Monday, September 30, 2019

Links: Kimberlites, Ecosystem Recovery, Early Atmosphere, Carbonates

Some readings on assorted subjects.

Enigmatic origin of diamond-bearing rocks revealed

These are volcanic rocks which are the primary source of diamonds. Kimberlite magmas originate from deep in the earth's mantle. A recent geochemical survey has provided insights into the nature of that source. In India, the famous Panna diamonds are derived from the Majghawan Kimberlite which erupted about 1073 million years ago in the Proterozoic Vindhyan Basin.

Diversity decoupled from ecosystem function and resilience during mass extinction recovery

The mass extinction that took place 66 million years ago devastated both marine and terrestrial ecosystems. How long does post-extinction recovery take and exactly how do community structure and ecosystem functions reboot? A study using a 13 million year record of nannoplankton (unicellular protists) spanning the mass extinction has yielded some insights.

The study suggests that essential ecosystem functions such as geochemical cycling of nutrients was established by few hardy species very soon in the extinction aftermath. This recovery preceded by million of  years the reestablishment of species richness.

Did Bacterial Enzymes Cap the Oxygen in Early Earth’s Atmosphere?

Photosynthetic cyanobacteria that expelled oxygen evolved by 2.4 billion years ago. But oceanic and atmospheric oxygen levels remained quite low, about 10% of current levels, until about 400 million years ago.

The Pre-Salt Hydrocarbon Reservoirs of the South Atlantic

A superb example of how an understanding of the environments in which sediments are deposited helps petroleum exploration strategy.  Focus is on the unusual alkaline lake carbonate deposits of Brazil, formed during the Cretaceous when South America and Africa started splitting away from each other.

Tuesday, September 24, 2019

Musings: Two Million Page Visits

Recently, someone who spends most of the day staring at excel spreadsheets told me that geology is a 'dry' subject.

Another typical reaction I get about geology is an inquiry as to why I choose this unusual or fringe field. That too mystifies me. How can a science that is so central to understanding how the earth works be 'fringe'?

Geological knowledge makes the world turn. But the search for metals, oil and coal is not its only utility. For the past 4.6 billion years, the earth has been in a state of constant churn, a dynamic driven by the transfer of chemicals and heat between its interior and the surface. Rocks, organisms, and air feed of each other in an intricate web of energy exchanges. As historians of the earth, we build narratives about this evolution by delving into the rocky archives of past oceans, terrains and climate. We try to understand the processes connecting these different realms on timescales both vast and fleeting.

These history lessons from the deep past give geologists a unique perspective on how the surface of the earth, our home, will change in the near and distant future, changes caused by the interaction of human activity and natural process. Geoscientists will have a critical role to play in solving the big challenges of resource management, environmental degradation and climate change.

Refreshingly, I saw a different attitude towards geology in younger minds. A few weeks back I was asked to judge a school earth sciences projects contest. The children had prepared some wonderful demonstrations of how geology and our daily lives intersect. They were curious about the subject and passionate about applying the science to better our future. This early immersion in earth sciences might just make them more responsible and better informed stewards of our planet.

That day gave me some hope for the coming decades.

I write to tell these richly rewarding stories about geology. Maybe I have succeeded somewhat in my endeavor.

I am forever seeking newer audiences for my writings. A request to you to pass on the link to my blog to your friends. You can also subscribe directly by email or follow me on Twitter.

As for my friend, I am happy to say that he responded well to a treatment of 'one week in the Himalaya', so much so that towards the end of the trip he asked for a geology book list.

Monday, September 16, 2019

Darwin: Citizen Science

After his return to England in 1836 from a five year round the world trip aboard the Beagle, Darwin did not travel again for any extended fieldwork. His home became his study and his laboratory, but he was no lonely isolated genius. His ideas stemmed from data that streamed in from all over the world.

From Darwin: The Life of a Tormented Evolutionist

Down House had become the hub of a correspondence network across the Empire, its tentacles touching every little England. The sack of mail brought gems daily to aid his sexual selection. Botanists from Ceylon to Calcutta sent reports on monkey manes and bearded Indians; mining engineers from Malacca to Nicaragua told of indigenous customs; tile manufacturers in Gibraltar attended to merino lambs; wine exporters in Portugal followed the local tailless dogs; Laplanders measured reindeer horns; New Zealanders heroically tackled the Maori's sense of beauty; and missionaries and magistrates from Queensland to Victoria ceased converting and incarcerating to observe aboriginal ways- with an old Beagle shipmate Philip King helping out. This is what Darwin excelled at: collecting and collating, tracking down facts, verifying,extending his old notebook speculations to embrace the globe.

Darwin had many India connections. His botanist friend Joseph Hooker who had traveled to India in the 1840's had been one source of information on indigenous plants, animals, and people. From 1855 or so, Edward Blyth, curator of the museum of the Royal Asiatic Society in Calcutta became his chief contact. He struck up a lively correspondence with Darwin. Details about monkey manes and bearded Indians would have come from him.

"his large and varied stories of knowledge, I should value more than that of almost anyone" he wrote of Blyth.

Vikram Doctor has written an insightful essay on Edward Blyth's life. It sketches the sharp contrast between the financially comfortable life Darwin lived in England against the hardscrabble existence of Blyth, who managed to stay on for 21 years in India on a salary of Rs 250 a month, supplementing it with a trade in exotic birds and animals.

A love for natural history drove Blyth on and Darwin benefited from that immensely.

Tuesday, September 10, 2019

Books: Timefulness And A New History Of Life

More books arrived in my mailbox.

I have been looking for an updated sweeping history of life survey. Peter Ward and Joe Kirschvink have written just that book, covering topics from the origin of life to mammalian evolution. I'm in the middle of the section on the origin of life, along which I am re-reading the relevant section from Nick Lane's superb book The Vital Question. Flipping ahead, I can see that the authors have developed broad narratives of how ecosystems changed, framed within the themes of catastrophic events and changes in levels of oxygen, carbon dioxide and hydrogen sulphide (very early in the history of life).

After enjoying her first book, Reading the Rocks, I had to order Timefulness, a long essay on the need to be aware of the multiple time scales on which geologic processes operate. Marcia Bjornerud stresses that inculcating time-literacy is vital for a sensible societal response to our epoch of rapid planetary change.

I'll be sharing excerpts from time to time.