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.

The Conversation

Meteor Crater in Arizona. (Photo: Angle Schatz/Flickr)
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How the internet has democratised pornography

With people now free to circumvent the big studios, different bodies, tastes and even pubic hair styles are being represented online.

Our opinions and tastes are influenced by the media we consume: that much is obvious. But although it’s easy to have that conversation if the medium we are discussing is “safe for work”, pornography carries so much stigma that we only engage with it on simple terms. Porn is either “good” or “bad”: a magical tool for ­empowerment or a destructive influence on society. Many “pro-porn” campaigners shy away from nuanced critique, fearing it could lead to censorship. “Anti-porn” campaigners, convinced that porn is harmful by definition, need look no further than the mainstream tube sites – essentially, aggregators of clips from elsewhere – to gather examples that will back them up.

When we talk about the influence of porn, the emphasis is usually on a particular type of video – hardcore sex scenes featuring mostly slim, pubic-hairless women and faceless men: porn made for men about women. This kind of porn is credited with everything from the pornification of pop music to changing what we actually do in bed. Last year the UK government released a policy note that suggested porn was responsible for a rise in the number of young people trying anal sex. Although the original researcher, Cicely Marston, pointed out that there was no clear link between the two, the note prompted a broad debate about the impact of porn. But in doing so, we have already lost – by accepting a definition of “porn” shaped less by our desires than by the dominant players in the industry.

On the day you read this, one single site, PornHub, will get somewhere between four and five million visits from within the UK. Millions more will visit YouPorn, Tube8, Redtube or similar sites. It’s clear that they’re influential. Perhaps less clear is that they are not unbiased aggregators: they don’t just reflect our tastes, they shape what we think and how we live. We can see this even in simple editorial decisions such as categorisation: PornHub offers 14 categories by default, including anal, threesome and milf (“mum I’d like to f***”), and then “For Women” as a separate category. So standard is it for mainstream sites to assume their audience is straight and male that “point of view” porn has become synonymous with “top-down view of a man getting a blow job”. Tropes that have entered everyday life – such as shaved pubic hair – abound here.

Alongside categories and tags, tube sites also decide what you see at the top of their results and on the home page. Hence the videos you see at the top tend towards escalation to get clicks: biggest gang bang ever. Dirtiest slut. Horniest milf. To find porn that doesn’t fit this mould you must go out of your way to search for it. Few people do, of course, so the clickbait gets promoted more frequently, and this in turn shapes what we click on next time. Is it any wonder we’ve ended up with such a narrow definition of porn? In reality, the front page of PornHub reflects our desires about as accurately as the Daily Mail “sidebar of shame” reflects Kim Kardashian.

Perhaps what we need is more competition? All the sites I have mentioned are owned by the same company – MindGeek. Besides porn tube sites, MindGeek has a stake in other adult websites and production companies: Brazzers, Digital Playground, Twistys, PornMD and many more. Even tube sites not owned by MindGeek, such as Xhamster, usually follow the same model: lots of free content, plus algorithms that chase page views aggressively, so tending towards hardcore clickbait.

Because porn is increasingly defined by these sites, steps taken to tackle its spread often end up doing the opposite of what was intended. For instance, the British government’s Digital Economy Bill aims to reduce the influence of porn on young people by forcing porn sites to age-verify users, but will in fact hand more power to large companies. The big players have the resources to implement age verification easily, and even to use legislation as a way to expand further into the market. MindGeek is already developing age-verification software that can be licensed to other websites; so it’s likely that, when the bill’s rules come in, small porn producers will either go out of business or be compelled to license software from the big players.

There are glimmers of hope for the ethical porn consumer. Tube sites may dominate search results, but the internet has also helped revolutionise porn production. Aspiring producers and performers no longer need a contract with a studio – all that’s required is a camera and a platform to distribute their work. That platform might be their own website, a dedicated cam site, or even something as simple as Snapchat.

This democratisation of porn has had positive effects. There’s more diversity of body shape, sexual taste and even pubic hair style on a cam site than on the home page of PornHub. Pleasure takes a more central role, too: one of the most popular “games” on the webcam site Chaturbate is for performers to hook up sex toys to the website, with users paying to try to give them an orgasm. Crucially, without a studio, performers can set their own boundaries.

Kelly Pierce, a performer who now works mostly on cam, told me that one of the main benefits of working independently is a sense of security. “As long as you put time in you know you are going to make money doing it,” she said. “You don’t spend your time searching for shoots, but actually working towards monetary gain.” She also has more freedom in her work: “You have nobody to answer to but yourself, and obviously your fans. Sometimes politics comes into play when you work for others than yourself.”

Cam sites are also big business, and the next logical step in the trickle-down of power is for performers to have their own distribution platforms. Unfortunately, no matter how well-meaning your indie porn project, the “Adult” label makes it most likely you’ll fail. Mainstream payment providers won’t work with adult businesses, and specialist providers take a huge cut of revenue. Major ad networks avoid porn, so the only advertising option is to sign up to an “adult” network, which is probably owned by a large porn company and will fill your site with bouncing-boob gifs and hot milfs “in your area”: exactly the kind of thing you’re trying to fight against. Those who are trying to take on the might of Big Porn need not just to change what we watch, but challenge what we think porn is, too.

The internet has given the porn industry a huge boost – cheaper production and distribution, the potential for more variety, and an influence that it would be ridiculous to ignore. But in our failure properly to analyse the industry, we are accepting a definition of porn that has been handed to us by the dominant players in the market.

Girl on the Net writes one of the UK’s most popular sex blogs: girlonthenet.com

This article first appeared in the 16 February 2017 issue of the New Statesman, The New Times