Earth’s Memory, Part One Abstract Every rock carries a fragment of Earth’s memory. Collectively, these fragments preserve an extraordinary geological record spanning more than 4.5 billion years of planetary evolution. This article traces that record through the deep-time history of our planet—from the formation of Earth’s earliest crust and the Great Oxidation Event, when microbial life transformed the planet’s atmosphere, to the five great mass extinctions that repeatedly reset the trajectory of life, and the Snowball Earth episodes, when our planet experienced its most extreme glaciation. Drawing on more than two decades of fieldwork across Himalaya and Peninsular India, among ancient rocks, minerals, and fossils that bear direct witness to these planetary transformations, it explores how geologists reconstruct Earth’s early history from evidence preserved in the geological archives. Taken together, these geological events reveal a recurring pattern: Earth is a dynamic system in which every major crisis has also created the conditions for new and often more complex forms of life to evolve. That pattern, written into rocks billions of years old, continues to shape the planet today.    I first learned to listen to rocks long before I had the words to describe what that meant.  It began in the Himalaya, the youngest mountain range on Earth, still rising, still deforming, and still recording the ongoing collision between continents. During my early fieldwork, I spent long days mapping folded strata, tracing fault scarps, and trying to understand how landscapes preserve evidence of processes operating across vastly different geological timescales. At that time, I often felt that the mountains were trying to say something in a language I had not yet learned. Over time, through fieldwork, mapping, and countless hours spent among rocks and sediments, I began to decipher that silent language.  The lesson deepened across many other landscapes of India....

Jaishri Sanwal Bhatt is an Indian geologist and paleoclimatologist based at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, where she combines scientific research with a strong commitment to public outreach, advocacy, and science communication. For more than twenty years, Sanwal’s work has centered on reconstructing past climate change and active tectonic processes through the study of cave records and other geological proxies, especially paleolakes and speleothems. Her research has spanned the Indian and Nepalese Himalayas, the Andaman Islands, and both the eastern and western coasts of India, engaging major questions related to earth systems, water security, and natural hazards. In this wide-ranging and engaging InterDialogue, we discuss deep geological time, the proposed nuclear energy transition in India, the value of interdisciplinarity and clearer scientific communication, Sanwal’s efforts to organize science outreach initiatives in rural India, and much more. Timestamps 2:22 – Sanwal’s background and introduction to geology 8:43 – Big History and the evolution of the Earth through geology 14:25 – Sanwal’s research 16:45 – Tracking historical precipitation patterns through sediment 21:10 – Connecting paleoclimatology to contemporary climate science 25:53 – Tracking and analyzing extreme events through rocks 29:07 – Comparing chronological dating systems 32:52 – Sanwal’s work with lake cores 37:34 – Tracking tsunami episodes in the Andamans 44:09 – Evidence of tsunamis in mangrove forests 49:00 – Local knowledge and community collaborations 52:32 – Nuclear energy transition in India and waste disposal 57:18 – Risks of geological repositories for nuclear waste 1:00:16 – Sanwal’s rural science outreach and education initiatives

In a complex and rapidly evolving technological, socio-economic and geopolitical landscape that is focused on a global “sustainable energy transition,” increased electromobility based on lithium batteries is often stated as a key objective. However, unbeknownst to the public, policy makers and most researchers alike, lithium in its enriched isotopic forms (6Li and 7Li) holds tremendous added value beyond its use in batteries. This is especially true in both present and future nuclear technologies. For those countries with large lithium reserves that are being prospected for rapid lithium exploitation in order to fuel the growing global electromobility sector, it is important to be aware of these added value uses when considering plans for expanding lithium extraction (plans that also hold negative environmental externalities, such as prodigious water use and contamination). Argentina – which has an established nuclear energy and research sector, as well as a current administration that seems committed to rapidly depleting the national lithium reserves – serves as a strong and dynamic case study for the importance of crafting long-term, science-based and sustainable policies around the exploitation and isotopic separation of lithium. Argentina owns almost a third of the lithium reserves in South America which, together with those of Chile and Bolivia, represent more than half of the world’s lithium availability. Battery-grade lithium carbonate (Li2CO3) is produced from the Puna brines in the Andes of Northwestern Argentina – it is exported and only a small fraction remains in Argentina as royalties (around 3%) and the declared profits of the mining companies.  This article analyzes the use of lithium isotopes (6Li and 7Li) in fission and fusion nuclear reactors and in nuclear technology devices, such as scintillation plates, neutron detectors and shields. These uses of lithium in nuclear technologies have the potential to add value to Argentina’s limited lithium reserves...

As an official in Colombia’s Ombudsman’s Office, I was a member of an interdisciplinary team that documented the issues faced by artisanal fishermen. I soon became aware of a serious widespread problem which receives minimal public attention. Those who engage in fishing activities in lentic inland waters, such as lakes, ponds and “ciénagas”, often share a common concern: the waters on which they depend have not been properly demarcated. In other words, the delineation process, known locally as “deslinde,” has not been completed to define the boundaries between ecosystems belonging to The Colombian State and those areas where private property rights apply. This is not a recent issue, on the contrary, this represents a long-standing information gap. The State does not have clear data in regards to delimited wetlands and academia has not extensively explored the problems associated with this process. The consequences of this lack of information are severe. Some of the most well-known include the appropriation of amphibious shores (floodplain lakes referred to in Colombia as “playones”), the loss of fauna and flora due to changes in land use, an increase in property concentration, and the abandonment of collective practices in flood-prone areas. This situation particularly affects the ciénagas, which are wetlands that play a crucial role in mitigating rising water levels during periods of heavy precipitation. They also help to regulate river flows and support the reproductive cycles of fish. Furthermore, there has not been a participatory process to delimit the ciénagas, where the limits of the wetlands are decided with the support of the local population. It is essential to recognize that rural communities are an integral part of these ecosystems, but the Colombian State fails to acknowledge the interdependence that exists between wetland ecosystems and artisanal fishermen. These fishermen, in many cases, have lived in...

In this interdialogue I spoke to Juan Manuel Quinche, an anthropologist from Bogota, Colombia, who at the time was completing an Erasmus Mundus Master’s Programme in Human Rights Policy and Practice in Europe.  Quinche has researched and worked on interrelated human and environmental rights issues within Colombia’s complex and often frustrating socio-political landscape, both as an official in the Colombian Ombudsman office, and as a graduate student at the National University of Colombia.  Much of his attention has been focused on the Northern Colombian wetlands and floodplain lakes known as “cienagas,” and the fishing and peasant communities that live amongst them. This is a fascinating and neglected region in the Lower Magdalena River basin, and much of our conversation focused on the cienagas as complex socio-ecological systems in which traditional fishermen and the wetlands coevolved, the long history and present realities of violent land appropriation in Colombia, and the importance of demarcating these vital and threatened wetlands.

Our Elemental Origins It is easy for us humans – with our self-proclaimed superior intelligence over other species, and ability to innovate and exploit the natural world to our whims – to forget or ignore that we are in fact part of nature. This is not solely an existential statement, or even an acknowledgement of the dependency that we have on nature for our long-term survival as a species. From our behaviors and physiology, to the very molecules, elements and atoms that makeup the cells of our body, we are nature. One must even expand the meaning of “the natural world” to truly appreciate where we come from. The history of those aforementioned atoms and elements in particular, extends well beyond the evolution of our species, and even beyond the evolution of our planet and solar system. The fundamental building blocks that makeup our bodies and the diverse and beautiful planet that we depend upon, are born from the cosmos. To illustrate this interconnectedness between our existence and health, the natural world here on earth, and the vast universe, let us focus in this article on one specific element: magnesium. But before we do so, let’s give a shout-out to carbon, lithium, iron, gold and so many other elements whose multi-billion year biographies can also uniquely illustrate the connection between our present reality as resource consuming earthlings and the high-energy events that have happened during the evolution of the universe. Magnesium Magnesium is a metal with the atomic number 12, and is believed to be the 9th most prevalent element in the universe. Magnesium is the 8th most abundant element found in the earth’s crust, which is made up of approximately two percent magnesium through a range of compounds (it does not occur on its own naturally on earth). Magnesium is also the third most dissolved...