Here I was trying to focus on the beautiful and colorful lines left on the rock as the glacier grinded away at it.
This is part of the Helena formation (the major carbonate formation of the Precambrian Belt Supergroup "sounds like the GC") which consists of medium to dark gray dolostone and limestone, often covered with honey-colored weathering rind. This also shows the Spokane Formation "Ys"(Belt Supergroup, Middle Proterozoic). This is how I found the Spokane Formation described: Siltite and argillite, pale red and moderate reddish brown, weathers moderate reddish brown, grayish red, and dusky red; laminated and very thin bedded, cross-laminated, locally ripple cross-laminated; dominantly silt and clay on partings surfaces; locally common ripup clasts and fluid escape structures; scattered lenses of fine-grained quartz sandstone as thick as 6 cm; beds of sandy limestone and rare stromatolitic limestone 20½-35 cm thick inter-bedded with greenish-gray siltite in basal 45 m.
This is at the head of the lake on the east flank of Gunsight Mtn.