Landscapes: Sunderdunga Valley Kumaon Himalaya

In mid November, I explored the Sunderdunga valley in the Kumaon region of Uttarakhand. It was a good rigorous walk through some extraordinarily beautiful landscapes. This area is better known for the famous Pindari Glacier trek. Kafni Glacier is another option for trekkers. All three routes begin at village Khati. The picture taken of the high ranges from nearby Dhakori shows the three glacial valleys.

And here are some more photos of the route with a brief commentary.

The entrance to Sunderdunga valley with the vigorous Sunderdunga river flowing through.

The first day walk to Jatoli village was through golden and green forests.

Village Jatoli in the mid November sun. We stayed there overnight at the Kumaon Mandal tourist guesthouse. They provide excellent clean accommodation. 

About 4 km walk upstream from Jatoli the next day and the land cover changes abruptly. The forest is gone. There is no marked trail from here on and a walk over a rugged boulder strewn region begins. 

We navigate our way over steeply dipping metamorphic rocks and scree cones. 

Numerous rock falls make for tricky passages. You can spot my companions climbing their way up the steep slope. 

After slogging for about 8 km through this terrain we arrive at Kathaliya, situated at about 10,500 feet ASL. We have climbed about 2500 feet from Jatoli to Kathaliya. A small trekkers shed has been constructed here. We stayed there for the next couple of days. 

Next morning, ahead of Kathaliya camp, we encountered the full glory of Sunderdunga valley. Here, it is a occupied by a wide boulder strewn river bed with several small active channels. The earthy colors of rock and grass were in stunning contrast to the blue sky. A solitary shepherd's hut can been seen in the lower right. 

Another view of the valley.

Boulder bed! The surrounding Greater Himalaya are made up of high grade metamorphic rocks. You can spot quartzo- feldspathic gneiss, amphibolite gneiss, mica schist and gneiss, and mica, garnet, and kyanite bearing schist and gneiss in the river bed. Quite a treat to walk along this metamorphic treasure! 

 Crossing the wider channels on rickety wooden bridges was fun! 

Here we are near Maiktoli Top, a high vantage point. Jagdish Bisht, me, Ratan Singh Danu, Lucky, and Kapil. They made my trip safe, comfortable, and memorable.

Why I go to these places. A clear view of the bands of metamorphic rocks exposed along the spectacular cliff face of the Sunderdunga ridge!

 

Village Khati is such a pretty place.

The high bare peaks in the background speak of a worrying trend. Everyone I talked to told me that this trek would have been impossible a few years ago in mid November. The upper part of the valley and the rocky ridges would have been blanketed in a thick snow pack. This area still had not received a single snowfall when I left on 22nd November. The two or three big snowfalls of the year now occur mostly in January and February. The pastoral and agriculture economy depends on a healthy winter snow cover to rejuvenate the high meadows, and to replenish springs and streams.

My guide tells me that Sunderdunga valley is the tougher route amongst the three treks to the nearby glaciers. I am so glad I walked this valley!

Darwin's House Plants, Water Diviners, Geology Podcast

 A couple of good articles and a geology podcast.

1) “Spontaneous Revolutions” Darwin’s Diagrams of Plant Movement: Darwin's unbounded curiosity for nature led him down many unexpected research pathways. Towards the end of his long career, his restless mind noticed the growth patterns of his house plants. Determined to understand more about their motion and the stimuli, he spent hours tracking tendrils grow and came up with innovative ways to record their movements on paper. Natalie Lawrence has written a lovely essay on this lesser known chapter of Darwin's life and work. 

2) Trust, cost go greater depths to sustain unscientific water divining practice: Large swaths of Indian agriculture is desperately dependent on access to groundwater. Simrin Sirur explores the reliance on water diviners in south India. Diviners use sticks, coppers tongs, coconuts, magnetic compass, and chains with keys as their instruments for sensing groundwater. Despite all this unscientific baggage, many diviners are not all that ignorant. They have a knowledge of the local landscape and groundwater availability. Their prediction relies more on their past experience and a dollop of common sense. 

I must tell you about my experience with a diviner. My neighbor requested that I accompany her to a plot of land outside Pune. She had hired a diviner to help her locate groundwater. We picked him up en route. He was the late Pandit Bhimsen Joshi's son! On reaching my friend's property he got to work with copper tongs. After a few minutes of walking  up and down the site the copper tongs started shaking. He indicated the spot to drill and suggested going down to a depth of 150 feet. On the way back he cheerfully told us that he knew that the adjacent plot owner had struck water at 150 feet. Past experience and common sense go a long way! 

3) Geology Bites Podcast:  Conversations with Geologists: Oliver Strimpel has had quite an unusual career beginning with a doctoral degree in astrophysics. He later became the director of the Computer Museum in Boston and then a patent attorney. But geology beckoned him. He has worked alongside geology researchers trying to date rocks and unravel the timing of movement of the Karkoram fault in Ladakh. Geology Bites grew out of his passion for the subject. You will find a wide range of geology topics discussed on this site. 

I have so far listened to experts talk about radioactive waste disposal, continental crust composition, the inherent bias in the global sedimentary record, and on the evolution of minerals through geologic time. All have been excellent. The talks are about half hour, so they don't tax your patience too much. 

If you have free time coming up this Diwali, I recommend you dive into this collection of geology talks.

The Garden Of Ediacara

I came across this lovely evocative passage in Nick Lane's book Transformer: The Deep Chemistry of Life and Death.

"You are not completely spineless. You have a notochord: a flexible rod made of cartilage, which in your descendant, millions of generations hence, will develop into a proper backbone. For now, you flex your rod like an eel to undulate through the water, never quite fast enough. Better to stay submerged in the soft mud at the bottom, with only your head visible, while you filter out grains of food from the swell. You have a wormlike head, with a small bulging of nerves that will one day become your brain. Your eyes aren't much use, but at least you can make out the looming of a monster, and swiftly bury your head again. Oh, times have changed. Not long ago, the world was full of gently filter feeders, swaying their fronds softly in unison, never harming a soul. Not that you remember, except in some hazy instinctive yearning for the garden of Ediacara. But now there are vast armour-plated war machines, bristling with claws and spikes and rows upon rows of crystalline eye facets fixing you from every dimension. You are a tender morsel, barely a couple of inches long, protein-rich muscle strapped to a crispy rod; a tasty snack for Anomalocaris. Better pull in your head again, just in case- being a little bit spineless might help you survive in this fearsome new world, outnumbered a thousand to one by spiny monsters".

The passage describes the early Cambrian world (540-510 million years ago) which saw the rapid diversification of the animal biosphere. The ancestors of vertebrates had worm like bodies, and Anomalocaris, an early arthropod, was top predator. Much before, the garden of Ediacara was a very different place. Complex multicellular life appears in the fossil record from about 570 million years ago in the Ediacaran Period. These creatures were sessile (fixed to the sea floor) filter feeders with body shapes resembling large leaves and fronds. Evidence of mobile animals manifests by 550 million years ago. Their tracks, trails, and burrows are preserved in soft sediment.

The graphic shows this  'Edicaran biota', a term that includes a diverse and unrelated groups of organisms. Three distinct phases, termed Avalon, White Sea, and Nama,  showing different community assemblages and increasing ecologic specialization are recognizable through the Ediacaran Period. Notice that mobile bilateral creatures first appear in the White Sea (B) assemblage. 

 Source: Rebecca Eden, Andrea Manica, Emily G. Mitchell: Plos Biology 2022.

Later in the chapter Nick Lane elaborates on how many of these Ediacaran filter feeders, simpler creatures without specialized tissues for different functions,  could not cope with the anoxic sulpur rich environments and died out. Sponges notably did survive. Mobile animals though had evolved a rudimentary circulatory system and molecules like myoglobin and haemoglobin, capable of storing oxygen and removing carbon dioxide. When oxygen levels increased in the Cambrian their descendants had metabolic machinery to take advantage of this high-octane environment. The radiation of animals utterly transformed our world. 

I highly recommend this book. It has a fair bit of chemistry in it. Nick Lane explains much of it using easier to follow diagrams instead of the dreaded chemical equations of our college years. He is a firm advocate of the metabolism first (as against a RNA/genes first) view of the origin of life and provides elegant explanations of energy flow and the evolution of metabolic pathways that build organic molecules to form biomass and breaks them up to power respiration. Disease and ageing is the inevitable consequence of the eventual degradation of these metabolic reactions. 

At the heart of all this is the Kreb's cycle, a series of reactions which burn sugars in oxygen to generate energy for cellular functions. But the surprise is that much of life can get by with only a partial Kreb's cycle. In many microbes, it is not a cycle at all, but a short linear path. Not at all what our biochemistry book taught us and a lesson for creationists who insist that systems like the Kreb's Cycle are irreducible complex, a sign of intelligent design, which could not have evolved through incremental steps.

Nick Lane- Transformer: The Deep Chemistry of Life and Death.

Dr. V.V. Peshwa, Geologist Extraordinaire, 1939-2024

My Guruji, Dr. V. V. Peshwa passed away on August 27, 2024. He was my thesis advisor during my Master's education in Pune. His career as a faculty with the Department of Geology, Pune University (now Savitribai Phule Pune University), was full of distinction and dedication to the noble cause of teaching. Field geology, remote sensing, and mineralogy. He had a mastery over these subjects and taught them with extraordinary clarity. His lectures on mineral optics, delivered without the aid of notes, remain some of the most lucid explanations I have heard on any aspects of geology.  

Dr. Peshwa also set up the remote sensing lab at Pune University in the early 1970's,  having received a specialized Master's degree from the Netherlands. Over the years he amassed a vast collection of aerial photographs and satellite imagery of Indian landscapes, teaching with great panache the fine skills of image interpretation. He was a formidable researcher too, with publications in igneous and metamorphic petrology, remote sensing of the Deccan Basalts and Proterozoic sedimentary basins, and on geohazards. 

I will recount two incidents from my association with him. I had to choose a thesis guide at the end of my first year of Master's course at Pune. I asked Dr. Peshwa if he was willing to be my guide. As was his style, he promptly said no! I was unsure how to persuade him, but fortunately my senior, Anand Kale, came up with a brilliant plan. I was told to sit on a chair outside his room and poke my head inside every few minutes until he said yes. I agreed, and like a security guard sat outside his room all morning. Towards early afternoon Dr. Peshwa had given up trying to ignore this motionless sentry outside his door and agreed to my request, but on one condition. I had to go and map an area in Andhra Pradesh in the Cuddapah Basin.  He had some aerial photos of this place and wanted someone to study a fold structure that was spectacularly exposed near Nandyal town. The imagery below is from ISRO Cartosat.

Folded Cuddapah Group and Kurnool Group sediments south of Gani.

Dr. Peshwa accompanied me during my second trip to the field area. It was mid January and one early morning we set off to the low range of hills, about an hour walk from where we were staying. We worked till the afternoon, and by around 3 pm decided to call it a day. We were running out of water and were famished. We thought we should walk to the next village which was just 15 minutes away, have a snack and then turn back to our camp in Gani village. To our surprise every shop in the village was closed. Dejectedly we started walking to Gani. After a while we spotted a man on a bicycle coming in our direction. We recognized him as a shopkeeper from Gani. He stopped and explained that it was the auspicious day of Pongal and everything was closed. He slipped his hand into a bag and gave us two round dry buns to eat and cycled away. We tried to bite into them, but they was rock hard, harder than the Cuddapah quartzites we were trying to break with a hammer. We collapsed with laughter and trudged along, where our host was waiting for us with a hot sumptuous meal! 

For all his exuberance and light heartedness, Dr. Peshwa never compromised on the quality of work he expected from his students. He supervised with an eagle eye my petrographic analysis, read every word of my thesis, and even sent me back to the library because he thought my literature search was not exhaustive enough. He gave me full independence to follow my interest in carbonate sedimentology, but cautioned me to remain within the bounds of data. He did not like grand theorizing or explanations by 'arm waving'. Some might call him conservative, but it made us into careful researchers, and brought a rigor to our work. 

He remained active in geology long after his retirement, accompanying younger faculty and students to the field and acting as their mentor and advisor. I live near his house and used to stop by once in a while for a chai and long conversations about geology. He will be missed greatly. The picture below shows Dr. Peshwa, seated center, on his 80th birthday.

Now, only all those memories remain to serve as inspiration and to help us stay true to what the rocks are telling us.

Jyotirao Phule On Watershed Management

Jyotirao Phule (1827-1890) was a social reformer from Maharashtra who worked for the emancipation of the lower castes and for improving the lives of peasant agriculturists. In Shetkaryacha Asud (The Cultivator's Whipcord), written in 1883, he describes the plight of poor farmers and offers some advice on improving yield through land management practices. 

An excerpt- 

The essence of leaf, grass, flower, dead insects and animals, is washed away by summer rain, therefore our industrious government should, as and when convenient, use the white and black soldiers and the extra manpower in the police department to construct small dams and bunds in such a way that this water should seep into the ground, and only later go and meet streams and rivers. This would make the land very fertile , and the soldiers in general, having got to working in [the] open air, will also improve their health and become strong. 

.....Therefore the government should maintain these bunds in good condition, especially the backwaters. The government should conduct surveys of all the lands in its territory, employing water specialists, and wherever it is found that there is enough water to be drawn from more than one source, these places should be clearly marked in the maps of the towns, and the government should give some awards to farmers who dig wells without its assistance. Also the government should allow the farmer to collect all the silt and other things extracted from rivers and lakes, as in the older times, and it should also return all the cow pastures to the villages, which it has included in its 'forest'. 

Phule covers many of the interventions that are recommended by watershed management specialists today. The last line of the passage I have quoted is telling. Preventing villagers from using what was traditionally considered 'village commons' has always been contested by the people. Phule also called for the destruction of the "oppressive Forest Department". The conflict between agriculturists, forest dwellers, pastoralists, and the forest department continues to this day. 

This essay, translated from Marathi to English by Aniket Jaaware, has been republished in Makers of Modern India, a compilation of essays written through the 19th and 20th century by influential Indian political activists and social reformers. The collection is edited and introduced by historian Ramachandra Guha.

Map: Paris Olympics Purple

I was hoping that this 1874 geological map of the Paris area was the inspiration behind the startling purple color theme for the recently concluded Paris Olympics. The map was shared on X (formerly Twitter) by the Geological Society of London.

The sedimentary strata are folded into an arc that looks like the purple athletics track! 

Alas, no. The purple color was selected because the organizers wanted a unique identity for the games. And apparently it made for better television viewing.

There is a geology connection to the athletics track though. A big component of the flooring is calcium carbonate usually obtained by grinding down quarried limestone. For these games, in keeping with the theme of sustainability promoted by the organizers, the purple track was made up of discarded mussel shells obtained from an Italian fishing cooperative. 

Oh well. I like my geology connection story better.

Remotely India: Bundelkhand Mafic Dikes and Quartz Veins

Remotely India #14

Do you see anything striking (pun intended) about this geologic map of the Bundelkhand craton?

Source: Sarada Mohanty 2023- Proterozoic Basins of the Bundelkhand Craton

Notice that the green lines are predominantly oriented in a NW-SE direction. The pink lines are predominantly striking NE-SW. These are magmatic and fluid intrusions into the Bundelkhand granitic crust. The green lines represent mafic dikes (Mg and Fe rich basaltic magma), and the pink lines represent quartz veins. 

The Bundelkhand craton is an Archean age block of continental crust. Like other Archean age terrains, it has a long history of magmatism, volcanism, and sedimentation. The oldest rocks, a suite of granitic rocks going by the term 'tonalite–trondhjemite–granodiorite', and associated volcanics and chemical sediments are as old as 3.4 billion years. Through the Archean the crust grew by repeated injections of magma. Voluminous magmatism petered out by around 2. 4 billion years ago with the formation of the Bundelkhand granodiorite batholith, an enormous subsurface body of congealed magma. Granodiorite is a calcium feldspar bearing variant of granite. This younger rock type covers most of the surface area of this terrain.

Geologic activity continued for hundred of millions of years after the emplacement of this batholith with the intrusion of these impressive dike swarms and quartz vein clusters.

Staying true to the objective of this series on Indian geology as seen from satellite imagery, the emphasis here will be on the field features of these intrusive bodies.

Giant Quartz Veins:

Locality- Northeast of Mauranipur, Uttar Pradesh.

The quartz vein stands out as a high long ridge. Steep sided blocks of quartz make up the spine of the ridge. Weathered boulders shed from the quartz vein have formed the surrounding slopes. This distinctive landform is instantly recognizable in the imagery as you explore this region.  

Locality: Southeast of Mohangarh, Madhya Pradesh.

Here you can observe the intrusive relationship between the giant quartz vein and the older Bundelkhand granite (BG) which crops up as low hills made up of a light toned fractured rock. The linear vein can be traced cutting across the host rock.

Locality: Southeast of Mauranipur, Uttar Pradesh.

At this location you can observe an unusual feature. Two quartz veins have split to form a tuning fork shaped geomorphic feature.

These quartz veins intruded the crust around 2.15 to 2 billion years ago. The quartz crystals contain bubbles of gas and minuscule amounts of liquid trapped inside them. They inform us about the temperature and pressure during precipitation of the crystals and about the salinity of the fluid. There are also tiny crystals of other hydrous minerals like chlorite and epidote found inside the quartz. These reveal the source of the fluid. Such studies conducted by Duttanjali Rout and colleagues identify two distinct sources of fluids involved in the formation of these veins. A hot moderate salinity fluid derived from the Bundelkhand granodiorite mixed with meteoric water percolation downwards through fractures. The deeper fluids were sourced from not more than 5 km in the subsurface.

A drop in the temperature and pressure of the rising silica saturated fluid as it encountered the colder meteoric water resulted in decrease of silica solubility and the precipitation of quartz. The giant quartz veins are the product of a vigorous Proterozoic geothermal system that lasted tens of millions of years. The researchers have drawn a comparison with Broadlands-Ohaaki geothermal system in Northland, New Zealand, and the Kakkonda geothermal system in NE Japan. Both are in granitic terrains and could be loose analogs for the processes in operation during the formation of the Bundelkhand quartz veins.  

There are differences in what we can observe in these ancient and modern systems. In the Proterozoic example, the surface expression of the silica rich geothermal system, the hot springs and geysers, have long since eroded away. We can study only the subsurface plumbing system. In the modern settings, the surface processes are apparent and the underground patterns of fluid flow have to be inferred. 

Mafic Dikes:

Locality- Northeast of Lalitput, Uttar Pradesh,

A NNW-SSE trending dike is exposed near Tera village. The surface expression of mafic dikes is very different from the quartz veins. The dikes weather away faster and are exposed as low relief hills with extensive boulder fields derived from the weathering of the dolerite rock. In the satellite imagery, you can see the dark toned nature of the boulders hinting at its mafic composition. Due to the spread of boulders around the dike, the width of the intrusion appears far more that its true width. 

Locality- Mahoba , Uttar Pradesh

An ENE-WSW trending mafic dike is surrounded by Mahoba town. As with the NW-SE trending cluster, these E-W trending intrusions also appear as dark toned low relief boulder strewn hills.

Locality- Mahoba, Uttar Pradesh.

This is a synoptic view of the E-W trending dike, captured by ISRO Cartosat. The white rectangle in the lower left of the image is the bounding area covered by the previous imagery. It is quite an extensive intrusion, and to the eastern end it can be seen cutting across outcrops of the Bundelkhand granite. 

Geochronologic work on these mafic dikes shows that the NW-SE trending dike swarm intruded around 1.9 to 1.8 billion years ago. The E-W trending group of dikes are much younger, dated to about 1.1 billion years ago. 

The geochemistry of these dikes point to an upper mantle source of the magma. The dikes are a variety of thoeliitic basalt, not too much different from the basalts of the Deccan Traps in Maharashtra. Unlike the shallow sourced fluid of the quartz veins, the source magma of the dikes was generated at least 50 km down in the mantle lithosphere.

The crisscrossing lines you see on a geologic map of the Bundelkhand craton are a record of geologic activity that continued long after voluminous granitic magmatism ended. In rare exposures, mafic dikes are seen cutting across quartz veins, indicating that they are the younger of the intrusives. Most of the geochronology data collected so far supports this field observation. Studies of the spatial patterns of the dikes and quartz veins too hint that they represent two independent deformation events. The formation of both these systems required extensive fracturing and faulting  of the crust by extensional forces. Geologists are still working out the reasons for these crustal disturbances. 

In the case of the quartz veins, the fracture systems tapped relatively shallow sources of heat and fluids. In the subsequent reactivation of the crust, much deeper fracture systems cutting across the crust tapped upper mantle sources of heat,  providing conduits for the passage of mafic magma to shallower crustal levels. 

These deep crust penetrating fractures and Proterozoic mafic dike swarms tell another story about the strength of the crust and the advent of plate tectonics, but that is fuel for another post!

I am having fun resurrecting my Remotely India series. Stay in touch for more explorations of Indian geology on this blog.

Ganga Earthquake, Nile, Deep Sea Habitats

Some readings over the past few weeks:

1) An Earthquake Changed the Course of the Ganges. Could It Happen Again?  Sediment load carried by big rivers like the Ganga often choke up channels and force the river to cut another path. Sudden channel shifts can also occur due to tectonic movements. A recent survey of the Ganga about 100 km south of Dhaka, Bangladesh , identified an old channel of the Ganga. Exploring this area, researchers came across veins of sand cutting across the sediment layers. These veins or sand dikes were  injected into the surrounding sediment. They are a sign of major ground trembling triggered by a large earthquake. Ground motion may pressurize buried sand and inject it  upwards. Further studies showed that this event may have been a 7-8 magnitude earthquake that occurred 2500 years ago. Kevin Krajick writes about this discovery and the larger geologic context.

2)  Lessons from the Nile about rivers and society. The Nile river has sustained agriculture, human habitation, and royal dynasties for millennia. A Nature Geoscience editorial summarizes a collection of sedimentological and geomorphologic studies that track the evolution of the Nile through the Holocene. Phases of the river cutting a deep valley changed to phases of the river flooding laterally and building fertile floodplains. This geomorphological evolution driven by climate change and more recent dam building have influenced agriculture and social systems in the past as well as the present. 

3) Ocean Exploration: Meet The Deep. I highly recommend this site. National Ocean and Atmospheric Administration, U.S.A., has compiled some stunning photographs and videos of deep sea habitats and the diverse forms of life that inhabit this little understood world. Corals, sponges, brittle stars, molluscs, worm tubes- attached to the bottom, living around energy sources such as hydrothermal vents and cold seeps. It is an absolutely fascinating exploration of the biodiversity of the deep sea. 

Octocoral and Brittle Star: Source NOAA Ocean Exploration

As a bonus, these images make great wallpaper for your mobile phone!

Field Photo: Unusual Himalaya Metamorphic Rock

My friend Emmanuel Theophilus, who spends a lot of time wandering in the high Kumaon Himalaya, sent me this photo of a feldspar rich gneiss.,

He observed this loose boulder near the small settlement of Bugdiyar in the Goriganga valley, north of Munsiyari town. Bugdiyar is located in the Greater Himalaya. This is a high grade metamorphic rock terrain. As you walk along the many trails that lead to places like Nandadevi Base Camp and Milam Glacier,  you can observe mica and amphibole rich schist with gleaming garnets, quartz and feldspar rich gneiss, migmatite gneiss (partially melted gneiss), and leucogranite (quartz and feldspar rich magma) intruding this high grade ensemble. 

This traverse takes you into the core of the Himalaya orogen, where high temperature and pressure during mountain building that took place 35 to 15 million years ago transformed the sedimentary protolith into metamorphic rocks. 

This particular gneiss rock has an extraordinary texture. I have never before seen such large feldspar (white crystals) in a metamorphic rock. Judging by the pebbles and other rocks strewn by the side, these are inches long feldspar grains. 

I want to introduce two terms used to describe texture in metamorphic rocks; porphyroblastic and porphyroclastic. Both these terms describe rocks with very large crystals surrounded by fine grained minerals. These are rocks with two distinct crystal size classes. 

Porphyroblastic texture forms when one mineral grows more quickly than other minerals during metamorphism. Large crystals of the rapidly growing mineral are set in a finer crystalline matrix. Both the large and small sized minerals have recrystallized, but at different rates.  

In contrast, porphyroclastic texture forms when there is a size reduction of some minerals , leaving one unaffected mineral larger than the rest. This situation occurs most commonly in fault zones where softer minerals may get crushed more easily leaving the resistant mineral as a large porphyroclast. These types of rocks have a broken appearance. The softer minerals become aligned to give the rock a prominent streaky banded texture. The more competent mineral may also develop an elongated shape.

Which of the above is the rock Theo found? My guess is that it is a porphyroblastic gneiss. Take a closer look at the beautiful large grains. They seem to be the result of growth during metamorphism, in the process engulfing small pockets of mica in their interiors. The rock lacks the streakiness and the often broken, bent, and stretched large grains characteristic of a porphyroclastic texture.

However, there is a subtle sign of deformation too. Have a look at this close up. 

The black arrows point to rugby ball shaped feldspar grains. They have a long axis and a short axis and appear to be stretched in one direction. Also notice the grey cracks running along the longer axis of many of these crystals and continuing into the rock. These are paper thin zones where force or stress was localized. The change in shape (strain) in the feldspar grains follows these very narrow zones of deformation. 

All of the above is my reasoned speculation on the origin of this texture. The next step is to meet up with Theo near Bugdiyar and walk along the Goriganga in search of the outcrop.

The Goriganga near Bugdiyar. It is spectacular out there!

Deep Sea Mining, Indian Ocean, Infectious Diseases

Some readings for you:

1) Mining the bottom of the sea: The deep sea bed is considered the last frontier on earth for mining. Large patches of the sea bed are littered with metallic lumps or nodules rich in manganese, cobalt, zinc, and nickel. These elements are considered vital for powering the world's green economy. Nauru, a tiny Pacific Ocean island nation situated northeast of Papau New Guinea, along with a Canadian mining company, wants to start mining a region of the Pacific between Hawaii and Mexico known as the Clarion-Clipperton Zone. Scientists warn that a hurried push to mine the deep ocean bed will result in an irreversible loss to biodiversity, ecologic functioning, and ocean health. Elizabeth Kolbert writes about the complex legal and regulatory issues and conflicts of interest related to international deep sea mining.

As things stand in June 2024, a deep sea mining code is still being decided by the International Sea Bed Authority. Rohini Krishnamurthy of Down to Earth has the latest news on the progress made on this issue. Negotiations are hampered by a lack of basic science and divergence of views between member states.

2) Indian Ocean headed for a near-permanent state of marine heat wave:  Rapid fossil fuel emissions over the past century or so has changed the earth's energy balance. More energy is now coming in than is being radiated out to space. More than 90% of this excess energy is ending up in the ocean as heat. As a result, the world's oceans are warming up. The Indian Ocean is warming rapidly too. Recent studies have found that it may be heading towards a scary sounding situation known as 'permanent heatwave state' where the sea surface temperatures exceed a threshold value for 220-250 days a year.

Environment and climate journalist Nidhi Jamwal summarizes the findings of this research and a new book titled The Indian Ocean and its Role in the Global Climate System. The consequences are far reaching, impacting tropical cyclones, biodiversity, and fisher folk livelihood.

3) Probing the pathogens that afflicted ancient humanity: Pathogens and humans have been co-evolving for millennia. Paleoanthropologist John Hawks charts out the history of some of the common infectious diseases afflicting humanity. Infection patterns are not random. Rather, they follow networks of transmission shaped by ecology and culture. Very illuminating essay!

Evolution Through Punctuated Equilibrium: History Of An Idea

Palaeontologist Niles Eldredge explains how one of the most famous papers on paleontology and evolution came to be published: 

Steve was determined to be a part of Tom’s plan to do a GSA symposium and publish a book of essays on this new-fangled concept of “paleobiology.” Tom had a list of topics and was shopping around for speakers to be assigned to each one. When Steve saw the list, he told me that he had first wanted “morphology”—but that was already assigned to Dave Raup. So he opted instead for “phylogeny”—but that had been grabbed up by Mike Ghiselin. That left only “speciation,” the last of the evolutionarily imbued topics on Tom’s list, as yet unassigned. Steve called me up, explained the situation, and said he had settled for speciation—but could not think of anything much to say about it beyond the manuscript I had written and recently submitted to Evolution—there of course being no Paleobiology as yet. “The Allopatric Model and Phylogeny in Paleozoic Invertebrates”—a distinctly un-Gouldian, plodding, if accurate, title (Eldredge 1971). Without Ralph Gordon Johnson in the editorial chair of Evolution at that time, I doubt that that early paper would have been accepted. As it was, it was likely to have gone relatively unnoticed—had not Tom come along, Steve grabbing “Speciation”—and Steve asking if we could coauthor the paper along the basic lines of my first effort. He was stuck with “speciation,” and couldn’t think of anything much to say beyond what I had said in the Allopatric Model manuscript.

This passage is from an article by Niles Eldredge titled Reflections On Punctuated Equilibria, published in a recent issue of Paleobiology. The 1972 paper he refers to, coauthored with Stephen Jay Gould, was, Punctuated equilibria: an alternative to phyletic gradualism. It marked the beginnings of a long debate on how to interpret the patterns of morphological change observed in the fossil record. Do species remain in stasis, showing little morphological change through much of their existence as Eldredge and Gould argued? Do periods of rapid morphological change coincide with the origin of new species (speciation)? Supporters hailed it as a revolutionary work. Critics called it 'evolution by jerks', a jibe aimed not just at the patterns of change.

Dr. Eldredge provides a very insightful look at the history of this idea including some fascinating snippets on Darwin's thinking about divergence and species origins. For Darwin, change accumulates incrementally over long passages of time. Divergence via natural selection can give rise to descendant varieties even without geographic isolation of a population. Later thinking has given more importance to exogenous factors like climate change in causing habitat fragmentation and reproductive isolation. Populations gets geographically isolated first, and then diverge from the ancestral species either through natural selection or random genetic drift. Eldredge and Gould applied this idea to the fossil record and emphasized that the sudden appearance of new fossil species is a manifestation of long periods of stability interrupted by episodes of isolation and geologically rapid shifts in morphology (allopatric speciation).

There is a lot to take in and think about the long term patterns of change preserved in the fossil record. But it is enriching reading. The article is open access.

Remotely India: Chittagong Tripura Fold Belt

Remotely India #13

Did you know that the easternmost part of the Bengal delta is being compressed into folded hill ranges? These go by the name Chittagong Tripura Fold Belt (CTFB), also referred to by geologists as the Outer Indo Burman (Myanmar) Ranges.

Take a look at the annotated satellite image below. The CTFB appears as a series of north south oriented ridges and valleys, extending from northern Tripura to south of Cox Bazaar in Bangladesh. 

Structurally they are made up of strata folded into anticlines (upwarps) and synclines (downwarps). To the east, they are separated from the inner Indo Burman (Myanmar) Ranges (IBR) by the north south trending Kaladan Fault. The Chittagong Coastal Fault marks the westernmost boundary of this fold belt, although the sedimentary pile below the sea bed of the Bay of Bengal to the west is also deforming. The 'deformation front' of this terrain is therefore further to the west of the Coastal Fault. 

As you might have guessed, these fold belts are a result of the Indian tectonic plate converging with Asia. But the nature of tectonic plate interaction is different from the plate collision that formed the Himalaya. In the case of the Himalaya, the continental crust of the Indian plate has collided with the continental crust of the Asia plate. The lower part of the Indian continental crust has slid under Tibet while thick slices of the Indian upper crust have been thrust up by faults to form the different geologic units of the Himalaya. 

Tracing the mountain arc southwards from its bend around Arunachal Pradesh, a different type of tectonic plate interaction is unfolding. In the Himalaya collision zone the more buoyant continental crust is sliding at a shallow angle underneath Tibet, a process known as underplating. In contrast, the Indian tectonic plate along this eastern convergence zone is made up of denser oceanic crust. As a result, along the zone of contact with Asia, this dense plate is subducting or taking a deep dive at a steeper angle into the mantle. 

Another difference apparent from the surface structure is the presence of both vertical and sideways movement of crustal blocks. This occurs because the Indian plate is pressing into Asia at an angle. Oblique convergence results in thrust faulting wherein rocks are moved up along east sloping fault planes. Collision at an angle also causes blocks to slide past each other along strike slip faults.  

The IBR is an older mountain chain formed by the subduction of the Tethyan oceanic crust underneath the Asia plate and the smaller Myanmar plate. This process, initiated in the Late Cretaceous around 100 million  years ago, eventually led to the formation of a complex fold belt by mid Miocene times (15-20 million years ago). 

This fold belt is made up of deep sea sediments and fragments of the Tethyan oceanic plate. These rocks were subjected to very high pressures during mountain building. Sheared and fractured rock units occur in a melange made up of dismembered blocks of varied rock types juxtaposed by faults. Heat and high pressure acting on rocks rich in aluminum, calcium, iron, titanium, and magnesium has resulted in the formation of deposits of exquisite gemstones such as jade, rubies, sapphires, spinel, and peridote. The IBR is studded with precious stones!

By Miocene (~20 million  years ago) the IBR had emerged above sea level as elevated ranges and had started eroding. Sediments shed from these hills were deposited in delta and shallow marine environments of the Bengal Basin to the west. During continued subduction of the Indian plate, between 2-4 million  years ago, this thin skin of the crust made up of about 5 km of sediment was scraped off, faulted, and crumpled up to form the CTFB. Geologists call these scraped off wedges of sediments that form along subduction zones as 'áccretionary prisms'. 

Further to the south, the Andaman Islands is also an accretionary prism formed along the plate junction between India and Asia.

The deformation of the CFTB diminishes from the east to the west. There are two distinct structural domains of this belt. To the east is a more tightly folded belt known as the Eastern Highly Compressed Fold Thrust Zone. Towards the west, is the more open Western Fold Thrust Zone. The emergent part of this fold belt is bounded to the west by the Chittagong Coastal Fault. However, geophysical studies show that the strata below the Bay of Bengal sea bed is also being warped and can be considered part of a westward growing CTFB.

The annotated satellite image below is a close up of the CTFB and the IBR. The black line is the Kaladan Fault separating the two, but even without my annotation, the two terrains have a distinctly different appearance. The older IBR have been more deeply dissected by streams. They have an etched faceted texture. To the west, the younger ranges of the CTFB have a more uniform even texture. 

Finally, I just wanted to put up a structural cross section of the CTFB. The folded and faulted nature of the sedimentary strata is apparent, as is the difference between the more tightly folded eastern zone compared with the more open western domain. Source: Md. Sakawat Hossian et.al. 2022: Lithosphere.

Scientists study terrains like the Chittagong Tripura Fold Belt to understand the mechanical response of the crust to different types of tectonic plate interactions. There is an economic incentive too. The IBR with its precious stone deposits has long been a target of exploration. In the CTFB natural gas seepage has been observed at many places. Geologists are interested in understanding the subsurface structure to target search for hydrocarbon accumulations.

As always, exploring Indian geology from satellite imagery is fun and a great learning experience for me. Stay tuned for more such stories!

Links: Europa Life, Moon Geology, Citizen Activism

Some readings I perused over the past couple of weeks.

1) Our picture of habitability on Europa, a top contender for hosting life, is changing. Jupiter's moon Europa has long been a contender for hosting life. But lately some scientists have expressed their doubts. Europa has an ocean beneath a 20 km icy crust. Geologists now think that the sea floor is not active. They simulated conditions which could generate shallow earthquakes leading to fault movement and exhumation of fresh rock. Reaction of sea water and freshly exposed rocks is necessary for chemical reactions that sustain life. Results suggest an inert sea floor. Another study implied no magmatism on Europa. Rising magma brings with it heat and chemicals. But, could these be transient conditions that we have caught? Maybe there is a cyclicity to Europa's energy flow. Some interesting thoughts in this article.

2) China's Moon atlas is the most detailed ever made. The Chinese Academy of Sciences has released a stunning 1:250,000 scale geologic map of the moon. A decade of research has revealed 17 rock types ( I used to think only basalt!), 81 basins, and 12,000 odd craters! Compiled from orbiting satellites and then sharpened using data from the two lander missions.

3) How Punekars fought for their hill, Vetal Tekdi, to save its ecology. My city Pune has a proud tradition of citizen activism. For the past few years citizens have vigorously protested a road planned along a forested hill slope. This hill has been a life saver for thousands of citizens as a recreation spot. It hosts rich biodiversity and is an important groundwater recharge zone. The Pune Municipal Corporation is insisting on building this road, despite their own reports admitting an adverse environmental impact, and pointing to at best a short term marginal improvement in traffic flow. The fight to save the hill goes back a couple of decades. Shobha Surin has done a good job summarizing this long battle in Question of Cities.   

Geological Contacts: Angular Unconformity Kaladgi Basin

 Remotely India Series #12

Through the Proterozoic Eon, beginning around 2 billion years ago,  extensional forces acting on continental crust opened up several sedimentary basins across what is now peninsular India. Crustal blocks subsided along faults and these depressions filled in with sediments deposited in fluvial and shallow marine environments. These basins were long lived, some lasting for more than a billion years. 

Sedimentation was not continuous.  Pulses of sediment deposition were punctuated by long periods of non deposition. Tectonic movements deformed early deposited piles of sediment. They were uplifted and an extensive basin wide erosional surface formed.

There was then a renewed phase of basin development. Sediment of these successor basins were deposited on tilted and folded older strata. Commonly, these younger packages of sediments are relatively undeformed. They are preserved as mesas and plateaus made up of flat lying strata. This discordance in attitude between two sets of strata separated by a widespread erosion surface is known as an angular unconformity.

In this post I will highlight an angular unconformity from the Kaladgi Basin from north Karnataka, south India. I have used high resolution imagery from Indian Space Research Organization's Cartosat.  Imagery is available for browsing and download from ISRO's Bhuvan 2D web maps.

The first image shows the area around Ramdurg village. The multi-stage history of the basin is readily apparent. The light colored strata exposed along narrow ridges are folded, while the rust brown hills are made up of undeformed sediments. The light toned strata are quartzites of the Bagalkot Group. The brown sandstone which rest on the Bagalkot quartzites are the Badami Group. Standard annotations show the varying dip and strike of the folded Bagalkot sediments. The white cross in grey circle denotes horizontal Badami strata. 

Kaladgi Basin history has become clearer based on recent geochronologic work by Shilpa Patil Pillai, Kanchan Pande, and Vivek S.Kale. They infer that basin initiation occurred around 1.4 billion years ago. Sedimentation of the Bagalkot Group terminated by 1.2 billion years ago. Movement along major WNW-ESE and tranverse NNE-SSE to NE-SW trending faults deformed the Bagalkot sediments into a series of folds around 1.1 billion years ago. This was followed by uplift and erosion of these folded sediments. Deformation was accompanied by low grade metamorphism of these rocks.

The basin floor subsided again around 900 million years ago initiating deposition of the Badami Group of sediments. The famous cave temples of Badami have been cut out from the lower part of the Badami sedimentary sequence.

The next imagery is a good example on how to recognize the relative timing of deformation events. Arrows point to fracture sets in the Bagalkot quartzites. These lineaments do not extend into the Badami sediments implying that fracturing occurred during an earlier phase of deformation. 

Let's look at a location that shows the angular discordance between the Bagalkot and Badami sediments. This is near Shirur town, north of Badami.  The lighter toned steeply tilted Bagalkot sediments outcrop as E-W trending narrow ribbons, north of Budanagad village. The brown colored Badami sediments form a more extensive plateau. Since these strata are horizontal, the traces of bedding planes form concentric bands mimicking contour lines. 

The final location is just south of Ramdurg village. The unconformity here is a little harder to decipher, but you can make out the tilt of the light colored Bagalkot quartzites, annotated by the standard notation of strike and dip. The quartzites form triangular facets sloping eastwards. Like the previous example, the concentric bands of brown in the adjacent hill indicates that this is the overlying horizontally disposed Badami sandstone.

Many Proterozoic basins of India contain such unconformity bounded sequences. Some more classic examples come from the Chattisgarh, Cuddapah, and Vindhyan basins. These sequences from different basins were not deposited synchronously. Each basin has it own trajectory of sedimentation, deformation, and erosion. 

Detailed field mapping, supplemented by absolute dating of rocks wherever possible, is elucidating the complex poly-phase history of Indian Proterozoic sedimentary basins in the context of global continental breakup and reassembly. For arm chair geologists and enthusiasts, easily available web mapping technology makes it possible to join in the excitement of teasing out these terrain's many secrets hiding in plain sight.

Links: Earthquake Detectives, Origin Of Life, India Water Act

Reading from the past few weeks- 

1) How earthquake scientists solved the mystery of the last “Big One” in the Pacific Northwest. The American northwest is a tectonically active region. About 150 km west of the Pacific coast is the Cascadia subduction zone. Here, the Juan de Fuca, Explorer, and Gorda tectonic plates slide underneath the continental plate of North America. Large earthquakes have occurred in the past and will occur in the future. 

Reporter Gregor Craige has written a book, On Borrowed Time: North America’s Next Big Quake, in which he explores the region's earthquake potential and the cross disciplinary studies that enable scientists to understand past earthquake history as well as the impact a big future earthquake will have. Canadian Geographic has shared an abstract from his book. The earthquake puzzle was solved by combining information from tree rings, Native American peoples memories of past events, and Japanese record of tsunamis. It is fascinating reading. 

2) To unravel the origin of life, treat findings as pieces of a bigger puzzle. Was life's beginnings in a warm little pond or in a deep sea hydrothermal vent? Did lightning provide the energy, did asteroids provide the organic matter? There are many many scenarios that try to provide an explanation to this vexing question. 

One of the leading researchers of this field, Nick Lane, and his colleague Joana Xavier, have summarized some of the key arguments and problems of the field in this tour de force of science writing. Highly recommended! 

3) Analysis: The Great Indian Water Act Of 2024. In more good news for industries, factories and foreign investors, yet another Indian environmental law has been diluted to facilitate “ease of business”. Shailendra Yashwant begins his analysis of The Water Amendment (Pollution and Prevention) Act, 2024 Bill on this depressing note. Amendments seek to "rationalize criminal provisions". Polluters can now escape jail time and get away by just paying a fine. All this when climate change and water security is one of the big challenges facing India. 

Patterns Of Angiosperms And Insect Evolution

Charles Darwin famously called it an 'ábominable mystery'. He was referring to the sudden appearance and diversification of flowering plants in the Cretaceous fossil record. He noticed that these early fossils resembled modern flowering plants. 'Primitive' or ancestral stages were missing. Today, biologists categorize these as crown and stem representatives of a group. 

The first fossil evidence of flowering plants is from 140-130 million year old sediments. These are early types of pollen grains with one aperture (uniaperturate). Triaperturate pollen is found in slightly younger 125 million year old rocks. Towards the end of the early Cretaceous, by around 100 million years ago, flowers, leaves, and other organs appear from several continents representing all the major groups of angiosperms.

The picture below is of an early Cretaceous (~100 million year old) flowering plant from the lotus family. The location is northeast Brazil. There is a remarkable preservation of the whole plant, with connected roots, rhizome, leaves, and aggregate fruit. 

Source: William Vieira Gobo et.al. Nature Scientific Reports 2023- A new remarkable Early Cretaceous nelumbonaceous fossil bridges the gap between herbaceous aquatic and woody protealeans.

Taking a long view of their evolutionary pattern, angiosperm diversification is structured in three phases. The first phase was a steady expansion through early to late Cretaceous. There was more rapid diversification in late Cretaceous by around 70 million years ago. Enumeration of floral species through the Cretaceous indicate that angiosperms made up about 5% of species in early Cretaceous, increasing to 80% by Maastrichtian times (late Cretaceous). Despite this increase in species numbers, in terms of biomass, angiosperms were still a small component of Cretaceous floras. Their domination of floral communities, including the origin of modern wet tropical forests, began in the Paleogene (65-24 million years ago) after the end Cretaceous mass extinction. Michael J. Benton, Peter Wilf, and Herve Sauquet have provided a good overview in New Phytologist of this pivotal phase of ecosystem change.

These evolutionary changes did not occur in isolation. Throughout the Cretaceous, significant changes were occurring to terrestrial ecosystems, with the origination of many plant and animal groups. This extended phase of ecosystem reorganization is known as the Cretaceous Terrestrial Revolution. Angiosperm diversification is thought to have played a key role in this transformation of land biodiversity, so much so, that the phase from about 100 million years to 50 million years ago is known as the Angiosperm Terrestrial Revolution.

The Cretaceous -Paleogene mass extinction hit angiosperms hard, as well as altering the trajectory of their evolution. For example, there was a 40% loss of diversity of flowering plants in Colombia following the mass extinction. But certain attributes of angiosperms, such as their partnerships with other organisms, their ability to efficiently capture energy and enhance photosynthetic rates, and an underlying genetic propensity to speciate, resulted in them expanding rapidly in the post extinction landscape. Angiosperm evolution opened up opportunities for a variety of land creatures including insects, spiders, lizards, birds, and mammals,  eventually driving up terrestrial biodiversity to 10 times more as marine biodiversity.

Paleobiologists are interested in understanding the interaction and impact angiosperm diversification could have had on other groups of plants and animals. Of particular interest is the diversification of insects in the Cretaceous and Paleogene.

Modern insect lineages began diversifying by 245 million years ago, long before angiosperms evolved. Gymnosperm and insect communities preserved in amber and sediments show that insects had an intricate relationship with host gymnosperms like cycads, conifers and ginkgoaleans.  Insect pollination of gymnosperms predated the origin of angiosperms by at least 100 million years and their fossil record show phases of diversification even when angiosperms were rare. 

Did angiosperm evolution also drive a rise in insect diversity? Pollinator insects particularly would seem to benefit from an abundance in flowering plants, and if so, what co-evolutionary patterns are apparent from the fossil record?

David Perise and Fabien Condamine have tackled this question in a new study in Nature Communications. I will share this beautifully compiled infographic from the paper that conveys so clearly the patterns of angiosperm and insect diversification through the Cretaceous and Cenozoic.

Digging into published databases, the researchers compiled data on the origination and extinction times of angiosperm and insect families. They then statistically analyzed whether angiosperm and insect origination and extinction times, and pulses of their diversification coincide. Their analysis showed that angiosperms seemed to have played a dual role in insect evolution. They mitigated insect extinction through the Cretaceous and spurred on the origination of new insect groups in the Cenozoic. Besides a broad analysis of insects, they also found that pollinator insects like bees and long proboscid butterflies show a pronounced diversification alongside angiosperm lineages. 

The success of angiosperms in the late Cretaceous and Cenozoic coincided with the decline in gymnosperms. Intrinsic mechanisms of genomic rearrangements in angiosperms resulted in repeated evolution of novel traits and specializations. They competitively displaced gymnosperms. The impact on gymnosperm dependent insects was variable. Generalist insect pollinators such as several beetle lineages transitioned to angiosperms. Much of the co-diversification of angiosperm and insects can be explained by this shift of gymnosperm pollinators to angiosperm hosts.  Gymnosperm specialized insect groups did not fare that well. For example, gymnosperms like Cheirolepidiaceae and Bennettitales went extinct by the latest Cretaceous. This was followed by the extinction of insect groups that were dependent on these plants such as some specialized long-proboscid flies, scorpionflies and lacewings.

Insect diversification did not depend only on angiosperms. Analysis also shows that warmer climate phases negatively impacted insect diversity and coincided with higher insect extinction rates. There seems also to be a relationship with other plant types. Spore plant and gymnosperm diversity had a positive impact on origination rates of insects. Ecosystem relationships and dependencies are multifarious and complex as this analysis between angiosperm and insect co-evolution shows.

Darwin's anxiety over flowering plants reflected his insistence that evolution is gradual. Nature does not make leaps, he stressed. He explained abruptness in the fossil record by invoking missing strata due to non deposition and erosion. Regarding flowering plants, he suggested that fossils were perhaps preceded by a period of cryptic evolution of that lineage that took place in a remote area or a lost continent, although he conceded that this was a poor explanation. However, this latter view, that a substantial lag time or a long fuse precedes the bang, continues to resonate among many biologists. Molecular methods that compares accumulated genetic difference to calculate the time of divergence of groups indicate a fairly long gap between the genetic branching of lineages and their first fossil appearance. 

Most familiar is the example of the origin of animals. Molecular data indicate that animals originated by 750 million years ago, yet unequivocal animal fossils appear by 570 million years ago, close to 200 million years later. Similarly, some molecular estimates put angiosperm origins to pre-Cretaceous times, stretching back 240-200 million years ago to Triassic-Jurassic, a good 100 million to 60 million years before first appearance of fossils.

This idea of a phylogenetic fuse has been recently criticized. Published in Systematic Biology, Graham E. Budd and Richard P. Mann have undertaken a critical examination of molecular clock methods. Their analysis indicate that popular methods used to assign probabilities to maximum age of lineages are biased against rapid lineage radiations being true evolutionary events. In their view, the mismatch between molecular dates of lineage origin and the timing of the first appearance of their fossils is an artifact. They point out that the coincident appearance of fossils from widespread localities in a particular sequence and across different modes of preservation faithfully records evolution. The time gap between the origin and later diversification of lineages is not that deep.

The 'abominable mystery' of the sudden appearance of fossil groups may in fact be a real biological motif in earth history, signalling the rapid radiation of lineages filling ecologic spaces following an environmental crises and evolutionary innovation.