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

Investment in science is a pillar for any dynamic, equitable modern society, and promoting scientific literacy across all levels of society can help foster innovation, dialogue, and consensus that crosses disciplinary and cultural boundaries. Science also helps to uncover answers to foundational questions that have captivated, confounded, and divided our species for millennia. But what is “science,” and what kind of “evidence” ensures that an approach is scientific? If we take “science” to broadly mean, in its purest sense, a “dynamic search for the truth,” or more explicitly, “the pursuit and application of knowledge and understanding of the natural and social world following a systematic methodology based on evidence,” as the Science Council aptly defines it, then science extends beyond the established, highly specialized disciplines of reductionist natural sciences (physics, chemistry, biology, geoscience, and space science) that have been so successful in fostering our understanding of our planet and the cosmos. Under this definition, science also includes the rigorous data-driven (qualitative and quantitative) social sciences, the inherently non-reductionist “holistic” sciences such as ecological and Earth system sciences, and the budding interdisciplinary field of complex systems science, as well as robust traditional knowledge systems based on multi-generational experiences, observations, and reasoning. As with science, “evidence” can mean a lot of things as well, including primary research, pre-existing data, past and planned experiments, and the referencing of peer-reviewed publications and primary sources. It can also include local and traditional knowledge, thought experiments, theoretical proofs, contemplation, verifiable personal experience, and empirical observation. Broadening and weaving together these forms of scientific evidence holds the potential to address complex, interconnected global challenges and explain deep mysteries that could help unify our polarized societies around foundational understandings. Foundational Questions Foundational questions can transcend the divides of generations and cultures: Cosmology, physics, and evolutionary biology have shed...

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...

Marcelino Sánchez Noé is an Indigenous leader and representative of the Ticuna People from the Colombian Amazon. He is the former general secretary and legal representative of the CIMTAR (Cabildo Indígena Mayor de Tarapacá) Association and has served as an Ethnoeducator in the Indigenous community of Caña Brava along the Cotuhue River, where he currently resides. This beautiful territory is deep in the Amazon Rainforest within the Putumayo River Basin, and near the border with Brazil. Since 2021 he has served as a senior advisor of the Greater Indigenous Council of Tarapacá and has participated in various intercultural collaborations with the Colombian State and with non-governmental organizations. His professional background is as a teacher and technician in comprehensive early childhood care, with a degree from SENA. In our Interdialogue we spoke about the beautiful culture and ancestral territory of the Tikuna, and how they have recently been roped into Colombia’s ongoing conflict, especially in relation to illegal gold mining. We then spoke about the central role of the “Chagra” (traditional rotational agriculture) for the Ticuna, and how circular bioeconomics focused on the Chagra and Non-timber forest products, as well as an appropriate integration of Western science and technology, can create sustainable livelihoods for the Ticuna. We also focused our conversation on the vital importance of autonomy and mutually respectful intercultural dialogue and collaborations, in order preserve both traditional cultures and the wider Andes-Amazon ecoregion. Note: This Interdialogue was recorded in Spanish and is subtitled in English. Timestamps 00:00:00 – Introduction 00:07:41 – Ancestral territory of the Ticuna and its place in Colombia’s ongoing conflict 00:11:53 – The importance of traditional knowledge, language and autonomous governance 00:16:52 – Bioeconomics, sustainable livelihoods and the central role of the “Chagra” 00:24:17 – Water, energy, communication, and the importance of weaving together science, technology...