Rocks seem almost like the dictionary example of “boring.” But in 1788, some curious guys standing on a rugged Scottish shoreline saw something entirely different — a revelation that shattered the known timeline of Earth and made them physically dizzy with wonder.
In this episode, we follow those guys to one of science’s greatest discoveries — and what it has to tell us about the nature of wonder itself.
It’s I Heart Rocks, my friends. I’m Ben Lord. Let’s talk about what we love.
Every semester of the ninth grade Earth science geology unit, I would take my classes on a field trip. We’d walk to a parking lot at the west end of campus and look at a rock.
That’s it. That was the whole field trip.
This wasn’t some fancy formation with glacial potholes or colorful mineral or garnet crystals or anything. These rocks were pretty much the same ones in the roadcut that everyone drove by on their way to school. They were brown and grey. Kinda flakey.
“You’ve got five minutes,” I’d tell the students, “To write down as much as you can about what you notice and what you wonder.” They’d look at me. Then, they’d exchange silent glances with each other. Some would jot down literally a word or two on their clipboard. But after about 45 seconds, almost everyone had run out of things to say.
A few weeks before, these same kids had been exuberantly curious about space and climate and oceans. Now they were stifling yawns. Almost every semester, some kid would grumble under their breath, “Oh, god! Not rocks again! I hated doing rocks in middle school.”
Let’s face it . . . rocks are not sexy. They’re not alive. They don’t do tricks or make weird noises or explode. Most of them aren’t even colorful.
There is nothing less interesting, nothing more common . . . than a rock.
That field trip was always less of a lesson on geology. And more of a lesson on the human mind.
For the next lesson, we’re going to have to go a bit farther than the parking lot. We’re going to have to go to the southeast shore of Scotland in the spring of 1788.
Our instructor will be one, John Playfair. John was a Presbyterian minister who got distracted from his ecclesiastical calling by the intellectual excitement of the movement we now call the Enlightenment. The city of Edinburgh, was a major hub of this new thinking. where people like David Hume (the philosopher), Adam Smith (the economist guy who wrote wealth of nations), James Watt (after whom the unit of power is named) and a whole bunch of other famous dead smart guys. They regularly gathered to talk about heady new ideas about liberty, progress, reason, and science.
John was smart, friendly, and charming, and because he was so smart and friendly and charming, the philosophers and thinkers of Edinburgh had welcomed him. He was a founding member of the Royal Society of Edinburgh, a swanky and exclusive science club. And a few years later he had gotten a job as a professor of mathematics at the University.
John was 40 years old when he set out with some friends on a voyage along the Scottish coast. I have no idea of his opinion on rocks.
But I do know that he greatly admired his travelling companion, a 62-year-old gentleman farmer named James Hutton. The cruise along the Scottish coast was Hutton’s idea. And I do know that Hutton, without a doubt, was a guy who found rocks very interesting.
Hutton had spent decades poking around in any ditch, hole, or riverbed he could. And now, finally, Hutton felt he was close to an answer. He’d developed a theory, and he was determined to find something that would put his idea to the test.
So, yeah, you guessed it. They were out looking for rocks.
They landed at an outcrop that stuck out into the sea not far from the English border. A place called Siccar Point. Look up pictures of it and you’ll see that the place has kind of a rugged beauty, but that rocks that make it up don’t immediately strike one as being anything special. They’re reddish-brown. They’re hard. They’re . . . y’know . . . rocks.
I can imagine my students yawning already.
But James Hutton wasn’t yawning.
The thing about Siccar Point is that, upon closer inspection, you begin to see two sets of layers. On the top are some layers arranged horizontally. Nothing particularly surprising. But beneath them are vertical layers of rock, like looking at the pages of a book from the side.
How did the rock get that way?
The question doesn’t occur to most of us. We’re looking out at the ocean. Or checking out the cute graduate student or mentally preparing our shopping list.
If anyone of Playfair’s colleagues did inquire about the origins of the rock, the relatively straightforward answer was Noah’s Flood. Most of the rock on Earth’s surface, so the thinking went, had crystallized from dissolved minerals in the Floodwaters. If you’ve ever tried to grow crystals in a jar or make rock candy, you’ll be familiar with the idea. By one Irish bishop’s oft-cited biblical calculation, that would have occurred in the year 2348 BC, about as old as the Great Pyramids in Egypt or about 4,136 years before Hutton and Playfair set foot on the point on that June day. Since that cataclysm, the Earth had remained relatively unchanged. The mountains were immovable. The rivers stuck to their courses.
But this explanation didn’t satisfy James Hutton. As a farmer, he was eminently aware that the land was always changing. His farm fields were always losing soil to the rain. He could see it washing away into his drainage ditches, ditches he was always having to dredge. But if the soils in his fields kept washing away, as they undeniably did, then why didn’t they run out of dirt? Why hadn’t they already?
It was a question that hardly anyone else had bothered to ask. But Hutton had chased it for years. He followed where the soil washed out of his fields would go. The ditch emptied into a stream, the stream into a river, the river into the ocean. And that little bit of soil would finally settle on the ocean floor.
Many of the rocks in Scotland looked just as if the sand or mud of the ocean bottom had solidified somehow. Could it be that once, long ago, they had been under the sea, and then pushed up by some unseen force to become land again? If they were, then that might explain why his fields had not entirely washed away. If rock from below was being lifted up and gradual, oh so gradually, being crumbled back into bits of sand and mud . . . well then, that might replenish the soils of his fields.
God, in his wisdom, had designed an Earth to constantly provide what people needed. It was a beautiful idea. But the real test was whether it could do a better job of explaining the real features of real landscapes . . . and real rocks.
Rocks like the kind that you find at Siccar Point.
This was why Hutton had invited his friends on this exploration. Hutton was thinking aloud. He was practically electric with what he saw. And as he worked it out in front of his friends, they began to feel the electricity too.
If Hutton was right, then all of these layers of rock had formed on the bottom of the ocean . . . built from the pieces washed off of some ancient land . . . which would then crystalize and solidify into layers of stone. The layers on the bottom were the oldest, of course. New layers could only form on top of the old, not under them. But why were they vertical? Well, if they had been pushed up by some underground force, the slow warping and buckling of the land could have easily tilted them.
By then, they would have been above sea level again. They would have been a different land. Now exposed to the wind and rain . . . which would slowly crumble them again. And their bits would wash out to sea.
But then what of the horizontal layers on top?
That would be easy to explain if this land then sank under the ocean again. Then, the eroded tops of the vertical layers would become a new sea bottom. And they would get covered over with new layers of mud and sand washed off of some other land nearby. Which would harden into new layers of stone. Which would then get pushed up above the ocean again.
I can almost imagine Hutton, looking up from the rocks at this point to take in the whole landscape … the sea, the cliffs, the sky.
It was still going on.
Right now.
These layers under his feet were slowly, inevitably, washing back into the ocean, making what would someday become new land again.
You can almost hear him saying in his brogue, “no vestige of a beginning, no prospect of an end.”
This was one of the first times in history that anyone had ever described what we now call the rock cycle. An idea that strikes ennui in the hearts of 9th graders the world over. And if their learning about it was anything like the dry and lifeless rendering of it that I got when I was in middle school, you can hardly blame them.
But it was not so for John Playfair. The vision of absolutely staggering lengths of time, made him physically dizzy. He was utterly and wholly convinced that his friend was right. How could he not be? At this spot, it was as if the Earth had been cut open like a dissection, to show exactly how the land had been formed. And here it was rising out of the sea. This wasn’t just an idea. You could see it happening. Recalling this moment many years later, John Playfair wrote, “The mind seemed to grow giddy by looking so far into the abyss of time; and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much farther reason may sometimes go than imagination can venture to follow.”
I first stumbled upon Playfair’s account of that day in an old textbook and immediately fell in love. Even in his long-winded, late-eighteenth century sentences, you can tell that he is breathless. That he is at a loss for words. He was watching the idea of the rock cycle being born, right in front of him. His whole world but being remade, literally and figuratively all at once.
I like to think of him picking up a stone there and seeing it as if for the first time. It looked solid, but how many times had it been made and unmade? Broken to bits and reassembled.
And then I imagine him realizing the implications. How long would it take for rain and wind to break the rock in his hand into bits. A few thousand years? Maybe as long as all the history that he thought there was? But at Siccar Point, he could see it had happened over and over and over. All the history that he thought there was … was just the last moment of time.
Suddenly, those boring rocks were more than just things to walk or trip on. They were the story of time itself, on a world that was roiling with change … at a scale too grand for people to see … until now.
Every rock tells a story. And their stories are long. When you look at one. You are peering into the great abyss of time that left Playfair feeling “giddy.” We are mayflies. To the rocks, we are as insubstantial as the mist that burns off in a sunrise.
In the twenty-first century, we are so used to hearing about how vast space and time are. We are so used to hearing about billions and trillions that I suspect that we’ve lost some of the giddiness of the realization that the Earth is billions of years old. Who can really absorb those numbers anyway? Anything that ends in -illions just basically means too much to think about.
If my students fail to see this when I take them to the rock outcrop by the West parking lot, that’s not a failure of character. How many generations of people lived good lives without thinking about rocks at all, except perhaps as something to build with.
Really, if we were open to all the wonders around us all the time, we would do nothing but stand amazed.
But it is wonderful to be amazed, and I like to give my students amazement when I can. So sometimes I tell them the story of Hutton and Playfair out at that rock outcropping in the parking lot. And I hope it helps them remember two things, the way it helps me.
The first, is that “boring” is not a property of rocks. It’s not a property of any object or subject. Boring is something that we bring. Just as interest is. Meaningfulness isn’t something we find, it is something we fill the world with by paying attention. We have the capacity to find wonder everywhere, even in something like a rock. Even to be so profoundly moved by that wonder that we find ourselves “giddy at the edge of a great abyss.”
The second thing is that we don’t just have the capacity to find wonder in something like a rock. But that we have the ability to pay that wonder forward. When we stop worrying about whether what we love is cool or useful or productive, and just love it, demonstratively, expressively … we can reveal how lovely it is for others. Through our own love, we can make the familiar strange again. Just as Hutton did for Playfair. Just as Playfair did for me. Even something as familiar as a rock.
Outro
Sometimes a rock is just a rock. And sometimes, it’s a keyhole to deep time. I Heart This strives in every episode to make the familiar strange again. To pay the wonder forward. So can you. Think of someone who would appreciate this story, or your favorite I Heart This episode. And send them a link or leave a review wherever you’re listening and thanks.
I Heart This is written, edited, and produced by me, Ben Lord. Our logo was designed by Briony Morrow-Cribbs. Our website is iheartthispodcast.com. You can email me at ben@iheartthispodcast.com. Thank you so much for listening. And, as always, Be kind. Be curious, and be thankful.