18.3 Top of Big Horn Mountain Range. 38.2 Precambrian granite gneiss. Gneiss is a coarse-grained metamorphic rock that forms as a result of regional metamorphism. It usually shows a high degree of recrystallization of minerals and occasionally signs of melting. The characteristic most useful in identifying a gneiss is banding .
Bands are the result of different minerals that form alternating layers in the rock.
This rock is called granite gneiss because it has a composition similar to the igneous rock granite. Gallatin Formation 53.5 Big Horn Formation and view down Wind River canyon. 56.0 Madison Formation. 58.2 Tensleep Formation. 62.5 Downtown Tensleep.