A NONCONFORMITY exists when sedimentary rocks rest directly on top of crystalline igneous or high grade metamorphic rocks. The geological implication of such an unconformity is that many years of erosion have exposed the crystalline rocks. (The crystalline rocks must have been formed deep beneath the surface of the Earth.) One eroded the crystalline rocks were then buried beneath layers of sediments. The exposure of the nonconformity then typically represents another episode of uplift and erosion.
This particular nonconformity can easily be seen from State Route 87 near milepost 258 north of Payson Arizona.
This pair of images shows the nonconformity as it is exposed naturally.
The right image shows the nonconformable surface that exists between the
Cambrian Tapeats sandstone and the Precambrian granite below.
This pair of images is of a road cut only a few hundred feet from the above pair
of images.
Road cut close up
Closer view Notice the spheroidal weathering in the granite.