Yellowstone’s Stories Are Written in It’s Stone

Blog by YW Lead Naturalist Laura L. Featured image courtesy of Rob Harwood.

We are all Earthlings, fellow passengers on a living planet spinning through the vastness of space. The Earth remembers its story in stone. Rocks hold the record of upheaval and renewal, of oceans that came and went, of creatures long gone and others still with us today. When we learn to listen, the land reminds us of who we are and where we’ve come from—a lineage stretching back billions of years.

Few places today share a more compelling story than Yellowstone. This land has been crushed and stretched, carved by glaciers and flooded by ancient water, fractured and remade by fire. To walk here is to step outside the rush of everyday life and into a place where time itself seems to move differently. Yellowstone invites us to set down our digital devices for a moment and reconnect with something enduring, something solid. After all, nothing is more grounded, more “analog,” than stone.

Reading the stories in the stone doesn’t require a degree in geology. It only asks for your curiosity, and a shift in perspective: to see time not as a clock ticking forward but as a vessel carrying us both back to the past and grounding us in the present. In Yellowstone, there are countless places to slip into this current. Two of them reveal the scale and wonder of deep time in ways that can leave us breathless.

The travertine terraces at Mammoth Hot Springs. Photo courtesy of NPS Archives – Yellowstone.

Near the North Entrance of the park, Mammoth Hot Springs,  mountain of travertine, is built of a type of marine limestone formed from an ancient ocean —a calm, shallow sea that ebbed and flowed over tens of millions of years, layering itself like a cake. Eventually, tectonic forces dragged those layers down to great depths and pressurized the sediments.  Today, these reinvented life forms build terraces in the form of calcium carbonate, where hot water flows and promotes the life of cyanobacteria that have been alive and thriving on our Earth for over two billion years. It is this cyanobacteria, a three dimensional, vibrantly colored “goo”, that we have to thank for the oxygen in our atmosphere.

The Mammoth Hot Springs Terraces are formed from ancient marine sea beds compressed over time and redeposited as travertine as a result of hydrothermal alteration. Photo by Laura L

This seemingly innocuous goo uses sunlight for energy and produces oxygen as a byproduct. Without an oxygen-rich atmosphere, fire would not be possible, and our vivid blue sky would appear a muted, hazy red color. There would be no plants, no animals, no us. 

This textured “goo” is a living mat of bacteria photosynthesizes sunlight, generating oxygen as a byproduct. Photo by Emil M.

Moving further to east, we enter wide-open valleys known as Little America and Lamar, where we begin to see thousands of  glacial erratics (coming from the Latin word ‘errare’ meaning ‘to wander’) strewn about. Huge boulders, transported hundreds of miles from the Beartooth Mountains northeast of the park, were plucked up and transported as if on a conveyor belt as glaciers up to a mile thick  began to recede thousands of years ago. Imagine the tale of this epic relocation as told from the point of view of these stony travelers: 

Notice the trees tucked up next to these glacial erratics. These boulders allow water to collect in shade pockets inviting trees to take root in otherwise inhospitable conditions.

“I was born in fire, deep beneath the Earth’s crust, pressed for millions of years under immense weight. Then tectonic forces stirred, lifting me toward the sky. Slowly, steadily, I rose into a world of howling winds and crackling lightning, where snow buried me and rain beat me down. Then came the glacier—a slow, grinding behemoth. It did not rush. It carried me gently, locked in ice and silence. Years passed. Centuries. Perhaps millennia. The ice crept ever so slowly, groaning and reshaping the land beneath it, until at last it set me down in my new home.And here I sit for you today: a boulder among the sage, far from the mountain kin I once knew. Bison wander past, calves bawling for their mothers. Children climb over me, families rest in my shade. Place your hand upon me, and you may feel the weight of my age, the memory of fire, storm, and ice. My story is written in stone—and in it, Yellowstone remembers”

Enormous glacial erratic in Yellowstone’s Northern Range. Photo by Rob Harwood

To read Yellowstone’s rocks is to read the Earth’s autobiography. This land is so much more than the dirt and stone seen with a quick glance. It is memory, resilience, and wonder, pressed into form. It asks us not just to witness, but to listen. And in listening, perhaps we begin to hear our own story too, written into the same long arc of time. What will you hear? And what story will you tell?

Glacial erratics dot Yellowstone’s Lamar Valley, Little America, and Northern Range as evidence of the parks complex geologic story. Photo by Rob Harwood

Blog written by YW Lead Naturalist Laura L.

To learn more about Laura and the rest of the Yellowstone Wild team visit our “About Us” webpage.