Must have been some incredible undergound activity on this Pinto Gneiss.

The banded and folded Pinto gneiss, approximately 1.7 billion years old, is most likely the oldest type of rock in the park. Gneiss, a metamorphic rock, has undergone change in mineral composition, grain size and orientation due to increases in pressure, heat and chemical activity. Gneiss, prior to its change, was a sedimentary rock. With directed pressure, mineral grains segregate and band together; this alternate banding of light and dark minerals is what defines a gneiss.