattern that could only be formed from extraterrestrial impacts or nuclear weapons.

In Kjær et al.’s publication on 14 November, they state that the crater is 31-kilometers wide, with the geochemical analysis indicating that the impactor was a fractionated iron asteroid. They further discuss that the Asteroid must have been more than a kilometer wide to produce the crater, and that the impact took place after the last glacial period.

This discovery leads to renewed debate over the cause of an inexplicable event that happened about 12800 years ago. The ice age had just ended, and with the increase in temperatures came a time when giant mammals prospered, and the prehistoric Clovis people had spread across North America. However, over the course of 1200 years, the Earth suddenly plunged into another major change, with temperatures in the Northern Hemisphere plunging almost 8 degrees Celsius, an event known as the Younger Dryas. It ended as abruptly as it began, but as the Earth warmed once more, many of the giant mammals were dying out, and the Clovis people had vanished.

A controversial theory about the Younger Dryas is that it was caused by a massive meteor impact which would’ve not only interfered with ocean circulation but also triggered wildfires across the North American continent as pieces of the object exploded in the atmosphere, producing enough soot and compounds to block out the sun. Supporters of the theory point to the 1908 Tunguska airburst that flattened over 2000 square kilometers of forest, producing as much energy as 1000 Hiroshima bombs. Critics have long contended that there is little to no evidence for any of the key arguments of the impact theory. However, with this new discovery that lines up almost perfectly with the time period, the argument once again surfaces.

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