Rapid Uplift

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

noreply@blogger.com (Suvrat Kher) — Fri, 10 Feb 2012 05:45:00 +0000

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.

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 and 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.

Below is a map of the study area.

Source: Clift et.al. 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 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 used. 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 many of these studies lacked the kind of hard evidence needed to pinpoint 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 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 and religious ideas that evolved into Vedic Hinduisim, 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 ephemeral river. In this scenario the glacial rivers change course only after 2500 - 2000 B.C or so. This argument is then taken further to claim that the Aryans built the Harappan civilization.

I have stressed that this attempt to link a hypothesis of a late river avulsion to the presence of Aryans is a misguided one. 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 in support of an early Aryan presence. I have commented on this evidence earlier in Pragati and on my blog (here and here ) and suggested that hard evidence is lacking for a late avulsion and further that this issue of the timing of Aryan presence doesn't really depend on glacial rivers flowing into the Ghaggar. Rivers can be mythologized and worshiped whether they are big or small.

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

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.

Paleowave Is A New Earth Science Blog By An Indian Academic

noreply@blogger.com (Suvrat Kher) — Tue, 07 Feb 2012 08:30:00 +0000

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.

Basin Analysis Lecture Series

noreply@blogger.com (Suvrat Kher) — Mon, 06 Feb 2012 09:30:00 +0000

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!

Out Of Siberia - Dogs Not Humans

noreply@blogger.com (Suvrat Kher) — Thu, 02 Feb 2012 18:50:00 +0000

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"?

Science And Nature Programming On Indian Television

noreply@blogger.com (Suvrat Kher) — Mon, 30 Jan 2012 10:18:00 +0000

Yesterday afternoon I watched a good documentary on the wild game trade and its social and ecological context on National Geographic. The setting was the Central African Republic and the hour long episode followed a researcher studying the hunters, traders and customers involved in Africa's bush meat trade. It was a sobering look at the decimation of wildlife that is occurring in these regions. Logging roads are reaching ever more in the interior and bush meat is highly prized, due to old social preferences and a lack of alternative sources of protein.

The documentary brought back memories of some fine programming that used to be common on National Geographic, Discovery and Animal Planet. I say this because I continue to be deeply disappointed with the recent programming on these channels. I looked through the guide and here is a sample of the programs which form the bulk of the repertoire these days. I have divided them up into themes - Science Fiction - Alien Invasion, Crop Circles.. Adventure/Reality - Banged up Abroad, Survivor, Gold Rush Alaska.... Wildlife / Nature - Man vs Wild, Monster Fish, River Monsters, Worlds Deadliest Animals, Duel in the Swamp...

All are fast paced action packed dramas, full of adventurers getting into trouble abroad, or trying to "survive" in a mountain range somewhere or diving into swamps and running through forests grabbing at otters, fish or whatever small animals that come their way. ..The wildlife shows focus on life's brutal side, with plenty of sequences of lions hunting and crocodiles dismembering prey, all with a hushed but triumphant voice telling us that might is right in the jungle.

The kind of unhurried slow paced shows that exposed - through conversations and fine camerawork - the intricacies of a particular topic are being overwhelmed by a gonzo reporting style. Maybe it's the Steve Irwin effect that many nature reporters now feel compelled to run and grab at wild animals. The science depicted on these shows is minimal at best. And what example for conservation and respect for wildlife does it set with such an aggressive and intrusive film-making?

I miss those old shows on so many varied topics - Vets of Rural England, A Social History of Tofu, The Ecology of Tasmanian Tigers, Indonesian Mining Industry, The Chinese Homo erectus, to name just a few. These shows were excellent examples of carefully thought out ideas and topics and were filled with richly detailed and nuanced contents on the cultural histories of people and communities and their interface with medicine, ecology, geology, evolution and genetics. Lots of relevant science was packed in an episode.

There are still a few shows in this vein being made even now.. Expedition To Borneo.. being a recent example. But mostly, inane "survival" and extreme adventure episodes, duels between humans and animals and sensational violent hunting sequences with blood and gore are dominating the television screens.The assumption seems to be that people these days have very little attention spans and the best educative value would be provided by rapid visual stimulation and bombarding viewers with an array of facts and conclusions.

That leaves little space for depicting science as it really is - a process of knowing, wherein constructing a hypothesis, gathering data and analyzing it and finding out that that has opened up more questions than answered your initial one is really how we gain new knowledge and clear a path for the discoveries of tomorrow.

On The Use Of The Word SUSTAINABLE

noreply@blogger.com (Suvrat Kher) — Wed, 25 Jan 2012 15:05:00 +0000

From xkcd comics:

From the extrapolation it looks like that by the year 2109 we haven't yet figured out a way to live "sustainably", which is why people are desperately repeating the word "sustainable"!

By the way, the trend up to 2010 in the figure isn't just made up. The increase in the word "sustainable" from 1960 to early part of this century is true. Here's the usage frequency of the word from 1900 to 2005 as depicted by Google Ngram. I have plotted it along with three other terms- climate change, global warming and sustainable development to understand why it might have increased.

The increase in the word sustainable begins in the 1970's as the environmental movement made its mark and books on that topic began to appear, while climate change and global warming start being used more and more from the mid-late 1980's onwards.

Conversations About Seismic Risk Of The Proposed Jaitapur Nuclear Plant

noreply@blogger.com (Suvrat Kher) — Wed, 18 Jan 2012 16:20:00 +0000

I get mails from reporters asking me geology questions. I got one today morning from a reporter of a big newspaper about the controversy regarding the siting of a proposed nuclear power plant near the village of Jaitapur in southern Maharashtra.

With his permission I have pasted his question and my reply below-

Dear Suvrat,

After the press conference by Dr Bilham regarding the earthquake hazard to Jaitapur. NPCIL has issued a press release, which mentions about the various studies carried out on behalf of NPCIL. They are mentioned in the file attached with this mail. I was wondering whether they have taken adequate test for the Jaitapur site.

I would be obliged if you could see the mail and give your feedback.

Warm Regards

Dr. Bilham is Dr. Roger Bilham who along with Dr. Vinod Gaur recently published a paper (open access) on the tectonic situation and seismic risk along the southern Maharashtra region. My post summarizing the paper is here. NPCIL is the Nuclear Power Corporation of India Limited and their press release can be found here.

Here is my reply. I've added a couple of words (in black for clarity) -

Hi XX-

The list itself covers all the geological studies that can be done. I cannot off course speak to whether individual studies were comprehensive or not. I am curious whether the NPCIL already has or is planning on making all these studies available to the public so that independent experts may evaluate the findings of the government scientists.

Geologically there are two limitations here. One is that, there is no reliable historical documentation of large seismic events from this area (Jaitapur). Second, there is no surface expression of faults and displacements along these faults that may give us some idea whether and with what frequency was this area affected by large earthquakes in pre-historic times. Therefore it is difficult to develop a robust statistical extrapolation of the risk of large earthquakes.

This uncertainty means that people can read what they want to into all the tests and theories about this area. People who don't want a nuclear plant can say.. look, an earthquake can hit any time.. just like Latur. No scientist can disagree with that.

On the other hand the nuclear establishment can say with some justification that over the life cycle of a nuclear plant (next 100 or so years) there is a small probability of a moderate size earthquake (6 -7 Richter) and an even minuter chance of a tsunami and we can deal with the engineering requirements.

I don't see any side giving way because the opposition to nuclear energy goes deeper than just geological considerations and its hard to change the government's mind on anything. From what I have read about the general geology of the area I suspect that everyone can beat the geological risk angle to death and get nothing new out of it.

One impression I did make when I followed some of the panel discussions on the Tamil Nadu nuclear plant on TV shows is that some of the nuclear scientists were dismissive and even contemptuous of civic society concerns. Maybe a similar attitude has aggravated the situation at Jaitapur.

Cheers

Suvrat

Latur is the area in southern Maharashtra which suffered a 6.4 mag earthquake in 1993. It was long thought to be at low seismic risk. The Indian government is promising to engage with civic society on all aspects of the construction of the many planned nuclear power plants and in that spirit of openness I hope they make the relevant geological studies available for anyone to critique.

I will post more on this topic as the story develops.

Self Help Against All Those I"ll Heal You Quacks

noreply@blogger.com (Suvrat Kher) — Tue, 17 Jan 2012 16:05:00 +0000

I love the link posted by David Bradley on his excellent science blog sciencebase. The site is called The Red Flags of Quackery and its a one stop checklist to guard yourself against fantastic claims about miracle cures and from self styled "experts" conjuring up explanations for the unexplained.

David Bradley gives some sound advice too:

If your putative sCAM practitioner mentions energy as being some kind of universally pervasive force, point out that energy is nothing more than the capacity to do work in the thermodynamic sense and ask them in what units they are measuring the mystical energy of which they speak. If they try to invoke ancient wisdom point out that demons, blood-letting and trepanning are ancient wisdom. If they hint at ancient eastern mysticism, remember the words of the mighty Tim Minchin: “There is no eastern and western medicine, there’s medicine and then there’s the stuff that hasn’t been proven to work.”

The bonus for going to his site is this incredibly funny video of comedian Dara O'Briain's put down of alternative medicine and homeopathy.

Outstanding Problems In Indian Geology And Some That I Just Made Up

noreply@blogger.com (Suvrat Kher) — Tue, 10 Jan 2012 16:24:00 +0000

In the October 2011 issue of the Journal of the Geological Society of India, K.S. Valdiya one of India's senior geologists and ardent spokesperson for earth sciences identifies some burning questions (behind paywall) in Indian geology.

Here is his list:

1) When did India dock with Asia? The question asks essentially when did land bridges form between the two continents. There are similarities in vertebrate fauna of the Maastrichtian Murree (~ 68 mya) sediments of Kashmir and those from Asia suggesting an earlier welding of the two continents than is generally accepted.

2) This one deals with the southern limit of the Himalayan orogen. What is the nature of deformation at and southwards of the Himalayan Frontal Thrust i.e. underneath the Gangetic alluvium?

3) What is the structural, tectonic and magmatic significance of the zones of "lineaments" along the Narmada-Tapi rift and along the Western coast of India? These lineaments are related to the stretching and rifting of India in the late Cretaceous but can we measure displacement along these fractures and are some of them conduits for the Deccan magmas? What is their relationship to seismic activity?

4) What is the nature of the Palghat Gap? This is a break several tens of kilometers wide in the Western Ghat mountain chain long interpreted to be an ancient shear zone. What do we make of a peneplained Precambrian terrain reaching great heights of over 7000 feet in the southern Western Ghats?

5) What is the relation between rift basins in Khambhat Gujarat and Sanchor -Barmer Rajasthan with the Marion hot spot. Is the genesis of these Jurassic-Cretaceous hydrocarbon bearing basins related to the passage of the Indian plate over the Marion "plume"?

6) How do we interpret the distinct structural and metamorphic boundaries in the various Precambrian terrains of Peninsular India? Are they ancient suture zones... recording Archaean collision events between micro-plates?

There is a lot here to chew on. These are questions that will require devoted research programs with expertise in a variety of geological sub-disciplines. There is a lot of work addressing these questions already going on but apparently K.S. Valdiya feels more needs to be done.

I have my own list of urgent questions. This list is not so much a list of unanswered questions or a list of great mysteries but more a collection of societal expectations that our scientists should fulfill. As a citizen of India these are the questions I would ask our geologists to pay attention to and devote their energies to studying.

1) A detailed quantitative hydro-geological characterization of the hard rock aquifers of Peninsular India. Vast areas of Peninsular India are underlain by basalts and granites. Water in this crust is stored in and flows through narrow zones of cracks and fractures. Tens of millions of farmers depend of ground water from these aquifers. Some more tens of millions are too poor to spend money on ground water exploration and digging wells in these hard terrains. They need help. And a more detailed understanding of these aquifers, their water bearing capacity and what would be their sustainable extraction limits under varying climatic and usage scenarios is urgently wanted.

2) Long term monitoring of Himalayan glaciers and the water budget of the rivers of the Himalayan foothills and Gangetic plains. Some recent studies suggest a gradual decline of Himalayan glaciers in response to global warming with implication for the future water supply to the glacially fed rivers of north India. We need to make an early start in understanding potential changes in water availability and their impact on agriculture and livelihoods.

3) Sediment budget of the Ganges-Brahmaputra delta region. This enormous delta has been built over the Cenozoic by sediment brought by rivers draining the Himalayas. How will shrinking glaciers, changing rainfall patterns and changing river flow regimes influence the sediment supply and its deposition in the alluvial plains and the delta region? Is there potential for the delta to degrade thus exacerbating the effects of sea level rise?

4) A detailed mapping of soil varieties and studying concerns over soil degradation and soil erosion.

5) How much shale gas is there in the many sedimentary basins of India?

6) Do we have enough understanding of contaminant transport through shallow and deep aquifers? Is groundwater quality given enough importance and is it studied in enough detail to answer apprehensions about potential contamination of ground water from fracking that may result from the hundreds of shale gas wells that will be drilled in the near future?

7) Is carbon sequestration at deeper crustal levels in the vicinity of some or many of the planned coal fired power plants geologically feasible?

8) Do we have significant uranium ore deposits?

There are probably many more questions, but I have given a sample that touches on three crucial subjects - Water Security, Food Security and Energy Security. Geology forms an important component of the foundational knowledge required for providing a better quality of life for hundreds of millions of Indians. Indian geologists must proactively wrestle with these questions and play an important role in answering to these three concerns of Water, Food and Energy in this century.

.... And finally, the biggest mystery of all in Indian geology... Why are there so few Indian geologist bloggers? .. :)

Besides my blog I know of only one other!

Musing About Cosmology and Evolution

noreply@blogger.com (Suvrat Kher) — Mon, 09 Jan 2012 09:47:00 +0000

Stephen Hawking's 70th birthday is making quite a bit of news. A few days ago science writer Kitty Ferguson talked about Hawking and his work and his life on Fresh Air. I enjoy talks on cosmology and I read popular articles on it. Up to the time I started graduate school in the United States I did not read much science beyond geology. Carl Sagan's Cosmos was my start on widening my reading to other sciences.

After reading a well written article on cosmology I come out feeling I have understood something...but just what..? Generally, I am unable to explain in any detail what I have read to friends or put it down in a coherent written format either. I think I know what Hawking radiation is and what is significant about the Higgs Boson but can't really express my thoughts beyond what I have read.

My experience with the theory of evolution has been somewhat different. I was completely ignorant about evolution well into graduate school. My adviser who doubles up as a sedimentary geologist and paleontologist encouraged me to start reading. Today I consider myself fairly well informed about the field. The difference from cosmology has been that I am confident enough to express my thoughts on evolution either in conversation or in writing. I find I am able to think about basic principles and apply them to different situations and contexts beyond say what I have read in a popular article or book. I occasionally read the primary literature too.

Is my not so strong math background preventing me from looking at cosmology under the hood? I get the feeling that without working through the equations I am stuck nodding my head at whatever article I happen to read and nothing much beyond that. Many sub fields of evolution are also intensely mathematical. But I found that there are also many principles of evolution I could happily think about without the math. Evolution is all about armchair theorizing for me. I came up with posts I am proud of on Tasmanian Devils And A Selfish Gene and another on the Red Queen one afternoon dreamily thinking about natural selection.

With Cosmology I don't have the wherewithal to write anything original. I have to get my kicks from Stephen Hawking on Fresh Air.

Minister Promises Evidence Based Science Policy

noreply@blogger.com (Suvrat Kher) — Thu, 05 Jan 2012 09:30:00 +0000

At the 99th edition of the Indian Science Congress held in Bhubaneswar Orissa, Minister of Science and Technology Mr. Vilasrao Deshmukh announced that India will pursue a “well-balanced, transparent and evidence-based science policy”.

Since he has stressed that the policy will be evidence-based, here is my recommendation - The Minister should issue a strong statement rejecting homeopathy and astrology as sciences and withdraw all government support for these fields.

oh.. and make Ben Goldacre's Bad Science compulsory reading in High School / College.

Tip: Indigenus

New Volcanic Island In The Red Sea

noreply@blogger.com (Suvrat Kher) — Tue, 03 Jan 2012 15:14:00 +0000

Nearly coinciding with the New Year, volcanic activity of the west coast of Yemen has given rise to a new volcanic island.

From the NASA Earth Observatory article:

An eruption occurred in the Red Sea in December 2011. According to news reports, fishermen witnessed lava fountains reaching up to 30 meters (90 feet) tall on December 19. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites observed plumes on December 20 and December 22. Meanwhile, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite detected elevated levels of sulfur dioxide, further indicating an eruption.

The activity in the Red Sea included more than an eruption. By December 23, 2011, what looked like a new island appeared in the region....

....The volcanic activity occurred along the Zubair Group, a collection of small islands off the west coast of Yemen. Running in a roughly northwest-southeast line, the islands poke above the sea surface, rising from a shield volcano. This region is part of the Red Sea Rift where the African and Arabian tectonic plates pull apart and new ocean crust regularly forms.

The Red Sea is one arm of a great three armed rift system that includes the Gulf of Aden and the East African rift valley as the other two arms. If you want to know more about divergent plate boundaries and rifting along this complex system I would recommend this primer at Geology.com.

And don't forget to check out the image comparison tool with its cool slider at the NASA Earth Observatory website by clicking on the View Image Comparison option.

Testosterone Tattoos And Tequila Equals Snake Bites

noreply@blogger.com (Suvrat Kher) — Mon, 02 Jan 2012 08:35:00 +0000

Here is a great way to begin the New Year. Start following Quirks & Quarks, a weekly science talk show of the Canadian Broadcasting Corporation hosted by the lively Bob McDonald.

I came across it recently and have heard some pretty interesting talks already. Here is a sample from the last couple of months -

The Dolphin In The Mirror
Pinning Down The Permian Extinction
Out Of Africa And Hybrid Humans
Cosmos And Dark Energy

As for the quirky post title?... Listen to the Show! :)

Have a great 2012..

Crazy About Rugby

noreply@blogger.com (Suvrat Kher) — Wed, 21 Dec 2011 11:30:00 +0000

I've been taking some time off and helping spread sports and particularly rugby in the rural areas around Pune. This is a project started by two of the rugby organizations in Pune - RFS Pune and KFANDRA .

Here are some pictures from Nanegaon which is about 40 km westwards of Pune. A friend farms here and its through him that we have started this initiative:

That's me looking very fit, surrounded by rugby crazy kids.

All Hands in groups of three:

The Pop-Up pass routine:

Keen eyes and hands- what a picturesque setting to a sports scene not very common in rural India:

All this action takes place against the backdrop of the vast layered Deccan Basalts. The village is quite attractive and has some of the classic elements and atmosphere of rural India like this temple square:

The countryside around is lush and there are some pretty picnic spots for the tired and weary - a basalt stream bed:

The idea is to encourage children to learn discipline, team work and good work ethics through sports. So far the children love taking part in this activity and we plan to keep this program running for the foreseeable future.

Most Difficult Geology Time Scale Mnemonic Ever

noreply@blogger.com (Suvrat Kher) — Tue, 20 Dec 2011 08:13:00 +0000

From xkcd comics:

Try beating that!

My Popular Posts Over The Last Two Years

noreply@blogger.com (Suvrat Kher) — Mon, 19 Dec 2011 10:30:00 +0000

Its nearly year end and time to get a little reflective. I'm basing this on Google Stats for the last two years. Here are 5 of my most popular posts:

Indian Sedimentary Basins And Shale Gas

Plate Motions: Is The Driver Bottom Up or Top Down

Mapping India: Land Degradation and Desertification

India Basin-Wise Shale Gas Estimates

Geology Will Be Central To India's Climate Change Challenge

Two of them are about the hot energy source of the day and two about ecological challenges we face. My post on the recent Sikkim / Nepal earthquake came a close sixth.

My blogging is not restricted to topics about India but in a sense I am pleased that my writings about Indian geology continue to capture a fair amount of attention. There is not much information about Indian geological issues in the popular media and in the public domain, so I guess I am contributing somewhat to redressing that lacunae.

Thanks all for supporting this blog.

Insights Into Plate Interior Earthquakes Of Peninsular India

noreply@blogger.com (Suvrat Kher) — Thu, 08 Dec 2011 15:48:00 +0000

A paper in Current Science (open access) by Roger Bilham and Vinod K Gaur gives interesting insights into the patterns of occurrences and causes of earthquakes in the plate interior regions of Peninsular India. In south Maharashtra for instance there have been moderate size earthquake of 6.3 - 6.4 magnitude in recent decades at Koyna and Latur. Earthquake risk assessment has shot to prominence recently due to a proposal to site a large nuclear power station in Jaitapur, which is close to Koyna.

The general understanding of earthquakes in Peninsular India is that the Precambrian terrain is heterogeneous in strength, criss-crossed with rifts, shear zones and old orogenic belts and these ancient zones of weak crust get reactivated from time to time and rupture.

But what is building up strain along these old faults? The graphic below from the paper is a good way to conceptualize the tectonic and stress situation.

The collision of the Indian plate with Tibet has resulted in the bending of the Indian plate underneath Tibet and the flexural buckling into a long waveform of the rigid Indian plate. At the northern end i.e. at the crest of the flexure the plate experiences tensional forces at shallow depths and compressional forces at the base of the plate. Farther south in the trough of the flexure known as the outer moat, the situation is reversed. The shallow part of the plate experiences compressional forces and the base of the plate experiences tensional forces.

Imagine now that this waveform is static in the sense that the stress fields described remain fixed in space. The rocks of the Indian plate are however moving northwards. They pass through the compressional stresses in the trough and many millions of years later pass through the tensional stresses of the crest. At the base of the plate its the other way around. Geodetic studies using GPS i.e. studies aimed at understanding slip along faults to estimate how quickly strain is building up, suggest a very low rate of strain buildup in Peninsular India. Calculations suggest that replenishment of strain is on the order of 300,000 years, meaning on average faults won't slip more than 3 times per million years. But given the millions of years these rocks have remained in either compressional or tensional stress fields and given the rarity of historical and recent earthquakes, the authors thesis is that there would be many many faults reaching a state of critical stress i.e. close to rupturing.

One practical implication of this is that the seismic hazard maps issued by various agencies don't always portray future risk accurately. These are based on a very short historical record and since the cycle of strain buildup is much longer, faults that may have slipped thousands of years ago and have been building up strain since, will remain unnoticed. That is what likely happened at Latur, an area considered to be at low seismic risk based on history, until the sudden large earthquake.

Koyna and Latur fall in the trough region of the flexure. So does Jaitapur. The faults at Koyna and Latur have slipped recently and given the low rate of strain buildup are unlikely to rupture for some time to come. But there is no record of recent or historical seismicity near Jaitapur. There is a lot of discussion in the paper on earthquake catalogs for India and their usefulness. The reliable historical record doesn't extend beyond a couple of hundred years or so. And further, its not known whether there is a subsurface fault underneath Jaitapur, but the regional picture tells us that Jaitapur would be subject to the same stress regime as Koyna and Latur and there is a possibility - albeit low - of a moderate size earthquake occurring underneath the proposed power plant site.

One quibble I have regarding the graphic above is the placing of Bhuj in the flexural trough. It is in fact located north of the flexural trough, in the crest domain. Bhuj refers to the town in Gujarat state which suffered a large 7. 6 magnitude earthquake in 2001. Bhuj had suffered an earlier earthquake of 7.9 magnitude in 1819. The area falls within the Kutch rift which was initiated during the late Triassic breakup of Gondwanaland. Rifting was aborted during the late Cretaceous pre collisional stage of the Indian plate. Since then under a compressional stress regime, the rift has developed strike slip faults with local transpressional zones i.e. the stress is oriented is such a way so as to cause local reverse faulting and strike slip faulting. Both the Bhuj earthquakes were located in this transpressional zone in the eastern part of the rift. So Bhuj is something of a special case. A relatively younger crustal structure with complex local stress fields and faults reactivated by the ongoing collision of India with Tibet.

Coming back to Maharashtra, it is difficult to get a handle on future seismic risk. This is because as I mentioned the historical record goes back only a couple of centuries and is patchy. Therefore, reliable statistics on the rate of earthquakes can't be developed so as to be used as a guide to future risk. Also because the Deccan volcanics have covered the Precambrian over most of the region, and because many of these ancient faults don't reach the surface, examining these faults so as to understand their slip history is not possible. So only broad zones of weaknesses are interpreted by extrapolating the structural grain of Precambrian terrains at the margins of the Deccan volcanics or by using geophysical methods like mapping gravity lows (which might point to the presence of a sedimentary rift basin underneath the Deccan volcanics).

Under these constraints, site specific earthquake risk assessment is not done. But the broad picture developed in this paper does point out that much of Peninsular India may be under a high incipient state of stress and there are possibly many faults within the flexural trough between latitudes 16 deg N and 19 deg N which are not exposed at the surface that represent seismic hazards.

Mea Culpa By Simon Winchester About His Newsweek Earthquake Article?

noreply@blogger.com (Suvrat Kher) — Wed, 07 Dec 2011 04:27:00 +0000

Earlier this year the science writer Simon Winchester started a controversy by claiming a little too assertively that large earthquakes like the Tohoku earthquake on the Pacific plate boundary of the coast of Japan has increased the chances of a large earthquake in California which is located on the other end of the Pacific plate. His claim was that - "[A] significant event on one side of a major tectonic plate is often - not invariably, but often enough to be noticeable- followed some weeks or months later by another on the plate’s far side".

He was roundly criticized for this claim by earthquake experts.

Now Real Climate reports from the AGU meeting in San Francisco:

The second general talk was by author Simon Winchester who excellently demonstrated how to communicate about geology by using human stories. He gave a number of vignettes from his latest book about the Atlantic ocean – including stories of the shipwreck of the Dunedin Star on the ‘Skeleton coast’ of Southern Africa, time on St Helena, and the fate of his book on the Pacific that apparently only sold 12 copies… He finished with a mea culpa and gracious apology to the assorted geophysicists for his rather hurried comments on the Tohoku earthquake disaster that caused some consternation earlier this year. In his defense, he only had 90 minutes to write what he was unaware would be the Newsweek cover story that week.

Any of you Geo-Bloggers attending AGU heard anything about this?

Geological Monuments Of Hyderabad Disappearing

noreply@blogger.com (Suvrat Kher) — Fri, 02 Dec 2011 03:59:00 +0000

The disappearance of wetlands and forests makes for news and media articles, but a pile of rocks? I came across this slideshow in The Hindu on the natural rock piles so typically seen in the city of Hyderabad. The rock is granite and it has weathered along sets of cracks to form these rounded boulders that are left balancing precariously. These piles of balanced rocks that form hillocks are called Tors. The graphic below depicts the formation of Tors.

Source

These formations are being quarried for construction material and Hyderabad is fast losing its unique landscapes.

Source

I hope the city decides to protect at least a few of these as national monuments.

Terrible Obituary Of Lynn Margulis Of Symbiosis Fame

noreply@blogger.com (Suvrat Kher) — Sat, 26 Nov 2011 05:17:00 +0000

There is a really awful misrepresentation of evolution in a New York Times obituary for Lynn Margulis, the biologist who proposed that the eukaryotic cell originated through a symbiotic merger of two free living bacterial cells. Life on earth is made of up one of two cell types, Prokaryotes or Eukaryotes. Eukaryotes are more complex. They contain their DNA in a nucleus and also possess organelles like mitochondria and chloroplasts which generate energy for cell metabolism.

At one time in the past, perhaps about a billion years ago, one prokaryotic bacterial cell engulfed another prokaryotic bacterial cell type. Instead of the engulfed cell being destroyed, the two evolved a partnership. The engulfed cell was perhaps good at certain tasks like burning food in the presence of oxygen. Over time this cell transferred most of its genes into the genome of the host cell and retained only a few needed for the specialized task of producing energy for cell metabolism. It evolved into the mitochondria. Lynn Margulis was ridiculed for proposing this but over time biologists have accepted this theory of the symbiotic origin of eukaryotes.

Here is a snippet from the obituary by Bruce Weber:

The hypothesis was a direct challenge to the prevailing neo-Darwinist belief that the primary evolutionary mechanism was random mutation.

Rather, Dr. Margulis argued that a more important mechanism was symbiosis; that is, evolution is a function of organisms that are mutually beneficial growing together to become one and reproducing. The theory undermined significant precepts of the study of evolution, underscoring the idea that evolution began at the level of micro-organisms long before it would be visible at the level of species.

I don't even know where to begin.

If there is any such thing as a neo-Darwinist "belief" then the mechanism of evolution in question is natural selection not random mutation. Mutations generate the variability on which natural selection acts.

And symbiosis doesn't underscore the idea that evolution began at the level of micro-organisms long before it would be visible at the level of species. What does that even mean? Very early life was a world of micro-organisms divided into many species and they evolved through a combination of natural selection and random genetic drift acting on random mutations. If a population of micro-organisms evolve then the species they belong to obviously also evolves! The micro-organisms may be of symbiotic origin or may not. The type of entity i.e. symbiotic or non-symbiotic has nothing to do with the mechanisms of evolution or whether evolution occurs through variations between individuals or variations between species.

Another misconception I have often heard is that symbiosis means that complex cells and complexity in general evolved through a co-operative venture. So evolution is less about competition through natural selection and more about cooperation.

Again, this is a misunderstanding about the nature of evolution.

Sure, at one point in time two cells merged to form one cell...... But then what?

After the merger, there was just one or few of these novel cells in a population of other cell types. The merged cell was more efficient at extracting energy from the environment and reproduced more than other cells. Every round of reproduction threw out varieties of merged cells. Out of these, the more efficient symbiotic cells out-reproduced not just other non-symbiotic cell types but also slightly less efficient symbiotic cells. The symbiotic arrangement became more refined and over time the novel cell type proliferated and became the dominant cell type in that particular ecologic niche. Symbiosis and the cell structure and functionality that is recognized as eukaryote didn't instantly originate through a merger but evolved through natural selection. Eukaryotes became a common cell type by out-competing less efficient versions of itself and other non-symbiotic cell types. Cooperative ventures in life also evolve through competition.

So symbiosis doesn't undermine natural selection. Yes it can create novelty by bringing together different components within one individual, but that novelty if beneficial then evolves. It gets modified and refined and changes through natural selection and genetic drift.

Gold Boom Times In Elko Nevada

noreply@blogger.com (Suvrat Kher) — Mon, 21 Nov 2011 07:16:00 +0000

Geology and Livelihoods # 11

After Australia its time to go to Nevada. In a really engaging talk on Planet Money Robert Smith and Zoe Chace take a look at life in Elko, Nevada which is going through boom times due to the high demand for gold.

The motels are full, the brothels are full and high school girls want to start a truck repair business to support the mining community. Archaeologists are being hired to survey for ancient American Indian settlements before the machines start ripping the earth open. The town is cash rich.

and yet no money is being spent on long terms investments for the town. A history of busts seen all around Elko in numerous ghost towns is preventing that.

There is an Australian general manager of a mine who keeps hopping from one gold mine to another all over the world. For him its always been boom time. That's the difference between being undereducated and having a good education. The undereducated may well profit for a short time in local booms but when the mines run out they won't find high paying jobs elsewhere. For the better educated ..there is more flexibility in finding work.

Listen

see more Geology and Livelihoods.

A 200K Job In Australian Gold Mines

noreply@blogger.com (Suvrat Kher) — Thu, 17 Nov 2011 03:39:00 +0000

Geology and Livelihoods # 10

The Wall Street Journal profiles Mr. James Dinnison, a high school dropout from Western Australia who is currently earning $200,000 a year working underground in gold mines.

Here is an eye catcher:

Despite having earned roughly US$1 million since he started, he has no savings and doesn't apologize. "The mines are so dull, that when you get back here, everything is stimulation and excitement," he said. "The money I spend supports other businesses because of the [stuff] I blow it on."

Mr. Dinnison proudly calls himself a Cub—a Cashed-up Bogan, a bogan referring to Australian slang for an uneducated blue-collar worker. Books and documentaries are coming out about this group, exploring the country's unease with the thought that conspicuous consumption by undereducated people is what is helping to keep the country afloat.

....Mr. Dinnison hopes to be promoted to another underground job paying $1,400 a day, up from $800 a day.

Take that all you educated losers!

via Geology News

see more Geology and Livelihoods

Some Thoughts On The Evolution Of Dogs

noreply@blogger.com (Suvrat Kher) — Thu, 10 Nov 2011 08:24:00 +0000

Let me begin though with David W. Anthony's musings about the domestication of horses from his book The Horse The Wheel And Language:

Modern horses are derived from very few original wild males, and many, varied females.

In wild horse society there is a female hierarchy and mares are disposed to follow the lead of a dominant mare. Stallions on the other hand are more independent and react violently when confronted.

...A relatively docile and controllable mare could be found at the bottom of the pecking order in many wild horse bands, but a relatively docile and controllable stallion was an unusual individual - and one that had little hope of reproducing in the wild. Horse domestication might have depended on a lucky coincidence: the appearance of a relatively manageable and docile male in a place where humans could use him as the breeder of a domesticated bloodline.

From the horses perspective, humans were the only way he could get a girl. From the human's perspective, he was the only sire they wanted.

Well said!

Horse domestication depended on active selection of traits by humans from the very start. It may have been different for dogs at least in the earliest stages of human wolf interaction suggests naturalist Mark Derr in an interview on Fresh Air.

There are many hypothesis on how wolves got domesticated into dogs.

The puppy hypothesis suggests that abandoned wolf puppies were adopted by humans and then the more sociable and docile amongst them were allowed to breed. This involves selection pressures imposed by humans from the very start.

Then there is the garbage midden hypothesis. Wolves started hanging around human camp rubbish sites. The key element in this hypothesis is that only wolves who were instinctively docile and perhaps not getting enough food in the wild engaged in this behavior. So there was a self selection for docile traits in the wolves who gradually got used to be near humans.

The third is the hunting band hypothesis. Humans began following wolves on hunts or maybe wolves started following humans on hunts. These bands of wolves became socialized with humans and isolated from other bands of wolves. Again it is possible that instinctively docile wolves were more likely to follow human hunts if the reward at the end was food which was hard to obtain otherwise. So there is an element of self selection in this hypothesis as well.

Mark Derr tilts towards this third hypothesis. To me, it hard to pick out the stronger contender. The three hypothesis are not mutually exclusive. The thing is that all three situations would have been a common occurrence. For example its reasonable to imagine a scenario whereby a docile male sifting through the garbage dump gets bold enough to latch on to a female adopted as a puppy and living amongst humans.

The three situations would have overlapped many times. Socialization could have occurred via all these three interactions. After that there would have been more severe direct intervention and selection by humans for traits like docility.

There are other interesting questions about dog domestication. For example, was there just one center of domestication or did domestication take place many times in different places? The Middle East is considered the likely place for dog domestication based on arguments that the dogs from this region show more genetic variation pointing to a source population of greater antiquity. There also have been a case put forward for China being the place where dogs were first domesticated.

Considering the likelihood of repeated contact between wolves and humans there were probably many independent attempts to domesticate the wolf. Fossils of dogs and wolf-dog hybrids as old as 30 thousand years ago have been discovered from various place in the Middle East, Europe and Siberia suggesting multiple domestication attempts, perhaps successful ones.

What comes to my mind is how incredibly violent the initial process of domestication would have been. Wolf-dog pups and young adults not to the liking of humans in terms of their temperament and behavior and form would have been put to death often by a whack to the head.

As a dog lover I shudder at the thought.

Article On New Madrid Fault Zone Earthquake Risk

noreply@blogger.com (Suvrat Kher) — Thu, 10 Nov 2011 04:23:00 +0000

In Nature News Richard Monastersky has an informative article (open access) on the New Madrid fault zone and the differing views between the USGS and other scientists on the risk of another big earthquake in that area. The New Madrid area in Missouri has been something of an enigma. Its lies far away from the present day plate boundaries and yet has suffered large earthquakes in the past couple of hundred years. Some scientists have suggested that faults which originated tens to hundreds of millions of years ago - when the New Madrid area was geologically more active - may have strain stored in them.

These faults have been reactivated after the last ice age when the Mississippi river started eroding bedrock and removing large amounts of sediment. The sudden removal of weight from above the faults may have altered stresses on faults on the verge of failing, resulting in the big earthquakes in the recent past.

The article focuses on the work of Northwestern University geophysicist Seth Stein who argues that on faults which have released strain in the recent past the risk of a big earthquake is quite low, a conclusion derived from GPS measurements which show that the crust is that area is not being warped at a rate that could be dangerous. On the other hand he suggests that the earthquake activity could shift to an adjacent system of faults. According to him its best to view the entire region as one with interactive systems of faults with earthquake activity hopping from one zone to another over a time scale of hundreds to thousands of years.

This is a still a hypothesis but one for which Dr. Stein hopes to find evidence by expanding GPS measurements over larger regions around New Madrid. The USGS disagrees with his risk assessment and the article brings together the different points of view.

Field Photos: Driving Through A Basalt Countryside

noreply@blogger.com (Suvrat Kher) — Thu, 03 Nov 2011 11:07:00 +0000

The most prominent topographic feature of the Deccan volcanic province is the Western Ghat Escarpment that runs north south, roughly parallel to the west coast of India. The escarpment is the edge of a deeply dissected easterly tilted plateau, a result of Cenozoic crustal movement. Near Pune, several streams flowing eastwards through narrow valleys have been damned and the backwaters of these dams have some great views of a basalt landscape comprising deep valleys and spectacular exposures of basalt cliffs.

Last Sunday I drove with some friends along the backwaters of Mulshi dam. In the interactive embedded map below (Pune in south center) the western ghat escarpment is the arcuate north south ridge line on the left side of the image. You can count more than ten dams situated to the east which have flooded narrow valleys. If you pan north south you will see more reservoirs. The water is used to generate electricity and for urban and agricultural use.

View Larger Map

All pictures courtesy Bharat Parikh and Rajesh Sarde.

The countryside was lush. Wild grasses in full bloom.

A wide grassland meets distant peaks and ridges.

Steep basalt cliffs. Notice the layering of the lava flows.

The edge of the plateau is penetrated by fracture sets oriented in the NNW-SSE direction parallel to the coast and a NE-SW set. Some of these represent extensional stresses developed during rifting of India from Seychelles around 66 my to 65 my years ago and may have been conduits for the magmas. There are plenty of dykes intruding the lava pile oriented in a north south and north-east south-west direction. There are fracture sets too which may represent a later Cenozoic stress regime related to the uplift of the province. These provide a structural control on drainage.

The image below shows a north-east south-west oriented fracture set (red arrow) which has controlled the dissection of a deep valley. I call it Anil's valley in honor of my friend who told me about it. White arrows point to the NNW-SSE oriented lineaments. They may represent dykes or fractures.

A view of Anil's valley. It is a box canyon with near vertical walls of basalt.

The main basalt flow type in this region are compound flows. These are made up of discrete blobs of lava that overlapped and coalesced with other blobs of lava to form a compound unit. During one eruptive episode several compound units may be stacked to form a thick lava pile. These compound flows have weathered over time into a steep hummocky topography with domal summits accentuated by erosion along fractures. (Picture below taken on a previous field trip in February 2010).

A lonely road in the woods.

Bed load! A dry bouldery stream bed. Its just three weeks after the rains stopped and the streams in the upland areas are dry already. Small farming communities make by mostly through water in the monsoons and then rely on small springs to water their fields. Life gets quite hard here after the rains.

Food of a civilization. Yellow ripe paddy grown in the lowlands near the water source. Lava flows in the backdrop. You can smell the fresh rice as you pass by.

Until next time..