Crazy About Rugby

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

From xkcd comics:

Try beating that!

My Popular Posts Over The Last Two Years

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

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?

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

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

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

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

 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

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Some Thoughts On The Evolution Of Dogs

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

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

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..

How Scientists Are Scamming The American People

From the inimitable The Daily Show, Aasif Mandvi reports on how scientists are scamming Americans for selfish financial gain and confusing them by teaching them facts and rational inquiry. The indoctrination begins -  as Mandvi finds out - at labor camps for the young known as school science fairs.

Check it out.

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U.S. Shale Basins Map On GeoCommons

GeoCommons, the public mapping site run by FortiusOne Inc. has added a map of shale basins of the United States to its database. Go here for the metadata and to create your own map. You can also download this data either as a kml file or a shape file or as a text file.

Since I last visited the site, Geocommons has brought more analytical capabilities into the public domain. Users can now select from a list of spatial analytical tasks like data merging, data aggregation, buffer, intersection, clip. A lot of the familiar GIS spatial functions are now available from the cloud.

You can search for geology and other data sets and can also subscribe to the feed to keep track of new additions. This is really a great open access mapping tool with a very attractive interface and plenty of options to thematically display your map attributes. You can also contribute data. Uploads can be in kml, shape or text format. You can also import data available through a web URL i.e. you can import say a kml file from another server or data that can be shared through a WMS (Web Map Service) which is a protocol for streaming map images over the internet. This way you are linking to data that is stored somewhere else. Your display will automatically update when the primary data changes.

Its really worth your time browsing through this site exploring their data collection and experimenting with making maps.

Darwin And Hitler And Other Interesting Evolution Talks And Readings

A compilation of evolution related news I came across the last week or so:

1)  How do new species evolve? Peter and Rosemary Grant have undertaken a monumental multi-decadal study of the finches of the Galapagos islands. They explain the conditions that lead to speciation, part of the Brilliantly Illuminating And Lively Lecture Series.  If you don't have time to sit through the talk, the Panda's Thumb has a summary of their findings.

2) Donald Prothero, author of the book Evolution: What The Fossils Say And Why It Matters writes about recent occasions of creationists organizing geology field trips with the aim of reinterpreting the geological record to fit a young-earth creationist view point and of creationists presenting papers at the Geological Society of America meetings.

3) Darwin and Hitler- that old bogey keeps getting raised again and again. At the Planets of the Apes blog Faye Flam puts down that bogey... again! The follow up posts  ( 1 2 3 4 ) on this topic are worth reading too.  P Z Myers at Pharyngula also pitches in and points to an upcoming scholarly work by Michael Lackey which shows that the Nazis were very much a Christian Reich.

4) At the Cosmos and Culture blog anthropologist Barbara J. King explains Paleolithic diets in the context of the recent fad adopted by some to revert to the diet of our hunter gatherer ancestors as a way to healthy living.

Encouraging The Return of Foreign Trained Indian Scientists

India is promising a rapid expansion of its higher education infrastructure. To cope with the demand for well trained faculty it is encouraging the return of Indian scientists who have been studying and researching abroad.

Current Science has carried an interesting series of articles  (all open access) on the problems of meeting the increasing demand for faculty and researchers.

P. Balaram in a lead editorial - citing other indicators such as the willingness of researchers to return - suggests, giving some examples from China that an obsession with foreign trained scientists and a neglect in improving the local talent pool may end up causing some harm to the research environment.

A. Lohia disagrees with the word "Luring" used by P. Balaram in his editorial and expresses faith in the initiatives taken by the government to encourage the return of Indian scientists.

Mukesh Pasupuleti  agrees that the word "Luring" is quite  appropriate. He writes about the experiences of a prospective returnee.

Thoughts On The "Irrefutable" Evidence Of The Yeti

Is there a connection between last year's discovery of Denisovans and the recent surge in interest in the Yeti. Last year a team of scientist found fragments of a human finger bone in a cave in the Altai region of Siberia. Materials dated in the cave indicate that these humans lived about 41,000 years ago.  The surprise was when DNA recovered from the bone was sequenced and compared with living humans and Neanderthals. The differences in the DNA sequence suggested that these fossils represented a distinct human population, as different from living humans as we are from the Neanderthals. They were called the Denisovans after the area where these remains were found.

What is the story of the origins of these Denisovans? After the origin of our genus Homo in Africa around 2 million years ago, humans from time to time migrated out of Africa.  Descendants of one such migration around half a million years or so evolved into the Neanderthals in Europe and the Denisovans in East Asia. These were long lived populations. Within Africa too there were probably different varieties of humans. We Homo sapiens evolved from one such population and when members of Homo sapiens migrated out of Africa around 75 thousand to 50 thousand years ago they would have encountered and interacted with the Neanderthals and Denisovans. Did we interbreed? The answer is most likely ..yes. Genetic analysis now strongly suggests that both Neanderthals and Denisovans have left a small but distinct genetic legacy in us.

The status of Neanderthals and Denisovans as separate species of humans now stands challenged. They had certainly evolved into a distinct variety of humans, much more different than the differences seen between the broad groups of living humans. But not enough so as to prevent them from successfully interbreeding with a population (us) they confronted after a few hundred thousand years of separation.

The Yeti off course would be the ideal candidate to imagine a still living Denisovan population in the isolation of Siberia. The ecology described historically for the Yeti includes remote mountainous regions, caves, cold weather, temperate forests.. landscapes that also describe one of habitats of the Denisovans, although the Denisovans probably had a range that include the tropics too.

Stories of a mysterious human-like creature wandering the wilds are part of the mythology of many cultures.  Such a creature thought to be living anywhere from Tibet to Siberia has been called the Yeti.  Now, Russian scientists a year after the sensational discovery of the Denisovans have found "irrefutable" evidence of the Yeti in the form of  impressions on the ground and some hair and a supposed bed from a setting uncannily similar to the Denisovan fossils.... In the cold of Siberia in a cave surrounded by temperate forests.

I can't help thinking that the Denisovans more than prompted this latest "evidence" of the Yeti.

The Yeti has always been thought of and pictured as a brutish sort of a creature.  It is usually described as a bipedal ape,  hinting at its proto-human like character. One famous picture of the Sasquatch (the Yeti's equivalent in north America) shows a hairy gorilla like creature  turning its head to face the camera.  The Yeti in East Asia has also been described as big and hairy. It has traditionally been a creature which has been emphasized to be more "primitive" than humans but occasionally with some redeeming qualities. In Tintin In Tibet ( Picture Source),  the Yeti saves and looks after Chang, a Chinese boy who is a survivor of a high altitude Himalayan plane crash.

These depictions of the Yeti may be a reflection of how we thought and maybe still do about archaic populations of humans. They were thought to be separate species. Different from us reproductively. We didn't breed with them. There was no intimacy between us. They were sub-human.  The Neanderthals for long were considered primitive dumb brutish cave dwellers whom we superior modern humans drove to extinction. We were wrong about that. As we learn more about Neanderthal society that perception has changed over the last couple of decades. And now we know that all of us are part Neanderthal and part Denisovans.

Will our description and iconography of the Yeti change to accommodate this new understanding of human evolution? Now that we understand that there is a continuity and not a chasm between us and other varieties of humans who lived on earth, will we depict the Yeti as a less grotesque, less intimidating, more empathetic social creature, and not the one solitary ape roaming the expanses of Tibet and Siberia. Will the Yeti become more human and less beast? Will science guide this particular theater of science fiction?

Will the Yeti become no more abominable, but just an ancient snowman?

Bhuvan Continues To Be A Mixed Bag As A Citizen Mapping Tool

After my last post on the use of Google Earth to identify illegal mining in Goa, I was curious to find out if I could replicate the same in Bhuvan, India's public mapping portal.

I was disappointed:

1)  There is no historical imagery available, or at least none that I could find.  So I could not pull out older imagery to verify claims made about the presence /absence of mining before a certain date.  This is not due to a lack of older imagery. The Indian Space Research Organization has had a remote sensing satellite program since the late 1980's and imagery  of at least 23 m resolution is available for  the last couple of decades and imagery of 5.8 meter resolution is available for the last 12 years or so (IRS - 1D). The 5.8 m resolution images are fine grained enough to identify large features like open pit mines.

2) I could not find the open pit mines using "search by name". In Google Earth I could zoom onto the area of the open pit mines by searching for the nearest settlement "Maina" which was mentioned in the article on the Goa mining scam by the newspaper Herald.   In Bhuvan, the search by name database works best for towns and cities. The village level data is still incomplete. Even when a small village is present in the database the imagery does not always zoom to that area, nor is the village annotated to allow easy navigation to it. These are the basics of interactive map navigation design and Bhuvan is falling short.

On a general note, its been close to three months since the government announced that 1 meter resolution data will now be available without need for security clearances. Yet Bhuvan still is not streaming imagery finer than 5.8 meter resolution.

On the data download front, elevation data of CartoDEM 1 arc second (Digital Elevation Model derived from Cartosat 1 imagery- 1 arc second corresponds to roughly 30 meters) and Resourcesat-1: AWiFS imagery (56m) of the Indian region can be downloaded from the NRSC Open EO Data Archive. You can choose the product and the area of interest from the Bhuvan interface. The DEM download is a welcome addition. You could previously download 1 km resolution DEM of India from the USGS and also 30 m relative DEM generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) from NASA.

However, regarding imagery the government's all too cautious approach is perplexing. If 5.8 meter resolution and 1 meter resolution data are available and now cleared for access to all users without further security checks, why not let users download that data too?

Catching Illegal Mining In Goa Using Google Earth

Ogle Earth points to the use of open access tools like Google Earth to alert us to the possibility of illegal mining. From their blog:

There is a juicy scandal unfolding in India’s smallest and richest state, Goa, where the State Assembly’s Public Accounts Committee (PAC) has prepared a report indicting ruling Congress Party politicians for benefiting from illegal mining in the state. Illegal mining is estimated (by the Hindustan Times) to have cost Goa over USD 600 million over the past five years in lost tax revenues, turning this into a whopper of a story.....

...India’s national Directorate of Mines and Geology has now also taken an interest in the mine, ordering it to immediately cease production until it is investigated. An article by Goa’s Herald spells it out for us:

Tarcar has cheated the government by avoiding huge amounts of export duty by under-invoicing of his exports.

When presented with evidence of massive ore dumps that could not have been produced within quota, his mining company contended that these were from earlier activities. Google Earth’s imagery from 2003 effectively catches the company in a lie.

Check out the imagery here. No open pit mines in 2003. The 2011 imagery shows large open pit mines.

These ores are part of the rich iron ore belt of Goa. They are Precambrian Banded Iron Formations generally thought to be of sedimentary origin and are associated with medium and high grade meta-sedimentary rocks of the Archean schist terrain that makes up large portions of south India.

Online Interactive Geological Map Of India

I keep tabs on the India Biodiversity Portal, one of the best India based open access web mapping applications focusing on natural resources.

They have online now an interactive geological layer created by digitizing likely 1 : 1 million scale Geological Survey Of India geology maps. The contributor is R. Ravindranath of the Foundation of Ecological Security. You can click on geological units and get a description of the unit. You can also thematically style the geology based on Geological Age and Lithology. And you can control transparency so as to get an idea of the relationship between say physiography and geology. The physiography layer is one of the Google base layers available for display.

Other geology related overlay layers are India Aquifers, India Soils, India Geomorphology and India River Basins. I wish they had different display styles like transparent cross hatch, dots, symbols and lines and so on to choose from to enable easy visualization of multiple themes but perhaps that is something for the future. Unfortunately none of these geology layers are available as downloads. Government owned vector data is still not being distributed freely in digital format. I hope there is a change in policy on that soon.

But this is an important and growing resource for geology and biodiversity data. You can register and contribute layers to the natural resources database. Most Layers not under government control are downloadable (as shape files, GML and text) but contributors are free to choose the level of restrictions they want under a Creative Commons license.

Scarcity Of Earth Science Specialists Hurting India

Shobhan Saxena's article in the Times of India on the scarcity of earth science specialists throws Indian geologists in poor light. She quotes a geologist:

"From the data available and signs in recent years, it's clear that a big earthquake of magnitude 7/8 is long overdue in north India, but we are not prepared. The government geologists are happy monitoring the Richter scale and announcing the intensity of the quake when it happens. That's it," says the expert who doesn't want to be named.

Ouch... that is harsh. But there is some truth in it. A case in point is the website of the Geological Survey of India. Apart from a four line statement, there has been no effort to explain the Sikkim /Nepal earthquake. And no easily accessible details that I could find of what the Geological Survey scientists are doing or attempting to do in terms of a sustained program to educate the citizenry about earthquakes and other geo-hazards.  The media coverage didn't help either. There were no lead articles by geologists in major newspapers and no geologists appeared on major news channels to talk about the earthquake and earthquake preparedness.

You can't pin the blame entirely on the scientists. The article points out that we have few scholars pursuing advanced degrees in geology and earthquake studies. That may be right. But the problem is not just the small number of geologists but that their recommendations regarding building standards and construction practices are flouted with impunity. If its accountability you are looking for then you need to cast the net wider to encompass the polity and civil governance. Politicians, civic officials of municipalities and builders must share the blame for allowing the growth of the unplanned chaotic tottering towns of the Himalayas.

New York Times Profiles Richard Dawkins

The New York Times Profiles In Science series features the evolutionary biologist Richard Dawkins.

Here is a gem:

Professor Dawkins often declines to talk in San Francisco and New York; these cities are too gloriously godless, as far as he is concerned. “As an atheistic lecturer, you are rather wasting your time,” he says. He prefers the Bible Belt, where controversy is raw.

I have first hand experience explaining evolution in the Bible belt. During graduate student days at Florida State University, I used to help my advisor on Science Day at the local mall with the fossils display.  " Well.. I can't see where the intermediate fossils are between this one and that one.." ..." I can't believe that amoeba can evolve into humans" were the kind of questions we often faced.

Teaching evolution comes with a risk of extreme reaction sometimes. Richard Dawkins though labors on and has done it better than anyone else.

Geological Framework Of the Sikkim Earthquake

Everyone is calling it the Sikkim earthquake (6.8 Richter) of September 18 2011 but the epicenter plots just west of the Sikkim border in Nepal. Information about the geological framework of the region and the tectonic elements responsible for the earthquake has been limited. At the USGS website I got the following:

The September 18, 2011 Sikkim, India earthquake occurred near the boundary between the India and Eurasia plates, in the mountainous region of northeast India near the Nepalese boarder.......

The preliminary focal mechanism of the earthquake suggests strike slip faulting, and thus an intraplate source within the upper Eurasian plate or the underlying India plate, rather than occurring on the thrust interface plate boundary between the two.

I have highlighted the sentence of interest to me. It is very unlikely that the earthquake source was within the upper Eurasian plate. It was almost certainly in the Indian plate.

Below the image shows the Himalayan orogen bounded between the Himalayan Frontal Thrust to the south and the Indus Tsangpo Suture to the north. It is along the Indus Tsangpo suture that the two continents have collided and the Indian plate has dived under the Asian plate.  The location of the Sikkim earthquake is a good 200 km or so south of this zone of thrust interface plate boundary between the two.

Source of Active Faults (red lines) - Styron, R., Taylor, M., & Okoronkwo, K. (2010). Database of active structures from the Indo-Asian Collision. Eos Trans. AGU, 91(20), 0-1. doi: 10.1130/GES00217.1 and Taylor and Yin (2009). Available as a kml file at HimaTibetMap-1.1.  See this post on the Rocks and Water blog for the story about the compilation of the fault database.

I have put up below a generalized cross section across the Himalayan orogen with the red arrow pointing to the approximate geographic position of the earthquake in relation to the major tectonic boundaries.

As you can see the location of the earthquake is between the Southern Tibetan Detachment (STD), a zone of normal faulting between unmetamorphosed Paleozoic sediments (Tethyan deposits) and high grade Greater Himalayan metamorphic rocks representing the Tethyan basement and the Main Central Thrust one of the major thrust faults that brings into contact the Greater Himalayan Proterozoic high grade metamorphic rocks (Tethyan basement) with the Lesser Himalayan low-medium grade Proterozoic metamorphic rocks. These represent deformed and exhumed upper to mid crustal levels of the Indian plate. The earthquake's epicenter estimated to be at most at 20 km depth lies firmly within the Indian plate. The Asian plate is far to the north.

Since two plates are pushing into each other, the major stress regime in the Himalayan orogen is one of compressional forces. This earthquake though was likely caused by movement along a strike-slip fault where two crustal blocks slide past each other and not towards and over the other as expected in an area where compressional forces are common.

Below is a geological map of the Sikkim Nepal region. The earthquake is located quite close to the Main Central Thrust. Geologists can learn about the type of fault that caused an earthquake by an analysis of the first motions of the seismic waves generated by the earthquake being recorded at different monitoring locations. See here for a good explanation of this method. Such a focal plane solution (yellow beach ball) for the Sikkim earthquake indicated a strike slip fault oriented NW- SE. The map also plots focal plane solutions (smaller red beach balls) for few of the recent earthquake's in this region and as you can see strike slip motion is a common type of earthquake movement here.

 Source: EIA of the TING TING H.E. PROJECT, SIKKIM - RS Envirolink Technologies Pvt Ltd (large file)

Detailed analysis of the seismicity in the Sikkim Himalayan region indicates that although earthquake activity is located in the region  near major thrust faults, many earthquakes are not associated with them. Instead movements along faults like the Gangtok lineament and the Tista lineament which are  transverse to the strike of the orogen seem to be responsible for many earthquakes including the September 18 earthquake. These are north northwest trending faults. The plate motion of India into Asia along the Himalayas is in a north north- east direction. Some geologists have suggested that in this part of the Sikkim Himalayas some of the crustal shortening is being accommodated by movement along these transverse strike slip faults rather than by underthrusting.

Crustal Shortening: The upper part of the Indian plate is being crumpled and squeezed into a narrower zone. How is the crustal material accommodated in that narrow zone. Commonly by piling crustal blocks on top of each other by thrusting along faults. This leads to crustal thickening and contributes to the elevation of the mountain chain. Or sometimes by sliding blocks past each other   along strike slip faults both transverse to the orogen as in the case of this earthquake and also parallel to the orogen as is possibly happening along the two east west strike slip faults north of the Sept 18 earthquake location seen in the first image of this post.

In the past 35 years there have been 18 earthquakes in this region of magnitude 5 or greater. No doubt there will be many more in the future. Some will be along the strike slip faults described above. Others may be along the major thrust faults like the Main Central Thrust.

..and no... you won't be able to predict them. Preparedness in the form of better building construction and a functioning disaster relief mechanism is the only way to save lives.

Why The Majority Of Scientists Believe In Evolution

Came across this golden oldie at JesusandMo.net.

Callan Bentley at Mountain Beltway has very ably demonstrated that the Dunning-Kruger effect afflicts most of the U.S. Republican Presidential candidates.

New Geosciences Blog By Author Of Basin Analysis

Professor Philip Allen of Imperial College London and one of the authors of the book Basin Analysis: Principles and Applications is blogging.

Check out this great post on Dynamic Topography.

Data Problems In The Indian Geospatial Industry

Geospatial World has several articles (1, 2, 3 ) on the current state of the Indian Geospatial Industry. As I have been writing on this blog, there have been several initiatives taken by the Indian government to encourage growth of this industry. Of primary concern to users is the unavailability or slow availability of useful data.

Aditi Bahn Assistant Editor, Geospatial Media and Communications Pvt. Ltd. writes:

There is no single window where all the information can be obtained. For example, if a user requires information about topography and demography of a place, he has to approach Survey of India and Census of India respectively. The two have their own procedures in place and would provide data in their own time frame. She quotes industry specialists : 

“The overhanging issue is the availability of data under one umbrella. Information is scattered and varied and have to be collated very frequently. It has become extremely challenging,” explains Aiyer.

..and (Mr. Agarwalla) -  “Even before we talk about public-private partnership, we need to talk about public-public partnership. For most of my users, just the map or census data by itself is not good enough. So can Survey of India and Census of India partner together?”

That is not unusual. Having data in two or several different places need not by itself be a big problem. Even in countries  where spatial data is relatively freely available like the U.S, many state agencies and federal agencies have ownership of their data. Finding it though is easier by going to a central data listing like the one maintained by the U.S. National Spatial Data Infrastructure. Most government agencies who produce spatial data are registered with their NSDI and follow agreed upon data standards and data dissemination practices.

In fact it is inevitable that various central and state agencies responsible for the data will want to keep ownership of it. The Indian National Spatial Data Infrastructure (NSDI) was meant to deal with exactly this problem by issuing guidelines and standards for data creation, data storage formats and data access thereby enabling users to find and combine data from different agencies with ease. The important challenge is not whether different agencies can partner each other, but getting agencies to follow standard practices in a time bound manner. The NSDI portal would then list agency addresses to go to for your data needs.

I remember talking to a senior geologist with the Geological Survey of India in 2004. I was told that digitization of 1:1 million scale geological maps is almost done and work is going on the 1:250K and selected 1:50k series. Most of this data would be ready to go online by 2006. Five years since this self-proclaimed deadline, there is still no easy way to access geology digital data.

Why has the NSDI not been successful in getting organizations to cooperate in a timely manner?

Bad Science Is Quite Funny

I am enjoying reading Bad Science by Ben Goldacre. As the back cover promises, it offers relief from scaremongering journalists, pill pushing nutritionists, flaky statistics and evil pharmaceutical corporations. I should add homeopathy to the list. It gets a thorough drubbing too.

The book is about exposing charlatans and quacks who misrepresent or ignore science and carve out a place for themselves as health experts promising cures and interventions to enhance the quality of your life.

It is fun to read not just because it is wittily written but it is a useful exposition on how sensible people can end up believing nonsense and how you can train yourself to critically weigh evidence and sift through the mountains of (mis)information and fantastic claims that self-serving experts throw at you.

The Easterly Tilt Of The Deccan Plateau

A reader came across an old post of mine on the uplift history of the Western Ghats and asked:

1) What is the relationship between the Deccan volcanics and the easterly tilt of the Indian plateau (i.e. the plateau covering the Deccan volcanics and the southern Indian peninsular region)

2) Why is the northern half of the Western Ghats composed of basalt and the southern half composed of gneiss?

The region south of the Tapi river covering the Deccan basalts  and the southern Indian peninsula exhibits an easterly drainage with the rivers flowing into the Bay of Bengal. Image below shows the Indian peninsular region with easterly drainage. The Deccan Plateau (in green) is the area covered by the Deccan basalts. South of this region is Precambrian terrain. Along the east coast there are Permian-Triassic and Cretaceous basins.

Source: Sheth H.C. (2007)

The relationship between the Deccan volcanics and this easterly tilt is indirect. There are many plausible reasons for the easterly tilt of the Indian crust. ,

a) The breakup of Gondwanaland produced Permian-Triassic rift basins along what is now the eastern margin of India. Initially the sources of sediment being deposited in these basins were from the east and south i.e elevated regions now forming continental shelves of  India and the continental margins  of Australia and Antarctica. Beginning late Jurassic rifting produced the now western margin of India. This younger rifting event generated topography to the west and reversed sediment distribution patterns. The Late Jurassic and Cretaceous basins of south India received sediments from the west i.e. via an easterly drainage.

b) The rifting event that created the western margin of India also eventually triggered the Deccan volcanic episode. Post volcanism in the Cenozoic the Deccan region has titled to the east due to the Western margin undergoing uplift. This has been explained as an isostatic response to denudational unloading of the crust i.e. erosion has stripped material away from the Western margin forming the coastal plain and the steep Western Ghat escarpment. All that eroded sediment has been deposited  within basins in the Arabian sea.  This removal of weight has led to the crust rebounding and tilting in an easterly direction. The schematic  shows the development of an easterly tilt  ( east to the left) due to rift flank uplift and isostatic rebound (source: Campanile et al 2008)

c) The eastern margin of India is older (about 130 my)  than the western margin (about 65 my). The oceanic lithosphere in the Bay of Bengal is colder and denser and it is sinking and dragging down the peninsular region with it.

d) The Bengal sediment fan i.e. the pile of sediment eroded from the Himalayas throughout  the Cenozoic and deposited in the Bay of Bengal is weighing the crust down and exerting a dragging down effect on the Indian peninsular region. There is about 22 km of sediment at the mouth of the Ganges -Brahmaputra delta and about 8 km of sediment as south as Chennai.

Likely all the above have acted in combination to produce the easterly tilt.

2) The reason why the southern part of the Western Ghats are made of gneiss is that the Deccan lavas never erupted and flowed that far south. So the boundary between the basalts and the gneiss marks the southern limit of Deccan volcanism.

The Ganges Delta And The Hungry Tide

Amitav Ghosh is his book The Hungry Tide  evocatively describes the Ganges -Brahmaputra delta, the place where these mighty rivers change form as in from a one major active meandering channel into many entangled entities:

In our legends it is said that the goddess Ganga's descent from the heavens would have split the earth had Lord Shiva not tamed here torrent by tying it into his ash-smeared locks. To hear this story is to see the river in a certain way: as a heavenly braid, for instance, an immense rope of water, unfurling through a wide and thirsty plain. That there is a further twist to the tale becomes apparent only in the final stages of the river's journey - and this part of the story always comes as a surprise, because it is never told and thus never imagined. It is this : there is a point at which the braid comes undone; where Lord Shiva's matted hair is washed apart into a vast  knotted tangle. Once past that point the river throws off its bindings and separates into hundreds, maybe thousands of tangled strands.

Until you behold it for yourself, it is almost impossible to believe that here, interposed between the sea and the plains of Bengal, lies an immense archipelago, stretching for almost three hundred kilometers, from the Hoogly River in West Bengal to the shores of the Meghna in Bangladesh. 

The islands are the trailing threads of India's fabric, the ragged fringe of her sari, the achol that follows her, half-wetted by the sea. They number in the thousands, these islands; some are immense and some no larger than sandbars; some have lasted through recorded history while others were washed into being just a year or two ago. These islands are the rivers restitution, the offerings through which they return to the earth what they have taken from it, but in such a form as to assert their permanent dominion over their gift. The rivers channels are spread across the land like a fine mesh net, creating a terrain where the boundaries between land and water are always mutating, always unpredictable.

The delta and its front end - the sediment fan -  that is present below sea level in the Bay of Bengal is essentially made up of Himalayan sediment worn down by the many rivers and redeposited in the Bay. A pile of sediment more than 10 km thick have accumulated since the early Cenozoic.  Image below shows the Ganges Brahmaputra delta and the region called the Sunderbans named for the mangrove forests that grow on the thousands of sandbars and islands.

India Asia Collision And The Evolution Of Hindu Thought

Wendy Doniger in her book The Hindus: An Alternative History draws the following parallel between the collision of a piece of Africa (the Indian plate) with the Asian plate and the evolution of Hindu thought:

In part because of the intertextuality and interpracticality of Hinduism, one text or ritual building on another through the centuries, right back to the Vedas, scholars looking at the history of transmission have assumed that the Veda was the base onto which other things were added in the course of Indian history, just as Central Asia was the base that absorbed the impact of that interloping piece of Africa so long ago. And in the textual tradition, at least, this is true enough of the form in which ideas were preserved, the chain of memorized texts. But from the standpoint of the ideas themselves, it was quite the opposite. The Vedas was the newcomer that, like the African island fusing onto a preexisting continental base, combined with a preexisting cultural world consisting perhaps of the Indus Valley, perhaps of any of several other, more widely dispersed non -Vedic cultures. 

One can get carried away to the point of silliness comparing geological evolution of India with the coming together of cultural and religious thinking during the evolution of Hinduism. So don't take this too seriously but I couldn't resist extending the comparison a little.

One aspect that comes to my mind is the retention of the original state. All along the geological landscape of the Indian subcontinent it is easy to make out which  is the original fragment of Africa (Gondwana)  and which the original Asian plate. Over much of the Indian subcontinent the original Gondwana characters of India remained unchanged after the two continents collided as is the case with the Asian continent. They are in proximity only along a narrow zone called the Indus-Tsangpo Suture in the Ladakh -Tibetan Himalayan region. Over there the crustal blocks of the two plates, their provenance recognizable, lie next to each other along  faulted contacts, slivers of ancient Gondwana pasted onto fragments of Central Asia. The boundaries between the two are sharp. It is like as Doniger puts it components of a salad. It may appear mixed but you can recognize the greens from the nuts easily. 

The coming together of the Vedic and non-Vedic worlds has resulted in a more diffuse landscape of ideas and people. Unlike geology there is no spatial boundary within the Indian subcontinent where the Vedic world collides with the non-Vedic. You might be tempted to put this at the junction where Indo-Aryan languages give way in the south to Dravidian languages..but that boundary between the two peoples has shifted geographically and evolved over time to be more a language boundary than a boundary of ideas. Gods and cultural and social practices have flown to and fro between Indo-Aryan and Dravidian speaking people across geography and social strata. So have genes, and the result is more a milkshake than a mixed salad. 

Beyond the Dravidian speaking pariah, farmers, merchants, kings and priest, a social hierarchy likely imported from the Indo-Aryan world, there were many groups speaking Austro-Asiatic and other now extinct languages who progressively became marginalized with the encroachment of Indo-Aryan and Dravidian farming communities and city states. These were the adivasis or tribal populations who at first sight might seem to be a world apart from Vedic and mainstream Hindu thought. They would seem to resemble the discrete pieces of Gondwana and Central Asia, living in close proximity but separated from mainstream Hindus by sharp social, cultural and genetic fault lines. There is some truth to the salad bowl analogy here. But over millenia these fault lines must have been breached and boundaries blurred. Once thought to be unchanged descendants of the first migrants from Africa many tribal populations have to a degree assimilated with the Indo-Aryan and Dravidian speaking populace. Recent studies have shown substantial amounts of Eurasian and south east Asian genetic components within different Indian tribal populations.

There must have been linguistic and cultural exchanges as well.. for example many marginalized groups adopted Indo-Aryan and Dravidian languages. Going the other way it is likely that both the elite Sanskrit literature and popular vernacular mythology borrowed from animist tribal traditions and folklore.

Within the Ladakh and Tibetan region and the Karakorum and Hindu Kush ranges though there are indicators of geological processes that resulted in the two plates not just residing side by side but forming a more complete mix. As the Indian plate subducted underneath the Asian plate, deep inside the crust, very high pressures and temperatures caused the rocks at the contact between the two plates to melt.  In that magma, elements scavenged from two different plates recombined into new minerals. The two plates created one entity.  These mixed rocks called anatexic granites form chains of plutons north of  the Indus -Tsangpo suture, the zone of collision of the two continents. 

So although the fault bounded terrain of the Indus-Tsango suture works as an analogy particularly for some marginalized groups, it is in these granites that geology comes to being the closest analogy to the evolution of mainstream Hindu thought in which ideas from the Vedic and non-Vedic worlds have come together, some traceable to their sources, others having synthesized into inseparable traditions, multiplicities within an individual.