Mississippian-age (340 Ma) cliff face of Redwall Limestone exposed near the Bright Angel Trail in Grand Canyon. For an excellent overview of the composition and conditions under which the Redwall formed, see Brian Gootee's 'The Redwall Limestone' https://library.azgs.arizona.edu/item/PPPP-1552427935358-657.
Photographer: Dale Nations
Photo Date: circa 1990