Oil Hunters Of India

At Independence in 1947, India had just a few operational oil wells situated in the northeastern region of the country. Most of the subcontinent's sedimentary basins remained unexplored for their hydrocarbon potential. The Oil Hunter: Journey of a Geologist for India's Oil Exploration by Dr. Shreekrishna Deshpande is a personal recollection of the immense effort undertaken by Indian geologists to re imagine these basins as hydrocarbon source and reservoir rocks. It is the story of the development of India's oil industry told with unconcealed pride.

Russia, France, and the U.S. offered personnel and technical help along the way, but the lion's share of the credit goes to geologists of the Oil and Natural Gas Corporation for their perseverance and resilience in the face of immense challenges.

Dr. Deshpande joined the ONGC in its early days in 1961 and describes vividly his field experience in remote locales all across the country, from scorching Kutch, to steep Himalaya terrain, to facing personal danger during an insurgency in Assam. There were inevitable career challenges along the way due to changing institutional structure and unrealistic political expectations. Their impact on company work culture and productivity is described in honest and direct language.

One of my favorite passages comes towards the end of the book where he explains the divergence between geologists and management in their basic understanding of exploration and discovery.

"Subsurface discoveries of oil reserves cannot be projected with certainty. The inputs to the discoveries are always deterministic, but the result is never so, and there is a strong factor of probability. Exploration efforts are to reduce the risk factor and increase the probability of discovery. Methods for direct detection of  hydrocarbons from the surface, are  yet to be evolved. This contrasts with any other industry, where the output is more predictable and proportionate to the input. 

.... As a simplistic approach the management decides the cost of discovery of one tonne of oil by dividing the amount of discovered oil by the expenditure met. It is expected by them that similar expenditure should proportionately result in additional discoveries.

When a sedimentary basin turns old and mature, the addition to the existing stock of subsurface oil becomes increasingly difficult. Non-geoscientists then blame geologists for such uncertainty. Only the high profitability in the oil industry is visible; its probabilistic nature and the risks involved are not so obvious. The stochastic nature of oil discoveries is not appreciated by non-explorationists". 

My one complaint about this book is that there is very little geology in it! Dr. Deshpande describes the geology work he and others undertook in very broad strokes. I felt that a few examples of how specific types of geologic data is useful for petroleum exploration would be illuminating for the non specialist reader. 

Let me give an example. Early in his career he is sent to Osmania University, Hyderabad, to analyze some sedimentary rock samples using Differential Thermal Analysis. He simply mentions that the results were used by ONGC in their exploration efforts, but how so? DTA is a way to understand whether the sedimentary rock was baked during burial to temperatures that are conducive for hydrocarbon formation. 

Another example, and one that involves his specialization, could have been a brief passage describing his work on limestones. What is a carbonate sedimentologist looking for in these rocks? The main reservoir of Mumbai High, India's biggest oilfield, are Miocene age limestone beds which were deposited repeatedly during phases of oscillating sea level. Among other things, exploration geologists want to know how open spaces or porosity in these rocks has evolved over time and whether its occurrence can be predicted throughout the sedimentary section. There was a geological detective story waiting to be told there. 

But these are mere quibbles. Overall, this is a very readable account of the productive and remarkable career of a pioneer exploration geologist of India.  Popular accounts of Indian geology and industry are rare. Recently, Himalaya geology expert Dr. Om N. Bhargava released his memoir, Travails and Ecstasy of a Geologist Addicted to the Himalaya, on his experiences of working in the Himalaya. Indian earth scientists are beginning to share the good work they have done with a more general audience, bringing a much needed familiarity with a lesser appreciated but critical field of study. 

Book: Up The Mountains Of India

Finally it arrived! The author Mala Kumar connected with me a couple of years ago. She was writing a book on the mountains of India aimed primarily at young readers and wanted a geologist to help with fact checking some of the contents. We have had quite a few email exchanges since then, and my curiosity about this book has been growing even since. Mala has written over 40 books for children and this one is sure to enthrall them. But why just children? Anyone interested in India's varied physiography, geology, and wildlife, should read this book. 

I loved the way Mala has used everyday analogies to describe complex geology. One of my favorite examples is using a stuck piano key to explain about fault block mountains. The stuck key is a horst or a block that has moved up relative to the adjacent depressed keys which are called grabens. India's mountains are geological varied. The Himalaya, the Satpura, and the Western Ghats, for example, have formed by very different processes. Mala has used clear language and everyday familiar examples to simplify explanations of their origins. 

But this book is much more than about geology. Forests, wildlife, and human communities living in these rugged provinces really are the heart of the book. There are evocative descriptions of the animal and plant life of the different mountains ranges. Tibetan gazelles and mysterious snow leopards of the Himalaya, hoolock gibbons of the northeastern hills, majestic tigers of the Satpura and the Aravalli, and the bewildering varieties of frogs and reptiles of the Western Ghats, make us proud of our magnificent wildlife. There are lovely photographs scattered through the book. I could not stop gazing at the clouded leopard sitting elegantly on a branch deep in forests of the Mizo Hills. 

People too have lived in these mountains and forests since times immemorial. Their lives and life practices are being threatened as more mountain and forest land is gobbled up for dams, mines and expanding townships. In the northern Aravallis, villagers fought for years to save the sacred grove of Mangar Bani. In the Nallamali hills of Andhra Pradesh, members of the Chenchu tribe along with other organizations protested uranium mining that would have transgressed on the Amrabad Tiger Reserve. The book tells many stories from across the country, from the Aravallis, to the Eastern Ghats, to the Himalaya, of people struggling to conserve forests and water sources. 

Sketches and insets provide a welcome addition to the text. There are fun stories about the people of the mountains, about their crafts, about intrepid explorers, along with short quizzes, crammed in the insets that make the mountains come alive. 

Mountain ranges form the most important watersheds of our big rivers. Today, rampant development of mountain slopes coupled with climate change are becoming big threats to our water security. Mala Kumar's urgent call for conservation and sustainable development emerges again and again throughout the book and she has chosen her audience well. Whom better to inculcate a love and awareness for nature than in our children. These young citizens will be living in an increasingly challenging world and the hope of changing it for the better lies in a deeper understanding of how nature works. 

Go out for a trek in the mountains. Keep a lookout for that bright bluetail, and that curious langur who is peering at you half hidden from behind the thick leaves. Pick up pebbles from the stream bed and ask yourself about its geological secrets. Take a mountain train to the scented Nilgiri heights.  If you are hesitating, this book is an ideal place to begin.

Up the Mountains of India: A Fun, Fact-Filled Trek across the Country's Major Ranges - Mala Kumar. 

Bihar: Where Many Rivers Meet

I came across this passage in Vipul Singh's interesting book, Speaking Rivers: Environmental History of A Mid-Ganga Flood Country, 1540-1885. 

 "In consequence of the frequent changes which take place in the channels of the principal rivers that intersect the territories immediately to the presidency of Fort William and the shifting of the sands which lie in the beds of those rivers chars or small islands are often thrown up by alluvion in the midst of the stream, or near one of the banks and large portions of land are carried away by an encroachment of the river on one side, whilst accession of land are at the same time, or in subsequent years gained by dereliction of the water on the opposite side;... the lands gained from the rivers or sea by the means above mentioned are a frequent source of contention and affray,and although the law and customs in the country have established rules applicable to such cases these rules not being generally known, The Courts of Justice have sometimes found it difficult to determine the rights of litigant parties claiming chars or other land gained in the manner above described". 

It is a section of the preamble of The Bengal Alluvion and Diluvion Regulation of 1825 which the East India Company passed to assure a regular income from Diara lands. 

Diara land are ephemeral parcels of land that accrete to river banks or emerge in the middle of the river channel by sediment deposition. They can disappear in a decade or so as a major flood cuts away the river bank or erodes an island, only for newer land to appear elsewhere along this meandering fluid riverine landscape.

The satellite imagery covering the region between Patna in the west to Munger in the east forms the heart of this mid -Ganga floodplain.

Diara lands were traditionally farmed by landless peasants for the few months of the year that they were above water and then abandoned during monsoon inundation. There was no concept of ownership of these lands. The East India Company in its quest to maximize land revenue decided to regulate ownership of the Diara. It didn't always work in practice. Zamindars were reluctant to report the ground situation accurately and maps became outdated as topography and landscapes shifted quickly. Diara lands remained and still are a source of dispute.

Fascinating is the struggle outlined in the book of two long lasting empires with this river system. Before the Mughals, the Afghan ruler Sher Shah Suri occupied this region and had adapted to the capricious environment to his advantage. The Mughals though faced a different problem. Their power center was far to the west in Delhi and Agra. Carrying grains and goods from Bihar to Agra-Delhi using pack animals wasn't possible, since the expenses of feeding these animals would have left very little surplus. Being children of the Eurasian steppe, they preferred the horse and land transport, and that meant that they were unable or unwilling to develop a river navigation network on a commercial scale. The direction of river flow also worked against them. Sailing goods-laden boats upstream was challenging, especially as Vipul Singh points out, the Ganga upstream of Varanasi becomes difficult to negotiate. As a result the Mughals could never exploit or control this region fully. 

The British though found the river to their liking. The Grant of Dewani of Bengal, which the East India Company won in 1765, extended to the mid Ganga floodplains. The Company's main port lay downstream in Calcutta and their major markets across the seas in China and Europe. Using their expertise in navigation they soon set up a thriving trade in saltpetre, calico, opium and silk. Slowly, they also began imposing a linear topography on these curving meandering rivers. The building of embankments, canals, and barrages was thought necessary to control the inundation that could lead to a loss of a cropping season. The various Regulations and Acts meant to ensure a permanent and uninterrupted stream of revenue ended up changing the people's interaction with the river. 

These land regulations, beginning with the Permanent Settlement of 1793, entrenched the power of hereditary Zamindars who became Company rent collecting agents. It became especially hard for the landless to eke out a living as they saw even the ephemeral parcels of Diara which they had been farming now being allocated to the nearest Zamindar and his tenants. Large scale flood control projects carried out by Zamindars and encouraged by Company revenue officers began reshaping the ecology of the floodplains with embankments preventing floods in one region but exacerbating them on the opposite side or in downstream areas. Embankments also prevented smaller local streams from draining into the larger rivers, resulting in the water-logging of fields. Praveen Singh in The colonial state, zamindars and the politics of flood control in north Bihar (1850-1945), details how a web of social and economic interests spurred on this construction spree despite warnings from irrigation engineers about the detrimental effects of embankments.

Vipul Singh also emphasizes the linkage between physical processes and cultural evolution.  A unique Bihari regional identity emerged based on the homogeneous ecology, similar agrarian practices and a shared reverence for the Ganga. 

The Ganga of the plains is a turbid river. It transports several hundred million tons of sediment to the Delta. In this section of Bihar, it is joined by the Sone from the south and the Ghaghara, the Gandak and the Kosi from the north. The Kosi and the Gandak are especially sediment rich, carrying a suspended sediment load of 80 million tons per year and 43 million tons per year respectively. All this sediment is what makes this region special. A significant fraction of it gets deposited every year in the river channel and its floodplains. Over time, the Ganga and its tributaries have built vast alluvial deposits, through which the river finds its way, often getting choked on its own sediment, and then breaking free by cutting a new path for itself. This abundance of water and sediment has formed a complex fluvial ecosystem of meandering channels, river islands, abandoned courses, oxbox lakes, ponds, and wetlands. The organic rich silt deposited across floodplains by the rivers during monsoon inundation nourishes multiple crops. Life's daily rhythms became embedded in this ecology and its inhabitants evolved farming practices adapted to the changing tune of the environment.

There was linguistic pride too, not in one common 'Bihari' language, but in the various dialects spoken 'eh /e paar' and 'oh o paar'; this side of the Ganga and on the other side. Bhojpuri was the dialect of the Champaner area north of the Ganga, while to its east on the north side was spoken Maithili. In the Patna region on the south side was Magahi and towards the east near about Munger was Angika. These vernaculars with their common folk tales, poetry, and myths about deities, changing seasons, local plants and animals, and the Ganga, knitted the region together, away from the pull of the Delhi-Agra-Awadhi influence which lay to the west and the Bengali cultural sphere towards the east.

Magh ke garmi, Jeth ke jar
Pahila pani bhar gail tar,
Ghag kahen ham hoban jogi,
Kuan ka pani dhoihen dhobi.

[Heat in Magh (January-February), cold in Jeth (May-June),and the tanks filled with the first fall of rain, are the signs of drought. Ghagh says that I will become a beggar, and the washer-men will wash with well-water.]  

This is a gem of a book. Highly recommended reading! 

Book: Indica- A Deep Natural History Of The Indian Subcontinent

I am not doing a general book review of Pranay Lal's book Indica: A Deep Natural History Of The Indian Subcontinent. For that, I recommend this fine literate piece by Pratik Kanjilal published in the Indian Express. And Prabha Chandran writes about it in the Huffington Post. Both are aimed at the general reader.

No one has, as far as I know, written critically about the science content of the book. I read through the book and have some comments on the geology.

Before I start, let me say that I enjoyed this book. Pranay Lal has read widely, traveled far, and has had immersive discussions with geologists and paleontologists.  The best sections of the book are when he is writing about the many fossil finds preserved in Indian sedimentary basins and their importance in interpreting paleo-geography, ecology and evolution. He certainly appears more comfortable writing about these themes than he is about geology.

There are many problems with the geology writing. Some are easy-to-fix errors, while others will, in my opinion, require some rethinking on the more effective presentation of ideas and processes.

Let's begin with the easy to fix errors-

1) Page 12: Ref: Structure of the earth-  "The innermost shell of the "core" was composed of iron  and nickel and was surrounded by a larger but less dense mass of molten iron called mantle". - The mantle which is the layer of the earth between the crust and the core is not molten. It is solid and is made up of silicates and not iron. The core itself has two layers, a solid inner core and an outer fluid layer made up of iron and nickel.

2) Page 13: Ref: Age of corals in Rajasthan and Kutch- " This coral colonized the seas about 380 million years ago". There are no 380 million year old sedimentary rocks in Rajasthan and Kutch (Devonian Period). This may be a typo. There are Jurassic age corals in Jaisalmer. They are about 170 million years old.

3) Page 45: Ref: Banded Iron Formations- "Both ferric iron and ferrous iron began to settle as successive bands at the bottom of the iron-rich seas and lakes as oxygen levels fluctuated. Once, deposited, the layers hardened one above the other and gave the appearance of a layered cake- thin strawberry-jam-coloured striations of highly oxidized iron (ferric oxide, Fe2O3) and dark coloured chocolate lines of less oxidized iron (ferrous oxide, FeO)" - In the vast majority of Banded Iron Formations the strawberry coloured striations are forms of silica, either chert or jasper. The dark coloured layers are hematite or magnetite ( ferric oxide Fe2O3). Ferrous iron (divalent) is usually in a dissolved state. Ferric oxides or hydroxide minerals and compounds form following oxidation of this dissolved ferrous iron. Some ferrous iron is trapped in carbonate and sulphide minerals.

4) Page 57: Ref: Coral mineralization- "When hard-bodied marine animals like corals evolved (around 2 to 1.7 billion years ago)" - Multicellular animals originated in the Neoproterozoic likely between 700 and 600 million years ago and acquired hard parts (mineral skeletons) by around 550 million years ago.

5) Page 57: Ref: Limestone formation- " ..the vast accumulation of shell and coral got pressed together into minerals like calcite and aragonite" - organisms combine Ca and CO3 ions to precipitate minerals like aragonite and calcite to build their shells. This accumulation of shells when pressed forms limestone rock.

6) Page 59: Ref: Picture of Cruziana- " This 565 million year old fossil is of Cruziana, one of the earliest multicellular animals and an ancestor of the trilobite which lived in shallow seas". Cruziana is an ichnofossil. It is a name for an impression of a particular shape made by trilobites disturbing the sediment on the sea floor (bioturbation). Cruziana is not an ancestor of the trilobite, it is evidence of the presence of trilobites. These ichnofossils from Rajasthan are in Cambrian age rocks and so have to be younger than 542 million years.

7) Page 60: Ref: Evolution of complex multicellular organisms and animals - " About 570 million years ago, a few enterprising organisms developed a new reproductive strategy - sex! Sex opened up a plethora of possibilities"  -  Sex evolved once in the unicellular eukaryote common ancestor of fungi, plants and animals more than a billion years ago. The oldest fossil evidence of a sexually reproducing multicellular organism is the protist Bangiomorpha pubescens. It is 1.2 billion years old. Preserved filaments show differential spore/gamete formation. So, sex evolved hundreds of millions of years before the evolution of animals.

8) Page 62: Ref: Animal family relationships- Comb jellies and jelly fish "evolved to become thin, pin-shaped worm like creatures with no arms or legs that wriggled on the bottom of the sea floor". The author is saying the creatures with bilateral symmetry arose from Cnetophores (comb jellies) and jelly fish (Cnidarians). Animal phylogeny reconstructed by genetic analysis shows that Cnetophores are a group which diverged from the animal family tree very early in its history. And Cnidarians and Bilaterans are sibling groups. They share a common ancestor. See this easy to understand essay by Jerry Coyne.

9) Page 154: Ref:  Bedaghat and  Makrana marble- The author says that the famous marble cliffs of Jabalpur (Bedaghat) and the Makrana marble used to build the Taj Mahal are Cretaceous in age.  He writes that Cretaceous sediment made up of calcium carbonate shells were deposited between 145 to 65 million years ago and were cooked by volcanic heat, which transformed these sediments into marble.  However, both these marble deposits are Proterozoic in age.  Calcium carbonate sediments accumulated in seas that covered Rajasthan and Central India in Proterozoic times. These deposits were then metamorphosed into marble during orogenic activity that took place during evolution of the Aravalli mountains (Makrana marble) and in Central India (Bedaghat marbles). Estimates are that deposition and metamorphism into marble took place between 2 billion to 1.5 billion years ago .

10) Page 131- Ref: Mid ocean ridges- "Deep sea trenches on the sea floor are the weakest points on the crust, made up as they are of a thin layer of rock and water above it.. " He goes on to explain that these are the spots where magma melts the crust and flows on to the surface creating new oceanic crust. Technically though, the term "deep sea trench" refers to places where tectonic plates are converging and oceanic crust is subducting underneath another tectonic plate. Lal on the other hand is describing regions where tectonic plates are spreading apart and new ocean crust is being generated. Such places are called "mid oceanic ridges".

11) Page 183: Ref:  Vivekanand rock as meeting place on Gondwana continents - "Geologists call the Vivekanand Rock memorial 'the Gondwana junction' because it marks a place where India, Madagascar, Sri Lanka, East Antarctica were once joined together". The Indian continental crust extends underneath the sea beyond the Vivekanand islet. The continental shelf edge, tens of kilometers away from the present day shoreline, is really the place where India would have been joined to Australia and Antarctica on the eastern margin and Madagascar on the western margin.

12) Page 210, 216, 222: Ref: Magma chambers in Deccan Traps- The authors points out examples of columnar jointing in basalts and calls them remnants of magma chambers. This is incorrect. Magma chambers are present several kilometers below the surface of the earth. If magma solidifies at this depth is won't be called a basalt (it will be called gabbro) and won't develop columnar jointing. These instances the author point out are either thick lava flows or volcanic plugs which have developed columnar jointing on account of cooling and shrinkage. Volcanic plugs are remnants of lava which solidifies in a volcanic vent at the surface.

13) Page 280: Ref: CO2 released by volcanism- " Most of the volume of CO2 in the atmosphere actually comes from volcanism and sea floor spreading. When sea floor spreading occurs, sediments on the ocean floor (including these shells) are dragged deep under the ocean floor where they heated and the trapped CO2 is released". At sea floor spreading centers volcanism releases CO2. Sediments and shells are dragged under the ocean floor at the other end of the plate at subduction zones. As they dive under, they get heated and release CO2.

Some longer discussions:

a) Page 18- Ore deposit formation- The author writes that collisions of meteorites during the early history of the earth up to 2.5 billion years ago kept puncturing the earth's crust releasing metals like iron from as deep as the core. These metals clumped together to form ore bodies. The early earth did go through a period of very heavy meteorite bombardment from 4.1 billion years ago up to 3. 8 known as the "Late Heavy Bombardment". Bombardment continued sporadically after that. No crust from this very early period is preserved as it kept getting smashed and recycled into the interiors. Any ore deposits that formed have also been destroyed.

The earth was much hotter then and after the easing of bombardment, intense magmatism from 3.8 billion to 2.5 billion years ago started forming the first continents. Geologists estimate that nearly 65% -70% of the present volume of the continental crust formed during this phase. The magmatism transferred metals from the mantle to the newly formed crust. 

A recent survey of  five years of research from 2011 to 2016 done by Indian geologists on ore deposits shows that not a single study invokes meteorite bombardment as the cause for ore concentration. Instead, internal forces like subduction zone magmatism, rift magmatism, hydrothermal circulation systems and near surface sedimentary processes are inferred. Now, there may be specific instances where meteorite impacts may have fractured the crust and initiated fluid circulation, but meteorite bombardment is a not a general explanation of metallogeny.

b) Chapter 7- Page 182 and subsequent pages- Pranay Lal discusses the breakup of Gondwanaland. How do continent breakup and what is the force that causes tectonic plates to move and drift for thousands of kilometer? He invokes volcanic eruptions as the cause of supercontinent breakup and the push exerted by magma upwelling through cracks as the force driving plate movement. He refers to a paper by Shanker Chatterjee and colleagues on the subject of India's epic northward journey after it broke up from Gondwana until it collided with Asia.

But an alternate view among geologists is that volcanic eruptions are the consequence of the break up of continents. And plate motion is driven not by the push of upwelling magma/lava but by the pull of cold dense lithosphere which sinks deep into the mantle at subduction zones. A perusal of the paper by Shanker Chatterjee shows that these scientists agree with this "slab pull" notion as the main force of plate motions. Mid oceanic ridge push is a secondary force. Unfortunately, the author does not even mention the slab pull force mechanism.

So, continents break up due to a variety of factors. Indeed, there could be an anomalous build up of heat underneath the continent, which thins and weakens the lithosphere (the rigid plate consisting of the crust and the upper part of the mantle). Hot buoyant mantle impinges the underside of the plate. At this point the mantle is still solid but can flow like silly putty. Continued stretching and thinning of the crust (caused by the slab pull force from a subduction zone at the other end of the plate) results in the underlying mantle decompressing. This results in the lowering of its melting point and magma generation. Magma rises through the fractures of the thinned crust and erupts on the surface.

In this view, volcanism did not prise apart fragments of Gondwanaland one by one. Rather, enormous episodes of volcanism like the Deccan Volcanic Event were triggered by rifting and Gondwana continents moving above anomalously heated portions of the mantle known as hot spots.

c) Page 261: Ref: Himalaya. Here is how Pranay Lal describes the rise of the Himalaya. "The Himalaya rose from below. The rubbing together of the immense plates and the monumental crushing and buckling of land produced a tremendous amount of heat and cause magma from below to ooze out of deep fissures which opened up on the surface. This melted and remelted granite, and pushed it upwards to the surface. As the granite slowly cooled, successive batches of molten granite thrust their way up,forcing the older granite slabs higher. Over time, this process created a pedestal for mountain building. Because the "cooking" process varied (different types of granite are cooked at various depths), the densities of rock slabs differed. This created large cracks or "faults" along places where the continental crust rasped, grinded and pushed slowly onward".

I didn't understand this at all.

Later he says that the Everest is made up of an initial four thousand odd meter foundation of granite overlain by another 3100 meter of sedimentary rock. The granite is 50-30 million years old while the sedimentary rocks are from the Paleozoic era (359 - 252 million years old).

During continental collision, there has been melting of the lower parts of the crust and this terrain has been intruded by pods and lenses of younger granite. Metamorphosed and partially melted Precambrian rock is the main component of the Greater Himalaya. In the Everest -Lhotse-Nuptsu region the granite intrusions are on a massive scale as described by Pranay Lal. These thick intrusive granite and high grade metamorphic rocks make up the base of Everest region. But, these younger granite intrusions are not this thick everywhere. They are present on a smaller scale along certain bands of the Greater Himalaya and are almost absent from the Lesser Himalaya.

Though the author may not mean it, phrases like "successive batches of molten granite thrust their way up, forcing the older granite slabs higher" may be misinterpreted by lay readers to mean that Himalayas formed as a result of magma pushing the crust up to form mountains. This is not how orogenic mountains like the Himalaya form.

As the Indian Plate collided with Asia it delaminated. You can think of this as the plate splitting into two tiers. The lower tier comprising the lower crust and upper mantle slid under Tibet. The upper tier impinged into Tibet and got squeezed, deformed and thickened. The Himalaya is this folded and faulted upper tier. The different Himalayan ranges are slices of the upper tier Indian crust stacked one on top of the other by a series of south moving thrust faults.

 The tectonic structure of the Himalaya with its geological divisions is summarized in the graphic below.

Source: Shankar Chatterjee et. al. 2013

What was the sequence of these thrust faulting events and how do they fit into the three pulses of mountain building that Pranay Lal mentions?  

Leaving the Tibet part aside, the Himalaya most people are familiar with are made up of four distinct geological terrains. I am listing them starting from the north and going south.  Tethyan sedimentary rocks (the ones making up the Everest and many other summits; These sediments  range in age from the Neoproterozoic to the Eocene- ~ 1000 million years to 40 million years, although the entire sequence is not exposed at one place), the Greater Himalaya Crystalline Complex (Proterozoic to Early Paleozoic, 1800 million years to 480 million years, with a younger imprint of metamorphism and granite intrusions), the Lesser Himalaya Sequence (Proterozoic to Cambrian; gneiss and low grade metamorphosed sediments, 1850 million years to 520 million years) and the Siwaliks which are Cenozoic sedimentary rocks deposited from around 15 million years to about 0.5 million year ago. The geological divisions roughly match up with the topographic divisions of the Greater Himalaya, the Lesser or Middle Himalaya and the Outer or Sub Himalaya.

The northern edge of the Indian plate was made up of  Proterozoic rocks, much as it is all across Peninsular India. This Proterozoic sequence was overlain by Paleozoic and Mesozoic sedimentary rocks. There is a more complete sequence of Paleozoic sediments in the Himalaya, since even though most of India was landlocked as part of Gondwanaland, the north edge of what was to become India was open to the Tethys sea all through the Paleozoic and Mesozoic.

As India collided with Asia:

1) Its continental crust impinged on the continental crust of Asia. The Neoproterozoic-Phanerozoic sedimentary cover was folded, faulted and scraped off and uplifted to form an early mountain range made up of the Tethyan sediments.

2) Horizontal shortening of the Indian crust during collision led to crustal thickening and rocks were subjected to high temperatures and pressures. They were metamorposed and partially melted into rocks known as migmatites and intruded by granites. Finally, compressive stresses broke the crust along a major fault known as the Main Central Thrust and uplifted this deeply buried terrain. The thrust moved crustal blocks upwards and southwards. Some geologists believe that the Great Himalaya Crystalline Complex is made up of hot soft rocks from the middle regions of the Indian crust which flowed towards the surface in response to the removal of  crustal cover by erosion. This ductile flow of rock from deep in the crust towards the surface is termed "channel flow" as hot soft rock is confined to a layer or channel between colder upper crust and a more rigid upper mantle.

Either way, with this thrusting and extrusion of high grade rock began the formation of the Greater Himalaya. The main activity of the Main Central Thrust is dated to between 16 million years to 25 million years or so. At about the same time the earlier uplifted Tethyan sediment detached themselves from the underlying crystalline basement and started sliding northwards along a major fault system known as the Southern Tibetan Detachment System.

3) As India continued to press into Asia, compressive stresses propagated southwards. Beginning around 16 million years to 11 million years, the terrain to the south of the Main Central Thrust began to get folded and faulted. Since it was further to the south from the collision zone, it did not experience the high levels of metamorphism and granite intrusions that the rocks of the Great Himalaya did. Eventually, these more distal rock formations were uplifted and moved southwards along the Main Boundary Thrust and associated faults to form the Lesser Himalaya.

4) The rise of the Greater Himalaya and the Lesser Himalaya loaded and depressed the crust in front of them in to a moat. In the alluvial plains, streams and lakes that formed were deposited sediments eroding from the rising Greater and Lesser Himalaya. These were the environments in which a lot of the mammalian evolution and diversification described in an earlier chapter took place. Beginning around a million years ago, maybe a little earlier, these sediments were folded, uplifted and thrust above the Gangetic alluvium along the Main Frontal Thrust to form the Siwalik ranges. The Main Frontal Thrust is still active, and Himalaya earthquakes which originate deep underground rupture along this fault plane. The Himalaya are growing southwards.

I am not writing a popular book for the lay public.  I realize I may have gone overboard with my Himalaya explanation and am not suggesting that Pranay Lal should include all this in his book. But any explanation should include at least the basic arrangement of the different lithologic terrains and their sequential uplift due to south progressing thrust faulting.

d)  Page 218 - Ref: Satpura mountains were uplifted due to the rise and push of magma leading up to the Deccan volcanism.- This is also a longer discussion but I'll stop on the geology aspects since this post is already too long. Let me refer to an article on the lack of pre- Deccan volcanic uplift in the Satpura region and elsewhere.  Many geologists have concluded that the uplift of the Satpura belt is not due to the push of magma. It occurred much later in the Cenozoic due to the various stresses on the Peninusular Indian crust.

e) I couldn't help elaborating on this:  Why do animals grow large? Pranay Lal mentions an intriguing evolutionary pattern seen in the fossil record. There is a trend towards an increase in body size in the early to mid Triassic following the Permian mass extinction. A second trend in increase in body size in seen in the Cretaceous when some lineages of dinosaurs evolved gigantism. The explanation given is that an increase in atmospheric oxygen levels favored an increase in body size.

Animals have a physiologically demanding lifestyle. That a certain threshold of oxygen will be required for them to prosper over the longer term is a given. It is too broad an explanation and it doesn't tell us why in a group one lineage evolved towards a larger size while a related lineage did not. In the two time periods that author points to, the reason why species evolved towards large size in the Triassic immediately after the Perman mass extinction may be different from why certain lineages evolved gigantism in the Cretaceous.

Let's take the case of body size trends during the early Triassic. Mass extinctions disproportionately cull larger bodied species . Since environmental condition are deteriorating rapidly, larger bodied species with  more energy expensive demands and slower reproduction rates cannot cope as well as species with a smaller body size. Survivor species in the aftermath of mass extinctions are small bodied, maybe as small as their biological limits. From this starting point, even if environmental conditions in the post mass extinction period are neutral in terms of favoring species with a particular body size, the only trend that will emerge is one towards a larger body size, since there is no room to get any smaller.

For Cretaceous too the oxygen hypothesis seems too pat. I could argue that Cretaceous was a time of high carbon dioxide levels. That would mean more food for plants. A lush healthy vegetated landscape means more food for herbivores, conditions favorable for evolution of larger size. Again this is a "just so story". Why did gigantism evolve in the Sauropoda? The answers may lie in phylogenetic heritage i.e. inheritance of ancestral characters which fortuitously proved advantageous, and evolutionary innovations that enabled them to acquire and utilize resources more efficiently than other groups. An avian style respiratory system enabled pnematization (air cavities in bones) of the axial skeleton. This evolved early in Sauropod history. A small head evolved because food was ingested without mastication. These two features enable a long neck to evolve (lighter head, lighter skeleton). A long neck enabled access to food not available to other herbivores.. a cascade of benefits due to inherited and newly acquired features.

Off course, these are ramblings about things that interest me. I have no expectation that Pranay Lal put all these details in his book.  

But, we need books like these to fire imaginations and inspire amateurs and students to go out and explore India's rich physical landscape. A good place to start will be the National Geological Monuments listed by the Geological Survey of India. A surge of visitor interest might put pressure on the government to expand protection to more sites of interest. The destruction of irreplaceable fossil sites and geological structures is a constant theme in Lal's book.

A second edition of this book will be welcome, but one that has gone scrutiny by a discerning geologist editor.

Quote: John Dewey On The Armchair Geologist

John Dewey in his review of Colliding Continents - a book about the geological evolution of the Himalayas by Mike Searle has these harsh words-

Reading a book like this makes one realise how shallow and limiting is the pseudo-geology done by those who sit in front of their computers composing drivel. As Francis Pettijohn remarked, ‘the truth resides in the rocks’ and that ‘there is nothing as sobering as an outcrop’. This work is a useful lesson to those who are not prepared to sweat and get tired and dirty and try to find out the message of the rocks.

Hard to argue against - but computer modeling when the inputs are acquired through hard fieldwork is a powerful tool to understand geological processes. John Dewey refers to the idea of middle crustal extrusion in Himalayan mountain building. This idea suggests that the rocks making up the High Himalayan Crystalline Series were initially a weak viscous middle crustal layer sandwiched between a strong upper crust and a strong mantle. These soft crustal rocks formed during the India-Asia collision and then were squeezed southwards and as denudation started removing the upper crust were extruded i.e. brought to the surface from underneath Tibet. This idea to be refined and to mature has required all possible ways of understanding the earth- fieldwork, high tech geochemistry, geophysical survey and .. yes... the computer geek... doing mathematical modelling.

Mountains Of Saint Francis - Walter Alvarez

A certain type of travel book or TV show on Italy features the adventurer driving through sun dappled rolling hills and winding narrow roads to a picturesque village in search of that one undiscovered Trattoria not featured in similar other books or TV shows. Walter Alvarez though refreshingly keeps driving past these rustic eating places to an old quarry just beyond the village. There, he begins poking around in the rocks in an attempt to unravel their secrets.

Walter Alvarez is quite a famous geologist. He was one of the proponents of the theory that a meteorite impact precipitated a mass extinction 65 million years ago, an idea that is now amply supported by evidence.  He has written a story about that discovery in T Rex And The Crater Of Doom (dinosaurs were the most famous casualty of this event). He has had a long professional relationship with Italian geologists and he uses the Italian rock record to explain the methods and basic principals used by geologists in this enjoyable book The Mountains Of Saint Francis: Discovering The Geologic Events That Shaped Our Earth. 

The Mountains of Saint Francis (after Francis of Assisi) is Alvarez's name for the Apennine mountains of the Tuscany and Umbria region and this books explains step by step how they came to be. Throughout the Mesozoic until mid Cenozoic, what is now Italy, was a promontory of the African continent sticking out like a north pointing thumb into the sea of Tethys that separated Africa and Europe. An enormous pile of mostly limestone accumulated on this submerged promontory. These Jurassic to mid Cenozoic limestones form the building block of the Apennine mountains. They stand spectacularly exposed in road cuts and cliffs and have attracted the attention of geologists from all over the world.  As a result, the Apennine rock exposures along with younger Pleistocene deposits have become some of the best studied strata in the world. They not only tell us about local geological evolution, but have provided key insights to answer some broad geological questions.

A New Book On The Geological Evolution Of India

In the latest issue of Current Science, C.P. Rajendran reviews a new book by K. S. Valdiya on the geological evolution of India titled: The Making of India: Geodynamic Evolution.

Prof. K.S. Valdiya has reached a stage in his career where the term "Grand Old Man of Indian Geology" is an entirely appropriate title for him. His deep expertise lies in the geology of the Himalayan mountain chain, but this book is a broader synthesis from Archean times to recent.

I have to admit I found earlier books which synthesized Indian geology in one volume quite disappointing and the review mentions a couple of them. They rambled on and on about formation names and local lithology types and fossils. Written in the days before plate tectonics and geophysical data about the Indian subsurface, the approach was descriptive or one that relied on concepts and terminology that was no longer part of current thinking.

Plate tectonics started appearing in geology textbooks by the early mid 1970's. I graduated in the late 1980's. That there was no textbook which discussed Indian geology within the framework of global plate tectonics more than a decade on is a telling reminder of how slow educational content has been in catching up with the latest developments in the field. Going by C.P. Rajendran's review there was still until 2010 no textbook incorporating all this essential content!

Forty years on, looks like this book will remove that lacuna.

Price is Rs 242/- ( ~$ 5/-) for a 816 page book, courtesy a generous subsidy from the Indian government. It is not yet listed on Amazon and likewise other online sellers. You might have to order it from the publishers Macmillan Publishers India Ltd.

Multitasking In 1800's India

I had to share this.

I am reading The Ruling Caste: Imperial Lives in the Victorian Raj by David Gilmour. It's an account of the day to day lives of British Civil Servants as they went about their administrative duties in 1800's India. The District Collector was one of the key positions - as it is today- and the Collector besides his responsibility as a revenue officer was also a Magistrate who heard cases and imposed fines up to Rs 1000/- and sentences of up to 2 years:

The Collector and the Magistrate had many different functions, but for his main two he also possessed different personas. He had separate offices for them , staffed by separate sets of clerks who enjoyed acrimonious correspondence with each other. One District Officer "used to find drafts of letters from myself as Magistrate to myself as Collector accusing myself of neglect and delay, and some very trenchant replies placed before me for signature".

Among the many responsibilities and expertise the Collector had to acquire was an ability to understand landscapes and read maps. Assessing property holdings and estimating tax was a tricky task and the land holdings were drawn on enormous pieces of linen with parcels shown at a scale 1 mile to 63 inches! That means over 5 feet of cloth was used to depict one mile of the earth.

These were local maps covering only one village and surrounding area and showing only property holdings. A much larger mapping effort to produce a seamless tapestry of the Indian landscape- also initiated by British geologists and surveyors- was going on in the 1800's, one that very carefully was measuring the lay of the land and producing a triangulation network which later survey projects used as the basis for generating topographic maps on a scale of 1 inch to 1 mile. That effort is described in The Great Arc by John Keay. It is an absorbing and startling account of a mapping project that lasted half a century and produced the baseline landscape information that were then used for additional survey, building roads, canals and railways.

Indians reading the Ruling Caste might feel that the book is perhaps too sympathetic towards the officers of the Civil Service. They were after all men carrying out the orders of a colonial exploitative regime. But the job was a genuinely tough one. A person with no experience of India at age 23 was suddenly given charge of as many as 2 million people. An Officer could be stuck at a remote station with no correspondence with headquarters for weeks. Decisions had to be made on the spot that could influence the lives of thousands.

The Civil officers or "Civilians" were always outsiders amongst what seemed a strange and bewildering people, yearning for "Home" and waiting eagerly for Furlough ( a two year sabbatical in England). But tragically they were strangers too when they went back to England on retirement. Most of them missed India on their return to England, missed the outdoor life and the responsibilty of office and the servants- in-waiting. And after a 30 year career they found that people in England regarded them to be bores too eager to tell India stories and completely out of touch with contemporary England society.

Rudyard Kipling famous for his evocative descriptions of the Raj despaired on being confronted with the dreary London sky-

It's Oh to see the morn ablaze

Above the mango-tope

When homeward through the dewy cane

The little jackels lope.

And half Bengal heaves into view,

New-washed - with sunlight soap.

If you read this book as a human interest story you will find it rewarding.

See: My Book Shelf

Men Are From Mars Women Are.....

Maybe, but I like this description of sex differences too:

Some would deny there is a deep difference. Some would psychobabble about a nurturant sex and a competitive sex. Geneticists would point to the XX and XY chromosomes, economists to the relative parental investments in offspring, veterinary students (and others who go around peering between animal legs) to the shape of the creatures genitals. Freudians, fundamentalists and sexual politicians could add their own ideas.

But from the perspective of organelle conflict, all these criteria (in so far as they are valid) are superficial. They specify things that derive from the deepest of the sex differences. Sex chromosomes, genital shape, reproductive investment and perhaps even personality all arguably follow from the resolved conflict of the organelles. The deep nature of maleness is to eject organelles from reproductive cells; the deep nature of females is to keep them.

Great! Males throw stuff out, females like to collect things. Didn't we all know that! These days I am in a mood for reaching out for a book from my shelf and rereading a passage or two. This one is from Mark Ridley's The Cooperative Gene. I highly recommend the book. It makes you think about the deep general features that all multicellular life share.

One of these features is anisogamy which is sexual reproduction involving reproductive cells or gametes of unequal size. The evolution of the eukaryotic cell initiated through a merger of two bacterial cells over a billion years ago made complex life possible, but the merger came with its own baggage, literally. The merged cell had two independent genomes. This was a situation with a potential for conflict between the two genomes. One analogy that helps is to think of a corporate merger which creates two independent management teams. It won't work. They will start undermining each other. One team has to go or turn submissive.

Evolution changed the eukaryotic cell through such mechanisms. Over time one genome ceded control by transferring most of its genes over to the other genome. This cell with the smaller genome evolved into the organelles; mitochondria (and chloroplasts). Human mitochondria have 37 genes. Ancestral mitochondria probably had 2500 genes a figure typical of bacteria. So over 98 percent of mitochondrial genes have been transferred or lost during evolution. Transfer of genes was one solution to genomic conflict. But sexual reproduction created another problem. It brought together two sets of the remaining organelle genes in one cell after fertilization. So the problem of organelle genomic conflict remained.

The evolutionary solution was for one type of reproductive cell to eject its organelles before fusing with the other type. The ejector gamete became the smaller sized sperm and the gametes which kept its organelles became the eggs. Ridley argues that sex differences follow from this great fundamental divergence.

Evolution is a quirky process. The specific evolutionary pathway taken by lineages is contingent upon historical and developmental constraints. Evolution develops one on one solutions to changing ecological pressures. But early in the history of multicellularity, the biggest limiting factor was within.

Sexual reproduction, gender and meiosis were evolution's across the board general solutions that enabled life to cross a threshold of complexity. You can think of this as the evolution of evolvability. I like big themes like the one presented in the book. This is a very readable account of various types of genomic conflicts and the ingenious devices that evolved through natural selection that minimized conflict.

I mean who would have thought that the evolution of gender helped resolve a conflict :-)

Is there a lesson here for humanity? Sure, and here is my prescription for harmonious relations between men and women. Let women keep all the stuff they want. Men, don't to try to argue, cajole, plead, sulk or throw a tantrum. It won't help. Females are good at keeping things. They have had a lot of practice. They have been doing it for more than a billion years.

Walking On A Jurassic Outcrop

I am rereading a couple of chapters from Simon Winchester's book The Map That Changed The World. It is the story of William Smith a canal digger by profession who embarked in the late 1700's and early 1800's on a pioneering and ultimately heroic effort to map the geology of England. In the chapter entitled A Jurassic Interlude I came across the following passage:

The general line of their outcrop, which extends all the way north from Dorset to the Humber in Yorkshire, some two hundred miles, is one of the great dividing lines of world geology, once seen, never forgotten. Around Bath, close to where a northbound traveler like me today, Smith two centuries before me, first came across it, it is stupendously memorable.

On the western side of the line are the timid, milquetoast clays and weakling shales of the Lias, of the Lower Jurassic; on the eastern side are the tough, thick oolitic limestones of the Middle Jurassic. On the western side the consequential scenery all is valley and marsh, river course and water meadow, lowing cattle and in high summer, a sticky, sultry heat. On the eastern side, underpinned by the limestones, everything has changed: there is upland plain and moor, high hills, high wind and flocks of sheep, and in winter fine white snows blowing on what can seem an endless and treeless expanse.

And on the very line itself, at the point where England has tipped itself up gracefully to expose the limestones at its core and to reveal the huge physical contrast between the hardness and the silky softness of the Lias clays below, is a long, high range of hills and cliffs. The line is, for the most part, an escarpment edge that rolls far to the horizon, separating vales and downlands, from high plains and uplands.

It is a wonderful piece of writing and not just because it invokes images of a bucolic England. Here is yet another example of the pervasive influence of geology and geological processes on livelihoods and human economies.

In the Jurassic depositional basins of England there was a lateral facies variation from clays being deposited to the west changing to carbonate sediments to the east. As these sediments turned into rock they acquired different physical properties. The carbonates i.e. the Jurassic oolite became hardened through the precipitation of copious amounts of calcite cement in its abundant pore spaces. That cement bound the initially loose oolite particles together and transformed the sediment into hard rock. The clays which were very fine grained were not cemented into toughness. Instead they were compressed into rock but remained relatively soft.

Over time these two different rocks types got exposed to the elements and were weathered and eroded at different rates. The clay bearing rocks were softer and formed valleys and lowlands with moist organic rich soils, the hard limestones formed hills, escarpments and highlands with poorer soils. An agricultural diary economy developed on the serene clay lowlands, while a pastoral sheep economy developed on the harsher windier limestone highlands.

In my previous post I wrote about the effect of aquifer yield in basalt provinces and their control on farmer poverty. That post was the first of a thread that I have continued here and plan to write on from time to time. Geology and livelihoods. I like making this connection. It is an under appreciated theme. People always nod in agreement when oil and gas and the mining industry is mentioned. It is not hard to make that connection between geology and economy. But facies change, diagenesis, weathering and rural economies? That usually takes a while to sink in.

Immigrating to America

A couple of days ago I finished reading The Eternal Frontier: An Ecological History of North America And Its Peoples by Tim Flannery, the Australian mammal expert and ecologist. I really enjoyed the book. It is written on an epic scale covering the natural history of the continent over last 65 millions years. The earth went through a rapid period of reorganization of its terrestrial and marine ecosystems following a mass extinction and Flannery chooses that event to begin his exploration. Covering 65 million years in 300 odd pages means that the book moves along at a fairly brisk pace but I thought Flannery has done an exceptionally skillful job of identifying the higher level geological and climatic controls on the transformation of North America over this period. This gives the book a well defined framework within which to think through the ecologic, bio geographic and evolutionary patterns exhibited by the continents fauna and flora. Cultural patterns too as Flannery devotes the last segment to the arrival of humans and their considerable impact on the terrestrial and marine biosphere.

North America at various times over the past 65 million years has been attached to Asia and Europe through land "bridges". That has enabled it to be the land of immigrants as mammalian groups of Asian and European stock made their way into the continent and evolved a unique north American characteristic over time. This has mostly been a one way traffic, of all the modern placental mammals, only camels, horses and dogs are north American exports of ancient pedegree. Apparently, no one wants to leave once inside the continent and Flannery sees a continuity in the immigration patterns of another mammal - Homo sapiens. Since I am not a vertebrate paleontologist or a mammal expert, I liked the part of the book that dealt with human arrival and impact more than some of the early pre-human history. The modern north American ecosystems have been rendered depauperate of mammalian megafauna and other animal and plant groups and Flannery gives ample evidence in the form of timings of extinctions and some ingenious research on mammoth tusks that it has been mostly human influence and not climatic changes that is to blame. The book deals with big themes, extinction, migration and evolutionary adaptation of groups of organisms over large periods of time, but I found enough small details and asides that weave through the narrative and makes reading a pleasure in the first place. Details that you can ruminate over, those that suddenly crystallize some nebulous ideas and thoughts you have. You also now possess some fodder to impress friends over coffee. Why is cactus common in the Sonaran desert of Arizona and not in the Australian desert? Answer: Even if scant, the plant does needs predictable rainfall and nutritious soil. The Australian desert is bereft of either. Why did the field of vertebrate paleontology develop to the extent it did in the U.S and not in Canada? Answer: The ice age glaciers covering large expanses of Canada but not the U.S. ground up literally to dust the sediment cover and entombed fossils. The Canadians had little to work with. And this gem: The key to the bison's role in the prairie ecosystem lay in the fact that the great grassland were piss-driven. Buffalo urine fertilized the grasslands!

Flannery is pretty severe on the human propensity and ability to devastate the environment and treat fellow human beings with astonishing intolerance. He has a lot to say about the relationship of native Indians and the Europeans. The conflicts and wars were known to me, but I learnt something new in his explanation on the different approaches taken by the Spanish, French and English settlers. The Spanish came as a state and having defeated the incumbent Indian state, simply took over possession of state property. They never worked the land themselves, but collected taxes and used labor just as the native Indian chiefs had done. This though limited their influence over only the captured property and not much beyond. The French came as fur traders and developed a sort of a business relationship with the Indians. This meant they had to maintain good relations with the Indians. Grabbing land was self-defeating as they had to rely on the Indians for sources of fur and other goods. The English though came either as Puritan rebels with a belief that this was the chosen land, or as commerical expansionists, who saw Indians are competitors for the rich soil and resources they craved for. Winning land became an all consuming goal and the eventual victory handed them the biggest share of the continent.

Flannery identifies three phases of human occupation in North America. A pioneer phase, a period of ecologic release and finally adaptation. According to him much of North America is still stuck in the second phase, one in which people are living as if on the frontier, appropriating resources with scant regard to the consequences. Adaptation, where one learns to live within the constraints imposed by the environment is slow in coming. It's hard to disagree with the general tone of this argument, but humans do have an ability to reinvent themselves, none more so than North Americans and change is slowly coming. Two recent news items caught my eye that gives me some hope. Plans are afoot to restore part of the great plains prairie, the vast sea of grasslands that was home to the great buffalo herds of the past. And yesterday came the news that Florida is planning to acquire several thousand hectares of land from sugar companies and revert in back into a marshland, connecting Lake Okeechobee to the southern everglades national park. This won't transform the landscape to a pre-human form, for the prairie and the everglades have themselves been forged by early human activity. There is a radical remedy proposed in the book to correct that too, namely the re-introduction of fauna which disappeared from North America 13,000 to 10,000 years ago. Let lions, camels and peccaries roam again on reserve lands. This may make ecologic sense, but just take notice of the vociferous objections by ranchers to the re-introduction of one carnivore species, the wolf, in Yellowstone and I have doubts about anything more ambitious being put into action in the foreeable future. As managers of the biosphere we need to find a compromise between development and bringing reserve areas back to an acceptable state of "pristineness", and these two experiments on the prairie and the everglades look promising.

This is a cracking good book. Go get it.