A scenic landscape view across the Blue Mesa Reservoir to the Dillion Pinnacles, Gunnison County, Colorado. Geologist believe the the story began about 65 million years ago when the surrounding landscape was slowly uplifted to form the Gunnison uplift and the Sawatch Range. The origin of the pinnacles began about 30-35 million years ago during a period of considerable volcanic activity. Repeated eruptions built up mountainous piles of debris to form West Elk Mountain and San Juan Mountains to the south. Lava, mud flows and rocks from exploding volcanic cones began to for the breccia that makes up the Dillion Pinnacles.