Mount Stephen Trilobite Beds

Mount Stephen Trilobite Beds is a protected fossil locality on the mountain above Field, known for unusually rich Cambrian shale. It’s a specialized, strenuous outing for people who want to study fossils in the rock where they were found, not a quick roadside stop. A guide is required; independent access isn’t allowed. If you’re after an easy walk or a scenic drive stop, choose somewhere else.

Meet at the Yoho National Park Visitor Centre in Field at the time on your confirmed booking. Plan on about 800 metres of climbing over steep, uneven ground. Published estimates differ: 8 or 10 kilometres return and roughly 7 to 7.5 hours. Use the itinerary your booking confirms. Sections can be slippery when wet, and the descent can be hard on knees and ankles. Field itself sits at 1,280 metres, so give yourself time to acclimatize before taking on the climb.

The fossil-bearing slabs formed in a shallow sea more than 500 million years ago, then ended up high on the mountain. Burgess Shale fossils can preserve fine details that usually disappear, including eyes, brains and internal organs. At Mount Stephen, look for several trilobite species alongside sponges, brachiopods and appendages of Anomalocaris canadensis. A close photo that includes both the fossil and its surrounding shale shows why the rock matters as much as the specimen.

Railway workers reported “stone bugs” in talus on Mount Stephen in 1886. Those finds led researchers to a site rich in Cambrian marine life. Mount Stephen has species that don’t occur at nearby Walcott Quarry, so this is its own chapter of the Burgess Shale story.