A vein of shale in Yoho National Park in the Canadian Rockies, in British Columbia, Canada. The site is a lagerstätte, rich in Cambrian period fossils, especially trilobites. Discovered and catalogued by Charles Walcott of the Smithsonian Institute in 1909. It's thought that a mudslide buried many of the soft-bodied fossils on the seabed, which many millions of years later was forced up into the high Rockies.
In addition to the trilobite, the site has many sponges and other soft forms. It also contains claws from Anomalocaris, thought for many years to be a creature in itself, and only later identified as the claw of a larger lifeform.
The site has been declared a UNESCO World Heritage Site.