Meteorite impacts leave behind time-capsules of ecosystems

Glass beads that form inside hot meteors as they fall to Earth capture particles from the atmosphere, creating a kind of permanent record of historic climates.

Meteorite impacts can be very destructive. One that fell in Mexico around 66m years ago created a 180km crater and caused the extinction of dinosaurs while spewing debris and molten rock into the air. Now, in what is a fascinating tale of serendipity, researchers have found that these events don’t entirely destroy all traces of life at the site of impact. Molten rocks can capture and preserve organic matter as they cool down to form glass beads.

When a meteor enters Earth’s atmosphere, the air around the meteor gets very quickly compressed causing it to heat up, scorching everything in its path. Most of the time that is where the story ends, as the meteor burns up in the sky as a “shooting star”. But sometimes it is big enough to reach all the way to the surface and transfer its remaining energy to the ground.

This energy is dissipated, as mild earthquakes, sound shockwaves – but mostly as heat. The heat energy can be so great that it melts rocks on the surface and hurls them up in the atmosphere. Anything that comes in contact with this molten rock would presumably get burnt, leaving nothing but rocky material that cools down in the atmosphere, forming glass beads and tektites (gravel-sized natural glass). This is what City University of New York researcher Kieren Howard assumed, but he was able to show that his assumptions were wrong.

For his PhD, Howard was studying the glass beads and tektites found near the Darwin crater in Tasmania. The 1.2km wide crater was created by a meteorite impact about 800,000 years ago.

The natural glass formed during cooling is (as implied by the term glass) not crystalline. Instead of a regular arrangement of atoms, the atoms inside it are randomly arranged. Howard’s analysis, however, kept showing the presence of crystals. At first, he dismissed this as a problem with the machine or with his method of analysis. But when it kept showing up, as a good scientist, he thought he should ask an expert to look at his data.

“This is unusual,” says Chris Jeynes, a physicist at the University of Surrey. “If there were indeed crystals, then it was the result of uneven cooling, which can occur when something gets trapped inside these glass beads.”

Jeynes used proton-beam analysis, a method to peer inside the glass to reveal its elemental make-up. Inside he found carbon. “Howard had no idea what his samples were, and he was very surprised when I told him,” Jeynes says.

The natural glass formed should contain only silicon, titanium, oxygen and other metallic elements in trace amounts. Detection of carbon meant that there was some organic matter inside. The only hypothesis was that, somehow during the formation of these glass beads, they captured organic matter that was floating in the atmosphere. That organic matter might have already been in the air, but it might also include material thrown up by the impact.

Howard then went to another expert to break open these glass beads and reveal what the carbon-rich matter was. It turned out that it included were cellulose, lignin and other biopolymers. This meant that somehow this matter, which originated from plants, had survived the temperature of more than 500°C, which is what the molten rock would have reached before cooling into a glass bead. Usually these temperatures will break down the organic matter, but clearly it didn’t in this case.

Mark Sephton, a geochemist at Imperial College London, was surprised and pleased: “What the results show is that these glass beads can capture an aliquot of the atmosphere of the planet at impact. It is like a time capsule of that ecosystem.” These results are published in Nature Geoscience.

The implications are enormous. It shows that other meteorite impacts, like the one that wiped out the dinosaurs, could have created such time capsules too. Sephton is now working on finding glass beads from other impact sites to reveal information about Earth’s ancient atmosphere.

This method of analysis means that we could also go looking for similar beads on other planets, like Mars, where meteorite impacts are common. They could also reveal vital information about the past atmosphere of those planets. Maybe they captured organic matter – if it ever existed there.

“We would not know any of this if it wasn’t for Howard,” Jeynes says, adding that Howard’s persistence to find out what “the wrong results” led the researchers to a phenomenon that nobody knew existed.

This article was originally published at The Conversation. Read the original article.

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Meteor Crater in Arizona. (Photo: Angle Schatz/Flickr)
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Fark.com’s censorship story is a striking insight into Google’s unchecked power

The founder of the community-driven website claims its advertising revenue was cut off for five weeks.

When Microsoft launched its new search engine Bing in 2009, it wasted no time in trying to get the word out. By striking a deal with the producers of the American teen drama Gossip Girl, it made a range of beautiful characters utter the words “Bing it!” in a way that fell clumsily on the audience’s ears. By the early Noughties, “search it” had already been universally replaced by the words “Google it”, a phrase that had become so ubiquitous that anything else sounded odd.

A screenshot from Gossip Girl, via ildarabbit.wordpress.com

Like Hoover and Tupperware before it, Google’s brand name has now become a generic term.

Yet only recently have concerns about Google’s pervasiveness received mainstream attention. Last month, The Observer ran a story about Google’s auto-fill pulling up the suggested question of “Are Jews evil?” and giving hate speech prominence in the first page of search results. Within a day, Google had altered the autocomplete results.

Though the company’s response may seem promising, it is important to remember that Google isn’t just a search engine (Google’s parent company, Alphabet, has too many subdivisions to mention). Google AdSense is an online advertising service that allows many websites to profit from hosting advertisements on its pages, including the New Statesman itself. Yesterday, Drew Curtis, the founder of the internet news aggregator Fark.com, shared a story about his experiences with the service.

Under the headline “Google farked us over”, Curtis wrote:

“This past October we suffered a huge financial hit because Google mistakenly identified an image that was posted in our comments section over half a decade ago as an underage adult image – which is a felony by the way. Our ads were turned off for almost five weeks – completely and totally their mistake – and they refuse to make it right.”

The image was of a fully-clothed actress who was an adult at the time, yet Curtis claims Google flagged it because of “a small pedo bear logo” – a meme used to mock paedophiles online. More troubling than Google’s decision, however, is the difficulty that Curtis had contacting the company and resolving the issue, a process which he claims took five weeks. He wrote:

“During this five week period where our ads were shut off, every single interaction with Google Policy took between one to five days. One example: Google Policy told us they shut our ads off due to an image. Without telling us where it was. When I immediately responded and asked them where it was, the response took three more days.”

Curtis claims that other sites have had these issues but are too afraid of Google to speak out publicly. A Google spokesperson says: "We constantly review publishers for compliance with our AdSense policies and take action in the event of violations. If publishers want to appeal or learn more about actions taken with respect to their account, they can find information at the help centre here.”

Fark.com has lost revenue because of Google’s decision, according to Curtis, who sent out a plea for new subscribers to help it “get back on track”. It is easy to see how a smaller website could have been ruined in a similar scenario.


The offending image, via Fark

Google’s decision was not sinister, and it is obviously important that it tackles things that violate its policies. The lack of transparency around such decisions, and the difficulty getting in touch with Google, are troubling, however, as much of the media relies on the AdSense service to exist.

Even if Google doesn’t actively abuse this power, it is disturbing that it has the means by which to strangle any online publication, and worrying that smaller organisations can have problems getting in contact with it to solve any issues. In light of the recent news about Google's search results, the picture painted becomes more even troubling.

Update, 13/01/17:

Another Google spokesperson got in touch to provide the following statement: “We have an existing set of publisher policies that govern where Google ads may be placed in order to protect users from harmful, misleading or inappropriate content.  We enforce these policies vigorously, and taking action may include suspending ads on their site. Publishers can appeal these actions.”

Amelia Tait is a technology and digital culture writer at the New Statesman.