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.