The Burgess Shale Formation — located in the Canadian Rockies of British Columbia — is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils. It is 505 million years (Middle Cambrian) old, one of the earliest soft-parts fossil beds. The rock unit is a black shale, and crops out at a number of localities near the town of Field in the Yoho National Park.