The Pinnacles, located adjacent to Crater Lake, were formed 7,700 years ago when the eruptions of Mt. Mazama reached their climax. Torrents of red-hot gas-charged pumice poured down the sides of Mazama’s slopes at speeds of over 100 mph. On top of this came a heavier layer of rock called scoria. Plumes of vapors appeared as gasses escaped from the settling rocks through fumaroles. Minerals in the gases combined with the extreme heat welded the sides of the fumaroles in the shape of slender cones. Over the years as the streams eroded the canyon and upper layers of rock, these cones, aka “pinnacles” were exposed.
Posted by: danielfee | September 10, 2013