13 February 2015
Pygmatic folds in the Precambrian Irving Formation. I think this is 1.7 Ga deformation, late in the Yavapai orogeny, which added various arcs in Colorado to North America. Good place to think about strain ellipses in progressive deformation.
Zooming in on the best part, and dialing up the contrast a bit:
Seriously strained rocks. What fun!