, its petals splayed across a creamy, beige-brown matrix like a fossilized whisper from a warmer world.
This precious bloom was hard-earned. Covered in dust and sweat, I grinned and held this elusive beauty to the light to take in its exceptional preservation and dusty beauty!
It was day three of my travels. I was hiking the hills around the town of Princeton in the Similkameen region of southern British Columbia, Canada.
The former mining and railway hub lies at the confluence of the Tulameen into the Similkameen River, just east of the Cascade Mountains. It is dry, arid country covered by native grasslands and low scrub.
Princeton, BC is located in the traditional territories of the Nlaka’pamux and Syilx (Okanagan) peoples.
The region has historical significance for the Syilx, particularly the Upper and Lower Similkameen Indian Bands, and has been an important area for gathering red ochre for thousands of years. I had first explored the region looking for red ochre deposits to photograph, always with an eye to the local fossils.
On this particular trip, I was searching for fossils and the iconic flower, Florissantia, in the slopes known locally as Hospital Hill.
A lucky split brought a eureka moment. Is it? Could it be? Yes! Peeling back the layers, I had uncovered a near perfect flower and the treasure I had long been seeking. Searching for Florissantia had brought me to the Princeton area on many occasions but my first was found on this trip.
Under a hand lens, its details unfurl: each vein etched in silica, each contour revealed with startling fidelity.
I had uncovered a perfect flower, a time capsule telling us about the landscape as it once was, lush, tropical, and steaming with life.
This singular fossil, preserved in almost impossibly fine detail, is one of the jewels of the Princeton Chert, a fossil treasure hidden in the hills of British Columbia.
Here, an entire ancient ecosystem—plants, fungi, fish, and the delicate traces of vanished warmth—was captured in stone with such precision that cell walls, stomata, and even parasitic fungi remain visible 48 million years later.
The Princeton Chert lies tucked along the east bank of the Similkameen River, 8.5 km south of the town of Princeton, B.C. At first glance, the exposures of the Allenby Formation appear unassuming: thinly layered bands of shale, coal, and pale chert.
But within these layers, we've discovered something extraordinary—an anatomically preserved flora, fossilized in three dimensions. Unlike typical compression fossils, these organisms were permeated by silica-rich waters so quickly and so thoroughly that even their internal structures survived.
Since the 1950s, collectors and researchers have pulled back the curtain on this Eocene world, but it was in the 1970s and onward that the Chert achieved global attention. Scientists recognized that the Princeton Chert wasn’t just another fossil site.
It was a Lagerstätte of unparalleled richness—one of the few places on Earth where entire plant communities are preserved down to the microscopic level.
Thin-sectioned under a microscope, these fossils show xylem vessels, aerenchyma, reproductive organs, pollen, seeds, roots, and fungal pathogens—all exquisitely intact. Few fossil floras in the world rival this clarity.
The Princeton Chert formed in a landscape shaped by fire and water. Its 49 known chert layers, ranging from thin wafers to thick beds over half a metre, alternate with volcanic ash, coal, and shale. Each layer represents a momentary pause in time—a lake or pond basin repeatedly drowned in silica-rich waters after nearby volcanic eruptions.
Radiometric dating now places the site at 48.7 million years old, deep within the Early Eocene Ypresian Stage, a time when Earth’s climate simmered near its all-time warmest. Greenhouse gases were high, ice was nearly absent, and tropical warmth lapped into polar regions.
The Princeton Chert flora thrived in shallow lakes and quiet backwaters. Many species were fully aquatic or semi-aquatic, and the fossils show unmistakable features of plants adapted to waterlogged conditions:
- Reduced vascular tissue (because buoyant plants need little support)
- Aerenchyma—honeycombed air chambers for floatation
- Protoxylem lacunae, ringed by thick-walled cells
Many of these plants have close relatives today:
- Allenbya – a water lily
- Keratosperma – an arum with curling, sculptural leaves
- Alismataceae – water plantains
- Ethela – rush-like monocots and sedges
Seeds, fruits, and roots appear in beautiful profusion. Meanwhile, terrestrial plants—those carried in by floods or dropped by birds—are rare but present.
The chert also preserves snippets of the animals that lived alongside these aquatic gardens. In the overlying shale beds, paleontologists have recovered Amia (bowfins), Amyzon, Libotonius, and even a soft-shelled turtle—a small but telling cast of freshwater neighbours.
One of the most remarkable aspects of the Princeton Chert is its preservation of fungi. Here, we have identified:
- Tar spot fungi parasitizing Uhlia palm leaves
- Cryptodidymosphaerites princetonensis, a mycoparasite attacking the tar spot fungus
- Ectomycorrhizae—the first ever documented fossil mycorrhizal symbiosis with Pinus
In Metasequoia milleri, the Eocene ancestor of modern dawn redwood, mycorrhizal relationships appear nearly identical to those in modern forests. It is as though 50 million years have passed with hardly a change.
The Princeton Chert has attracted generations of paleobotanists, sedimentologists, and fossil enthusiasts, each drawn to its exquisite three-dimensional preservation and its window into Eocene ecosystems.
Charles William “Chuck” Basinger, a Canadian paleobotanist renowned for his work on anatomically preserved plants and early conifer evolution. His meticulous studies helped illuminate the internal structures of Princeton Chert flora at cellular resolution.
Ruth A. Stockey, a leading paleobotanist specialising in fossil conifers, seed plants, and reproductive biology, has published (along with her many grad students) extensively on the chert’s gymnosperms and angiosperms, reconstructing entire plants from roots to reproductive organs.
Together with many collaborators over the decades, these scientists have pieced together a vivid portrait of ancient wetland forests—lush, diverse, and humming with microscopic and macroscopic life.
The site is also beloved within the fossil-collecting community. The Vancouver Paleontological Society (VanPS) has organized field trips here for decades.
Many members remember their first visit: crouched on a hot summer slope, poking about the roadcuts, collecting fossil insects and plants. One of the first large scale field trips to the region by the VanPS was part of the first BCPA Symposium held in 1998 at the University of British Columbia in Vancouver.
Smaller field trips became a regular occurrence, usually one every year or two, and that trend continues. The result of all that exploration is a greater understanding of the many fossil species to be found here.
Dan Bowden of the VanPS has done some wonderful work cataloguing the many fossils found here, with a particularly good eye in identifying the fossil insects.
These excursions have helped train new generations of citizen scientists, fostering a deep respect for the site’s scientific importance.
If you plan to head to Princeton, be sure to include the Princeton & District Museum on your travels. The museum holds a good selection of the local fossils. It is located at 167 Vermillion Avenue, Princeton, BC, V0X 1W0. You can confirm their house on their website at princetonmuseum.org
Know Before You Go: Exploring the Fossil Lakes of British Columbia
Getting There from Vancouver
- Drive east on Highway 1 through Hope, then continue along Highway 3 (the Crowsnest Highway). The town of Hope offers a good place to stop for a meal and gas up your vehicle.
- Pass through Manning Park and descend into the Similkameen Valley toward Princeton.
- The Princeton Chert itself is on private and protected land; access requires permission and often participation in sanctioned society trips.
- Surface collecting yields a wonderful assortment of fossils.
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