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)
Show Hide image

New Times: David Runciman on networks and the digital revolution

The digital revolution has had two profound effects on how power is distributed – both of which squeeze the state's power.

Left-wing political parties exist to use the power of the state to rectify unjust distributions of power in society. What has gone wrong with this project? First, the political parties bit. Established parties everywhere are struggling to seem relevant to most people’s everyday concerns: they look increasingly like the tired relics of a more hierarchical age. The exception, of course, is the current Labour Party, which has opened itself up to become the biggest mass-membership party in Europe. But the trade-off has been to move away from seeing the acquisition of power as its primary purpose. These days parties can only really draw people in by offering to be vehicles for the expression of political resentment and disenchantment. But that is no way to rectify the causes of their resentment; neglecting the challenge of power usually ends up making things worse.

However, this is just a symptom of the wider problem, which is the changing nature of power. Technology lies at the heart of it. The digital revolution has had two profound effects on how power is distributed. First, it has empowered individuals, by providing them with unprecedented access to information, tools of communication and the means of expression. This is power exercised as choice: we all now have multiple ways of registering our likes and dislikes that never existed before.

Second, the digital revolution has empowered networks, creating vast new webs that span the globe. Some of them, such as Facebook, are close to being monopolies. We end up joining the networks that other people have joined, because that’s where the action is. This gives a small number of networks an awful lot of power.

Both of these developments are deeply problematic for the power of the state. The proliferation of choice makes citizens much harder to satisfy. Many of us have got used to micromanaging our lives in ways that leaves government looking flat-footed and unresponsive, no matter how hard it tries. At the same time, states face global networks that they have no idea how to control. International finance is one of these: money is information and information now has too many different ways to flow. States are getting squeezed.

The paradox is that the same forces that are squeezing the state are also giving impetus to left-wing politics. There are huge imbalances of power being created in networked societies. The monopolists are hoovering up money and influence. Personal connections count for more than ever, now that networked connections have become ubiquitous. Education is turning into a way of pulling up the drawbridge rather than moving up the ladder. One temptation for the left is to assume that the evidence of injustice will sooner or later outweigh the disabling effects of these social forces on the state. That is part of the Corbyn gamble: hang around until people are sufficiently pissed off to start demanding social-democratic solutions to their problems.

I don’t think this is going to happen. There is nothing to suggest that popular dissatisfaction will find its way back to the state as its best outlet. It will be channelled through the networks that are making the life of the state increasingly difficult.

The other temptation is to think that the left can achieve its goals by bypassing conventional social democracy and channelling its own ambitions into network politics. This is the other side of the Corbyn gamble, or at least the view of some of the people who have attached themselves to him: a new politics is coming that uses digital technology to mobilise fleet-footed networks of activists who can generate change without going through the cumbersome and time-consuming process of winning general elections. That also looks pretty wishful to me. These networks are just another vehicle for expressing personal preferences. They don’t have any means of changing the preferences of people who think differently. You need to win power to do that.

The state’s power is being squeezed by networks of empowered individuals, but these networks don’t have the kind of power necessary to do the redistributive work of the state. What is the left to do? It needs to try to find value in the fact that the state is not just another network. The right does this instinctively, by talking up the state’s security functions and championing ideas of sovereignty and national identity. But that does nothing to address the deleterious effects of living in a modern networked society, where we are swamped by personal choice but impotent in the face of corporate and financial power.

Rather than trying to harness the power of networks, the left should stand up for people against the dehumanising power of Big Data. The state isn’t Google and should not try to pretend to be. We don’t need more choice. We don’t need more efficiency of the kind that digital technology is endlessly supplying. We need protection from the mindless bureaucratic demands of the new machine age: the relentless pursuit of information, regardless of the human cost. There are limits to what the state can do but it retains some real power. It still employs real human beings; it educates them and provides them with welfare. It should do what is in its power to make the work tolerable and the education meaningful, to provide welfare in ways that don’t leave people at the mercy of faceless systems. The left needs to humanise the state.

At the moment, too much energy is being spent trying to humanise the party. We are told that people are tired of robotic, careerist politicians; they want unspun versions of people like themselves. But robotic politicians aren’t the problem; the coming age of robots is. While the party tries to feel more comfortable with itself, the effects of a networked society are running rampant. Acquiring the power of the state is still the best way to fight back. It doesn’t matter if that has to be done in an ugly, mechanised, artificial way, by careerist politicians with whom we wouldn’t choose to spend our personal time. Better an ugly, artificial politics than an ugly, artificial world. 

David Runciman is a professor of politics and the head of the department of politics and international studies at Cambridge

This article is part of a New Times collection of the future of the left. Read the other pieces here.


This article first appeared in the 22 September 2016 issue of the New Statesman, The New Times