AZGS's Brian Gootee characterizes the Redwall Limestone of Grand Canyon, Arizona, in a 27-page powerpoint PDF. The cavernous Redwall Limestone 99.5% pure limestone that formed in the Mississippian about 350 Ma. Today, the Redwall is an important source of freshwater in central and northern Arizona.
https://library.azgs.arizona.edu/item/PPPP-1552427935358-657
Photographer: Brian Gootee
Photo Date: 2014