Burgess Shale

The Burgess Shale is a fossil-bearing deposit of black shale exposed in the Canadian Rockies of British Columbia, dating to the middle Cambrian period, roughly 505 million years ago, in the Miaolingian stage. The unit reaches about 161 meters thick and correlates with the associated Stephen Formation, a collection of slightly calcareous dark mudstones. It crops out near Field, British Columbia, within Yoho National Park close to Kicking Horse Pass, with a second outcrop in Kootenay National Park 42 kilometers to the south and a significant additional site discovered in 2012. The Burgess Shale is famous for the exceptional preservation of the soft parts of its fossils, ranking among the earliest fossil beds anywhere to preserve soft-tissue imprints; its organisms are thought to have been rapidly entombed by sediment-laden water currents before decay could destroy them. Paleontologist Charles Walcott discovered the site on August 30, 1909, and went on to collect more than 65,000 specimens through excavations that continued into the 1920s. This entity documents the Burgess Shale specifically as a geological formation, a Cambrian marine shale deposit renowned as a Konservat-Lagerstatte.