Wednesday, February 29, 2012

The State Of Higher Education In Pakistan

Physicist Pervez Hoodbhoy writes in The Express Tribune:

Pakistan’s university teachers and researchers have roughly the same ethical standards as its politicians, generals, judges, and shopkeepers. Hiding in the shadows is even easier because it is hard for non-academics to tell the difference between trivial and significant works. So once the PCST and HEC announced cash awards and other perks, almost overnight a research-poor country started producing a bumper crop of “research articles” year after year. The HEC claimed victory but many papers were tired repetitions, contained fake data, were plagiarised, or published in fly-by-night journals. Dr Isa Daudpota, an intrepid academic trouble-shooter has, over the years, documented the academic sleaze. Such stark evidence has, unfortunately, had scant effect upon the HEC.

Prof. Hoodbhoy has been harsh before about the state of science education in Pakistan and has gotten into trouble danger of being harmed physically.. over teaching human evolution at a University.

Kenneth Chang wrote an article about that incident in the New York Times a while ago-

Pervez A. Hoodbhoy, a prominent atomic physicist at Quaid-e-Azam University in Pakistan, said that when he gave lectures covering the sweep of cosmological history from the Big Bang to the evolution of life on Earth, the audience listened without objection to most of it. “Everything is O.K. until the apes stand up,” Dr. Hoodbhoy said.

Mentioning human evolution led to near riots, and he had to be escorted out. “That’s the one thing that will never be possible to bridge,” he said. “Your lineage is what determines your worth.”

Its disheartening to see that Prof. Hoodbhoy judges it as something that will never be possible to bridge. Religious fundamentalism is destroying science education.  I doubt the cancer will be going away any time soon.

HT: Nanopolitan

Thursday, February 23, 2012

Field Photos: Red Layers Within Deccan Lavas And Mass Extinction

I'll lead you into the field photos in a minute, but I just want to comment on something else first.

Prof. Gerta Keller and her collaborators are at it again. Two new papers in the Journal of the Geological Society of India and Earth and Planetary Science Letters  have come out in recent months in support of the theory that the Deccan volcanism played a large role in the mass extinction that took place 65 mya.  The mass extinction resulted in biologically new conditions on earth and we recognize that formally by naming post extinction geological layers to represent the beginning of the Cenozoic Era.

I haven't read the papers but from following some early work of this group and the abstracts it is worth summarizing Prof. Keller's argument

1) The Chicxulub meteorite impact which is dated to around 65 mya and considered to be the main cause of the mass extinction occurred 300,000 years before the mass extinction and so couldn't have been the sole cause of the extinction. This conclusion is arrived at by studying Maastrichtian (latest Cretaceous) to Danian (earliest Cenozoic) sections near the impact crater in Mexico and Brazos river, Texas. The sections show a meter or so of sediment between the   impact breccia and the Cretaceous -Cenozoic boundary layer which is recognizable by C-13 shifts and an irridium anomaly, marking a pronounced environmental shift. Sedimentological analysis of the meter of sediment suggest normal quiet conditions of deposition and biostratigraphy suggests a time lag of about 300,000 years between the impact breccia and the boundary layer. The irridium anomaly thus points to a second meteorite impact.

2) On the other hand, the main pulse of the Deccan volcanism accounting for some 80% of lava volume erupted in the latest Maastrichtian in magnetic polarity zone C29R.  Planktic foraminifera and other ecological indicators from marine sediments spanning Maastrichtian to Danian deposited between lava flows in the Krishna Godavari basin show drastic drops in species richness, an indicator of extreme environmental stress. Formaminfera in Danian sediments between younger lava flows are represented by just a few species. These are survivor fauna. This then demonstrates a cause and effect relationship between the Deccan volcanism and environmental stress.

The mass extinction according to Prof. Keller had multiple causes, Chicxulub impact, then Deccan volcanism and then a second meteorite impact.

Most scientists working on this problem reject this scenario. This is not because they object to the premise that the Deccan volcanics would have been harmful. Their objection is to Prof. Keller's interpretation that the Chicxulub meteorite impact took place 300,000 years before the mass extinction. They interpret the meter or so sediment near the impact crater and the Brazos section as a tsunami deposit and not indicative of a long period of quiet conditions. And in many many sections spanning Maastrichtian to Danian around the world, there is no sediment between the impact layer (recognized by typical glass spherules and shocked quartz) and the boundary layer. No sediment therefore no time lag say the scientists and so Chicxulub meteorite impact coincides with the boundary layer and is the main cause of the mass extinction. Take a look at this great photo of the Cretaceous -Paleogene boundary layer at the Wooster Geologists blog.

Prof Keller argues that such sections wherein the impact layer coincides with the boundary layers are condensed sections i.e. there was no sedimentation at all in the interval between the impact and the mass extinction and therefore the two seem to appear the same! One problem has been the lack of high resolution dating which could separate these events and settle the issue. 

The main pulse of the Deccan volcanism lasted maybe half a million years or so and temporally does seem to coincide with the mass extinction. This would have resulted in at least severe regional environmental stress and extinction. The paper in Earth and Planetary Science Letters documents regional environmental effects. But would it have global impact?

A couple of months ago I was driving west of Pune (location in image below) and came across a road section that exposed several red clayey layers (red arrows) between lava flows. 

 These red layers locally known as red bole have been interpreted as weathering products formed during a hiatus in volcanic activity. Some are debris and soil that formed on top of a flow which then got fossilized due to burial by the subsequent flow. Others though are weathered tuffs or ash fall deposits. They have been found to contain basaltic shards (silicate glass that forms from sudden chilling of lava) diagnostic of an explosive pyroclastic origin. These explosive ash layers settled on lava flows and in a period of quiescence that followed got altered to a clay bearing layer.

These pyroclastic layers occur at regular stratigraphic intervals throughout the main Deccan volcanic phase. Ideas about their origins are not new. There is work dating back to the late 1970's by geologists from Pune (Dr. L.K. Kshirsagar - Ph.D thesis) that had recognized the pyroclastic nature of these layers. But the environmental connection to the mass extinction was not made then. There has been more recent work on these red layers and the idea is being floated around that such type of explosive volcanism may have resulted in columns of ash being ejected tens of km up to stratospheric levels and that would have influenced global climate leading to environmental perturbations.

 okay.. so finally here are the photos of these red layers. I can't say whether these represent in situ soils or ash fall deposits.

Long view of a red layer-

Close up of a red layer - 

Red layers containing broken blocks of basalt -

A rubbly top of a lava flow. You can see red material infiltrating through the cracks and opening between the basalt rubble. 

The Deccan volcanics are considered to be non explosive fissure type eruptions. Can explosive volcanic eruptions resulting in Plinian columns ( ash columns reaching great heights) form in such a volcanic setting? I am not a volcanologist but I have always associated such eruptions with classic volcanic cone formation. Have such cones and eruptive vents been identified in the Deccan volcanics?   Is this a problem of preservation, the cones being weathered away, or is it that cones need not always be associated with explosive volcanism? And were there enough of these episodes to have influenced global climate?

Tuesday, February 21, 2012

I Am Tweeting...

Groundwater Is Important In The Himalayas Too

The steep gushing streams of the Himalayas leads one to think of water flow within the Himalayas as primarily a surface phenomenon. Water that falls on the Himalayas is temporarily stored in different types of reservoirs before being discharged into rivers. These include soils, snow, glaciers and groundwater.

A recent paper (behind paywall) in Nature Geoscience by Christoff Andermann and colleagues that has estimated the water budget of the Central Himalayas (Nepal region). I don't have access to the paper but from the abstract I gather that using a combination of river chemistry and models of water budgets the researchers conclude that groundwater contributes more than snow and glaciers to the annual discharge of rivers in that region. The fractured rock of the Nepal Himalayas is an important aquifer.

Last year I was trekking in the Kumaon region of the Lesser Himalayas, west of the study area of this paper. I am not at all surprised that groundwater can be an important component of the water budget of many Himalayan terrains. The rocks are foliated i.e. they are made up of flaky and platy minerals that part and offer passageway to water and further the rocks are tectonically fractured, thus offering a secondary system of conduits for water flow.

I noticed that spring discharge was being used to irrigate just about all the agriculture and personal consumption needs. A couple of pictures from the Mukhteshwar area of the Kumaon Himalayas.

The image below is of a spring. The discharge is quite vigorous .. and soothing for a weary trekker!

The water is channeled into irrigating the fields and orchards you see in the image below.

And here is a useful map of the relative contribution to the annual discharge from various sources. In the westernmost and easternmost Himalayas, the major contributor are snow and ice melt. In the central regions, high rainfall and glacial melt contribute a lot.. In Nepal, groundwater is an increasingly important contributor to rivers.

Source: Hydrology: Himalayan groundwater

I suspect that while comparing across these regions the geographical location of the catchments will matter. In the westernmost and easternmost regions outlined in the figure, larger stretches of the Indus and Brahmatputra catchments lie in very high terrain. Ice and snow melt will contribute significantly here. In Nepal, there is a much broader belt of the lesser Himalayas with relatively less snow and ice.

Tuesday, February 14, 2012

Psycho-Shrinking The Neanderthals

On Quirks & Quarks host Bob McDonald and psychologist Prof. Frederick Coolidge have an entertaining discussion on Neanderthal behavior.

Apparently, the fossil record suggests that the Neanderthals recovered from injuries sustained above the waist. Injuries to the foot though were generally fatal. Prof.  Frederick Coolidge suggested that while Neanderthals took care of their injured, a foot injury meant that that individual couldn't take part in a hunt and move around with the band and may have been left behind to die.

I don't get this. If empathy was extended to individuals who were injured above the waist and presumably couldn't be useful in a hunt in that state and possibly had to be helped move from place to place, why would that empathy stop below the waist?

Here is one for keeps. Frederick Coolidge agrees with Bob McDonald that the Neanderthals would have had a sense of humor, but a slapstick kind of a humor. More like the Three Stooges. They would be lost on puns and word play.

I wonder if Prof. John Hawks considers this damaging enough to be placed in his Neanderthal anti-defamation files!

Friday, February 10, 2012

Yamuna And Sutlej Stopped Flowing Into Ghaggar / Sarasvati By Early Holocene

The Yamuna stopped flowing into the Ghaggar / Sarasvati and shifted course eastwards into the Ganga as early as around fifty thousand years ago. The Beas and the Sutlej stopped flowing into the Ghaggar / Sarasvati and joined the Indus before ten thousand years ago, several thousand years before the beginnings of the Harappan civilization.

That is the conclusion reached in a paper in Geology  (behind paywall) by Peter Clift and colleagues using U-Pb (Uranium - Lead) dating of zircon crystals from ancient channels and alluvium of the Ghaggar / Hakra river.

I had earlier suggested that the Ghaggar likely never had any glacial connection. That statement now needs to be modified to read that there is a strong possibility that the Yamuna flowed into the Ghaggar in the Pleistocene and the Sutlej until the early Holocene.

Detailed mapping of the region between the Indus and the Yamuna where the present day Ghaggar / Hakra flows  has revealed the presence of many dried up channels suggesting that a much larger Ghaggar river existed in the past. The Harappan urban civilization declined and was abandoned by around 2000 B.C to 1800 B.C. One of the main reasons given is a prolonged drying of the region which made agriculture unsustainable. Monsoonal strength over this region has fluctuated for the last ten's of thousands of years and evidence from many different sources indicates that this region began experiencing aridity by mid Holocene and this arid phase moved eastwards over time slowing making urban centers and agriculture unsustainable. The larger dried up channels point to this climate change.

Another explanation of many of these dried up channels is the hypothesis that large glacially fed rivers like the Yamuna and Sutlej once flowed into the Ghaggar. They shifted course away from the Ghaggar  in the late Holocene, dramatically reducing water supply to the Harappan urban centers and contributing along with climate change to their decline and eventual collapse.

How does one figure out whether ancient channels represent glacially fed rivers and match them to known rivers? Clift and colleagues use a conceptually simple yet technologically challenging geochemical technique to make this match between ancient channels, present day rivers and their source in the Himalayas.

The Himalayan mountains are made up of several geological terrains of different ages. The Karakorum and Kohistan terrain (Trans -Himalayas) are younger than 300 million years old, the Tethyan Himalayas are 300 -750 million years old, the Greater Himalayas are 750 - 1250 million years old and the Lesser Himalayas are 1500 -2300 million years old. The ages of these terrains have been well characterized over the decades using a number of different radioactive clocks.

For this study the U-Pb clock contained within zircon crystals was selected. Zircon (zirconium silicate) is a hard mineral which occurs in granites and metamorphic rocks which make up large portions of these terrains. It can survive physical attrition during long transport by streams. It is also chemically quite stable and there is less chance of chemical weathering leaching out U or Pb from the crystal. Another advantage is that there are two clocks inside zircon. One through the decay of U-235 to lead-207 and another through the decay of U-238 to lead-206. So there is an inbuilt crosscheck on your results.

Why not just use the types of minerals to fingerprint the source rocks? That method does work is certain contexts but geological terrains of different ages can contain similar suite of minerals making discrimination based on a unique signal difficult.

Below is a map of the study area.

Source: Clift 2012

Black dots represent trenches. Stars represent drill sites and white squares represent samples from modern rivers. Dotted lines are proposed courses of ancient Yamuna and Sutlej. U-Pb dates were calculated from zircons sampled from the Indus, Ghaggar,  Beas, Sutlej and the Yamuna. The idea is that the headwaters of each of these rivers would be eroding sediment predominantly from different geological  terrains and therefore if enough zircon crystals were analyzed it would be possible to identify a geological age signal that is unique to each river. For that though large number of crystals need to be dated for a statistically robust result.

For this study more than hundred grains per sample were analyzed using a scary sounding instrument- the Laser Ablation Inductively Coupled Plasma Mass Spectrometer.  It was found that individual rivers do cluster at different ages i.e. they contain a population of grains within a distinct age range and could be discriminated from each other. For example the Beas showed a major population of zircon grains of age 300 -750 million years ago implying that its headwaters drained mostly the Tethyan Himalayas. Similarly the  the Yamuna sample contained a major population which clustered around 1875 million years. The Sutlej has two populations clusters, one at 750 -1000 million years ago and another at around 1830 million years or so.

The next step was to find out whether ancient sediments from dried up channels associated with the Ghaggar river contained zircon populations with age clusters that could be matched to modern rivers. If they did, then that would mean that that particular river was flowing in that channel in the past. And carbon-14  or Optical Stimulated Luminesence (OSL) dating of the sediment could tell when. So there are two kinds of dating techniques used here. The U-Pb technique dates the geological age of the rocks in the Himalayan headwaters of the rivers. The carbon-14 and OSL techniques date the timing of deposition of sediments in the various channels.

Channel and overbank sediments close to Harappan archaeological sites along the northern edge of the Thar desert were sampled. The sediments were dated using a combination of 14C which dates organic matter and OSL, a technique that is used to calculate the time since the sediment was last exposed to sunlight.

Analysis showed that ancient sediments did contain populations of zircons of distinct age ranges that could be matched to the Yamuna, Sutlej and the Beas implying that these rivers were flowing through these channels sometime in the past. Constrained by carbon-14 and OSL dates of the sediment, the patterns indicate that the Yamuna signal was lost around fifty thousand years ago implying a change of course of the Yamuna eastwards towards the Ganga at that time. The Beas and Sutlej signal was lost prior to ten thousand years ago, these two rivers migrating north-northwestwards and joining the Indus.

All this sampling is in Cholistan, the portion of the Ghaggar/Hakra in Pakistan. Some studies has mentioned ancient channels interpreted as the Sutlej joining the Ghaggar in Haryana in India, upstream of these sites. These channels were not sampled in this study. However, the site at Fort Abbas samples the main Ghaggar channel. Any signal of the Yamuna or Sutlej  joining upstream would have shown up here. The results indicate no signal from these rivers in the oldest sediments which are five thousand seven hundred years old or so.

If possible, these analysis could be extended in the future to sample more extensively the dried up large channels upstream in India too for a more expansive analysis. Over the last year some more studies (preliminary results presented at last year's AGU meeting) have shown an earlier episode of the Ghaggar drying up in the latest Pleistocene that coincides with a regional climate shift towards drier conditions. Did tectonically driven avulsion coincide with this climate change?

On the other hand, a paper in the GSA Bulletin by Sinha et. al. 2009. suggest a younger Yamuna, meaning that the Yamuna has been flowing in its present course for only the last 2-3 thousand years and may have been flowing westwards towards the Ghaggar before that. This study was based on detrital grains provenance studies and OSL dating of the Yamuna and Chambal sediments. I found the provenance analysis itself to be sound but the young Yamuna interpretation questionable, due to lack of sampling upstream of the cratonic rivers confluence and just one OSL date from the present day Yamuna channel.

So,  there are still answers to be found regarding the interplay of tectonics, climate and the Pleistocene and Holocene geography of these rivers.

Having said that, this is one of the more convincing studies of Ghaggar sediment and water provenance that I have come across so far.  Many earlier studies have suggested a much later river avulsion scenario wherein the Yamuna and the Sutlej change course as late as 2000 B.C. My impression was that these studies lacked the kind of hard evidence needed to pinpoint the dates of the deposition and the origin of the sediments. They relied mainly on the size of the channels without demonstrating physical continuity with the large glacial rivers,  or the presence of certain metamorphic grains and pebbles. Both these parameters are open to multiple interpretations and are not convincing of a high Himalayan source by themselves.

This study by Clift and colleagues along with some earlier isotope dating and provenance work on Indus and Ghaggar sediments by some of the authors and independent work on oxygen isotopes of ancient Ghaggar /Hakra channel water are strong results in favor of the Yamuna and Sutlej leaving the Ghaggar river thousands of years before the beginnings of the Harappan civilization.

The results also imply that these two rivers most likely stopped flowing into the Ghaggar thousands of years before the presence of Aryans in this region.

This is a touchy topic and it deals with whether the Aryans migrated into northwest India from central Asia around 1500 B.C. or so, bringing with them cultural habits and religious ideas that evolved into the Vedic Culture, or whether the Aryans were indigenous to this part since times immemorial. The Ghaggar has been equated with the river Sarasvati mentioned in the Rig-Veda by supporters of the indigenous Aryan theory.

It is described as a mighty river flowing from the high Himalayas. This in turn has been interpreted to mean that the Sarasvati would have been flowing out of glaciers for it to be mighty, and therefore the Aryans must have been present in northwest India before 2500 - 3000 B.C., because there is evidence that since then the Ghaggar became a smaller river.  This argument is then taken further to claim that the Aryans built the Harappan civilization. In this scenario the glacial rivers change course only after 2500 - 2000 B.C or so and the resulting water crisis forces the "Vedic" Harappans to disperse eastwards towards the Gangetic basin.

I have stressed that this attempt to link a hypothesis of a mighty Sarasvati to the presence of Aryans is misguided and one that has caused harm to the public understanding of the topic and to what constitutes good science. Many geologists and archaeologists accepted the validity of a glacial Sarasvati without critically weighing the evidence. Taking their cue, in web forums and books, supporters of a glacial Sarasvati have popularized the hypothesis of a late river avulsion and often presented it as irrefutable evidence favoring the indigenous Aryan theory.

I have commented on this earlier in Pragati and on my blog (here and here ) and suggested that evidence at that time did not support a late avulsion and further that this issue of the timing of Aryan presence in this region doesn't really depend on  glacial rivers flowing into the Ghaggar. Rivers can be mythologized and worshiped whether they are big or small. The Aryans could just as well have considered holy a Siwalik fed river and exaggerated its size in their hymns.

Linguistics, cultural evidence, archaeology and perhaps in the future higher resolution genetic data are better placed to answer the question of Aryan origins. Unfortunately, during this saga of the search for the glacial Sarasvati some very questionable geological scenarios have been put forth as being definitive. Perhaps the time has come for supporters of that theory to at the very least start being more cautious when promoting the late river avulsion theory.

Meanwhile, whether there were glacial rivers connecting the Ghaggar during Harappan times is not just an interesting geological question but has implications in understanding  Harappan water use and agriculture patterns. Head over to Dorian Fuller's (one of the authors of this study) blog The Archaeobotanist for some comments.

Clift, P., Carter, A., Giosan, L., Durcan, J., Duller, G., Macklin, M., Alizai, A., Tabrez, A., Danish, M., VanLaningham, S., & Fuller, D. (2012). U-Pb zircon dating evidence for a Pleistocene Sarasvati River and capture of the Yamuna River Geology DOI: 10.1130/G32840.1

Also see additional posts on this topic - 1) New Geomorphological Work on Ghaggar
2) K.S. Valdiya on the glacial Saraswati in Current Science


Tuesday, February 7, 2012

Paleowave Is A New Earth Science Blog By An Indian Academic

A few weeks ago I complained that I knew of only one geology blog by an Indian geologist besides mine. Kaustubh Thirumalai responded by pointing out that he has been blogging at Isotope Dope. That was his old blog. He now has a brand new blog titled Paleowave.

Kaustubh is a stable isotope geochemist with an interest in  reconstruction of Holocene paleo-climate and paleo-oceanographic conditions using foraminifera as a proxy.

I have dabbled quite a bit in stable isotopes of oxygen and carbon for my research on diagenesis in Ordovician carbonate rocks, using the proportions of different isotopes of oxygen and carbon that occur in carbonate rocks to infer both the origin of fluids flowing through the rock and the temperature of the fluid. That in turn can be used to infer basin history, more specifically the timing and extent of sea-levels changes and the establishment of fresh water aquifers and also the subsequent burial history of the sediment.

So I am looking forward to reading and learning more about Kaustubh's research which applies the stable isotope tool to understand a different aspect of the more recent past.

Monday, February 6, 2012

Basin Analysis Lecture Series

On Earth-Literally blog Prof. Philip Allen of Imperial College London has posted key learning points of a series of lectures on Basin Analysis.

1) Introduction And Genetic Basin Classification

2) More Of Lithospheric Stretching, Including Passive Margins

3) Flexure Of The Lithosphere And Foreland Basin Systems

4) Burial And Thermal History Of The Basin-Fill

Terrific educational value for students and professionals too!

Friday, February 3, 2012

Out Of Siberia - Dogs Not Humans

The endearingly fascinating topic of dog domestication is in the news again. A skull with features that are a mix of wolf and dog was found in the Altai mountains of Siberia. It has been dated to around 33,000 years ago, before the Last Glacial Maximum, a period of intense expansion of polar and mountain ice sheets that began around 26,000 years ago and lasted until around 19,000 years ago.  It may represent an early wolf to dog domestication "in progress", but one that researchers feel was aborted by the advent of the last Glacial Maximum, when human populations in this region dispersed.  There is no evidence in younger deposits from this area of domesticated dogs, despite there being an occasional human presence.

I wrote about this topic some weeks ago and I commented that there probably were many such instances of marginal members of wolf packs getting acculturated to humans and getting self-domesticated or being pushed in that direction by human selection of docile traits. This is after all a meeting between two hyper-social species and contact between wolf and humans would have been a very common occurrence. Another equally old dog skull from a cave in Belgium suggests that there were multiple instances of dog domestication.

What struck me about this latest discovery is the age and the place - 33,000 years ago in the Altai region...... Denisovans??

Modern humans were not the only inhabitants of this region of Siberia.  A  population of another distinct human "species" or variety, descendants of an earlier human migration from Africa about half a million years ago, also lived in this region. Their remains  were found near Denisova cave in the Altai mountains of Siberia and judged to about 41,000 years old.

Its fascinating to speculate on whether there were any instances of wolf domestication in the company of these other human species. The Denisovans  (and the Neanderthals) were human lineages that had a long presence lasting more than one hundred thousand years in Asia and Europe and they would have encountered wolves routinely. We don't know anything about the social and cultural aspects of Denisovan society, but we do know that their cousins the Neanderthals lived in closely knit social groups.

A lot has been said about what the differences may have been between these archaic human groups and "modern" humans. Put forward are differences in cognition (we were just smarter), language and communication skills, division of labor (modern humans had more efficient food gathering strategies),  home range and mobility affecting trade and cooperation with other groups (Neanderthals did not trade as much with other groups). These are all speculative and maybe we can add one more.

These archaic humans did not or were unable to domesticate the wolf. No remains of domestication have been found so far, associated with the Neanderthals. Does the same apply to the Denisovans and other archaic human groups scattered across Africa and Asia?

That off course could be a reflection of something about their behavior as individuals and as a society. Perhaps the wolves themselves stayed away sensing a lack of that bit of empathy, perhaps their hunting methods did not require cooperation with a willing canine partner. If there is evidence for dog domestication or partial domestication about 33,000 years ago, could there be even earlier instances of the dog? And if the timing of dog domestication overlapped with modern human contact with Neanderthals and Denisovans from 45,000 to 30,000 years ago,  did the dog give some advantage to modern humans in eking out a living over these other human "species"?