Granite Rock Formations Near Sylvan Lake, Custer State Park

Sylvan Lake sits in the Black Hills of Custer State Park, South Dakota, at an elevation of roughly 6,145 feet. The granite spires and boulders surrounding the lake are part of the Harney Peak granite formation, among the oldest exposed rock in the region at nearly 1.7 billion years old. A trail from the lake's shore climbs through these formations toward Black Elk Peak, the highest point in South Dakota at 7,244 feet and the highest peak east of the Rockies. The lake itself was created in 1881 when a dam was built across Sunday Gulch Creek, originally to power a nearby mill.

Photo taken in July 2019.