Science Friday - How To Tap Into The Hidden Histories Of Rocks

Episode Date: December 1, 2025

When we try to commune with nature, many of us turn toward the living: a walk in the woods among swaying trees, chirping birds, blooming flowers.But earth scientist Anjana Khatwa says not to overlook the inanimate—don’t sleep on rocks. She joins Host Flora Lichtman to talk about her love for rocks beyond the scientific and her new book, The Whispers of Rock.Read an excerpt from The Whispers of Rock: The Stories That Stone Tells about Our World and Our Lives.Guest: Dr. Anjana Khatwa is a geologist and author of The Whispers of Rock: The Stories That Stone Tells about Our World and Our Lives.Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Hey, before we get started, if Science Friday is important to you, it is a great time to support the show. In honor of giving Tuesday, we have a dollar-for-dollar match going on. So whatever you give will be doubled. We count on listener support to make this show and to keep Science Friday free for everyone. So if you can, please head to Science Friday.com slash donate to make a gift. Hey, I'm Flora Lickman, and you're listening to Science Friday. When we commune with nature, I think most of us turn towards the living. A walk in the woods with big trees, chirping birds, blooming flowers, humming insects. But my next guest says, don't overlook the inanimate.

Don't sleep on rocks. Dr. Angina Kotwa is an earth scientist, but her love for rocks isn't just scientific. It's spiritual, poetic, and lyrical, which she writes about in her new book, The Whispers of Rock, the stories that Stone tells about our world and our lives. Angina, welcome to Science Friday. Oh, thank you for having me, Flora. I'm so excited to talk to you today to learn all the things that I, you know, have been overlooking about rocks.

Where did this love story begin for you? Oh, it began as long time ago when I was about 13 years old. I was a teenager and my parents are from Nairobi in Kenya. And whilst on a holiday there, we stopped off at this course. incredible place called the Shetani Lava Flows, which is now in the Sarvo West National Park in southeast in Kenya. And I grew up in a town just on the outskirts of London, a place called Slough. And it's not a place where you tend to go to see nature. Let's just say that. It's very, very urban. And walking across this incredible African savannah, it was covered in

this jagged black rock. And when I was walking across these rocks, I didn't really understand why they were there, why they looked the way they did. But I knew that they had an incredible story to tell. Now, the interpretation signs said they were lava flows. And of course, my imagination ran riot. And I could imagine seas of lava, you know, churning over this landscape. And as I walked over those rocks, they spoke to me. And on that day, my parents took a photo of all of us, you know, kind of standing by the obligatory tourist sign. But also, I picked up a rock and here it is. And And it's a piece of basalt. You still have it.

I still have it. And, you know, I think about, you know, the passage of time, passage of deep time, obviously. But my own life, it's all recorded in this moment that I picked this rock up. I was 13. And I made a decision. I thought, oh, this is what I want to do. I want to tell stories about rocks. This is what I want to do as a job.

And now I'm 50. I've written a book about it. So it's quite a journey. You did it. You did it. I mean, you know, the thing that I love about that story is that most people go to Kenya to see these charismatic megafauna, the amazing animals. And your takeaway from Kenya was a rock. Yeah, I've heard that a lot.

When I went back two years ago as part of the research for the book, I went back to that place where I picked up this rock. And that was one of the key conversations I had with some of the wildlife rangers I went with. You're not here to see the elephants or any of the other wildlife. I said, no, no, no, no, I want to see these rocks. They were very, very puzzled. That's generally the reaction that I get. So how did you go from a 13-year-old who had this experience to doing what you do now? What was that journey like? It was tough. I'm not going to lie. I kind of grew up in a traditional South Asian culture in the UK that where my parents just felt maybe I should choose a sensible career, like working in a bank or becoming a lawyer or a doctor. And as soon as I said, you know, actually,

this is what I want to study. I want to study rocks. I want to study the creation of our earth. They were very, very puzzled. There's a movie like Bend It Like Beckham, you know, where that young Asian girl says, you know, I want to be a footballer. And the parents say to her, who's going to want to marry a girl that, you know, wants to kick a football all day? These are the kind of conversations I had with my parents. So I kind of went on to university nonetheless to study a degree in Earth Sciences and then a PhD at the University of Southampton. Wait, pause for a second. Because that's actually quite difficult. If you're hearing your family or community say, why would you do this to say, well, I still am going to do it, whether you think that's a good idea or not. How did you make that decision?

Sort of how did you get through that period? That was probably the toughest part because caused a rift in my family between me and my parents. And that rift went on for a couple of years. And I had to make a decision. I thought, well, this is actually what I want to do. This is where my heart is calling me. And my dad in particular didn't quite understand it. My mum was sympathetic. But I needed a few years away from that kind of debate about who I wanted to be. And those few years away when I was studying my PhD, they allowed me to become the woman that I was, you know, strong, stubborn, you know, very hard-headed about what I wanted to achieve. Now, of course, they're couldn't be prouder. They're so delighted with what I've done.

That's amazing. Well, transmit some of that passion to me. What do you think most people just don't get about rocks? I think rocks, they look at objects like this and they'll walk past them every day and they won't talk to you. They won't sing a song. They won't even move for the most part because they take hundreds, if not millions of years to actually change and shape themselves, if you like. And I'm going to hold one in my hand. It's a green-colored rock. and the mineral that makes it green is a mineral called chloride. It's quite hard. And on the surface of the rock, there are these chevron-type ripples that kind of run across the rock.

There are layers. And the chevron zigzag kind of texture is because this rock marks a moment when a mountain was born. And it's called a green schist. And a green schist is a rock that's formed under intense heat and pressure. The moment it was born was when two continents began to move towards each other and collide. And in between them was an ocean called the Ayapitus Ocean. At the bottom of that ocean were some muddy sediments like silts and clays. And those two continents, and this is North America where you are, and me, well, I say Baltica,

but that kind of continent which became Scandinavia in northern Europe, those two continents were very gradually moving towards each other. they closed that ocean and the sediments at that bottom of the ocean were squashed and moved upwards to create an incredible range of mountains. Now that heat and pressure changed those muddy sediments into this rock. And so when I'm looking at these kind of beautiful chevron zigzag texture in the rock, that's the moment when that mountain was born. And I think it's when you recognize that those are the stories that the rocks hold inside them. If we can unlock them, it just gives you this immense sense of gravity of the time that passes, the immense sense of planetary processes that

creates our earth. I find it awesome, actually. It is awesome. I mean, hearing you talk about it, I have that same feeling of awe and wonder that I feel when we talk about outer space or the universe, you know, the cosmos, but it's our own planet, which makes it sort of even more special somehow. It does. And I mean, you can contrast it with this rock. So this one is a piece of siltstone from Bozcastle in Cornwall. And what you can see in this rock, it's very grey and it's interleaved with kind of brown layers. It's very, very finely laminated. It's almost like a ream of papers that have been stacked up. It looks like puff pastry, like brown, like black puff pastry. Yeah, yeah, exactly. And in contrast to the other rock that signifies immense planetary power, continents crashing together, in my hand, they signifies silence and solitude.

Because what this rock is, it's a rock that signifies that moment when silts and clays, which are so tiny, tiny, tiny grains of sediments, they're settling on the bottom of a seafloor and it's utterly quiet and they're able to settle in such undisturbed conditions. they're able to build very, very fine layers, and those layers have eventually become this rock. So it is, it's like holding silence in my hands. We've got to take a quick break, but don't go anywhere. We have got lots more when we come back. Hi, it's Ira Flato. The SciFri Book Club's December pick

is the biggest ideas in the universe by Sean M. Carroll, and we're bringing those ideas to life with a special live event. So if you're in New York City, Join Sean and me at the Green Space on Friday, December 5th. We'll also be streaming it live for free so everyone can be part of the fun. Sign up for the SciFribe Book Club now at ScienceFriiday.com slash book club. Okay, you travel the world for this book. Tell me one of your favorite trips.

One of my favorite trips was to Petra Archaeological Site in Jordan. I think that's on a bucket list for any. geologist or anybody that's interested in how people have lived in very challenging environments like deserts. Now, Petra was incredibly special because the rocks there are probably some of the most beautiful rocks I've seen in my life, actually. They are the colours of the rainbow. They're pink, orange, yellow, turquoise. And it was special for me because I could witness how the ancient Nabatians had survived in quite a harsh landscape, but also had. they had harnessed the way nature had carved a niche into the rocks so they could live and

survive and prosper in that region. I just thought it was one of the most extraordinary places I'd ever been. What did it feel like to be there? It felt magical because when I place my hands on the rocks, I'm feeling, I'm listening to their stories. And when I look at those beautiful, arqueath bands of sandstone with all the amazing colors, I can sense that it's a river literally dancing over a plane carrying in the waters grains of sand that eventually come to rest on a riverbed or on a riffle or on a bank. And so sand grains collect, they cement together over time and they form a sandstone. And then much later, mineral-rich groundwaters filter through that rock, staining the cement, creating the beautiful spectacle that we can see in Petra. And all of this

is something that I feel implicitly when I was in that environment. You spoke with many indigenous leaders about their tribal histories with rocks. What did you learn? I learned that science sits in a space that needs to reflect and understand and be tolerant of different belief systems. I realize that we need to come to a place of equity in how we tell stories about. about the way the world was created. And the more I kind of delved into the origin stories that I had the privilege to retell in this book,

the more I understood how our understanding of the scientific creation of the world is very much built upon indigenous stories and myths and legends and folklore because actually their understanding of natural processes and change over time can be charted back 10, 20, 30, thousand years. And it's this building of human experience and observation upon our scientific research and understanding that makes our appreciation of how the world has come to be so much richer.

You also write about a granite peak in Yosemite, Haphton, as some of us know it. Tell us that story. That's perhaps one of the most magical stories that captured my heart. Halfdome, as it's known in, the Awenichi language, Miwuk First Nations. She's known as Tiseac, and the story goes as follows because the Awenichi people were living in Yosemite Valley for perhaps about 6,000 years before the white settlers came. And the story is that a man and a woman were traveling through Yosemite Valley and they were hungry and thirsty and tired. The man was walking with a stick and his wife was carrying a heavy basket. And as a woman reached a lake, she drank the lake dry because she was so thirsty. And when our husband arrived, he was angry because

she'd left him no water to quench his own thirst. He was so angry he reached for his stick to strike her. And she was terrified and she ran away with tears streaming down her face. And in her own anger, she threw her basket at him. Now, the great spirit that was watching all of this debacle unfold, he became quite angered. And so he turned the both of them into stone. The man became Washington tower, which is on one side of Yosemite Valley. And the woman, Tseic, was turned into what we call half dome, this incredible granitic peak that is one of probably, I think, the most iconic features in Yosemite National Park. Now, the reason why this is such a spectacular and moving story is that even after 6,000 years, we can still feel a sense of gravitous and emotion when we look at

to say that because you can still see the streaks of her tears lining the face of the granite. Now, scientists know the streaks, these black streaks on the grey rock as lichen. The fact that this story is still told in Muwak First Nations communities gives us some indication as to how slowly the rock weathers and changes. And for me, it kind of helps us to view landscapes like this through a completely different lens because as you and I probably know, Halfdome is quite an achievement for climbers that wish to scale it. But through First Nations eyes,

we see it as a monument to regret and sadness and essentially to be kind to each other. Was Haftome forged in a moment of geologic passion? I mean, is there some continuity there? I think there is. I think Halfdome was formed because of a... plume of magma rising upwards due to the formation of the Sierra Nevada. So here you have the Farallon plate, which is an oceanic crust, subducting, so it's sinking beneath the North American

plate. And as it does so, there are big plumes of magma that rise up and intrude into the crust above. Now, they don't achieve their destiny, which is erupting through a volcanic eruption. They get trapped within the crust. And they take perhaps two to three million years to cool down these magma. plumes and over that time they they crystallize and they form granite and I think what that teaches us in especially in reference to the story of Taseac is patience to remain calm underneath all conditions to basically you know wait and see what transpires if we can control and hold on to our emotions beautiful things will happen easier said than done easiest and then done. You have an emotional connection with rocks so you can hear it in your

in your voice. Have you faced pushback from, you know, the capital S scientific community for that? Yes, I have. I think some people have called me romantic and I think you can make of that what you will because I think that in itself has lots and different meanings, whether they look at me as a woman and think I'm less of a scientist because I bring emotion into the work that I do. But I think to counter that narrative, the most important lesson of the book is that through fostering a sense of love, we can perhaps rekindle that sense of custodianship and care and ethical thinking that we need to build into our science. Because one of the key things I've been told time and time again is that the book is challenging. It's challenging because of some of the concepts it

discovers and reveals to the reader, but it's also very challenging in the sense that it's putting feelings, feelings of love that I don't think scientists talk about too much. It puts that up front and centre. And I think it does take courage to do that. But what I'm hearing is that I think people are pleased that I've done that, that I've been one of the first people to step forward and say, I love this. I genuinely am saying it with my chest. I love rocks and I want other people to see that joy in the same way that I do. Do you think you got that courage from your, you know, from your own personal journey where you had to figure out what you believed in and stand up for it? And do you think you put that in your backpack for this moment too?

Yes. I think my whole background of having to challenge obstacles to having to prove myself, not just as a woman, but as a woman of color in the science, I think it makes you slightly risk taking, you know, I have nothing to lose. I really do want everybody around me to see rocks as a vivid, as an animate and exciting part of the natural world as much as the trees and the wildlife and the rivers. And I think by saying that with my full chest, with my full heart, I think that's how you win people over because that honesty and that force of feeling, people can't ignore it. But all of the hardships I've had to go through have strengthened me to do that. Dr. Angina Katwa, Earth scientist and the author of the new book, The Whispers of Rock, the stories that Stone tells

about our world and our lives. Thanks for joining me today. Oh, thank you for having me, Flora. It's been an absolute joy. Likewise. Today's episode was produced by Shoshana Bucksbaum. I'm Flora Lichtman. Thanks for listening.