Buttress Unconformity | Maricopa County | One can observe this buttress unconformity at Roosevelt Dam, east of Phoenix.
From AGS Field Trip Guide Nov 18, 2000: A 90-foot-deep channel was incised into Troy Quartzite, Mescal Limestone, and basalt. The channel fill includes a ferruginous sandstone, overlain by very poorly sorted feldspathic sandstone. (photo by Esty Pape)
