Category Archives: End of year summaries, general musings

The Time Lords of Geology

Posted on April 16, 2013 by | Leave a comment
Epic Time Lord

Time Lord, possibly outside the offices of the International Commission on Stratigraphy (credit: Sorcyress via Flickr)

Because it is the ultimate historical discipline, the essence of geology centres on time, measuring its passage and establishing correlations in time on a global scale so that an interlinked story of Earth evolution can be related. In fact geology is not just about a record of what happened in the four dimensions of place and time; it is a great deal more multidimensional, involving temperature, strain, chemistry, erosion, deposition, sea-level , the course of life and much more besides. Ever more multifaceted and, sadly, divided into subdisciplines and interfaces with other aspects of natural science that few if any individuals can grasp, an almost legally enforceable set of rules is needed to keep the order orderly. Unlike history and more akin to archaeology geological time is of two kinds, its precisely quantitative measure being a relative newcomer.

Since it emerged in the Enlightenment since the late 17th century geology has been dominated by a relative sense of timing: Steno’s Law of Superposition, and those relating to deformation, igneous eructations, erosion and deposition first properly addressed by James Hutton being the most familiar. The notion of an absolute time scale into which events separated relative to one another could be fitted with confidence is a real latecomer. Although around since James Ussher, Archbishop of Armagh, reckoned from the first two chapters of Books of Genesis that everything began on Sunday 23 October 4004 BCE, the only useful and broadly believable approach to absolute time has been based on the decay of radioactive isotopes incorporated into minerals once they had formed within a rock. But that is no panacea for the simple reason that most of them form through igneous or metamorphic processes and only rarely in the course of sedimentation. It also has only become reliable and precise in the last two or three decades.

Tying together global records of all the kinds of process that have made, shaped and changed the Earth has therefore become an increasingly complex blend between local relative dating, burgeoning regional to global means of correlation and the odd point in absolute time. What has arisen is a dual system that, if truth were told, is often used in a cavalier fashion. Equally to the point, the rules have of late become unfit for purpose and are in need of revision, which is a task for the Time Lords, properly known as the International Commission on Stratigraphy (ICS). The trouble is, the rules have themselves evolved somewhat episodically while their subject is appropriately in continual motion and change, if not anarchic. To the outsider things can seem very odd indeed. Most reasonably well-read souls will have heard of the Cambrian and the Jurassic, largely because of the popularity of trilobites that blossomed in the one and dinosaurs that strutted the land in the other. What is less well known is that the two names have different usages as adjectives: one to signify an interval of time called a Period, the other a System of essentially piled-up sedimentary rocks.

There are greater dualisms that group the Period/System divisions: the largest Eon/Eonothem groupings of Archaean, Proterozoic and Phanerozoic; the Era/Erathem signifiers such as Palaeoproterozoic, Mesozoic and Cenozoic. Incidentally, the time between the formation of the Earth and the first palpable rocks, from about 4550 to 4000 Ma, has been called the Hadean but has no designated status, possibly because it has no rock record whatsoever. Divisions of Periods/Systems apply only to the time since fossils became abundant 541 Ma ago, and in order of fineness of division are Epoch/Series and Age/Stage. Example of the first can be Lower, Middle and Upper – to spice things up, Middle maybe omitted from some Periods/Systems – or they might be given names derived from type areas, such as the ever popular Llandovery at the base of the Silurian Period/System. Helpfully, the Cambrian contains Terreneuvian, Series 2, Series 3 and Furongian from early to late/bottom to top. The final global division has always floored undergraduates and shows little sign of relief – there are a great many Ages/Stages, in fact a round 100 (I may have miscounted), 98 with names, 2 currently unnamed and 4 in the Cambrian called Stages 2 to 5: confusing, that… has anyone spoken of the Stage 3 Stage or the Stage 5 Age of the Cambrian?

Worryingly, in my hasty overview of the ICS International Stratigraphic Chart above I have reversed the official designation of chronstratigraphic/geochronological nomenclature: is this likely to have me committed to the geoscientific equivalent of Guantanamo Bay, or merely limbo?

I have by no means exhausted officialise. Readers may not be surprised to learn that the Time Lords have bent Heaven and Earth literally to concretise the double entendres of geology. The base of almost every Age/Stage in the Phanerozoic Eonothem/Eon is defined at a suitably agreed point on the ground by, in a few cases, a real golden spike (I may be mistaken on this, as the only one I tried to visit was at the base of a Welsh cliff suitable only to be visited by – in the timeless phrase – ‘a strong party’). More prosaically there are monuments of various ethically appealing designs that go by the sonorous name Global Boundary Stratotype Section and Point. I have it on reasonably good authority that ICS delegates have, on occasion, needed to be physically restrained from huge fist fights over which nation shall host a particular GSSP (the ‘B’ in the acronym is aspirated).

This is the point that all readers will have been waiting for: it has been suggested to ICS that the whole edifice is looked at very closely and perhaps revised (Zalasiewicz, J, et al. 2013. Chronostratigraphy and geochronology: A proposed realignment. GSA Today, v. 23 (March 2013), p. 4-8). For professionals this is an obligatory read, for others optional: there is no excuse as it is downloadable for free – click on the title. While you are about it, you can also download from GSA Today the famous proposal for an entirely new series/epoch called the Anthropocene (see also A sign of the times: the ‘Anthropocene’ in EPN issue of May 2011)

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The production of geoscientists: a cautionary tale from the Open University

Posted on February 4, 2013 by | 2 Comments

Despite global recession, worldwide job opportunities for geoscientists are increasing faster than the number of available applicants. In the US the Bureau of Labor Statistics predicts 21% growth in this sector in 2010-2020 (Perkins, S. 2011. Geosciences: Earth works.  Nature, v. 473, p. 243–244). That figure does not include jobs freed-up by retirement: the demographics of employed geoscientists in the petroleum and mining industries are skewed markedly to the over-40s, peaking at age 50.

The American Geological Institute’s Geoscience Workforce Program has reported that the regions that produce most geoscience graduates, the US, Europe, Russia and China, are not meeting their domestic needs let alone global requirements. The demand stems from the traditional petroleum and mineral industries that are booming, together with the renewable energy sector and growing concern about environmental hazards and impacts attending global warming.

An editorial (Rare Earth scientists) in the December 2012 issue of Nature Geoscience is headlined, ‘Not enough young people enter the geosciences. A passion for the subject should be sparked early on.’ It then comments that the decline in young people studying the geosciences at school stems from Earth science not being taken seriously, under-education of their teachers and budgetary sacrifice of geoscience to preserve the more ‘traditional’ science subjects. The leading article concludes, ‘On an increasingly vulnerable planet, governments need to teach the young people of their country an understanding of the Earth’s basic make-up and dynamics, along with inspiring a fascination for its age and beauty. How else can we expect humanity to survive the Anthropocene?’

Open University

Creative work on the Open University campus (Photo credit: ianonline)

For over 40 years the Open University has been a key UK educator in geoscience. Since 1971 a total of about 170 thousand, mainly British students have studied at home through the OU for a science-based degree. Discovering tectonics, Earth structure, geology and palaeontology through studying the Science Foundation Course must have been a thrilling experience because since 1972, when the OU began to offer a level-2 course in Geology, around 30 thousand of its science ‘beginners’ decided to find out more; an average enrolment of 760 per year. The OU’s Department of Earth Sciences added more level-2 courses so that by 2000, students could also study economic geology (The Earth’s Physical Resources – 18 500 students from 1974 to 2009, averaging 544 per year), planetary science (The Earth: Structure, Composition and Evolution- 14 100 students from 1981 to 2005, averaging 590 per year) and Earth-system science (Earth and Life –7121 students from 1997 to 2006, averaging 712 per year).

After 1981 Open University students could, and many did, aim for a geoscience-oriented degree that also took in three, more advanced, level-3 studies. These were Oceanography (12 121 students from 1989 to 2012, averaging 505 per year), stratigraphy (The Geological Record of Environmental Change – 7968 students from 1976 to 2012, averaging 295 per year) and Earth’s internal processes (Understanding the Continents – 6994 students from 1976 to 2012, averaging 259 per year).

In this way the Open University became one of the world’s largest single providers of geoscience education, if not the largest: in the whole of the United States fewer than 3000 first degrees majoring in geoscience are awarded annually. Yet from its inception the OU’s Department of Earth Sciences had never claimed to be training professional geologists: had it been, its graduates would have significantly affected the world’s employment opportunities in the discipline. In fact that claim could never have been made, for one simple reason: distance learning for part-time students would always struggle to provide the volume of hands-on practical training that is the quintessence of this pre-eminently field- and lab-based discipline. Nevertheless the OU’s range of residential schools where practical activities were intensively provided for went a good way towards filling this gap.

English: Waterfall Geologists, from the Open U...

Open University students at the now defunct Geology summer school, inspecting a fault. (Photo credit: Wikipedia)

So, to those unfamiliar with the realities of the OU milieu it will seem odd that in 2012 the world’s largest provider of distance learning axed all residential courses right across the science spectrum, including those in practical geoscience. But to those directly involved this move was the logical final step in a series of changes since 2001. Before that, for those courses that included a residential component attendance had been compulsory, except in special circumstances. Yet after 2001 university authorities deemed that the residential schools continue only as optional components for degree study and should carry an additional registration fee. Not surprisingly, in the case of the core level-2 Geology course attendance at the re-branded residential school declined to 30% after 2001.

Two other important developments attended this change in the Earth Science degree programme. After 2001 pass rates fell abruptly. For example, in the Science Foundation Course the rate fell from an annual average of 69 to 54%, and in level-2 Geology from 65 to 55%. Because residential schools played a vital role in boosting confidence and reinforcing home studies, equally as important as transferring practical skills, this dramatic fall in performance was only too predictable.

The other post-2001 development was an across-the-board fall in new registrants for Earth Science level-2 courses, especially in those that had previously not been served by residential studies: The Earth: Structure, Composition and Evolution from a pre-2001 average of 680 per year to 470 thereafter; Earth and Life from 866 to 558; The Earth’s Physical Resources from 795 to 456. The majority of those who enrolled for these courses having previously studied the core Geology course such dramatic declines are easily explained. Those who had opted out of the residential course missed its undoubted boost to confidence and enthusiasm, and reinforcement in basic geoscientific principles. More likely to underperform in the Geology course, they would not have felt equipped to deal with other level-2 courses, and ‘voted with their feet’.

Since its launch, The Earth’s Physical Resources course had been acclaimed by geoscience teachers internationally for having made economic geology fascinating rather than a chore. In 2005-7 it had been completely refurbished and rising registrations bucked the downward trend. Yet in 2009, it was axed with little discussion. Declining enrolment for The Earth and Earth and Life prompted management to withdraw both and combine parts of their content in a single course Our Dynamic Planet: Earth and Life. Launched in 2007, by 2012 it attracted a mere 217 applicants. In 2013 it too will be withdrawn from the curriculum.

In late 2010 the OU’s Department of Earth Sciences held a celebration of its 40-year existence; yet only a year later in 2011 the department that had brought plate tectonics, advanced palaeontology, unravelling past climates, physical resources; planetary science and much besides to the widest student audience ever achieved ceased to be. It was merged into a restructured entity called the Department of Environment, Earth and Ecosystems. There seems to have been a failure of nerve and leadership that may have important consequences not only for the future of geoscience as a discipline and among the wider public but for the very knowledge necessary for our national and human survival.  The future availability of remaining geoscience courses is uncertain, with all being expected to start for the last time within the next year or two. Perhaps some major transformation to meet increased needs for general public awareness of the way our planet works is being planned: let’s hope so and that any new offerings have as much impact as the earlier courses did before the start of the 21st century. It will be a hard task, as the Open University tripled its fees for students entering the OU system from 2012 onwards.

NOTE: (added 11 February 2013) The Open University has been offered the right of reply to this item.

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Publishing: is it worth the effort?

Posted on December 31, 2012 by | Leave a comment

A measure of the esteem in which a peer-reviewed paper is held is supposedly the number of times to which it is referred in other papers. Of course, the older a paper is the more chance that such citations will have built up; but the annual rate of citation is likely to fizzle out over time. Papers that create a frisson of initial excitement and command enduring citation are few and far between: they probably launched a new line of inquiry.

It is instructive to try to nail Alfred Wegener’s influence in tectonics using the Web of Science, which ought to have been pretty high. Superficially, he had none and is remembered through that arm of Thomson Reuters for six papers: four on atmospheric physics – his speciality; one on lunar craters and a sixth on the patterns of cracking seen on rotten wood. These give him a mere 20 citations. Wegener’s posthumous problem was that Die Entstehung der Kontinente first appeared in the fourth issue of Geologische Rundshau in 1912, and seemingly the Web of Science doesn’t have that journal in its archives of a century ago. Later, extended editions appeared in book format which were not peer reviewed (most geoscientists would not touch his ideas with a barge pole until long after his death in 1930), and are therefore outside the academic pale. The key to a plausible mechanism for continental drift – symmetrical magnetic striping above ocean basins – was first described by Fred Vine and Drummond Matthews in an issue of Nature in 1963. In 50 years their work, ranking with discovering the structure of DNA, has accumulated 709 citations; i.e. 38.5 citations per year on average, which is not much for fuelling a revolution.

Photograph of Alfred Wegener, the scientist

Alfred Wegener, the unsung hero of continental drift(credit: Wikipedia)

Of course, citation is not the same as the frequency at which a paper is read. It is no secret that a not inconsiderable number of papers that appear in published reference lists haven’t been read by the authors who cite them. They are there by proxy, and you will probably find them in the bibliography of later papers that those same authors have cited. There is perhaps a certain kudos in such proxy citations, for it may be that the cited paper has achieved the equivalent of canonical status in the field.

Citation frequency is something of a lottery: language of publication; discipline (since 1953 Crick and Watson achieved three times Vine and Matthews’s average citations); date of publication (E. Komatsu of the University of Texas at Austin has already had 1939 citations for his February 2011 paper ‘Seven-Year Wilkinson Microwave Anisotropy Probe Observations: Cosmological Interpretations’ published in a supplement to the Astrophysical Journal; nine times the rate of Crick and Watson, but the paper is about the origin of everything)

Interestingly, the December 2012 issue of Geology presents stats on the most cited papers that it has published since 2000 (Cowie, P.A. 2012. Highly cited Geology papers (2000-2010) – What were they and who wrote them? Geology, v.  40, p. 1147-1148). Geology is among the highest ranking journals in the geoscience field, and had an impact factor of 4.8 over the last 5 years. A journal’s impact factor is the number of times all articles published in a 2-year period were cited in all indexed journals in the year following them, divided by the total number of articles published in the two years by the assessed journal. So, papers published in Geology between2007 and 2011 were cited on average 4.8 times in the year following publication. This journal is a useful source of citation statistics as it covers the full range of geoscience and all papers are limited to 4 printed pages, thereby forcing authors to be concise and clear in their writing and illustration. Consequently it is popular, which, incidentally, may explain its high impact factor.

Of the 33 papers cited most between 2000 and 2010, 14 are on topics relating to Tibet and China. There are 3 on oceanography; 3 on paleontology and extinctions; 6 on palaeoclimatology; 10 on tectonics and 10 on magmatism (3 of which were about rare adakites formed by partial melting of subducted oceanic crust). I haven’t read all of the papers, and the stats on topics may tell us very little, but I would bet that papers about geology in high-population emerging countries – China, India and Brazil – are met gleefully by rapidly growing communities of eager young geoscientists. It may even be worth a flutter on adakites as the ‘next big thing’ in petrogenesis. Mind you, it looks like I am not likely to be the best punter for hot papers, as out of the 33 ‘top-3′ papers since 2000, only 6 made it into Earth Pages, and of those only one between 2004-2010.

The digest goes on to show that year-by-year as many as 10 % of papers in Geology are not cited at all, up to 70% are cited between 1 and 5 times per year, while less than 10% get 10 or more citations in a year. Oddly, the author suggests that a dip in citations of Geology papers in recent years may reflect the launch of Nature Geoscience in 2008. Yet glossy as that new addition to the Nature stable might be, it has become something of a desert for papers on geology. Then there is evidence for both ‘vintage’ and ‘just-about-drinkable’ years  in Geology citations: the ‘top ten’ papers in 2001, 2005, 2006, 2008 and 2010 ranged from 10-15 citations for the tenth to 20-25 for the ‘hottest’ paper, while in 2000, 2002, 2003, 2004, 2007 and 2009 the most cited papers stood well above the rest at 32 to 55 citations per year. But that may just reflect the uneven pace at which well-received and provocative work emerges.

So, it begins to seem, from Geology at least, that for most geoscience authors publishing isn’t going to raise much hope as far as jobs or promotions are concerned. Yet if results are not published funding agencies may become fractious about your next grant application, and of course, university science departments puff themselves with annual publication rates (though rarely citation records, which as far as geosciences goes could be a wise move). But it is a matter of academic duty to publish for the record; even if a paper fills just one tiny niche the cumulative effect of publically available knowledge does eventually result in breaks through – one never knows… It could be a salutary lesson should publishers release data on hits for on-line PDFs of papers, as that would give some indication of how many readers individual papers have, but as for a ‘like this’ button or a means of star rating I think we have to venture into the deeper recesses of academic conservatism one small step at a time.

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Probing the Earth’s mantle using noise

Posted on December 4, 2012 by | Leave a comment
sesmic tomography

Artistic impression of a global seismic tomogram – beneath Mercator projection – dividing the mantle into ‘warm’ and ‘cool’ regions (Credit: Cornell University Geology Department – http://www.geo.cornell.edu/geology/classes/Geo101/graphics/s12fsl.jpg)

It goes without saying that it is difficult to sample the mantle. The only direct samples are inclusions found in igneous rocks that formed by partial melting at depth so that the magma incorporated fragments of mantle rock as it rose, or where tectonics has shoved once very deep blocks to the surface. Even if such samples were not contaminated in some way, they are isolated from any context. For 20 years geophysicists have been analysing seismograms from many stations across the globe for every digitally recordable earthquake to use in a form of depth sounding. This seismic tomography assesses variations in the speed of body (P and S) waves according to the path that they travelled through the Earth.

Unusually high speeds at a particular depth suggests more rigid rock and thus cooler temperatures whereas hotter materials slow down body waves. The result is images of deep structure in vertical 2-D slices, but the quality of such sections depends, ironically, on plate tectonics. Earthquakes, by definition mainly occur at plate boundaries, which are lines at the surface. Such a one-dimensional source for seismic tomograms inevitably leaves the bulk of the mantle as a blur. But there are more ways of killing a cat than drowning it in melted butter. All kinds of processes unconnected with tectonics, such as ocean waves hitting the shore and interfering with one another across the ocean basins, plus changes in atmospheric pressure especially associated with storms, also create waves similar in kind to seismic ones that pass through the solid Earth.

Such aseismic energy produces the background noise seen on any seismogram. Even though this noise is way below the energy and amplitude associated with earthquakes, it is continuous and all pervading: the cumulative energy. Given highly sensitive modern detectors and sophisticated processing much the same kind of depth sounding is possible using micro-seismic noise, but for the entire planet and at high resolution. Rather than imaging speed variations this approach can pick up reflections from physical boundaries in the solid Earth. Surface micro-seismic waves exactly the same as Rayleigh and Love waves from earthquakes have already been used to analyse the Mohorovičić discontinuity between crust and upper mantle as well as features in the continental crust; indeed the potential of noise was recognized in the 1960s. But the deep mantle and core are the principle targets, being far out of reach of experimental seismic surveys using artificial energy input. It seems they are now accessible using body-wave noise (Poli, P. et al. 2012. Body-wave imaging of Earth’s mantle discontinuities from ambient seismic noise. Science, v. 338, p. 1063-1065).

Poli and colleagues from the University of Grenoble, France and Finland used a temporary network of 42 seismometers laid out in Arctic Finland to pick up noise, and sophisticated signal processing to separate surface waves from body waves. Their experiment resolved two major mantle discontinuities at ~410 and 660 km depth that define a transition zone between the upper and lower mantle, where the dominant mineral of the upper mantle – olivine – changes its molecular state to a more closely packed configuration akin to that of the mineral perovskite that is thought to characterize the lower mantle. Moreover, they were able to demonstrate that the 2-step shift to perovskite occupies depth changes of about 10-15 km.

Applying the method elsewhere doesn’t need a flurry of new closely-spaced seismic networks. Data are already available from arrays that aimed at conventional seismic tomography, such as USArray that deploys  400 portable stations in area-by-area steps across the United States (http://earth-pages.co.uk/2009/11/01/the-march-of-the-seismometers/)

It is early days, but micro-seismic noise seems very like the dreams of planetary probing foreseen by several science fiction writers, such as Larry Niven who envisaged ‘deep radar’ being deployed for exploration by his piratical hero Louis Wu. Trouble is, radar of that kind would need a stupendous power source and would probably fry any living beings unwise enough to use it. Noise may be a free lunch to the well-equipped geophysicist of the future.

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  • Prieto, G.A. 2012. Imaging the deep Earth. Science (Perspectives), v. 338, p. 1037-1038.

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Hominin round-up

Posted on August 10, 2012 by | 1 Comment

Neanderthal ‘high-carb’ diet and self-medication

Reconstruction of a Neanderthal man (H. Neumann / Neanderthal Museum)

There is no doubt that the reconstruction of DNA from Neanderthal and Denisovan fossils is the most important forensic breakthrough as regards hominin evolution and relationships, but another approach has is starting to shed light on past lifestyles. Most workers have regarded Neanderthals as being predominantly meat-eaters from the evidence for their big-game hunting feats. In an attempt to get close to their actual diet some researchers have begun to exploit the lack of dental hygiene among fossil hominins: many teeth bear plaque or dental calculus (hardy, K. and 16 others 2012. Neanderthal medics? Evidence for food, cooking, and medicinal plants entrapped in dental calculus. Naturwissenschaften, v. 99, p. 617-626). Karen Hardy of the Universitat Autònoma de Barcelona and British, Spanish and Australian colleagues used gas chromatography and mass spectrometry and analysis of trapped microfossils in Neanderthal teeth to explore their everyday lives.

The results show signs of wood smoke: a good indicator of cooking and perhaps smoke preservation. Bitumen traces help confirm its use in hafting tools. But the most interesting feature is the consistent identification of cooked carbohydrate residues, enzyme activity on which would have produced the sugars strongly implicated in the formation of substantial plaque deposits. The data suggest that nuts, grass seeds, and possibly even green vegetables were a major part of the Neanderthal diet, A fascinating outcome is the discovery of molecules of the compounds that confer bitterness on a number of herbs with known medicinal properties, such as yarrow and chamomile. That does not prove that Neanderthals were accomplished herbalists, for many primates seek out such plants when feeling ill and even domestic cats will be seen eating grass if they have digestive problems or worms. Yet practical knowledge of herbal remedies cannot be ruled out. This novel, hi-tech approach to life-style analysis will surely blossom for most fossilized hominin dentition bears plenty of plaque. We await with interest the first signs of regular use of tooth-cleaning with woody fibres.

Neanderthals and Aurignacians survived massive volcanic disaster

About 39 thousand years ago the famous volcanic field of the Campi Flegrei west of Naples underwent a massive explosive eruption that created a huge ash plume whose deposition blanketed most of southeastern and eastern Europe with the Campanian Ignimbrite.  The ashfall and the probable disruption of climate and ecosystems over a number of years would have greatly stressed both Neanderthal and modern human (Aurignacian) populations of the area. There are a few sites in the Ukraine and Russia where tools occur below, within and above the ash deposit, but little to suggest the extent to which both populations were affected. However, tangible ash deposits are not the only evidence for volcanic events in human history: fine ash would have permeated everything during the eruption. A host of European geologists and archaeologists have sought microscopic evidence of the Campanian Ignimbrite in sediments within caves that were occupied at this time (Lowe, J. and 41 others 2012. Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards. Proceedings of the National Academy of Sciences doi/10.1073/pnas.1204579109): ignimbrite events are signified in cave deposits by ash dominated by minute glassy shards, whose shape is distinctive. The study was able to show that although the effects of the 39 ka eruption must have been devastating for local humans, both groups pulled through. The fact that Neanderthals survived the eruption and attendant prolonged climatic cooling suggests indirectly that their eventual demise was probably not a result of ecological disaster and more likely to have reflected their incapacity to compete successfully with the Aurignacian and later fully-modern human cultures.

Quite a crowd

Olduvai gorge

Olduvai gorge Tanzania (credit: Ingvar via Wikipedia) See also: http://upload.wikimedia.org/wikipedia/commons/archive/5/51/20080801124518%21Olduvai_Gorge.jpg

Who was the earliest human? Initially this accolade went to Homo habilis, first found by Louis Leakey at Olduvai Gorge, Tanzania in 2 Ma old sediments. Similar fossils turned up at Koobi Fora on the shores of Lake Turkana (formerly Lake Rudolr) in Kenya also thanks to the Leakey dynasty. Yet as more remains of that antiquity were found differences among them began to emerge, which some ascribed to different species and others to effects of sexual dimorphism among H. habilis. The majority view emerged of two distinct species H. habilis and ergaster but the possibility of a third cohabiting member of the early East African  human family was clung to in the shape of the single-fossil ‘H. rudolfensis’ . There the issue stood for more than two decades. Then, in the manner of London Transport, fossils of three individual humans were unearthed at Koobi Fora by the determined Leakey family (Leakey, M.G. et al. 2012. New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo. Nature, v. 488, p. 201-204). They seem to have confirmed three separate cohabiting species of human in Kenya in the period between 1.8 and 2.0 Ma: habils, rudolfensis and erectus/ergaster. Now, this is quite odd as the threefold morphological distinction ought to reflect three lifestyles sufficiently different to support the species over several hundred thousand years. Hopefully, there are teeth and dental plaque…

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Time wars flare up again

Posted on February 15, 2012 by | 3 Comments
English: A diagram of the geological time scal...

Time's spiral Image via Wikipedia

Last year Earth Pages News reported a rationalisation of the way in which geological time is signified (Rationalising geological time 7 May 2011). A working group set up by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Geological Sciences (IUGS) defined the year as the base unit, standardizing it to the time in seconds between one solstice and the next at the equator for year 2000 (3.1556925445 × 107 s) thereby linking it to the Système international d’unités or SI base unit of the second, itself defined in terms of behaviour of the caesium atom. It is to be signified by ‘a’ for annus (year in Latin) and preceded by ‘k’, ‘M’ and ‘G’  for thousands, millions and billion years, complying with the SI progression in steps of 103 for units.

The sticking point for some, mainly in the US (e.g. Science magazine and many geoscientists there) is that the ka, Ma, Ga symbols are to apply not only to times before the present but also to spans of geological time. Since the agreed convention is incorporated into SI it has almost the force of law for scientists , so that the Cretaceous Period will be said to have begun at 145.5±4.0 Ma ago, ended at 65.5±0.3 Ma ago and was 80 Ma long, instead of the latter being in m.y., m.yr., mya  or Myr according to what seem to have been personal quirks or those of scientific journals.

Somewhat florid reaction against the rationalisation (Christie-Blick, N. 2012 Geological time conventions and symbols. GSA Today, v. 22 (February 2012 issue), p. 28) seems to have flowed from a deliberation on the IUPAC-IUGS proposal (in Prague, Spring 2010) by a lesser world body: the International Commission on Stratigraphy’s  (ICS) International Subcommission on Stratigraphic Classification (ISSC). The meeting voted 16 to 2 to reject the proposal – a substantial number of voting members abstained – claiming that it violated SI ‘rules’ regarding base- and derived units. The issue, on reaching the ICS meeting, as the same Prague workshop, seems to have been greeted by a 50:50 split. A closed meeting of the ICS Bureau (now we can begin to see the kind of thinking involved here…) on the workshop’s last day unanimously adopted the motion ‘We neither accept nor reject the IUGS-IUPAC Task Group’s recommendation to apply Ma, generally, as the unit of deep time. We accept the argument for Ma as a single unit for time but would recommend flexibility, allowing for the retention of Ma as specific notation for points in time (i.e., dates) and myr as a unit of time denoting duration. We agree with the spirit of this statement’ [my italics]. ‘Neither accepting nor rejecting’ is something familiar from minutes of the Central Committee of the former USSR, being rumoured to have been Joseph Vissarionovich Stalin’s favoured formulation in moments of uncertainty: a little like the old ‘Belfast Question’, ‘Are you for us or against us’ from someone whose politics is not entirely clear.

An argument proffered by Christie-Blick is, ‘No one objects to the storming of the Bastille on 14 July 1789 (a date) or to the construction of Stonehenge from 2600–1600 BC (an interval specified by two dates). In the case of the latter, we say that the job took 1000 years, not 1000 BC.’ This forgets something quite practical: geochronologist rarely if ever, ‘neither accept nor reject’ AD, BC BCE, or CE but express time in years before present, with the odd convention that ‘the present’ was 1950, before atmospheric testing of thermonuclear devices. What is wrong with the answer to the question, ‘When did the Cretaceous begin?’ being 145.5 Ma ago, or ‘80 Ma’ in answer to, ‘How long did it last?’ Who would prefer the alternative to the second question –  80 (choose your preferred symbol from the following: m.y., m.yr., mya.  Myr., million years or millions of years)?

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Geophysics reveals secrets of the beaver

Posted on February 4, 2012 by | 1 Comment
Beaver Hut

Beaver lodge and dam (Photo credit: Bemep)

One of the interesting things about the beaver is that its obsession with civil engineering may have a profound effect upon landscape. Before Europeans set foot in North America, it is estimated that up to 400 million of them inhabited the continent. The ponds that they create by building the dams in which they live securely, encourage sedimentation. It is quite possible that this creates recognisable stratigraphic formations; but no-one really knows as active and wet beaver habitats hide what lies beneath them. It is clearly urgent to obtain this intelligence: the Geological Society of America’s monthly Geology contained in its first issue for 2012 a paper that indeed probes the legacy of large rodents long gone (Kramer, N. et al. 2012. Using ground penetrating radar to ‘unearth’ buried beaver dams. Geology, v. 40, p. 43-46).

The target for surveillance was the eponymous Beaver Meadows in Colorado, USA, and not only did the researchers from Colorado State University deploy ground-penetrating radar, but used the seismic reflection method as well, to quantify volumes of beaver-induced sedimentation. Fortunately, despite their past presence in some strength, beavers no longer frequent Beaver Meadows and no ethical lines in the sand were crossed. Beaver and elk seemingly have long competed for the meagre resources of Beaver Meadows, the rodent having finally succumbed locally to determined efforts by the elk to consume the beavers’ victuals. As disconcerted and no doubt sulking beavers failed to maintain their dams and lodges, the water table fell, further encouraging the elk. Eventually, at some time after the Beaver Survey of 1947, the last of them moved to new meadows. Their ravages (see http://animal.discovery.com/videos/fooled-by-nature-beaver-dams.html) of what would otherwise be dense woodland have, however, made it possible for geophysicists to try out their sophisticated kit on a new and thorny issue: they ran 6 km of GPR and seismic profiles.

I came across this handsome animal (Castor can...

A beaver. Image via Wikipedia

In much the same way as larger scale geophysical data are interpreted for petroleum traps, signs of hydrocarbons, mighty listric faults and zones of tectonic inversion, the beaver-oriented sections potentially yield considerable insight to the trained eye. There are indeed beaverine sedimentary aggradations of Holocene age above the local glacial tills. Beneath Beaver Meadow they amount to as much as 50% of post-glacial sediment. Apparently, the deposits have a linear element that follows the local drainages.

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Research misconduct

Posted on January 25, 2012 by | Leave a comment

whistleblowerIn 2011 there was a growing trickle of news about various kinds of research malpractice: data fabrication, falsification and obfuscation (not reporting adverse outcomes); plagiarism (http://earth-pages.co.uk/2008/01/01/watch-out-burglars-about/) ; repeated publication of data, text and diagrams (self-plagiarism); ‘guest’ contributors; plus other kinds of scientific fraud and chicanery (http://en.wikipedia.org/wiki/Scientific_misconduct). Motives are many, from malice to laziness, but more often than not are a mixture of ambition, greed, jealousy, desperation and paranoia that increasingly form the downside of academic life – not the least in science. Life is so hard in a career dominated by promotion, which in academe rests on: publication lists; peer citations; journal impact factors; institutional income generation and, let’s face it, by the kind of individual self-regard and hubris that drives people to seek fame and celebrity. The wider population has grown accustomed to this as bystanders watching Big Brother, the X-Factor and Fame Academy.

Fiddling research has reached such a level as to provoke the world’s most prestigious research outlet, Nature, to include an editorial on the topic (Editorial 19 January 2012. Face up to fraud. Nature, v. 481, p. 237-238), albeit after a first lead about the Antarctic Treaty at the centenary of the race to the South Pole, and followed by a puff for articles in the same issue on how to get research funding from the public or philanthropists.

As many scientists suspect, in fact what does emerge about research malpractice is the tip of the proverbial iceberg, some admitting to wandering from the path of righteousness themselves (but not saying how or where). One mild form is making unsubstantiated claims: a great many geologists (including me) have trodden very thin ice in this regard (unless they wisely included the ‘Get Out of Jail’ verb ‘to speculate’), but few innocent bystanders, if any, have met a horrid fate as a result of resultant health and safety ‘issues’. A great deal that should not does get through peer-review to enter the canon of whichever discipline. Academic fraud is a quasi-crime with few risks of detection, though punishment can be swingeing,  in the manner of being cast into the ‘dark place’.

According to Nature, what makes Britain seem to be a haven of academic honesty is the risk that both journals and ‘whistleblowers’ face from libel laws, should deeds and authors be named and linked. Moreover, certain kinds of gross malpractice never reach peer-reviewed publication. Examples are: malicious falsification of someone else’s data by a perpetrator with access to the data on, say, a lab server; swapping analytical sample labels; destroying lab records(http://earth-pages.co.uk/2010/11/04/sabotage-in-science-4/); petty theft of ideas (on which there is no formal copyright), for instance through copying poster presentations at conferences; misuse of peer-review privileges – generally anonymous (http://earth-pages.co.uk/2006/08/01/anonymous-referees-2/); menacing a presenter at a conference or disrupting their presentation. Victims of such actions rarely have any redress, unless the perpetrator is actually caught ‘in flagrante delicto’, so to speak (http://earth-pages.co.uk/2010/11/04/sabotage-in-science-4/).

‘Whistle blowers’ or complainants then face the defensive mechanisms of the academic world: not dissimilar to those of the musk ox. How far you get as regards redress depends to a large extent on the seniority of the perpetrator. An extremely brave friend cited, with abundant evidence, his vice-chancellor for gross cronyism: he was soon ‘on the cobbles’ with the VC (male) remaining ‘virgo intacto. Yet an Industrial Tribunal took a very dim view of the whole affair: my pal paid off his mortgage and lives well in retirement from the compensation awarded by the tribunal. It takes an exceptionally brave graduate student to take on their supervisor(s) for malfeasance (or even the lesser misfeasance and nonfeasance – http://en.wikipedia.org/wiki/Misfeasance). The likely best outcome (after long and harrowing procedures) is a kind of bribe – more time to complete – but most victims just disappear without completing. Unless the perpetrators are low on the academic scale (they might get a reprimand at worst), promotion to management or enhanced early retirement is a common response by senior management to mounds of incontrovertible evidence of guilt. The oddest fate for someone flying high in the institutional firmament was rumoured to be a posting to a far-flung outpost of the former British Empire: but I digress…

The geosciences seem immune to research malpractice, which may reflect at best the small numbers involved in the discipline or at worst because no-one notices, or cares for that matter. Unless, that is, dear reader, you know different…  Most important, for graduate students who are the most usual victims: protect yourselves (http://earth-pages.co.uk/2003/12/01/protecting-your-intellectual-property-2/).

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A sign of the times; the ‘Anthropocene’

Posted on May 30, 2011 by | 1 Comment
Alternative version of image:Wooden hourglass ...

Image via Wikipedia

On 11 May 2011, the Geological Society of London hosted a conference, co-sponsored by the British Geological Survey, to discuss evidence for the dawn of a new geological Epoch: the Anthropocene, supposed to mark the impact on the Earth of our species. The Society, and no doubt others internationally, is interested in gathering thoughts, reflections and observations about the Anthropocene. There is indeed a a powerful and vocal, though not necessarily large, lobby directed at the International Commission on Stratigraphy (ICS) to enshrine this new division. That lobby  has been active since 2000 (see: No escape from global warming;  Changing the world; Epoch, Age, Zone or Nonsense in EPN issues of November 2000, April 2005 and March 2008 respectively)

We currently live in the Holocene (‘entirely recent’), an Epoch with ICS imprimatur. Yet the last 11.7 ka has been but one of very many interglacials since about 2.6 Ma ago; the start of the Pleistocene Epoch and the Quaternary Period – Arduino’s last surviving division of geological time, and lately resurrected from an untimely demise! The ‘golden spike’ for the Pleistocene/Holocene boundary is at the agreed combination of signals – ‘deuterium excess values, accompanied by more gradual changes in 18O, dust concentration, a range of chemical species, and annual layer thickness’ – of the end of the Younger Dryas/Greenland Stadial 1 in a single Greenland ice core (NGRIP) held in a cold store in Copenhagen.

The Holocene itself was based on anthropocentric grounds; i.e. it roughly coincides with the transition from human foraging to sedentary life, agriculture, the relentless development of exploitation of the majority of humans and the commodification of the physical and organic environments following the Younger Dryas stadial. I guess that paraphrases how the ‘Anthropocene’ is proposed to be defined – a signal of the beginning of irreversible global change due to human activities whose future we cannot predict.

Even if it was possible to agree on some definitive signal of the onset of human-induced global change in the geological record there remains the formal difficulty for the ICS of agreeing on the location as well as the age and likely durability of the GSSP that would mark the beginning of the ‘Anthropocene’. The originator of the idea, Nobel Prize winning chemist Paul Crutzen, argued vaguely for the ‘start of the Industrial Revolution’. Recently it has been proposed by some to be 6 August 1945 marked by long-lived radioactive fallout from the atomic massacres of civilians at Hiroshima and Nagasaki.  Quaternary researchers decided some time back that the ‘present’ (as in ‘before present’ or b.p.) should be the year 1950 when atmospheric testing of thermonuclear weapons created excess 14C that will make radiocarbon dating of the next 50 ka somewhat more uncertain than it otherwise would have been. The ICS may well have a lengthy debate on its hands if the proposal ever reaches its deliberations.

Furthermore, the advocates are concerned that we are living in the transition into their ‘Anthropocene’ and that it will be so rapid and biologically disastrous as to manifest itself in stratigraphic sections of the future as a mass-extinction event. No previous mass extinction event has been allocated epochal status, being so brief, though never so brief (~10 ka) as the Holocene or any other interglacial of the past 2.6 Ma.

All that I can conclude is that should there still be geologists in, say, a million years time, who will be living in conditions and possessing intellects about which we would be ill advised to guess, they will still be in awe of the vast tracts of geological time and their stratigraphic and tectonic records over the last 4.55 Ga. Consequently, it is possible that they may well regard the then ancient proposal for an ‘Anthropocene’ as premature, hubristic and not a little reminiscent of the fable of Chicken Little; a humorous legacy of their somewhat startled predecessors. By all means let us be concerned  about and take action to halt adverse human influences on the planet, but sloganeering to climb aboard a bandwagon does neither. At the Geological Society meeting, Paul Crutzen observed  “… it will probably take another 20 years before it is formally accepted.” Thank goodness for a sense of reality: we may all be extinct by then…

Added 12 August 2011: Between 11.5 and 3.5 ka the greatest event in the evolution of modern humans took place on all continents except Australia and Antarctica; a foraging lifestyle gave way to settlement and the domestication of both plants and animals – the Neolithic Agricultural Revolution. The production of surplus value, stored in the form of livestock herds and grain, marked by this transition set humanity on the road to its current social, ecological and economic crisis. Interestingly, William Ruddiman of the University of Virginia in 2005 noted a shift in the CO2 content of glacial ice around 8 ka, which he ascribed to intense farming and suggested that if there were to be an Anthropocene Epoch it should coincide with the start of agriculture. Combining geological and societal factors points unerringly to the start of the Holocene, so there is little need for a new Epoch. That sensible view receives support from a palaeo-demographic survey of 133 burial sites in the Northern Hemisphere: some before the local transition to agriculture, others following it (Boquet-Appel, J.-P. 2011. When the world’s population took off: the springboard of the Neolithic demographic transition. Science, v. 333, p. 560-561). The proportion of 5 to 19 year-old remains in the cemeteries shows a marked rise in the thousand years after the first local signs of agriculture thereafter to stabilise at a new higher level. This indicates a significant increase in female fertility, perhaps by as much as two births per woman. That would set in train the relentless, 1200-fold rise in world population from the estimated 6 million at the start of the Holocene to 7 billion at present.

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Top story and most flawed hype of 2010

Posted on January 13, 2011 by | Leave a comment
Reconstruction of Neandertaler at Neanderthal ...

Reconstruction of a middle-aged Neanderthal man. Image via Wikipedia

EPN might seem to include a disproportionate number of items on hominin evolution, including several on genetic evidence. An outcome of the Earth System’s 4.5 billion-year evolution increasingly depending on physical resources, we lie at the focus of our own curiosity studying the past primarily for ourselves. That is why the discovery from the partial genome of Neanderthal remains that all humans outside those who live in Africa carry in our DNA the ‘fruits’ of intimate relations with Neanderthals is surely the most explosive development of the 21st century so far (see Yes, it seems that they did…in May 2010 issue of EPN). It is deepened by the publication in late 2010 (Reich, D and 27 others 2010. Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature, v. 468, p. 1053-1060) of genetic findings from remains of a third distinct hominin group that inhabited central Siberia 30 to 50 ka ago (see Other rich hominin pickings in the May 2010 issue of EPN). [Thanks go to Dr Bill Deller, legal historian, for alerting me to this.] The DNA from a tooth and a finger bone show that the individual female was genetically neither a fully modern human nor a Neanderthal in a statistical sense, but parts of the sequence, as with the Neanderthal genome, pop up in the genomes of living people. The ‘Denisovan’ signature – the authors do not assign the female to a new species – contributes 4 to 6 % of the genomes of present-day inhabitants of Papua-New Guinea and other Melanesian people of the Pacific north of Australia, but appears in no others. Since Melanesians carry some Neanderthal genetic material the new finding can be interpreted as the result of similar interfertile mating between the ‘Denisovans’ and a limited group of early fully human travellers who crossed central Asia and eventually moved through Indonesia to cross the West Pacific to Papua-New Guinea and Melanesia about 45 ka ago. For up to a twentieth of the genetic outcome of such liaisons to survive to the present suggests no idle dalliance, but proportionately common relationships.

Solo tiene 400.000 años. Un chaval, vamos.

Reconstruction of Homo heidelbergensis, perhaps similar to a Denisovan. Image via Wikipedia

Denisovans shared a common ancestor with Neanderthals and ourselves, but seem to have followed a separate evolutionary path. Analysis of their DNA suggests that they diverged from Neanderthals around 640 ka  and from modern Africans around 800 ka. Although these ‘molecular clock’ dates show considerable uncertainty, they extend back to a period when fossil evidence suggests the presence in Europe and Africa of Homo heidelbergensis and H. erectus respectively. The molar tooth has a morphology similar to African H. erectus and to even earlier hominins, but distinct from the teeth of Neanderthals and fully modern humans. Could the ‘Denisovans’ represent a distinct wave of emigrants from Africa? Some hominin fossils from China are dissimilar to Neanderthals and Asian H. erectus and efforts will certainly be made to establish their genetic make-up. For the moment, these findings deny any simple linear explanation for the ‘Out-of-Africa’ movement of people. Equally important, and the reason why the researchers refuse to assign the ‘Denisovans’ to a new species, is that interfertility is generally accepted as the sign of mating between members of the same species. To some extent this harks back to the ideas of the ecologist Jonathan Kingdon (Kingdon, J. 1993, Self-made Man and His Undoing. Simon & Schuster: London) that humans are a line that did not speciate over the last couple of million years, but show morphological differences that arose within the growing protection from selection pressures conferred by the use and development of tools. Kingdon’s parsimonious approach to human evolution found little favour with palaeoanthropologists, perhaps because of the kudos associated with finding and naming new species.

See also: Callaway, E. 2010. Fossil genome reveals ancestral link. Nature, v. 468, p. 1012; Bustamante, C.D. & Henn, B.M. 2010. Shadows of early migrations. Nature, v. 468, p. 1044-1045.

Perhaps it is a generational thing, stemming from popular science fiction and scientists’ speculation in the 1970s and 80s, that has encouraged the growth of exo-, xeno- and astrobiology as subdisciplines. There is a certain sadness in that all practitioners can do at present is examine the organic diversity offered by our home world and speculate about alien life forms based on that terrestrial evidence. The Earth offers plenty of scope for studying the biologically odd and awesome, especially among prokaryotes, as there are extremophiles of all kinds: the hot, the cold and the deep biospheres. But all are based on the nucleic acids shared by all life on Earth; traces of familiar amino acids occur far and wide in the cosmos, but none whatsoever of anything more complicated that could source self-replication and evolution. So it was in a mood of solemn gaiety that EPN greeted the hint of truly alien life forms among us by NASA press officers in November. It turned out to presage a paper concerning bacteria peculiar to Mono Lake in California (Wolfe-Simon, F. And 11 others 2010. A bacterium that can grow by using arsenic instead of phosphorus. Science Express, DOI:10.1126/science.1197258). The paper hinted at arsenic being used to substitute for phosphorus in the structure of nucleic acids in the bacterium when it lived in low-phosphate environments. The paper’s substance was culturing the bacterium in vitro in increasingly P-deficient water that also contained arsenic. If replicable the notion of arsenic-DNA would seem to be pretty startling, but the paper faced a storm of adverse comment.

Mono Lake Tufa

Biomineralised columns at Mono Lake, California. Image via Wikipedia

A crucial feature of the DNA molecule is the bond between the sugar of one nucleotide and the phosphate group of another. As any geochemist knows, it is possible for elements to substitute for one another if they have similar atomic properties. Arsenic, being adjacent to phosphorus in the same group of the periodic table, is a potential substitute -  arsenate for phosphate, although the former is far less stable than phosphate. Wolfe-Simon’s team is not claiming the peculiar bacterium as a candidate for alien life forms, but that is the spin widely being put on their work. All they suggest is that some bacteria can survive high-As low-P conditions and may be found in chemically highly toxic environments elsewhere. Since the cosmic abundance of arsenic is about three orders of magnitude less than that of phosphorus it is unlikely that alien genetic material somehow uses arsenic in its architecture. Besides, why should DNA be the sole basis for self-replication, the essence of truly living beings?

Added 14 January 2011: Science gave Felisa Wolfe-Simon the opportunity to reply to critics (Pennisi, E. 2010. Discoverer asks for time, patience over arsenic bacteria controversy. Science, v. 330, p. 1734-1735). Personally, I sympathise with the beleaguered team: on the launch of Stepping Stones in 1999 I was pestered continuously by journalists from both low- and highbrow newspapers. In that case I had made a joke that perhaps the human coughing reflex had stemmed from ancestral reptiles that survived the Permian-Triassic mass extinction and the emissions of the Siberian Traps: the journalists actually believed it

See also: Pennisi, E. 2010. What Poison? Bacterium uses arsenic to build DNA and other molecules. Science, v. 330, p. 1302.

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