A Massive Impact Crater Has Been Detected Beneath Greenland's Ice Sheet (gizmodo.com)

An anonymous reader quotes a report from Gizmodo: An unusually large asteroid crater measuring 19 miles wide has been discovered under a continental ice sheet in Greenland. Roughly the size of Paris, it's now among the 25 biggest asteroid craters on Earth. An iron-rich asteroid measuring nearly a kilometer wide (0.6 miles) struck Greenland's ice-covered surface at some point between 3 million and 12,000 years ago, according to a new study published today in Science Advances. The impact would've flung horrific amounts of water vapor and debris into the atmosphere, while sending torrents of meltwater into the North Atlantic -- events that likely triggered global cooling (a phenomenon sometimes referred to as a nuclear or volcanic winter). Over time, however, the gaping hole was obscured by a 1,000-meter-tall (3,200-foot) layer of ice, where it remained hidden for thousands of years. Remarkably, the crater was discovered quite by chance -- and it's now the first large crater to be discovered beneath a continental ice sheet.

Comments

Re:range

[ClarkMills]

<quote>
Some pre-glacial channels were seen below the ice sheet at the site of the crater, which suggests the Greenland Ice Sheet was already in place when the asteroid struck. The exact timing of the asteroid strike, however, is fairly vague, with the researchers saying it happened between 3 million and 12,000 years ago. But preliminary evidence suggests it happened relatively recently. The crater appears to be well-preserved—a surprising observation given that ice is a powerful erosive force. The crater is likely fairly young from a geological perspective.

“It is correct that the crater is not well dated but there’s good evidence that it is geologically young, that is, it formed within the last 2 to 3 million years, and most likely it is as young as the last Ice Age [which ended around 12,000 years ago],” Larsen explained to Gizmodo. “We are currently trying to come up with ideas on how to date the impact. One idea is to drill through the ice and get bedrock samples that can be used for numerical dating.”
<unquote>

Re:Dinosaurs had feathers

[AlanObject]

Which to believe

Which to believe? The most obvious thing to believe is that your concept of science is drastically wrong.

What you should believe is that scientists will update their hypotheses and conclusions as new data becomes available. Try that out. Then you won't be so perplexed by the list you posted.

Asteroid estimator

[jd]

https://impact.ese.ic.ac.uk/Im...

So, you get a crater roughly the right size in that sort of rock if it is 2.5 km in diameter. You get 0.85 megatonnes equivalent energy, which is next to nothing. No significant global effect.