This piece is part of a special project on deep time examining what the Western U.S. was like thousands, millions and even billions of years ago, and how that history is still visible and consequential today. Read more stories from the series.
I lead tours into deep time. Specifically, I take people around downtown Seattle to explore the stone that makes up our buildings. On the corner of Second Avenue and Cherry Street is an elegant six-story structure built with two-foot-tall blocks of rough-hewn sandstone, about 44 million years old, quarried in Tenino, Washington. The building rose soon after much of downtown Seattle burned to the ground in 1889, and the jagged stone gives it a feeling of rugged permanence, certainly what the city needed after the great fire.
Nearby on Fourth Avenue, 330 million-year-old oatmeal-colored limestone from Indiana adorns a social club listed on the National Register of Historic Places. Peering through a hand lens, I can tease out a diverse array of fossil invertebrates in the stone: conical horn corals, poker-chip-like crinoid stems and pieces of bryozoans, a colonial invertebrate that resembles Rice Chex. And up the street and one block over, 1.6 billion-year-old granite from Finland clads a 44-story skyscraper; on sunny days, its jigsaw-puzzle texture of red, white, black, clear and veined crystals shines with refulgent beauty. Standing on the street, I see the shallow seas, inexorable tectonic shifts and roiling magma that produced these rocks and marvel at the persistent geological change of our 4.54 billion-year-old planet.
I first discovered deep time in the urban environment when my wife and I moved to Boston from Utah’s red-rock country. My love for all things geological had begun in Utah. Exploring its sandstone canyons solidified my bonds to the natural world, grounding me in the deep past and helping me understand what made this otherworldly landscape. In Boston, I felt disconnected; the only regional geology I knew was Plymouth Rock. But eventually, I noticed the stone in Boston’s buildings. When I realized that Harvard Hall’s sandstone, what Easterners call brownstone, was the same material as my beloved Utah red rocks — iron-stained sandstone — I reconnected with the geologic world that meant so much to me.
Then my wife and I moved back to my hometown of Seattle. In the city’s downtown, I came across a beautiful stone consisting of pink and black blobs, layers and swirls, what I imagine it would be like to mix bubble gum and brownie batter, on the side of the Exchange Building at Second Avenue and Marion Street. I recognized it as gneiss, a metamorphic rock forged by immense pressure and temperature, which often produces layers of dark and light rock. Known as Morton gneiss and quarried in Minnesota, the multihued rock looked as if it was still in motion. I was astounded to learn it was 3.52 billion years old.
Touching that ancient but easily accessible stone, I knew I was connecting with some serious deep time. I was reaching far back in our planet’s history to a time when plate tectonics, the central driver of Earth’s geology, may not have operated as it does at present. Microorganisms were the only form of life. No plants or animals; few of the colors and little of the diversity of today. This stone on the side of a building told a story of when Earth was still a youngster and the planet we know and love now was no sure thing.
This stone on the side of a building told a story of when Earth was still a youngster and the planet we know and love now was no sure thing.
Seattle is not unique. Go to any city, and you’ll likely find a similar variety of rocks — granite, marble, limestone, sandstone, slate and gneiss — rivaling any assembled by plate tectonics within such a small footprint. Generally, pure white or mottled cladding panels are made of marble, while fine-grained ones, often layered and featuring fossils that can range from the size of a pea to a cinnamon roll, are sandstone or limestone. Multihued or salt-and-pepper stone tends to be granite. Any basic guide to rocks and minerals should help you identify rock types.
We are often told that the way to find nature is to go to the wild. But nature is all around us, even in the stones of our cities, for anyone willing to slow down and pay attention. And it’s right in front of us, every day.
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This article appeared in the January 2026 print edition of the magazine with the headline “Seattle rocks.”
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