26 April, 2006

Murphy's Law strikes again

I've had a fairly mad few days this week. Yesterday morning I had to present a double lecture in a "short fat course". "Short fat" roughly translates as "cram a whole terms' worth of material into two intensive weeks, and hope some of it hammers its way into the students' little brains". I'm yet to be convinced of the merits of this approach - it just seems to play into the students' preference to only actually retain what you're trying to teach them until they've passed the course, after which they can (and do) promptly forget it.

This particular course is entitled "Formation and evolution of the ocean crust", and I was obviously down to do the magnetism - the source and origin of the "magnetic stripes" and what they tell us about plate tectonics, the behaviour of the Earth's magnetic field over time, and construction of the oceanic crust (which, now I think of it, would make a rather nice series, if I ever get the time).

Anyway, I was asked to do this lecture at rather short notice, so I had to work quite hard to get the reading done, then sort out the presentation. It was tight, but by yesterday morning I had just about got everything ready - all I had to do was print and photocopy the handouts. Sadly, I then ran into the universal law of printers - they always stop working when you really need them. Leaving it until half an hour before the lecture starts to print the handouts certainly qualifies.

An hour of running around the building between various computers and printers, the lecture room and the IT department later, I had my handouts, as well as severely elevated blood pressure and adrenalin levels. I'm just thankful I brought in my laptop to run the presentation from...

22 April, 2006

How lonely is Lake Vostok?

For the last few years, there has been much excitement about Lake Vostok, and the numerous other bodies of water which have been found trapped under Antarctica’s 4 km-thick ice sheet. Much speculation has centred on the potential presence of weird and wonderful lifeforms, living in complete isolation from the rest of the Earth’s ecosystems. Such life would be cut off from the sun’s energy, and would have to eke out an existence at low temperatures and very high pressures (due to the overlying ice) – conditions similar to those life would have to endure on Europa, or Enceladus, if it does indeed exist there.

But are these lakes as isolated as we think?

In this week’s Nature, Wingham et al. [1] present an analysis of radar altimetry data from the ERS-2 satellite. This can measure changes in the topography of the ice sheet over time by measuring the distance between the satellite and the surface at the same location on successive orbits. In the data for 1997, they discovered that at three of these ‘crossing points’ in Eastern Antarctica (marked by the green squares, one of which is marked L1, in the rather crowded diagram above), the surface of the ice sheet dropped by 3 metres. Simultaneously, in a region 290 km away, they found three more crossing points (red squares marked U1-U3) where the surface rose by 1-2 m.

The authors propose that this seesaw effect is the result of water being transferred from a large, previously unknown (approximately 600 km2) subsurface lake in the L region to other lakes in the U region (where subsurface lakes – the yellow squares in the first figure – are known to exist). A pressure increase in the first lake, perhaps from the addition of meltwater, was enough to force open channels beneath the ice sheet and allow some water to escape.

Although the actual amount of water transported in this event was a mere 1.8 km3, this research demonstrates that water from these lakes can move around quite quickly, despite the fact that they are covered by many kilometres of ice; large floods could even reach the ocean, affecting sea-level and ocean circulation. These effects seem to be small; even if you completely emptied Lake Vostok, sea-level would only rise by about 1.6 cm (Given an ocean surface area of about 335,258,000 km2, and an estimated volume for Lake Vostok of 5400 km3). Perhaps more important are the biological implications of this work, if (and this is an important if) this phenomenon turns out to be widespread. The BBC report, where I first picked up this story, seemed to very quite gloomy about the chances now of finding unique organisms beneath the ice, with the lead scientist saying:

I think the idea that they have an isolated biological environment where things have gone their own way will have to be re-examined.

I found this quite puzzling; I’m certainly not an expert, but whilst these new data suggest that the Antarctic lakes may be much more interconnected than we thought, they are still effectively cut off from the outside world; I would have thought that a more dynamic environment would be more likely to produce something resembling an interesting ecology. Although it does make the mad dash to drill into Vostok and other lakes seem even more foolish, because if we contaminate one lake, it might not just stop there.

[1] Nature 440, p1033-1036 (doi)

19 April, 2006

Scantily clad women distract men shocker

I couldn’t help but be amused by this news item in Nature (if you have non-subscription troubles the BBC also have a report), about a study soon to be published in The Proceedings of the Royal Society B, which comes to the shocking conclusion that the men’s judgement may be somewhat impaired by provocative images of the female form – but it appears that some are more susceptible than others.

In the study, researchers from the University of Leuven in Belgium showed groups of men different images, which were either “sexual cues” (images of women and lingerie; much to the delight of geeks everywhere, Nature sportingly did an impersonation of FHM by providing an illustrative picture) or more mundane (landscapes), before asking pairs in each group to play an ultimatum game. In this game, one player was given 10 euros and had to suggest a split with the other. The two players would keep the money only if the offered cut was higher than the second man’s secretly pre-declared minimum; if it was not, both players got nothing. This is basically an interaction between the boldness of the proposing player (‘how little can I get away with offering?’), and the pride of the responder (‘how little would I accept’?). The researchers also compared the performance of the players to their testosterone levels (specifically, the level the subjects had been exposed to in the womb, measured by comparing the length of the index finger to that of the ring finger; if the ring finger is longest, it indicates a high testosterone level).

High-testosterone men drove the hardest bargain [more likely to offer a low cut, and less likely to accept one]— unless they had previously viewed pictures of bikini-clad models, in which case they were more likely to accept a poorer deal.

For these men, even handling a bra was enough to sap their resolve… Pictures of landscapes or elderly women, or handling a t-shirt, had no effect on the men's steely bartering power.

So, some good news for you who, having worked out which is your index finger and which is your ring finger (much easier if you’re married, I’m sure), have discovered yourself to be embarrassingly lacking in macho hormones; negotiations will become much easier if you have a lad’s magazine handy. Not only that, but the same trick won’t work as well on you.

The sight of flesh had less effect on the bargaining tactics of low-testosterone men.

This gives me an idea for when I next write a grant proposal…

14 April, 2006

Geological postcards from Almeria

The recent tectonic history of Almeria, SE Spain, has produced some varied and interesting geology, a key ingredient of any successful field trip. The region lies within the Cordillera, a mountain range produced as Africa has collided with Europe in the Alpine orogeny. The thrust sheets, or nappes, generated by this collision form the high Sierras. Around Carboneras, where we stayed on our recent excursion, they are made of dark metamorphic rocks – sediments which have been deeply buried, causing the growth of new minerals at higher temperature and pressures, then brought back to the surface (exhumed) by the thrusting.

This photo also shows two other common sights in the region: vast acres of greenhouses which supply the rest of Europe with their tomatoes, and a forest of cranes building ever more holiday apartments, probably for us Brits.

Following formation of the Betics, the tectonic regime changed from about 10 million years ago, with the initiation of left lateral strike-slip faults (like the San Andreas Fault, but with the opposite sense of movement). Historical records of Almeria and other nearby cities being flattened show that some are still active today – the last recorded big earthquake was in 1865. The Grantilla River cuts across the Carboneras Fault, exposing a ‘neapolitan ice-cream slice’.

Large faults rarely consist of a single narrow fissure in the earth; instead motion occurs along a number of interlinked faults across a broader fault zone. Within these zones fault-bounded ‘slices’ of rocks of different ages and types are all randomly mixed together. This process is perfectly illustrated in this section because all the different rocks have distinctive colours.

This new tectonic activity also included the formation of sedimentary basins, possibly pull-apart basins at bends in the strike-slip faults. The sequence of rocks deposited in these basins records a sequence of increasingly shallow marine environments. This shallowing-up sequence is not only due to sedimentation (if you make a hole it fills up), but also because the Africa-Europe collision has continued to uplift the region, as is obvious from the fact that all of these marine deposits are now above sea level. The very oldest sediments record very deep water environments, punctuated with periodic debris flows, where landslides at the edge of the continental shelf have transferred material into deeper waters. Some of these must have been massive; the next picture shows ‘El Gordo’, a truly stupendous chunk, or megaclast, of deformed sediments within one of these debris flows.

A few million years later, and the water depths are shallow enough for coral reefs to grow. In most places the corals themselves haven’t preserved too well – they’ve dissolved away, leaving holes marking where they once were.

The youngest sediments in these basins preserve a mud-flat environment, complete with preserved raindrop marks.

You can also see dessication cracks and bird footprints (the three-pronged feature on this photo may be one, although I didn’t notice it at the time).

Towards the coast, things are a bit different, with a lot of evidence of volcanic activity. One of the ancient volcanoes in this area is especially interesting, because the lavas contain large garnet crystals.

This is odd, because garnets are metamorphic minerals which only form at much greater depths than a typical magma chamber. What seems to have happened is that the volcano has erupted through metamorphic rock, melting it and incorporating the garnets into the magma. There is evidence for this, in the form of xenoliths of garnet-bearing metamorphic rock that have also been incorporated into the volcanics.

Volcanic activity also caused hot, mineral rich fluids and gases to circulate through the surrounding sediments, producing deposits rich in economically important minerals such as barite, and galena (lead ore). We visited a couple of mines, and even saw some fossil fumaroles, where the gases and fluids were released at the surface (a bit like the black smokers at mid-ocean ridges).

Hopefully these pictures have given you some idea of why we take our students to Almeria – there’s some really cool geology to be seen here. The nice weather, tapas and coffee are mere bonuses…

13 April, 2006

Steve Jones at the Royal Society

On Tuesday evening, Steve Jones gave his talk entitled ‘Why Creationism is wrong and Evolution is right’ at the Royal Society. When I first mentioned this I was quite tempted to go along; as it turned out, my housemate was having his PhD viva that day and I was committed to haunting the pubs of Southampton in celebration (the
success of other bloggers suggests that I may not have made it in anyway). Fortunately, the Royal Society has now put a recording online (although annoyingly, the camera rarely shows the slides). Sometimes the Internet is more than a Tool of Procrastination…

Jones has won several awards for his science communication and it’s not hard to see why: he’s an engaging speaker, capable of explaining important points without lapsing into jargon, and adding humour without it seeming too forced. What was interesting was that despite the provocative title, he barely discussed creationism at all, and he certainly didn’t waste time debunking irreducible complexity or any other ID ‘science’. Instead, he allocated most of his time to making a positive argument for ‘descent with modification’ in action, using the examples of human languages and the evolution of the HIV virus. These were well chosen: in both cases changes are happening over decades and centuries rather than millions of years, which are much more comprehensible timescales for the average person; in both cases there is a wealth of available data which allows lines of descent to be reconstructed more easily and robustly; and HIV is also a highly relevant illustration of how understanding evolution is vital for fighting diseases. I especially liked the phrase he used to link his two examples:

you can’t learn to speak any language properly without understanding the grammar, and you can’t be a biologist without understanding evolution.

Jones returned to language at the end of his talk, where he suggested that we as a species have ‘stepped outside the universe of Darwin’ by developing a means of information transfer outside of DNA, which is an interesting line to take. he seems to feel that a weak point exploited by creationists is the idea that accepting evolution, particularly our primate ancestry, demeans us as human beings in some way, and he is trying to take the sting out of that implication - ‘don’t worry folks, science says we’re special too!’

So, it wasn’t what I was expecting, but I was impressed; I think Steve Jones has thought quite hard about the creationism issue and how to confront it. He said that until recently he was in agreement with Richard Dawkins’ assertion that debating with creationists was a non-starter. In some ways, he has not changed that view, but has instead decided that he can still contribute, by giving the kind of talk that a creationist/IDer cannot give, because their arguments are pretty exclusively negative denunciations of evolutionary science. The contrast was certainly striking, at least to me.

10 April, 2006

It's official - I don't totally suck at lecturing

While I'm working on sorting out the photographic highlights of the Spain field trip, I though I'd share some more good news with you. Student feedback from one of the courses I lectured last semester is in. One of the things the students are asked to do is to rate each lecturer, with possible scores ranging from 1 (poor) to 5 (excellent). My mean score was 3.8. Not great, but I was expecting much worse!

This has cheered me up no end - these were my first lectures, and I learnt an awful lot from them: the importance of preparation, of having a coherent narrative, and the judicious use of worked examples and case studies. Talking to some of the students on this field trip (who I lectured in a different course) also provided me with some useful feedback, reminding me how easy it is to pitch the level just too high - perhaps by not properly explaining terminology - and therefore lose a large part of the audience (which may not bode well for the feedback from that course...). It was a precipice-like learning curve, and I wasn't particularly confident that I'd ascended fast enough to really be any use at all, especially after seeing the students' exam papers. Knowing I wasn't too appalling, whilst realising that I can do much better with a bit of work, is helping to ease my current existential crisis.

08 April, 2006

Viva L'Espagna

My last post was probably a poor place to leave things before running off for a couple of weeks. Fear not, however; I did not sign off my computer and run away to start a rock-lovers' commune in deepest Wales, and neither have I exchanged my lab for a faceless office. Instead, I was part of the teaching staff on a two-week undergraduate field trip to Almeria, in south-east Spain, which I've enjoyed immensely. I'll post a full report, together with some pretty pictures, in the next few days.