Exposures of the Great Unconformity in Garden Canyon occur in the Tapeats narrows, about four-tenths of a mile below the junction of the Bright Angel Trail and Tonto Trail; the unconformity here is characterized by well-weathered crystalline basement overhung by more resistant Tapeats Sandstone (A), the contact itself exhibits broken up fragments of granitic rock in a matrix of coarse, quartz-rich sand (B).