Spearfish Canyon is a deep gorge in the northern Black Hills of South Dakota, carved by Spearfish Creek and followed today by U.S. Route 14A along a former railroad grade abandoned after the 1933 flood. Formed through long geologic processes as ancient seas receded and erosion cut through softer rock, it is notable for exposed Precambrian rocks and striking layers of Deadwood Shale, Englewood Limestone, and Paha Sapa Limestone. The canyon also brings together plant communities from several regions, supporting unusual botanical diversity and wildlife including mountain goats near Bridal Veil Falls and the Black Hills’ rare Pahasapa mountain snail.