Porphyry Peak and Castle Rock (left) prominently exhibit the wild colors sometimes found in the Challis volcanics.
This is a small, scenic, and little-visited roadless area at the north end of the White Knob Mountains. Unlike the high core of the range, the northern White Knobs are a big pile of Challis volcanics, dating from the Eocene.
Porphyry Peak in the photo is just over 10,000 feet. The area has very little timber, but beautiful rock formations. There are also many spring-fed creeks surrounded by bright green corridors of aspen and willow, ideal deer and elk country, but there is too much livestock.